- Email: [email protected]
GWP-SA symposium: Water and sustainable development for improved livelihoods
Physics and Chemistry of the Earth 34 (2009) 707–710
Contents lists available at ScienceDirect
Physics and Chemistry of the Earth journal homepage: www.elsevier.com/locate/pce
Editorial
9th WaterNet/WARFSA/GWP-SA symposium: Water and sustainable development for improved livelihoods
1. Introduction
2. Hydrology Sub-Theme
This special issue contains selected and peer reviewed papers which were presented during the 9th annual symposium organized by WaterNet, Water Research Fund for Southern Africa (WARFSA), and Global Water Partnership Southern Africa (GWP-SA), and held in Johannesburg, 29–31 October 2008. This symposium attracted participants from east and southern Africa, and other parts of the world, and had ‘‘Water and Sustainable Development for Improved Livelihoods” as the theme. The symposium has become an annual event providing researchers, policy makers, and water resources planners and managers opportunities for sharing ideas on capacity building in implementing integrated water resources management approaches. Papers in this special issue have been grouped following the sub-themes of the symposium which were:
Papers in this sub-theme are mainly investigating models or modelling approaches for overcoming limitations arising from lack of adequate hydrological data for water resources analysis. Lack of adequate hydrological data for water resources planning and management is a major problem in the east and southern Africa region. The WaterNet/WARFSA/GWP-SA Annual Symposium has had each year a special session on the Predictions in Ungauged Basins, which is a research agenda of the International Association of Hydrological Sciences. Previous papers in this journal have also investigated possible solutions for overcoming this problem (Mazvimavi et al., 2005; Nyabeze, 2005; Parida et al., 2006). Satellite imagery has the potential to provide much needed data for water resources planning and management. Two papers in this sub-theme, Onema et al. and Munyaneze et al. are investigating the potential for quantifying hydrological variables using data derived from satellite images. Onema et al. investigated use of the normalized difference vegetation index (NDVI) to estimate monthly rainfall on the Semliki Basin located in the humid equatorial region between the Democratic Republic of Congo and Uganda. On a month to month basis, NDVI was weakly correlated to monthly rainfall on some of the sub-basins. A high correlation existed between monthly rainfall and NDVI with a 1-month lag. This reflects that the state of vegetation is a reflection of the influence of rainfall during the previous month. The strength of the relationship between NDVI and rainfall was found to vary in space. Basins at different elevation levels had different correlation between NDVI and rainfall. It is likely that topography has an influence on the NDVI – rainfall relationship due to the variation of vegetation type with altitude and soil types (Grist et al. 1997; du Pleiss, 1999). Munyaneza et al. related satellite derived lake levels to those obtained from bathymetric studies of Lake Kivu which is located between the Democratic Republic of Congo and Rwanda. Both ENVISAT and ER-2 derived lake levels were positively related to gauged lake levels with the coefficient of determination being 0.86 and 0.77, respectively, while the standard error was 0.642 m and 0.701 m, respectively. This study demonstrated that satellite altimetry can be used for monitoring changes in available water in lakes. A major problem in rainfall–runoff modelling is estimating model parameter values that are physically meaningful. Some
Hydrology Water and Environment Water and Land Water for People Water for Society Water Resources Management There are however no papers that were considered for publication under the Water Resources Management Sub-Theme. The Editorial highlights important findings of the papers in this issue and attempts to point out some of the research gaps. Where the name of the author appears in this Editorial without the year of publication, this means the paper being referred to is in this special issue. There is an increasing number of papers investigating the potential for using satellite imagery for water resources planning. This is a welcome development particularly in the east and southern Africa region where there is generally inadequate data to accurately represent temporal and spatial variations of aspects of water resources. Contamination of water due to lack of sanitation and mining operations is a major problem in the east and southern Africa region, and this is reflected by several papers in this issue exploring methods for removing some of the contaminants. Understanding issues that affect access to water and water-related resources especially in rural areas is another topical issue examined by some of the papers.
1474-7065/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.pce.2009.08.002
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Editorial / Physics and Chemistry of the Earth 34 (2009) 707–710
modellers argue for manual calibration based on an understanding of the structure of the model and hydrological processes dominant on a particular basin. This approach has the risk of being subjective leading in some cases to over- or under-estimation of the importance of some of the hydrological processes. In addition the existence of equifinality of model parameters creates a problem in determining model parameter values that are physically relevant. Ndirutu has compared the performance of automatic and manual calibration of model parameters on basins in South Africa and Zambia. The results of the study did not prove that automatic calibration performed better than manual calibration. Ndirutu recommends a combination of manual and automatic calibration with manual calibration being used to set the physically realistic range of model parameter values followed by automatic calibration. 3. Water and the Environment Sub-Theme The papers in this sub-theme have mainly focused on using satellite imagery for estimating water quality factors in a lake. The motivation of these studies has again been to overcome problems arising from the lack of adequate hydrological data. Chavula et al. (a) investigated the prediction of temperatures of surface waters in Lake Malawi using Advance High Resolution Radiometer (AVHRR) and Moderate Resolution Spectroradiometer (MODIS) imagery. Lake surface temperature was predicted with a coefficient of determination of 0.74 from the Terra/MODIS Ocean Colour data. The study revealed the existence of complex circulation patterns within Lake Malawi. Chavula et al. (b) made a second study to predict chlorophyll concentration in Lake Malawi from MODIS satellite imagery. The predicted chlorophyll concentrations were generally six times more than values obtained through in situ measurements. This poor prediction of chlorophyll concentration could be due to the predictive equation used being inapplicable to oligotrophic lakes such as Lake Malawi. In situ measurements of chlorophyll concentrations were made at a location close to the shore. There is a possibility that the in situ measurements were not representative of chlorophyll concentration at a large scale reflected on satellite imagery. Further studies with data collected at spatially more representative sites need to be carried out to fully explore the feasibility of using satellite imagery for estimating chlorophyll concentration. 4. Water and Land Sub-Theme The main focus of the papers in the Water and Land Sub-Theