Economic and environmental rehabilitation through soil and water conservation, the case of Tigray in northern Ethiopia

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Journal of Arid Environments journal homepage: www.elsevier.com/locate/jaridenv

Economic and environmental rehabilitation through soil and water conservation, the case of Tigray in northern Ethiopia Gebremedhin Gebremeskela,∗, T.G. Gebremicaela,b, Abbadi Girmaya a b

Tigray Agricultural Research Institute, P. O. Box 492, Mekelle, Ethiopia UNESCO-IHE Institute for Water Education, P.O. Box 3015, Delft, The Netherlands

A R T I C L E I N F O

A B S T R A C T

Keywords: Environmental rehabilitation Integrated catchment management Soil and water conservation Tigray

The natural resources in the semi-arid area of Tigray, northern Ethiopia, have been exploited for years. This has caused severe land degradation, which in turn led to recurrent drought and poverty. To recover the degraded lands, soil and water conservation (SWC) interventions were given a policy attention since the 1970s. Starting 1990s, SWC-based integrated catchment management (ICM) implementation programmes, complemented by conservation-based agricultural development strategy, have been implemented. Many studies on ICM interventions and associated benefits have been reported so far. However, as most of the studies were conducted on experimental plots/small catchment scale, none of them have attempted to report the achievements and lessons at large scale. Hence, a comprehensive review is needed to explore and publicize the interventions and associated benefits. This review was conducted through detailed analysis of evidence and facts from literature, field observations and farmers’ perceptions. The reviewed literature explicitly showed that ICM interventions have been successful in Tigray. Collective evidence has shown that most of the degraded landscapes are considerably restored, of which the soil fertility, availability of water, and rainfed and irrigated crop productivity have significantly increased over the last two decades. Consequently, environmental, ecological and socio-economic changes have been observed when compared to pre-implementation of ICM. Despite these achievements, some interventions often suffer from over-ambition, upward accountability and a top-down approach. Failures of Horeye and roof water harvesting, mismanagement of fertilisers, low survival of tree seedlings and lack of income from exclosures can be considered pitfalls that may affect the sustainability of the achievements. An important lesson drawn from Tigray is the participation of all stakeholders and the strong commitment and sense of ownership by the people and local government, which many projects lack worldwide. Observed experiences, achievements and implementation pitfalls can provide a lesson to other regions with similar agro-ecological, environmental and socio-economic setups.

1. Introduction Because of the unwise use of land and water resources, the quality and quantity of different landscapes have been degraded globally (Darghouth et al., 2008). For restoring the degraded landscapes, soil and water conservation (SWC) intervention plays an inevitable role (Pimentel, 1993). SWC intervention has the capacity to sustainably maintain environmental and ecological services if properly implemented (Nyssen et al., 2015). Moreover, SWC interventions can improve livelihoods and societal developments (Hurni et al., 2015). To this effect, SWC interventions have been successfully implemented in various forms across the world. Degraded lands have been converted into well-established environmental and economic achievements throughout the world (Cooper

∗

et al., 2008; Brooks and Eckman, 2000; Hurni et al., 2015). Examples are the Loess Plateau and the Three Gorge Area in China (Zhao et al., 2013; Zhang et al., 2015; Shi et al., 2004); Mayurakshi, Salaiyur and Adarsha Watersheds in India (Chowdary et al., 2009; Sikka et al., 2002; Wani et al., 2003); Sepetiba Bay watershed in Brazil (Neto et al., 2006); Anyangcheon watershed in Korea (Lee and Chung, 2007; Lee et al., 2008); Lam Sonthi watershed in Thailand (Phomcha et al., 2011); Kiroka village in Tanzania (Cooper et al., 2008); Merguellil catchment in Tunisia (Lacombe et al., 2008); Machakos district in Kenya (Tiffen and Mortimore, 1994; Cooper et al., 2008; FAO, 2014); and Enabereid, Abraha Atsbaha, Haro, Maybar and Debre Mawi catchments in Ethiopia (Haregeweyn et al., 2012; Cooper et al., 2008; Tesfaye et al., 2016). These studies showed that SWC has been employed to mitigate land degradation. However, despite substantial efforts to reverse the

Corresponding author. E-mail address: [email protected] (G. Gebremeskel).

https://doi.org/10.1016/j.jaridenv.2017.12.002 Received 20 June 2016; Received in revised form 13 June 2017; Accepted 5 December 2017 0140-1963/ © 2017 Elsevier Ltd. All rights reserved.

Please cite this article as: Gebremeskel, G., Journal of Arid Environments (2017), https://doi.org/10.1016/j.jaridenv.2017.12.002

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Sauerborn, 2001). Slope gradient-based SWC approach that considers the construction of physical SWC structures at farmlands was applied since the initiation of SWC works (Hurni, 1993a,b; Ciampalini et al., 2012; Esser et al., 2002). The Tigray Peoples Liberation Front started to implement this approach in the liberated areas of Tigray during 1988–1990 (Esser et al., 2002; Segers et al., 2008a). However, this approach lacked sustainable conservation of natural resources at a catchment level. Rehabilitation of degraded lands at catchment scale was introduced in Gira Kahsu of southern Tigray since the mid-1980s (Asfaha et al., 2014). Continued construction of physical SWC structures has been given due attention during this period (Gebremichael et al., 2005; Nyssen et al., 2009a). The main actors of the conservation activities were the peasant associations (PAs), the SWC department of the Bureau of Agriculture, the forestry and wildlife conservation development authority (FWCDA) and different NGOs such as those related to churches, the Red Cross, the Relief Society of Tigray and Oxfam (Osman and Sauerborn, 2001). After the change of government in 1991, the new government has initiated the SWC works to implement during January as free service for 20 consecutive working days, followed by food for work for the remaining days of the dry season. Nowadays, it is a common habitual exercise by all farmers under the ICM principles. The ICM is now strongly promoted in Tigray under various land and socioeconomic conditions.

degraded areas, the achievements are far below the expectations (Amdihu et al., 2014; Garg et al., 2012; Mu et al., 2007; Baptista et al., 2015). The outcome of many SWC projects has not been sufficiently achieved because of the poor management of the before and after implementations, mainly top-down intervention approaches (Smith, 1999; Segers et al., 2008a), less integration among disciplines (social, technical and institutional) (German et al., 2006; Mekonen and Fekadu, 2015), lack of consistent biophysical impacts and benefits (Baptista et al., 2015), and high labour and capital intensive (Smith, 1999; Ruthenberg, 1974). As a result, the corresponding framework for participatory SWC implementation remains fragmented. On the contrary, achievements from Tigray can be considered a model of the implementations and positive impacts achieved from the SWC programmes (Nyssen et al., 2009b; Lanckriet et al., 2014a). Tigray from northern Ethiopia is known for its drought-prone area where agriculture has been practiced for years (Sulas et al., 2009; Esser et al., 2002; Walraevens et al., 2009). This long-term unlimited use of farmlands for crop production combined with the unwise use of vegetation has caused severe land degradation (Frankl et al., 2012; Munro et al., 2008). The land degradation coupled with erratic distribution of rainfall has caused a recurrent drought and famine, which was historically demonstrated during 1888–1892, 1973–1974 and 1984–1985 (Gebrehiwot et al., 2011; Legesse et al., 2003; Osman and Sauerborn, 2001). These situations had delivered a clear message to the people, government and stakeholders that SWC interventions are essential for land restorations and to protect from drought occurrence. SWC interventions were initially implemented in farmlands; however, during the 1990s, integrated catchment management (ICM) approach was introduced into all landscapes (Nyssen et al., 2014; Asfaha et al., 2014). This programme was also strengthened by designing a conservationbased agricultural development strategy (Lal, 1989; van der Veen and Tagel, 2011). Implementations of SWC based on the ICM intervention have significantly improved natural resources in the last two decades (Alemayeuh et al., 2009). As a result, land management through SWC has become an integral part of the farming system in Tigray, and these experiences are being shared worldwide (Munro et al., 2008; Nyssen et al., 2010; WFP, 2012; Walraevens et al., 2015). Although Tigray is known for its vast experience in SWC implementation programmes, the success and challenges observed have not been well documented and disseminated to users. Most of the previous studies (e.g. Alemayehu et al., 2009; Frankl et al., 2012; Nyssen et al., 2007, 2010; Taye et al., 2015; Hurni et al., 2015) focussed on experimental plots, and none of them tried to show their achievements and lessons at large scale. Thus, this study was proposed to review the experiences on SWC implementations and associated benefits with the specific objective (i) to summarise the experiences and lessons of SWC implementation programmes, (ii) to indicate the major challenges and issues to be considered in SWC implementation programmes and (iii) to compare SWC experiences of Tigray with related experiences around the world.

3. Study area description Tigray is located in northern Ethiopia (Fig. 1) between 12°15′ and 14°50′N and between 36° 27′ and 39° 59′E with an area of 80,000 km2 (Hagos et al., 1999, 2016). It is surrounded by Sudan in the west, Eritrea in the north, and the Ethiopian regions of Amhara and Afar in the south and east, respectively. Altitude varies from 500 m.a.s.l. in the northeast to 4000 m.a.s.l. in the southwest (Hagos et al., 1999). It is characterised by undulating terrain and steep slopes, fragile environment, erratic rainfall and sparse vegetation coverage, which in turn facilitate soil erosion (Esser et al., 2002; Hagos et al., 1999). The climate of Tigray is semi-arid, dominated by distinctive dry and wet seasons (Meire et al., 2013; Walraevens et al., 2015). The region receives 80% of its rainfall during the rainy season from June to September (Nyssen et al., 2011; Walraevens et al., 2009). The average rainfall varies from about 200 mm in the northeast lowlands to over 1000 mm in the south western highlands (Hagos et al., 1999). The dry period over the region extends up to 10 months, and the maximum effective rainy season extends from 50 to 60 days (Zenebe et al., 2013). Variations in rainfall are mainly associated with the seasonal migration of the inter-tropical convergence zone and complex topography (Nyssen et al., 2005, 2009d). The average temperature is estimated to be 18 °C, which reaches approximately 40 °C around Humera (Hagos et al., 1999). Four land-use types, including cropland, villages and built-up areas, exclosures, and pastures and rangelands are identified in Tigray (Meire et al., 2013). Croplands are the dominant land-use type in Tigray. Thirteen major soil types are identified: cambisols, rendzinas, lithosols, acrisols, fluvisols, luvisols, regosols, nitosols, arenosols, vertisols, xerosols, solonchacks and andosol (Hunting, 1974, 1976; Virgo and Munro, 1977; Hagos et al., 1999). Texturally, these soil types cover from light to heavy soils. The Tigray highlands drain toward the African Rift Valley in the east, the Mereb River in the north and the Tekeze River in North western (Lanckriet et al., 2015a,b). The geological formations consist of Precambrian metavolcanics and Mesozoic sedimentary rocks such as Adigrat sandstone, Antalo limestone, Agula shales and Amba Aradam sandstone, which in turn are intruded by Cenozoic dolerite dykes/sills (Merla et al., 1979; Gebreyohannes et al., 2013; Lanckriet et al., 2015a,b; Haregeweyn et al., 2008b). Tertiary basalts are found overlaying the Precambrian and Mesozoic rocks. In addition, the Enticho

2. Background of SWC in Tigray Indigenous SWC practices date back to 400 BCE (Ciampalini et al., 2012). However, planned SWC works were started through food aids by the World Food Program in the early 1970s (Ciampalini et al., 2012; Haregeweyn et al., 2015; Nana-Sinkam, 1995; Osman and Sauerborn, 2001). Since then, traditional terracing through stone bunds has been commonly practiced on cultivable lands in the highlands of Tigray (Munro et al., 2008; Hunting, 1974; Virgo and Munro, 1977; Hurni, 1993a,b). In addition, indigenous knowledge of farmers such as knowledge on Daget (local terracing) and improved physical SWC measures has been integrated at various slopes (Nyssen et al., 2000). However, the then existing SWC programme was mainly focused on physical measures and tree plantations, which lacked participatory planning and voluntary participation of the people (Osman and 2

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Fig. 1. Location map of the study area.

4. Review methods

Sandstone and Edag Arbai Tillites are commonly found among the Paleozoic rocks in Tigray (Merla et al., 1979; Gebreyohannes et al., 2013; Lanckriet et al., 2015a,b). The three major rock groups (sedimentary, igneous and metamorphic) are found well exposed in Tigray (Berhane et al., 2016). Tigray has a population of 4.4 million growing by 3% annually (CSA, 2007). The farming system is dominated by small-scale rainfed agriculture (Virgo and Munro, 1977). It is entirely dominated by traditional methods of crop production and livestock rearing (Hagos et al., 2016). Approximately 90% of the population depends on plough-based cultivation, having 1.2 ha average landholdings per household (Pender and Gebremedhin, 2008). Subsistence farming has been practiced on the plateau and the mountain slopes of the Tigray highlands for centuries (Ciampalini et al., 2012; Nyssen et al., 2008a). Dominant cereal crops grown are tef (Eragrostis tef), barley (Hordeum vulgare L.), wheat (Triticum sp.), sorghum (Sorghum bicolor) and maize (Zea mays), accompanied by leguminous crops such as field peas (Pisum sativum), chickpeas (Cicer arietinum) and horse bean (Vicia faba). Gesho (Rhamnus prinoides) and eucalyptus are often planted around homesteads and are used to produce cash earnings. Cattle, sheep, goat, equines, beehives and poultry are dominantly found in Tigray. In summary, agriculture accounts for more than 60% of the regional total gross domestic product (Hagos et al., 2016).

This review was conducted through detailed analysis of information collected from peer-reviewed articles, proceedings, case studies, field observations, farmers’ perceptions and our lifelong experiences in the SWC works. Existing published documents emphasising on social, economic and environmental impacts were critically reviewed. In-depth interviews with key informants mainly working in SWC were conducted to identify the practices, trends, achievements and impacts, lessons and experiences, roles and involvement of gender, and related policy and strategy issues. Furthermore, a structured observation of the type of practices, extent and design of SWC structures, its sustainability and overall environmental rehabilitations were carried out. The reviewed literature consists of information collected from field measurements, observations, interviews and modelling systems. Studies evaluating SWC works and its effects have significantly increased since the 1990s. These studies are mainly concentrated in the highlands because of the existence of intensive SWC interventions. The characteristics of the studies and their respective outputs are summarised in Table 1 and Appendix A (Tables A1 and A2, in the appendix). The SWC structures were reviewed according to the criteria explained in terms of the type of materials used for intervention (e.g. stone, soil or biological species) and the approaches and systems followed in the ICM implementation.

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Table 1 Summary of studies on the effect of SWC-based ICM interventions, before and after intervention comparisons for various conservation indicators. Intervention type

Study watershed/site

Area(ha)

Mean rainfall (mm)

Land use type

Methodology used

Change/impact

Water harvesting

upper Agula watershed

14,500

515–872

Crop land

GIS and remote sensing

Exclosures

upper Agula watershed Dogua Tembein district May Ba'ati & Kunale areas Adwa district

14,500

515–872

1.1 × 105

753

Forests and shrubs Mixed

GIS and remote sensing Cost benefit analysis

1.5–8

700 742

Forest and shrubs Crop land

Field measurement SDSS

Exclosures

Exclosure Physical SWC

3.7 × 10

5

187

724

Mixed

Plot experiment

NA

700

Crop land

Survey and measurement

Exclosures

May zeg zeg catchment Dogu'a Tembien district May zeg zeg

199

774

Exclosures and physical SWC

May zeg zeg catchment

187

724

Bushes and shrubs Mixed

Field survey and interview Plot experiment

Exclosures

Dogu'a Tembien district May zeg zeg catchment Mendae catchment Mendae catchment

NA

700

Bushes and shrubs

Field surveys

200

626

Crop land

1037

565.8

Mixed

survey and measurement Water balance

1037

565.8

Mixed

Water balance

NA

769

Crop land

Survey and measurement

14,500

515872 515872

Crop land

GIS and remote sensing GIS and remote sensing

Exclosures and physical SWC Physical SWC

xclosures and physical SWC Water harvesting Water harvesting

Physical SWC

Farm land Farm land

Farm land

Dogu'a Tembien district upper Agula watershed upper Agula watershed upper Agula watershed

14,500

14,500

515872

Crop land

Crop land

GIS and remote sensing

Study period (years)

Sources

Before SWC intervention

After SWC intervention

7 ha (irrigation coverage) 32.4 ha (forest coverage) ETB 0 ha−1 (NPV)

222.4 ha (irrigation coverage)

40

Alemayehu et al., 2009

98 ha (forest coverage) ETB 5620 ha−1 (NPV)

40

Alemayehu et al., 2009 Balana et al., 2012

20 g m−2(litter production) 4.5 t ha−1 yr−1 (soil loss) 14.3 t ha−1 yr−1 (soil loss) 57 t ha−1 yr−1 (soil loss)

600 g m−2 (litter production) 0.5 t ha−1 yr−1 (soil loss) 9.0 t ha−1 yr−1 (soil loss) 20 t ha−1 yr−1 (soil loss)

6 t ha-1 yr-1 (soil loss) 5.8 t ha−1 yr−1 (sediment deposition) 26 Mg ha−1 yr−1 (sediment deposition) 26.5 mm (runoff) 152 mm (run off)

NA

2 NA

Descheemaeker et al., 2006a Dragan et al., 2003

7

Nyssen et al., 2009b

3–21

Gebremichael et al., 2005

2.2 t ha-1 yr-1 (soil loss) 7.1 t ha−1 yr−1 (sediment deposition) 123 Mg ha−1 yr1 (sediment deposition) 5 mm (runoff)

7

Nyssen et al., 2008b

7

Nyssen et al., 2009b

20

Descheemaeker et al., 2006c

7

Nyssen et al., 2010

97.3 mm (run off)

18

Negusse et al., 2013

8 mm (Groundwater recharge) 0.58 t ha−1 (crop yield)

107.7 mm (Groundwater recharge) 0.65 t ha−1 (crop yield)

18

Negusse et al., 2013

3–21

Nyssen et al., 2007

0.3 t ha−1 (tef productivity) 0.5 t ha−1 (wheat productivity) 0.45 t ha−1 (barley productivity)

0.6 t ha−1 (tef productivity) 0.8 t ha−1 (wheat productivity)

40

Alemayehu et al., 2009 Alemayehu et al., 2009

0.75 t ha−1 (barley productivity)

40

40

Alemayehu et al., 2009

NA = not available, SDSS = spatial decision support system, NPV = net profit value, ETB = Ethiopian Birr (the legal Ethiopian currency); at the time of the study, the exchange rate was US$ 1 = ETB 9.16.

5. SWC interventions

productive safety net programmes (PSNPs) and the national Sustainable Land Management Project (SLMP) (German et al., 2006, 2007; Segers et al., 2008b; Haregeweyn et al., 2015). Through these programmes and active participation of the people, different types and forms of SWC measures have been implemented in Tigray.

Implementations of SWC based on the ICM approach are effective in reducing runoff, soil losses and overall catchment management (Nyssen et al., 2009c; Taye et al., 2013; Asfaha et al., 2014). It contributes to have a collective action, including gender and equity within the catchment (German et al., 2006). It considers the whole catchment (inlet-outlet) as a unit during the implementation of the SWC works. This approach is a participatory, multidisciplinary and holistic catchment development approach that integrates various interventions within the catchment (German et al., 2006, 2007; Haregeweyn et al., 2012). Physical (mechanical) and biological SWC interventions are implemented in an integrated manner, starting from the upstream and ending at the outlet of the catchment. As a result, this approach has been popularly used, and significant changes have been achieved in controlling land degradation (Shi et al., 2012; Hurni et al., 2015; Barbier, 2000; Haregeweyn et al., 2008a,b). The ICM approach has been used by different initiatives, including community mobilisation through free labour days, food for work, managing environmental resources to enable transition (MERET) to more sustainable livelihoods,

5.1. Physical SWC measures Common physical SWC structures that have been introduced are terraces, stone and soil bunds, trenches and percolation pits, fanya juu, micro basins, semi-circle terraces and tied ridges (Asfaha et al., 2014; Haile et al., 2006; Taye et al., 2015; Virgo and Munro, 1977; Gebreegziabher et al., 2009; Gebremichael et al., 2005; Nyssen et al., 2007, 2008b, 2010, 2015; Herweg and Ludi, 1999). Special attention was also given for the construction of soil and water harvesting structures such as check dams (Asfaha et al., 2014; Nyssen et al., 2004), sand storage dams, micro-dams, river diversions, ponds and shallow handdug wells (Zeleke et al., 2014). Moreover, geomorphic dynamics of gully and river networks and their contribution towards agricultural and land management were also considered (Zenebe et al., 2013; Frankl 4

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Fig. 2. Commonly implemented SWC measures in Tigray. (a) Hillside terraces in a steep slope, (b) semi-circle terraces in exclosures, (c) deep trench for harvesting water, (d) exclosure in degraded steep slopes, (e) bench terraces and (f) animal feed through a cut-and-carry system after exclosures.

labour for construction and maintenance (Gebremedhin and Swinton, 2003). Despite the limitations, physical SWC structures are vital for conserving soil and moisture for crop production and enhancing infiltrations (Herweg and Ludi, 1999). For example, Nyssen et al. (2007) confirmed that stone bunds can reduce soil erosion by 68% and conserve sediment up to 59 t ha−1yr−1. These structures are important in conserving moisture and produce a better crop yield in the farmlands. Construction of stone bunds and terraces aged from 3 to 21 years can increase crop yield up to 53% (Nyssen et al., 2007; Gebremichael et al., 2005). Investments in stone bunds, explained in terms of farm profit, can also give a return rate of 50% (Gebremedhin et al., 1999). In general, physical SWC can reduce soil erosion and increase crop yields by more than double if properly implemented. In recent years, efforts have been given to integrate both biological and physical SWC measures. As a result, the ICM intervention has become a successful SWC programme in Tigray (Descheemaeker et al., 2006b; Nyssen et al., 2015).

et al., 2011, 2012, 2013; Asfaha et al., 2014; Lanckriet et al., 2015a,b). Structures including soil bunds, stone bunds, stone-faced soil bunds, hillside terrace (Fig. 2a) and tie ridging have been widely implemented at farmlands by farmers. These structures have also been implemented on steep slopes, although they are less sufficient to conserve moisture (Nyssen et al., 2007). Other structures including bench terrace (Fig. 2e), semi-circle terraces (Fig. 2b), eyebrow basin, gulley reshaping, percolation pits, trenches and deep trenches (Fig. 2c) are the most important physical measures used in non-agricultural areas (Nyssen et al., 2015). These structures have the capacity to improve groundwater recharge by intercepting surface runoff and curb floods by increasing the time of concentration. Moreover, these structures are effective in trapping eroded fertile soils from steep slopes if constructed in a staggered position. However, there are some limitations of the physical SWC structures. For example, bunds can be home for some rodents that could feed on the cultivated crops (Nyssen et al., 2007; Balana et al., 2012; Meheretu et al., 2014). For instance, rodents can generate crop damage up to 225 kg ha−1, which is equivalent to 1688 Birr (121 USD) in a narrowly spaced (approximately 10 m) stone bund density (Meheretu et al., 2014). The SWC takes some land out of production if narrowly spaced and has limited stability if it is not integrated with re-vegetation (Nyssen et al., 2007). Moreover, these structures demand intensive

5.2. Biological SWC measures Beyond the environmental and ecological benefits, increasing vegetation cover on degraded lands has been stabilised with physical SWC structures. Worldwide experiences show that biological SWC practices 5

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Fig. 3. Effect of SWC on natural resource improvements: (a1) gully formation before 2005, (a2) gulley reshaping supported by plantations and check dams constructed across gullies in between 2006 and 2008, and (a3) after interventions in 2009 (Haregeweyn et al., 2012).

Reubens et al. (2009) showed that shallow-rooted plants are effective for controlling gulleys. However, they are not able to replace physical SWC measures in protecting rill and gully developments during overland flows (Phomcha et al., 2011). These structures are also less effective during the onset of rains after a long dry season (Haile et al., 2006). Therefore, sustainable catchment management intervention requires the harmonisation of both physical and biological SWC interventions (Descheemaeker et al., 2006c; Haile et al., 2006; Nyssen et al., 2009a).

are the most productive measures for conserving soil and water resources (Descheemaeker et al., 2006a; Shi et al., 2012; Haregeweyn et al., 2015). These measures are cheap, easily acceptable by farmers, and even effective in reducing soil erosions and enhancing infiltrations. However, less attention was given until the beginning of the 2000s because of technical biasedness towards physical SWC measures (Descheemaeker et al., 2006b). Among the common forms of biological SWC practices widely implemented are exclosures (Fig. 2d; Descheemaeker et al., 2006b; Muys et al., 2014), plantations (Zeleke et al., 2014; Nyssen et al., 2015), agroforestry (Girmay et al., 2009; Hengsdijk et al., 2005), gully re-vegetation (Nyssen et al., 2009a) and soil fertility-enhancing plantations (Araya et al., 2011; Lanckriet et al., 2012). Human-induced biological interventions are commonly planted on either side of physical SWCs or gully formations for structure stabilisation (Figs. 3 and 4). A study by

5.2.1. Conservation agriculture Conservation agriculture (CA) practices have been tested in Tigray to increase crop productivity through various tillage practices and insitu moisture conservations (Araya and Stroosnijder, 2010; Araya et al., 2011, 2012, 2016; Gebreegziabher et al., 2009; Gebremichael et al.,

Fig. 4. Available water from shallow wells and springs and associated benefits after ICM in Tigray.

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seedlings in Tigray. In summary, exclosures and enrichment plantations have a remarkable contribution in restoring the landscape and reducing soil erosions through making sediment and flood buffers. The formation of exclosures substantiated by enrichment planting on slopes greater than 30% has significantly enhanced vegetation coverage. Exclosures are also important for habitat and biodiversity enrichments, and the number of large wild mammals are increasing with increasing age of exclosures (Yami et al., 2007). As a result, these exclosures are becoming a habitat for wildlife in addition to its economic benefits.

2005; Nyssen et al., 2007, 2011; Tesfay et al., 2011; Lanckriet et al., 2014b). However, only well-experimented traditional techniques such as “terwah” and “shilshalo” are widely implemented across the region. Farmers have been using ox-drawn ard plough (“marasha” plough), “terwah”/“derdero” and “shilshalo” for various in-situ SWC interventions by creating farm depressions (Nyssen et al., 2011). Research outputs from experimental plots indicate that practicing CA can reduce surface runoff and soil loss up to 51% and 81%, respectively, (Nyssen et al., 2011; Araya et al., 2012, 2016). Experimental comparison on permanent bed, “Terwah” and traditional ploughing in Gumselassa clearly indicates that “Terwah” and traditional ploughing are better in conserving moisture (Gebreegziabher et al., 2009). Both “Terwah” and traditional ploughing can be suggested as immediate measures to reduce runoff, reduce soil loss and increase crop yield; however, the permanent raised bed farming system can be an everlasting measure for better production from vertisols (Araya et al., 2011). Lanckriet et al. (2012) reported that soil loss and runoff were 35.4 t ha−1yr−1 and 27.9 mm with plain tillage, while with CA, it was only 14.4 t ha-1yr−1 and 23.5 mm, respectively, which suggests that improved moisture conserving practices can have a considerable effect on soil erosion reduction. Tied ridging and mulching practices were also introduced as in-situ moisture conservation measures, and these practices can improve soil moisture by 13% and increase crop yield up to 44% (Araya and Stroosnijder, 2010). Similarly, application of minimum tillage showed a reduction in runoff and soil loss up to 61% and 17%, respectively (Haregeweyn et al., 2015). Overall, research outputs from experimental plots indicate that the CA is an effective resource-saving and moistureconserving practice in the farmlands of the semi-arid area. Despite its importance in dry land agriculture, its implementation has been constrained because of lack of farmers’ awareness (Lanckriet et al., 2014b). Hence, CA cannot be considered as a success story in Tigray as it has not yet transferred to the farming community as a means of SWC intervention.

5.4. Water harvesting Water harvesting was needed in Tigray because of scarcity of water and the erratic nature of rainfall. In addition to the SWC interventions, special emphasis was also given to harvest water for irrigation and domestic uses. To this effect, construction of small and medium dams was given due attention after the downfall of the Derg regime in 1991. Accordingly, more than 92 micro-dams have been constructed by different stakeholders including Sustainable Agriculture and Environmental Rehabilitation in Tigray, Relief Society of Tigray and the regional government (Haregeweyn et al., 2006, 2008a; Nana-Sinkam, 1995; Hagos et al., 2016; Berhane et al., 2016). However, the sustainability of benefits from these water harvesting structures are threatened by siltation (61%), leakage (53%), structural damages (25%), insufficient inflow (22%) and spillway erosion (21%) (Berhane et al., 2016). Despite the poor performance, these interventions have played a vital role towards improving crop production and the water balance system (Haregeweyn et al., 2006; Teka et al., 2013). Water harvesting structures including roof rainwater harvesting, flood water harvesting (spate irrigation), and water storing structures such as “Horeye” and ponds (Fig. 4) were introduced by the government for improving water accessibility at the household level (Segers et al., 2008b; Teklehaimanot, 2006). The “Horeye” is a water harvesting trapezoidal pond covered by plastic, stone riprap or compacted clay. It was widely introduced by the government for harvesting water at the household level with huge investments. However, since it was introduced with top-down approaches without consulting the farmers, many plastic sheets that were purchased for this purpose are now reconverted for other uses; consultation with farmers should have been a prerequisite to get this technique accepted by the farmers (Segers et al., 2008b; Teklehaimanot, 2006). Segers et al. (2008b) also clearly showed that the “Horeye” failed because of adoption and technical shortcomings during construction. Introduction of roof rainwater harvesting structures has also been attempted at farmers’ houses for small-scale irrigation. However, its sustainability was constrained by high seasonal rainfall variability and feasibility issues. Spate irrigation practices have long been in use in the Raya Valley and other marginal grabens of the Rift Valley (Erkossa et al., 2014), which mainly uses floods coming from the highlands. This technique is used to supplement water for crops during pre- and post-rainfed seasons. With such interventions, it is evident that ICM has benefited smallholder farmers in transforming their lives from the agrarian system to intensive irrigated agriculture (Walraevens et al., 2015).

5.3. Exclosures and enrichment planting In response to land degradation, environmental rehabilitation through exclosures was initiated in the mid-1980s (Asfaha et al., 2014) and has been more pronounced since 1991 (Fig. 2d; Mekuria et al., 2007). Exclosures are widely applied in the semi-arid areas of Tigray as a means of degraded land rehabilitation (Aerts et al., 2007, 2009). Subsequently, rehabilitation of degraded lands through exclosures has significantly contributed to the restoration of natural resources (Alemayehu et al., 2009; Belay et al., 2014; Lanckriet et al., 2012; Mekuria et al., 2007). Observed changes can be expressed in terms of increased vegetation cover, enhanced soil nutrient status, reduced soil erosion and improvements in soil water storage capacity (Yami et al., 2007; Descheemaeker et al., 2006a; Haregeweyn et al., 2012). Exclosures are also climate change-resilient practices because carbon stocks emerging from green gas emissions can be trapped in plant leaves and the soil. Descheemaeker et al. (2006a) revealed that 20 and 600 g m−2 of total annual litters were produced from grazing lands and exclosures, respectively. Exclosures and enrichment plantations on degraded steep slopes are also effective in controlling runoff, sediment and sediment-associated nutrient losses (Girmay et al., 2009; Haregeweyn et al., 2008a; Nyssen et al., 2009b). Apart from exclosures, tree seedlings have been planted in treated catchments every year, although the survival rates were very low (Aerts et al., 2007; Reubens et al., 2009). For example, Mekonen and Brhane (2011) confirmed that only 45% of the transplanted seedlings in Madego watershed survived after 15 months. The survival rate of tree seedlings was strongly associated with watering, sheltering and planting conditions (Reubens et al., 2009). Moreover, the survival, growth and development of seedlings strongly depend upon the treatment used and the growth conditions. This has resulted in the lowest overall survival rate of

6. Effects of SWC interventions Various studies (e.g. Alemayehu et al., 2009; Belay et al., 2014; Descheemaeker et al., 2006b, 2006c; Gebremichael et al., 2005; Haile et al., 2006; Hengsdijk et al., 2005; Lanckriet et al., 2012; Mekonen and Tesfahunegn, 2011; Mekuria and Aynekulu, 2013; Negusse et al., 2013; Nyssen et al., 2008a, 2009a, 2010, 2015) on SWC interventions and their associated benefits evidenced that positive effects on natural resource enrichment and land degradation reduction have been achieved. Comparing the pre- and post-implementation of ICM, soil loss and runoff have significantly reduced in Tigray. The average soil losses are much lower than that before ICM implementation, which was more 7

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than the estimated country-wide average of 42 t ha−1 yr−1 (Hurni, 1988). Several case studies are summarised in Table 1 to show the impacts/changes brought about by various SWC parameters. These changes/impacts are explained in terms of improvements in different SWC indicators across the region.

sediment supply to streams, suggesting that the rate of soil erosion has considerably reduced in the study area. Implementation of ICM has also significantly improved soil fertility in Tigray. Descheemaeker et al. (2006b) showed that soil organic matter, total nitrogen, available phosphorus and soil bulk density have significantly increased after the implementation of exclosures. According to Nyssen et al. (2008a), soil fertility expressed in terms of organic matter, bulk density, water holding capacity and hydraulic conductivity has significantly increased after ICM implementations in Atsbi-Wonberta district. Soil fertility improvements are observed dominantly in areas having higher vegetation cover (Hadgu et al., 2009). These studies have also confirmed that soil fertility enhancements are higher at downstream than upstream of the treated catchments, which implies that eroded soils in the upstream are trapped gradually towards the catchment outlet. Increased organic matter content of the soil (either by increasing inputs or decreasing losses from the catchment) has also enhanced the carbon sequestration of the soil (Garg et al., 2012; Girmay et al., 2009; Lanckriet et al., 2012). Overall, the above achievements are caused by the combined effects of both physical and biological conservation measures at the catchment level.

6.1. Environmental rehabilitation Environmental rehabilitation can be expressed in terms of reversing a degraded land into its former conditions (Hurni et al., 2015; Nyssen et al., 2010). Several studies (e.g., Belay et al., 2014; Descheemaeker et al., 2006b; Lanckriet et al., 2012; Negusse et al., 2013; Nyssen et al., 2008a, 2009a,b, 2010, 2014, 2015) indicated that the SWC measures undertaken in the last two decades have significantly contributed to the rehabilitation of the landscapes. Accordingly, ICM-based SWCs have led to significant improvements in vegetation cover and soil fertility of the degraded catchments. After comparing old terrestrial photographs with their present-day images (1868–2008; 140 years), Meire et al. (2013) detected that landuse/cover changes explained by woody vegetation and built-up area have been significantly increased at the expense of bushland. Using similar techniques, de Mûelenaere et al. (2014) showed that area of bare land declined from 32% to 8%, bushland increased from 25% to 43% and total forest area increased from 2.6% to 6.3%. Munro et al. (2008) assessed land cover trends from 51 historical landscape images and reported a significant change of bare lands into the grasslands and bushlands. Nyssen et al. (2009a) studied the occurrence of desertification in Tigray for the last 140 years through repeat photo techniques, and the result shows that the recovery of vegetation cover significantly increased. Alemayehu et al. (2009) and Belay et al. (2014) have also shown that arable and range lands in the eastern escarpment of Tigray have been significantly converted into shrubs, bushes and forest lands. In summary, vegetation coverage in most landscapes has improved by 30–302% (Alemayehu et al., 2009; Descheemaeker et al., 2006b; Mekonen and Brhane, 2011; Nyssen et al., 2015). These success stories are attributed to SWC interventions and growing awareness of local communities to reverse the damage to degraded lands. The majority of the studies showed that physical and biological SWC measures have contributed to reverse the damage to degraded lands (Haregeweyn et al., 2012; Meire et al., 2013; de Mûelenaere et al., 2014; Lanckriet et al., 2014a,b). For example, Fig. 3 shows how a degraded gully in the Enabereid watershed of Adwa district has been restored after 4 years of interventions (Dragan et al., 2003; Haregeweyn et al., 2012). Improving vegetation cover in exclosures has also increased the diversity of fauna and flora (Yami et al., 2007; Balana et al., 2012). In addition to environmental rehabilitation, farmers have been benefited from the exclosures by selling tree biomass production. Balana et al. (2012) revealed that 5620 ha−1 Ethiopian Birr can be obtained by selling biomass products from exclosures. However, much effort is still needed to convert these exclosures into sources of income for the community to make them sustainable. SWC intervention has also played an important role in reducing soil erosion and enhancing soil fertility of arable lands (Girmay et al., 2009; Hengsdijk et al., 2005; Nyssen et al., 2006; Taye et al., 2015). After ICM implementation and SWC interventions, Nyssen et al. (2006) reported that the rate of gully erosion reduced from 6.2 to 1.1 t ha−1 y−1. Similarly, Nyssen et al. (2008a,b) compared 30-year-old landscape photographs with their current status and found that erosion rates have decreased by 68% after ICM. Integrated SWC measures at catchment scale have also reduce soil loss up to 78% (Haregeweyn et al., 2015; Hengsdijk et al., 2005). Many pilot studies (e.g. Descheemaeker et al., 2006b; Mekuria and Aynekulu, 2013; Haregeweyn et al., 2015) showed that soil loss significantly reduced (14–69%) after making exclosures out of the degraded hillsides. These results are also supported by Asfaha et al. (2014) and Hadgu et al. (2009) who revealed that ICM implementation has significantly decreased the size and amount of

6.2. Water resources development One of the major effects of the ICM programme is improving water resource availability at the catchment level. The hydrological processes of a catchment can be modified by changing the partitioning of rainfall on the land surface (Gates et al., 2011). This can improve the availability of water during the dry season while decreasing peak flow during the rainy season (Nyssen et al., 2010). Several studies showed that surface runoff volume considerably reduced after the implementation of ICM. For example, Taye et al. (2015) and Haregeweyn et al. (2015) reported that physical SWC has decreased runoff up to 88%. Nyssen et al. (2010) also investigated the overall effect of ICM at the May Zeg Zeg catchment and found a decrease of 81% in the surface runoff volume. Descheemaeker et al. (2006b) found a reduction of 80% in the surface runoff after the restoration of vegetation cover in the same watershed. This indicates that the runoff water is trapped and infiltrated to the catchments, which could be a potential source for increasing the availability of water. After the implementation of ICM, surface and groundwater levels have tremendously increased in previously degraded lands (Alemayehu et al., 2009; Descheemaeker et al., 2006b; Gebreyohannes et al., 2013; Mekonen and Brhane, 2011; Nyssen et al., 2008a, 2010, 2015; Taye et al., 2013). Different quantitative and qualitative studies on small catchments including Agulae (Alemayehu et al., 2009), May Zeg Zeg (Nyssen et al., 2010), May Leiba (Taye et al., 2015) and Abraha Atsbaha (Walraevens et al., 2015) confirmed that groundwater levels have increased after ICM practices. The availabilities and distributions of shallow wells across the study area are also an indication of water availability in the catchments. More shallow and deep wells are found in the treated catchments, which implies that the groundwater table has increased significantly (Fig. 4). After studying 73 active wells, Walraevens et al. (2015) reported that water for irrigation is found at 6 m depth in Abraha Atsbaha. This availability of groundwater was enhanced by building small dams and trenches under ICM in the catchment (Walraevens et al., 2015). This clearly shows that ICM increases the infiltration rate to raise the water table and improve water availability for irrigation and domestic purposes. ICM achievements from this catchment were the main reason for winning the United Nations Development Program Equator Prize at the Rio+20 conference in June 2012 (WFP, 2012). SWC-based ICM has shown promising results with regard to water resource availability (Alemayehu et al., 2009; Lanckriet et al., 2012; Negusse et al., 2013; Nyssen et al., 2010,2015). These achievements can also be evidenced by the rapid expansion of small-scale irrigated agriculture and improved livelihoods (Mekonen and Tesfahunegn, 2011) 8

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Improved soil fertility and water availability increased the production and productivity of both rainfed and irrigated agriculture after ICM interventions. Similar efforts have been made worldwide to restore the vegetation cover of degraded lands (e.g., Barbier, 2000; Baptista et al., 2015; Mutisya et al., 2010; Chowdary et al., 2009; Neto et al., 2006). However, the achievements were not satisfactory because of lack of integration and appropriate implementation approaches followed. Hence, the best SWC intervention approaches made in Tigray could be a good lesson to be considered for future interventions in other countries with similar socio-economic and environmental setups. Adoption of the ICM approach from this area can be regarded as a risk reduction strategy, which could bring about resilience of the farming system (Gates et al., 2011; Hurni et al., 2015; FAO, 2014). The most important finding of this review is the integration of disciplines (social, technical and institutional) during the implementation of the interventions. Stakeholder involvement during the entire process of SWC implementations (e.g., problem identification, planning and monitoring) was also one of the best achievements in Tigray, which many projects around the world lack (Mutisya et al., 2010; Baptista et al., 2015). More importantly, the commitment of the people during implementations and in keeping the land's sustainability is remarkable. In Tigray, ICM was implemented by mobilising the community through free labour days, which were subsequently followed by food for work in each year. Such mobilisation approaches might have contributed to create a common habitual action and sense of ownership by the farmers. Adoption and spreading of this approach to the international community can offer a base to overcome the challenges of SWC implementations around the world. For example, SWC interventions in China (Mu et al., 2007: Garg et al., 2012), Cape Verde (Baptista et al., 2015), India (Smith, 1999), Tunisia (Lacombe et al., 2008) and Kenya (Mutisya et al., 2010) indicated that implementation of SWC has been done without the involvement of local people in the planning stage while the farmers were forced to participate during implementations. Such projects have resulted in a low sense of ownership by the community and contributed to a limited level of success. This explicitly shows that the experiences from Tigray can provide a solid example to tackle such limiting factors. Another important lesson is the involvement of policy instruments that have been embedded on the future uses of recovered environments to benefit the local people in a sustainable way. For example, animal and human interference in the exclosures is prohibited by community bylaw; however, a cut and carry system of forage management approach is allowed for livestock feed. Moreover, in most recovered areas, landless young farmers are using the land for honeybee and cash crop productions without affecting its sustainability. Overall, physical and biological SWC practices are now perceived to be sustainable for surface and groundwater enrichment, environmental rehabilitation and agricultural and economic developments, which can be considered an essential lesson on SWC implementation approaches to be adopted by others countries. However, it is also essential to point out some of the drawbacks associated with SWC implementations in Tigray that should be considered when adopting this experience. A top-down implementation approach was followed, especially on new SWC techniques such as rainwater harvesting structures and the Horeye. Rainwater Harvesting Pond Program and the public work component of the Productive Safety Net Programs were important for livelihood; however, these interventions were intertwined together without farmers’ consultation and technical feasibility studies (Segers et al., 2008b). Such management problems have led to an unequal look by the people on the SWC initiatives. Planning and implementation of some SWC interventions often suffer from over-ambition, upward accountability and a top-down blanket approach. There is also lack of income generation and problems of benefit sharing from the exclosures and overall observed achievements. Farmers are inclined to short-term benefits; however, ICM interventions have been implemented mainly focusing on long-term

and in nearby similar regions (Nyssen et al., 2009c). However, largescale implementations of SWC can have considerable effect on water resource availabilities in the downstream users. Some studies (Garg et al., 2012; Gates et al., 2011) showed that water outflows from treated catchments are halved when compared to the untreated catchments, which implies potential negative effects on downstream users. Reconciliation of this issues needs consideration of detail study in the upstream-downstream linkages of the treated watersheds. 6.3. Agricultural productivity and economic developments SWC measures implemented in all landscapes have played an important role in improving food security and bettering the livelihood of the people. The reviewed materials and field investigations showed that soil erosion and gully formation have reduced significantly. It is a mainstream perception that the soil in most landscapes has been protected from severe erosion. Because of this effect, the production and productivity of crops and forages have increased tremendously in the last two decades (Nyssen et al., 2008a; Hadgu et al., 2009). Improving soil fertility and availability of water increased the land productivity and crop production. For example, Alemayehu et al. (2009) showed that the productivity of tef, wheat and barley increased from 0.3 to 0.6 t ha−1, 0.5 to 0.8 t ha−1 and 0.45 to 0.75 t ha−1, respectively. This implies that ICM interventions, combined with application of fertilisers and in-situ moisture conservation practices, increased the productivity of rainfed crops by 50% (Alemayeuh et al., 2009). Application of fertilisers has also considerably increased in the last two decades, which also played a huge role in increasing crop production. However, fertilizer use and management has been hindered by a top-down extension system (Rahmato et al., 2013). Blanket recommendation of fertilizer application has resulted in limited adaptation to use in the moisture-stressed area of Tigray (Pender and Gebremedhin, 2008). Farmers purchase fertilisers on credit, and many of them sell it at a lesser price (Rahmato et al., 2013; Pender and Gebremedhin, 2008; Segers et al., 2008a). Despite these problems, fertilisers do have an inevitable role to play if farming in Tigray is to develop. Small-scale irrigated agriculture has increased substantially in the last two decades (Alemayehu et al., 2009; Gebreyohannes et al., 2013; Nyssen et al., 2010, 2015; Wondumagegnehu et al., 2007). Life of the watershed dwellers are improving through producing and selling market-oriented horticultural crops from the irrigated agriculture (Alemayehu et al., 2009 Walraevens et al., 2015). The intensified agriculture after ICM implementation has increased the total crop production. Associated with this, Nyssen et al. (2015) showed that country-wide food production per capita in 2005–2010 was 160% of that in 1985–1990. After ICM implementation programmes, the total crop production is now higher than ever in Tigray. Intensive SWC interventions for the last two decades might have considerably contributed to the current poverty reduction in Tigray (Belay et al., 2014). Farmers have started to change their feeding style and are wearing better dresses, sending their children to school, spending more money for their health status and living in relatively better houses. It is certain that the continuous efforts made to conserve the soil and water have significantly contributed to this achievement. 7. Lessons and experiences This investigation confirmed that SWC based on ICM has significantly contributed to environmental recovery and improved food security in Tigray. Exclosures and enriching plantations at degraded landscapes were found to be the most important for the observed environmental recovery. Formation of exclosures on slopes greater than 30%, on which crop cultivation is not commonly practiced, substantiated by enrichment plantation, brought a rapid way of land restoration and became a habitat for wildlife (Yami et al., 2007). 9

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Appendix A. Supplementary data

environmental rehabilitations, whereas people prefer to get immediate benefits. Such challenges may constrain its sustainability and future acceptance by the local people. Although there has been much effort in implementing ICM, mobilising the watershed communities for the maintenance of the existing structures is the major challenges. Because of this, regular maintenances of the SWC structures become a big challenge in these implementation programmes. Linked to this challenge is the very low survival rate of tree seedlings planted in treated catchments every year (Aerts et al., 2007; Mekonen and Tesfahunegn 2011). This low rate of survival is mainly associated with lack of watering, sheltering and maintaining planting conditions (Reubens et al., 2009). In summary, although substantial efforts have been made to rehabilitate the degraded lands of Tigray, the above-mentioned challenges may jeopardise its future sustainability.

Supplementary data related to this article can be found at http://dx. doi.org/10.1016/j.jaridenv.2017.12.002. References Aerts, R., Negussie, A., Maes, W., November, E., Hermy, M., Muys, B., 2007. Restoration of dry Afromontane forest using pioneer shrubs as nurse-plants for Olea europaea ssp cuspidata. Restor. Ecol. 15, 129–138. Aerts, R., Nyssen, J., Haile, M., 2009. On the difference between ‘exclosures’ and ‘enclosures’ in ecology and the environment. J. Arid Environ. 73, 762–763. Alemayehu, F., Taha, N., Nyssen, J., Girma, A., Zenebe, A., Behailu, M., Poesen, J., 2009. The impacts of watershed management on land use and land cover dynamics in Eastern Tigray (Ethiopia). Resour. Conserv. Recycl. 53 (4), 192–198. Amdihu, A., Ephrem, G., Lisa-Maria, R., Zeleke, G., 2014. Suitability and scenario modeling to support soil and water conservation interventions in the Blue Nile Basin, Ethiopia. Environ. Syst. Res. 3 (23), 1–13. Araya, A., Stroosnijder, L., 2010. Effects of tied ridges and mulch on barley (Hordeum vulgare) rainwater use efficiency and production in Northern Ethiopia. Agric. Water Manag. 97 (6), 841–847. Araya, T., Cornelis, W.M., Nyssen, J., Govaerts, B., Getnet, F., Bauer, H., Amare, K., Raes, D., Haile, M., Deckers, J., 2012. Medium-term effects of conservation agriculture based cropping systems for sustainable soil and water management and crop productivity in the Ethiopian highlands. Field Crops Res. 132, 53–62. Araya, T., Nyssen, J., Govaerts, B., Baudron, F., Carpentier, L., Bauer, H., Lanckriet, S., Deckers, J., Cornelis, W.M., 2016. Restoring cropland productivity and profitability in northern Ethiopian drylands after nine years of Resource-Conserving Agriculture. Exp. Agric. 52 (2), 165–187. Araya, T., Cornelis, W.M., Nyssen, J., Govaerts, B., Bauer, H., Tewodros, G., Tigist, O., Raes, D., Sayre, K.D., Mitiku, H., Deckers, J., 2011. Effects of conservation agriculture on runoff, soil loss and crop yield under rainfed conditions in Tigray, Northern Ethiopia. Soil Use Manag. 27 (3), 404–414. Asfaha, T.G., Frankl, A., Haile, M., Nyssen, J., 2014. Catchment rehabilitation and hydrogeomorphic characteristics of mountain streams in the western Rift Valley escarpment of northern Ethiopia. Land Degrad. Dev. 27, 26–34. Balana, B.B., Muys, B., Haregeweyn, N., Descheemaeker, K., Deckers, J., Poesen, J., Nyssen, J., Mathijs, E., 2012. Cost-benefit analysis of soil and water conservation measure: the case of exclosures in northern Ethiopia. For. Policy Econ. 15, 27–36. Baptista, I., Fleskens, L., Ritsema, C., Querido, A., Tavares, J., Ferreira, A.D., Reis, E.A., Gomes, S., Varela, A., 2015. Soil and water conservation strategies in Cape Verde (Cabo Verde in Portuguese) and their impacts on livelihoods: an overview from the Ribeira Seca Watershed. Land 4 (1), 22–44. Barbier, E.B., 2000. The economic linkages between rural poverty and land degradation: some evidence from Africa. Agriculture. Ecosyst. Environ. 82, 355–370. Belay, K.T., Van Rompaey, A., Poesen, J., Van Bruyssel, S., Deckers, J., Amare, K., 2014. Spatial analysis of land cover changes in eastern Tigray (Ethiopia) from 1965 to 2007: are there signs of a forest transition? Land Degrad. Dev. 26 (7), 680–689. Berhane, G., Gebreyohannes, T., Martens, K., Walraevens, K., 2016. Overview of microdam reservoirs (MDR) in Tigray (northern Ethiopia): challenges and benefits. J. Afr. Earth Sci. 123, 210–222. Brooks, K.N., Eckman, K., 2000. Global perspective of watershed management. Land stewardship in the 21st century: the contributions of watershed management. In: Proceedings. RMRS-P-13. US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fort Collins, CO. Chowdary, V.M., Ramakrishnan, D., Srivastava, Y.K., Chandran, V., Jeyaram, A., 2009. Integrated water resource development plan for sustainable management of Mayurakshi watershed, India using remote sensing and GIS. Water Resour. Manag. 23 (8), 1581–1602. Ciampalini, R., Billi, P., Ferrari, G., 2012. Soil erosion induced by land use changes as determined by plough marks and field evidence in the Aksum area (Ethiopia). Agric. Ecosyst. Environ. 146, 197–208. Cooper, P.J.M., Dimes, J., Rao, K.P.C., Shapiro, B., Shiferaw, B., Twomlow, S., 2008. Coping better with current climatic variability in the rain-fed farming systems of subSaharan Africa: an essential first step in adapting to future climate change? Agric. Ecosyst. Environ. 126 (1), 24–35. CSA (Central Statistical Agency of Ethiopia), 2007. The 2007 Population and Housing Census of Ethiopia: Statistical Report for Tigray Region, Ethiopia. Darghouth, S., Ward, C., Gambarelli, G., Styger, E., Roux, J., 2008. Watershed Management Approaches, Policies, and Operations:Lessons for Scaling up. Paper No. 11. The World Bank, Washington, DC. de Mûelenaere, S., Frankl, A., Haile, M., Poesen, J., Deckers, J., Munro, N., Veraverbeke, S., Nyssen, J., 2014. Historical landscape photographs for calibration of Landsat land use/cover in the Northern Ethiopian highlands. Land Degrad. Dev. 25 (4), 319–335. Descheemaeker, K., Muys, B., Nyssen, J., Poesen, J., Raes, D., Mitiku, H., Deckers, J., 2006a. Litter production and organic matter accumulation in exclosures of the Tigray highlands, Ethiopia. For. Ecol. Manag. 233 (1), 21–35. Descheemaeker, K., Nyssen, J., Rossi, J., Poesen, J., Haile, M., Raes, D., Deckers, S., 2006c. Sediment deposition and pedogenesis in exclosures in the Tigray highlands. Geoderma 132, 291–314. Descheemaeker, K., Nyssen, J., Poesen, J., Raes, D., Mitiku, H., Muys, B., Deckers, S., 2006b. Runoff on slopes with restoring vegetation: a case study from the Tigray highlands, Ethiopia. J. Hydrol. 331 (1–2), 219–241. Dragan, M., Feoli, E., Fernetti, M., Zerihun, W., 2003. Application of a spatial decision

8. Conclusions and recommendations The main challenges of economic development in Tigray were severe natural resource degradation, which has resulted in poverty. To overcome this challenge, various efforts have been made to introduce SWC interventions. These interventions have been implemented aiming at environmental rehabilitation and improving food security. Collective evidence has shown that most of the degraded landscapes have been considerably restored. Vegetation cover, soil fertility and availability of water have increased over the last two decades. The majority of the reviewed literature confirmed that rainfed and irrigated agriculture significantly intensified after ICM interventions. SWC interventions based on ICM have become a successful programme in improving natural resources. Physical SWC measures were better in conserving moisture for crop production, while biological measures were also powerful tools to stabilise the physical structure and increase the infiltration capacity of the soil. Exclosures in the hillsides are found to be effective for rapid landscape restoration. Water harvesting structures were also integrated with ICM interventions to store water for irrigation and domestic uses. As a result of these achievements, Tigray is currently recognised as a successful case in transforming degraded lands into stable living environments. However, because of the top-down implementation approach, some of the SWC activities were not successfully adopted by the farmers. Lack of income generation from exclosures, problems of benefit sharing, low survival of the planted trees, lack of regular maintenance of existing structures, and use and management of fertilisers are important pitfalls of ICM implementation programmes. An important lesson drawn from Tigray is that all stakeholders should participate throughout the entire process of SWC, which many projects around the world lack. The main challenges of SWC implementation programmes in different countries are the lack of commitment and sense of ownership by the watershed communities. The Tigray experience can be a model implementation approach, which brings all the development partners on board at the planning phase. Moreover, the strong commitment and ownership by local government are also important success factors to reach the watershed community. SWC-based ICM has become a witness for economic and environmental rehabilitation in Tigray. This experience and achievements could be scaled out to regions with similar environmental, ecological, and socioeconomic conditions. Acknowledgements The authors would like to acknowledge the authors of the cited materials throughout this paper. Farmers and bureau of agricultural and rural development have also contributed to this paper by providing information about SWC. Many thanks go to the three anonymous reviewers for their valuable comments on an earlier version of this paper. This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors. 10

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G. Gebremeskel et al.

water conservation practices in Tigray, Ethiopia. Agriculture. Ecosyst. Environ. 105 (1), 29–40. Herweg, K., Ludi, E., 1999. The performance of selected soil and water conservation measures—case studies from Ethiopia and Eritrea. Catena 36 (1–2), 99–114. Hunting, 1974. Central Tigre Development Study, Working Paper 1. Soils and Land Classification. Hunting Technical Services, Hemel Hempstead. Hunting, 1976. Tigray Rural Development Report. Hunting Technical Service, Hemel Hempstead. Hurni, H., 1988. Degradation and conservation of soil resources in the Ethiopian highlands. Mt. Res. Dev. 8, 123–130. Hurni, H., 1993a. Soil Formation Rates in Ethiopia. Ethiopian Highlands Reclamation Study, FAO/MOA Joint Project, Working Paper No 2. Addis Ababa, Ethiopia. Hurni, H., 1993b. Land degradation, famine, and land resource scenarios in Ethiopia. In: Pimentel, D. (Ed.), World Soil Erosion and Conservation. Cambridge, pp. 27–61. Hurni, K., Zeleke, G., Kassie, M., Tegegne, B., Kassawmar, T., Teferi, E., Moges, A., Tadesse, D., Ahmed, M., Degu, Y., Kebebew, Z., Hodel, E., Amdihun, A., Mekuriaw, A., Debele, B., Deichert, G., Hurni, H., 2015. Economics of Land Degradation (ELD) Ethiopia Case Study. Soil Degradation and Sustainable Land Management in the Rainfed Agricultural Areas of Ethiopia: an Assessment of the Economic Implications. Report for the Economics of Land Degradation Initiative. pp. 94. Lacombe, G., Cappelaere, B., Leduc, C., 2008. Hydrological impact of water and soil conservation works in the Merguellil catchment of central Tunisia. J. Hydrol. 359 (3), 210–224. Lal, R., 1989. Soil management options in the tropics as alternatives to splash and bum. Soil Technol. 2, 253–270. Lanckriet, S., Araya, T., Cornelis, W., Verfaillie, E., Poesen, J., Govaerts, B., Nyssen, J., 2012. Impact of conservation agriculture on catchment runoff and soil loss under changing climate conditions in May Zeg-zeg (Ethiopia). J. Hydrol. 475, 336–349. Lanckriet, S., Araya, T., Derudder, B., Cornelis, W., Bauer, H., Govaerts, B., Deckers, J., Haile, M., Naudts, J., Nyssen, J., 2014b. Toward practical implementation of conservation agriculture: a case study in the May Zeg-Zeg Catchment (Ethiopia). Agroecol. Sustain. food Syst. 38 (8), 913–935. Lanckriet, S., Derudder, B., Naudts, J., Bauer, H., Deckers, J., Haile, M., Nyssen, J., 2014a. A political ecology perspective of land degradation in the north Ethiopian highlands. Land Degrad. Dev. 26 (5), 521–530. Lanckriet, S., Frankl, A., Mesfin, G., Descheemaeker, K., Nyssen, J., 2015a. Gully cut-andfill cycles as related to agro-management: a historical curve number simulation in the Tigray Highlands. Earth Surf. Process. Landforms 40 (6), 796–808. Lanckriet, S., Schwenninger, J.L., Frankl, A., Nyssen, J., 2015b. The late-holocene geomorphic history of the ethiopian highlands: supportive evidence from May Tsimble. Catena 135, 290–303. Lee, K.S., Chung, E.S., Kim, Y.O., 2008. Integrated watershed management for mitigating streamflow depletion in an urbanized watershed in Korea. Phys. Chem. Earth 33 (5), 382–394. Lee, K.S., Chung, E.S., 2007. Development of integrated watershed management schemes for an intensively urbanized region in Korea. J. Hydro-environment Res. 1 (2), 95–109. Legesse, D., Vallet-Coulomb, C., Gasse, F., 2003. Hydrological response of a catchment to climate and land use changes in Tropical Africa: case study South Central Ethiopia. J. Hydrol. 275 (1), 67–85. Meheretu, Y., Sluydts, V., Welegerima, K., Bauer, H., Teferi, M., Yirga, G., Mulungu, L., Haile, M., Nyssen, J., Deckers, J., Makundi, R., 2014. Rodent abundance, stone bund density and its effects on crop damage in the Tigray highlands, Ethiopia. Crop Prot. 55, 61–67. Meire, E., Frankl, A., De Wulf, A., Haile, M., Deckers, J., Nyssen, J., 2013. Land use and cover dynamics in Africa since the nineteenth century: warped terrestrial photographs of North Ethiopia. Reg. Environ. Change 13 (3), 717–737. Mekonen, K., Brhane, G., 2011. Impact assessment of soil and water conservation measures at Medego watershed in Tigray, Northern Ethiopia. Maejo Int. J. Sci. Technol. 5 (3), 312–330. Mekonen, G., Fekadu, A., 2015. Experiences and challenges of integrated watershed management in central zones of southern Ethiopia. Int. J. Curr. Res. 7 (10), 20973–20979. Mekonen, K., Tesfahunegn, G.B., 2011. Impact assessment of soil and water conservation measures at Medego watershed in Tigray, Northern Ethiopia. Maejo Int. J. Sci. Technol. 5 (3), 312–330. Mekuria, W., Aynekulu, E., 2013. Exclosure land management for restoration of the soils in degraded communal grazing lands in northern Ethiopia. Land Degrad. Dev. 24 (6), 528–538. Mekuria, W., Haile, M., Nyssen, J., Muys, B., Gebrehiwot, K., 2007. Effectiveness of exclosures to restore degraded soils as a result of overgrazing in Tigray, Ethiopia. J. Arid Environ. 69 (2), 270–284. Merla, G., Abbate, E., Azzaroli, A., Bruni, P., Canuti, P., Fazzuoli, M., Sagri, M., Tacconi, P., 1979. A Geological Map of Ethiopia and Somalia: 1973; 1: 2.000.000 and Comment with a Map of Major Landforms. University of Florence, Firenze, Italy. Mu, X., Zhang, L., McVicar, T.R., Chille, B., Gau, P., 2007. Analysis of the impact of conservation measures on stream flow regime in catchments of the Loess Plateau, China. Hydrol. Process. 21 (16), 2124–2134. Munro, N.R., Deckers, J., Mitiku, H., Grove, A.T., Poesen, J., Nyssen, J., 2008. Soil landscapes, land cover change and erosion features of the Central Plateau region of Tigray, Ethiopia: photo-monitoring with an interval of 30 years. Catena 75 (1), 55–64. Mutisya, T., Zejiao, L., Juma, N., 2010. Soil and water conservation in Kenya-Operations, achievements and challenges of the national agriculture and livestock extension programme (NALEP). J. Am. Sci. 6 (3). Muys, B., Nyssen, J., du Toit, B., Vidale, E., Prokofieva, I., Mavsar, R., Palahi, M., 2014.

support system (SDSS) to reduce soil erosion in northern Ethiopia. Environ. Model. Softw. 18, 861–868. Erkossa, T., Langan, S.J., Hagos, F., 2014. Constraints to the development, operation and maintenance of spate irrigation schemes in Ethiopia. In: Erkossa, T., Hagos, F., Lefore, N. (Eds.), Potential, Development Status, and Challenges. International Water Management Institute, Colombo, Sri Lanka, pp. 5–22. Esser, K., Vågen, T., Tilahun, Y., Mitiku, H., 2002. Soil Conservation in Tigray, Ethiopia. Noragric Report No. 5. Mekelle, Ethiopia. . FAO, 2014. Adapting to Climate Change through Land and Water Management in Eastern Africa Results of Pilot Projects in Ethiopia, Kenya and Tanzania, Rome, Italy. Frankl, A., Nyssen, J., De Dapper, M., Haile, M., Billi, P., Munro, R.N., Deckers, J., Poesen, J., 2011. Linking long-term gully and river channel dynamics to environmental change using repeat photography (Northern Ethiopia). Geomorphology 129, 238–251. Frankl, A., Poesen, J., Deckers, J., Haile, M., Nyssen, J., 2012. Gully head retreat rates in the semi-arid highlands of Northern Ethiopia. Geomorphology 173–174, 185–195. Frankl, A., Poesen, J., Haile, H., Deckers, J., Nyssen, J., 2013. Quantifying long-term changes in gully networks and volumes in dryland environments: the case of Northern Ethiopia. Geomorphology 201, 254–263. Garg, K.K., Karlberg, L., Barron, J., Wani, S.P., Rockstrom, J., 2012. Assessing impacts of agricultural water interventions in the Kothapally watershed, Southern India. Hydrol. Process. 26 (3), 387–404. Gates, J.B., Scanlon, B.R., Mu, X., Zhang, L., 2011. Impacts of soil conservation on groundwater recharge in the semi-arid Loess Plateau, China. Hydrogeol. J. 19 (4), 865–875. Gebreegziabher, T., Nyssen, J., Govaerts, B., Getnet, F., Behailu, M., Haile, M., Deckers, J., 2009. Contour furrows for in situ soil and water conservation, Tigray, Northern Ethiopia. Soil Tillage Res. 103 (2), 257–264. Gebrehiwot, T., van der Veen, A., Maathuis, B., 2011. Spatial and temporal assessment of drought in the Northern highlands of Ethiopia. Int. J. Appl. Earth Obs. Geo Inf. 13 (3), 309–321. Gebremedhin, B., Swinton, S.M., 2003. Investment in soil conservation in northern Ethiopia: the role of land tenure security and public programs. Agric. Econ. 29, 69–84. Gebremedhin, B., Swinton, S.M., Tilahun, Y., 1999. Effects of stone terraces on crop yields and farm profitability: results of on-farm research in Tigray, Northern Ethiopia. J. Soil Water Conserv. 54 (3), 568–573. Gebremichael, D., Nyssen, J., Poesen, J., Deckers, J., Haile, M., Govers, G., Moeyersons, J., 2005. Effectiveness of stone bunds in controlling soil erosion on cropland in the Tigray Highlands, northern Ethiopia. Soil Use Manag. 21 (3), 287–297. Gebreyohannes, T., De Smedt, F., Walraevens, K., Gebresilassie, S., Hussien, A., Hagos, M., Gebrehiwot, K., 2013. Application of a spatially distributed water balance model for assessing surface water and groundwater resources in the Geba basin, Tigray, Ethiopia. J. Hydrol. 499, 110–123. German, L., Mansoor, H., Alemu, G., Mazengia, W., Amede, T., Stroud, A., 2007. Participatory integrated watershed management: evolution of concepts and methods in an Ecoregional program of the eastern African highlands. Agric. Syst. 94 (2), 189–204. German, L., Taye, H., Charamila, S., 2006. The Many Meanings of Collective Action: Lessons on Enhancing Gender Inclusion and Equity in Watershed Management. CAPRi Working Paper No. 52. International Food Policy Research Institute, Washington, DC, USA. Girmay, G., Singh, B.R., Nyssen, J., Borrosen, T., 2009. Runoff and sediment-associated nutrient losses under different land uses in Tigray, Northern Ethiopia. J. Hydrol. 376 (1–2), 70–80. Hadgu, K.M., Rossing, W.A.H., Kooistra, L., van Bruggen, A.H.C., 2009. Spatial variation in biodiversity, soil degradation and productivity in agricultural landscapes in the highlands of Tigray, northern Ethiopia. Food Sec 1, 83–97. Hagos, E.Y., Schultz, B., Depeweg, H., 2016. Reservoir operation in view of effective utilization of limited water in semi-arid areas, the case of gumsalasa earthen dam irrigation scheme in Tigray, Ethiopia. Irrigat. Drain. 65 (3), 294–307. Hagos, F., Pender, J., Gebreselassie, N., 1999. Land Degradation in the Highlands of Tigray and Strategies for Sustainable Land Management. Socioeconomic and Policy Research Working Paper 25. ILRI, Addis Ababa, Ethiopia. Haile, M., Herweg, K., Stillhardt, B., 2006. Sustainable Land Management–A New Approach to Soil and Water Conservation in Ethiopia. Land Resources Management and Environmental Protection Department, Mekelle University; Bern, Switzerland: Centre for Development and Environment (CDE), University of Bern, and Swiss National Centre of Competence in Research (NCCR) North-South, Mekelle, Ethiopia, pp. 269. Haregeweyn, N., Poesen, J., Deckers, J., Nyssen, J., Haile, M., Govers, G., Verstraeten, G., Moeyersons, J., 2008a. Sediment-bound nutrient export and associated costs from micro-dam catchments of Northern Ethiopia. Land Degrad. Dev. 19, 136–152. Haregeweyn, N., Berhe, A., Tsunekawa, A., Tsubo, M., Meshesha, D.T., 2012. Integrated watershed management, an effective approach to curb land degradation: a case study of the Enaberied watershed, northern Ethiopia. J. Environ. Manag. 50, 1219–1233. Haregeweyn, N., Poesen, J., Nyssen, J., De Wit, J., Haile, M., Govers, G., Deckers, S., 2006. Reservoirs in Tigray (Northern Ethiopia): characteristics and sediment deposition problems. Land Degrad. Dev. 17 (2), 211–230. Haregeweyn, N., Poesen, J., Nyssen, J., Govers, G., Verstraeten, G., de Vente, J., Deckers, J., Moeyersons, J., Haile, M., 2008b. Sediment yield variability in Northern Ethiopia: a quantitative analysis of its controlling factors. Catena 75 (1), 65–76. Haregeweyn, N., Tsunekawa, A., Nyssen, J., Poesen, J., Tsubo, M., Meshesha, D.T., Schutt, B., Adgo, E., Tegegne, F., 2015. Soil erosion and conservation in Ethiopia: a review. Prog. Phys. Geogr. 1–25. Hengsdijk, H., Meijerink, G., Mosugu, M., 2005. Modeling the effect of three soil and

11

Journal of Arid Environments xxx (xxxx) xxx–xxx

G. Gebremeskel et al.

intertwining interventions: the case of rainwater harvesting and food-for-work in Degua Temben, Tigray, Ethiopia'. Int. J. Agric. Sustain. 6 (3), 173–182. Shi, Z., Ai, L., Fang, N., Zhu, H., 2012. Modeling the impacts of integrated small watershed management on soil erosion and sediment delivery: a case study in the Three Gorges Area, China. J. hydrol. 439, 156–167. Shi, Z.H., Cai, C.F., Ding, S.W., Wang, T.W., Chow, T.L., 2004. Soil conservation planning at the small watershed level using RUSLE with GIS: a case study in the Three Gorge Area of China. Catena 55 (1), 33–48. Sikka, A.K., Madhu, M., Selvi, V., Jeevarathanam, K., Chand, S., Singh, D.V., 2002. Participatory watershed management: a case study of Salaiyur watershed in Coimbatore, India. In: 12th ISCO Conference, Beijing, China. Smith, P., 1999. Participatory soil and water conservation in India-Experinces from Kribcho Indo-British rainfed prokect. In: Paper Presented at the 10th International Conference on Soil and Water Conservation, May 24-29. Purdue University, UK. Sulas, F., Marco, M., Charles, F., 2009. State formation and water resources management in the Horn of Africa: the Aksumite Kingdom of the northern Ethiopian highlands. World Archaeol. 41 (1), 2–15. Taye, G., Poesen, J., Wesemael, B.V., Vanmaercke, M., Teka, D., Deckers, J., Goosse, T., Maetens, W., Nyssen, J., Hallet, V., Haregeweyn, N., 2013. Effects of land use, slope gradient, and soil and water conservation structures on runoff and soil loss in semiarid Northern Ethiopia. Phys. Geogr. 34 (3), 236–259. Taye, G., Poesen, J., Vanmaercke, M., van Wesemael, B., Martens, L., Teka, D., Nyssen, J., Deckers, J., Vanacker, V., Haregeweyn, N., Hallet, V., 2015. Evolution of the effectiveness of stone bunds and trenches in reducing runoff and soil loss in the semi-arid Ethiopian highlands. Z. für Geomorphol. 59 (4), 477–493. Teka, D., van Wesemael, B., Vanacker, V., Poesen, J., Hallet, V., Taye, G., Deckers, J., Haregeweyn, N., 2013. Evaluating the performance of reservoirs in semi-arid catchments of Tigray: tradeoff between water harvesting and soil and water conservation. Catena 110, 146–154. Teklehaimanot, A., 2006. Analysis of Social Economic and Institutional Issues Affecting Utilization of Rainwater Harvesting Technology, Eastern Tigray, Ehiopia. MSc Thesis School of Graduate Studies. Alemaya University, Ethiopia, pp. 162. Tesfay, G., Mitiku, H., Girmay, G., Araya, A., Daniel, T., Wubetu, B., Dereje, A., 2011. Onfarm Water Harvesting for Rain Fed Agriculture Development and Food Security in Tigray, Northern Ethiopia. Drylands Coordination Group Report. 61. Oslo, Norway. . Tesfaye, G., Assefa, A., Kidane, D., 2016. Runoff, sediment load and land use/cover change relationship: the case of Maybar sub-watershed, South Wollo, Ethiopia. Int. J. River Basin Manag. 1–13. Tiffen, M., Mortimore, M., 1994. Environment, Population Growth and Productivity in Kenya: a Case Study of Machakos District. International Institute for Environment and Development Working paper No. 47. van der Veen, A., Tagel, G., 2011. Effect of policy interventions on food security in Tigray, Northern Ethiopia. Ecol. Soc. 16 (1), 18. Virgo, K.J., Munro, R.N., 1977. Soil and erosion features of the central plateau region of Tigray, Ethiopia. Geoderma 20 (2), 131–157. Walraevens, K., Gebreyohannes Tewolde, T., Amare, K., Hussein, A., Berhane, G., Baert, R., Ronsse, S., Kebede, S., Van Hulle, L., Deckers, J., Martens, K., 2015. Water balance components for sustainability assessment of groundwater-dependent agriculture: example of the mendae plain (Tigray, Ethiopia). Land Degrad. Dev. 26 (7), 725–736. Walraevens, K., Vandecasteele, I., Martens, K., Nyssen, J., Moeyersons, J., Gebreyohannes, T., De Smedt, F., Poesen, J., Deckers, J., Van Camp, M., 2009. Groundwater recharge and flow in a small mountain catchment in northern Ethiopia. Hydrol. Sci. J. 54 (4), 739–753. Wani, S.P., Singh, H.P., Sreedevi, T.K., Pathak, P., Rego, T.J., Shiferaw, B., Iyer, S.R., 2003. Farmer-participatory integrated watershed management: Adarsha watershed, Kothapally India-an innovative and upscalable approach. J. SAT Agric. Res. 2 (1), 1–27. WFP (World Food Programme), 2012. Ethiopian Village Recognized at Rio+20 for Innovative Hunger Solution, Retrieved in November, 2015. http://www.wfp.org. Wondumagegnehu, F., Tsegay, A., Ashebir, D., Tekie, H., Gebre, A., Kiros, M., Deckers, J., 2007. Household Water Harvesting Structures in Geba Catchment. Tigray Livelihood Papers. pp. 5. Yami, M., Gebrehiwot, K., Moe, S., Mekuria, W., 2007. Impact of area enclosures on density and diversity of large wild mammals: the case of May Ba’ati, Douga Tembien district, Central Tigray, Ethiopia. East Afr. J. Sci. 1, 55–68. Zeleke, G., Bewke, W., Alemu, D., Tibebu, K., Venusia, G., Cyriaque, M., 2014. Transforming Environment and Rural Livelihoods in Ethiopia: Best Practices and Principles of MERET Project and its Future Strategic Orientation. Water and Land Resource Centre (WLRC) and Centre for Development and Environment (CDE), University of Bern, Germany. Zenebe, A., Vanmaercke, M., Poesen, J., Verstraeten, G., Haregeweyn, N., Haile, M., Amare, K., Deckers, J., Nyssen, J., 2013. Spatial and temporal variability of river flows in the degraded semi-arid tropical mountains of northern Ethiopia. Z. für Geomorphol. 57 (2), 143–169. Zhang, Y., Guo, S., Liu, Q., Jiang, J., Wang, R., Li, N., 2015. Responses of soil respiration to land use conversions in degraded ecosystem of the semi-arid Loess Plateau. Ecol. Eng. 74, 196–205. Zhao, G., Mu, X., Wen, Z., Wang, F., Gao, P., 2013. Soil erosion, conservation, and ecoenvironment changes in the loess plateau of China. Land Degrad. Dev. 24 (5), 499–510.

Water-related ecosystem services of forests: learning from regional cases. In: Forests under Pressure: Local Responses to Global Issues. International Union of Forest Research Organizations (IUFRO) World Series 32, 423–440, Vienna, Austria. Nana-Sinkam, S.C., 1995. Land and Environmental Degradation and Desertification in Africa. Joint ECA/FAO Agriculture Division, Rome, Italy. Negusse, T., Yazew, E., Tadesse, N., 2013. Quantification of the impact of integrated soil and water conservation measures on groundwater availability in Mendae catchment, Abraha Atsebaha, eastern Tigray, Ethiopia. Momona Ethiop. J. Sci. 5 (2), 117–136. Neto, A.D.C.L., Legey, L.F., González-Araya, M.C., Jablonski, S., 2006. A system dynamics model for the environmental management of the Sepetiba Bay watershed, Brazil. Environ. Manag. 38 (5), 879–888. Nyssen, J., Poesen, J., Moeyersons, J., Haile, M., Deckers, J., 2008b. Dynamics of soil erosion rates and controlling factors in the Northern Ethiopian Highlands: towards a sediment budget. Earth Surf. Process. Landforms 33 (5), 655–711. Nyssen, J., Clymans, W., Descheemaeker, K., Poesen, J., Vandecasteele, I., Vanmaercke, M., Haregeweyn, N., 2010. Impact of soil and water conservation measures on catchment hydrological response-a case in north Ethiopia. Hydrol. Process. 24, 1880–1895. Nyssen, J., Clymans, W., Poesen, J., Vandecasteele, I., Baets, S.D., Haregeweyn, N., Naudts, J., Hadera, A., Moeyersons, J., Haile, M., Deckers, J., 2009b. How soil conservation affects the catchment sediment budget a comprehensive study in the north Ethiopian highlands. Earth Surf. Process. Landforms 34 (9), 1216–1233. Nyssen, J., Frankl, A., Haile, M., 2014. Environmental conditions and human drivers for changes to north Ethiopian mountain landscapes over 145 years. Sci. Total Environ. 485–486, 164–179. Nyssen, J., Frankl, A., Zenebe, A., Deckers, J., Poesen, J., 2015. Land management in the northern Ethiopian highlands: local and global perspectives; past, present and future. Land Degrad. Dev. 26 (7), 759–764. Nyssen, J., Govaerts, B., Araya, Tesfay, Cornelis, W.M., Bauer, H., Haile, Mitiku, Sayre, K., Deckers, J., 2011. The use of the marasha ard plough for conservation agriculture in Northern Ethiopia. Agron. Sustain. Dev. 31 (2), 287–297. Nyssen, J., Mitiku, H., Moeyersons, J., Poesen, J., Deckers, J., 2000. Soil and water conservation in Tigray (Northern Ethiopia): the traditional dagat technique and its integration with introduced techniques. Land Degrad. Dev. 11 (3), 199–208. Nyssen, J., Poesen, J., Veyret-Picot, M., Moeyersons, J., Haile, M., Deckers, J., Dewit, J., Naudts, J., Teka, K., Govers, G., 2006. Assessment of gully erosion rates through interviews and measurements: a case study from northern Ethiopia. Earth Surf. Process Landforms 31 (2), 167–185. Nyssen, J., Poesen, J., Deckers, J., 2009c. Land degradation and soil and water conservation in tropical highlands. Soil Tillage Res. 103 (2), 197–202. Nyssen, J., Poesen, J., Haile, M., Moeyersons, J., Deckers, J., Hurni, H., 2009d. Effects of land use and land cover on sheet and rill erosion rates in the Tigray highlands, Ethiopia. Z. für Geomorphol. 53 (2), 171–197. Nyssen, J., Poesen, J., Gebremichael, D., 2007. Interdisciplinary on-site evaluation of stone bunds to control soil erosion on cropland in northern Ethiopia. Soil Tillage Res. 94 (1), 151–163. Nyssen, J., Vandenreyken, H., Poesen, J., Moeyersons, J., Deckers, J., Haile, M., Govers, G., 2005. Rainfall erosivity and variability in the northern ethiopian highlands. J. Hydrol. 311 (1), 172–187. Nyssen, J., Veyret-Picot, M., Poesen, J., Moeyersons, J., Haile, M., Deckers, J., Govers, G., 2004. The effectiveness of loose rock check dams for gully control in Tigray. Soil Use Manag. 20 (1), 55–64. Nyssen, J., Haile, M., Naudts, J., Munro, N., Poesen, J., Moeyersons, J., Frankl, A., Deckers, J., Pankhurst, R., 2009a. Desertification? Northern Ethiopia re-photographed after 140 years. Sci. Total Environ. 407 (8), 2749–2755. Nyssen, J., Poesen, J., Descheemaeker, K., Haregeweyn, N., Haile, M., Moeyersons, J., Frankl, A., Govers, G., Munro, N., Deckers, J., 2008a. Effects of region-wide soil and water conservation in semi-arid areas: the case of northern Ethiopia. Z. für Geomorphol. 52 (3), 291–315. Osman, M., Sauerborn, P., 2001. Soil and water conservation in Ethiopia experiences and lessons. Soils Sediment 1 (2), 117–123. Pender, J., Gebremedhin, B., 2008. Determinants of agricultural and land management practices and impacts on crop production and household income in the highlands of Tigray, Ethiopia. J. Afr. Econ. 17 (3), 395–450. Phomcha, P., Wirojanagud, P., Vangpaisal, T., Thaveevouthti, T., 2011. Predicting sediment discharge in an agricultural watershed: a case study of the Lam Sonthi watershed. Thail. Sci. Asia 37, 43–50. Pimentel, D., 1993. World Soil Erosion and Conservation. Cambridge University Press, Cambridge, England, pp. 349. Rahmato, D., Pankhurst, A., van Uffelen, J.G. (Eds.), 2013. Food Security, Safety Nets and Social Protection in Ethiopia. African Books Collective. Forum for Social Studies, Addis Ababa, Ethiopia. Reubens, B., Poesen, J., Nyssen, J., Leduc, Y., Abraha, A.Z., Tewoldeberhan, S., Bauer, H., Gebrehiwot, K., Deckers, J., Muys, B., 2009. Establishment and management of woody seedlings in gullies in a semi-arid environment (Tigray, Ethiopia). Plant Soil 324 (1–2), 131–156. Ruthenberg, H., 1974. Farming Systems in the Tropics. Clarendon press, Oxford, USA. Segers, K., Dessein, J., Hagberg, S., Develtere, P., Haile, M., Deckers, J., 2008a. Be like bees – the politics of mobilizing farmers for development in Tigray, Ethiopia. Afr. Aff. 1–19. Segers, K., Dessein, J., Nyssen, J., Haile, M., Deckers, J., 2008b. 'Developers and farmers

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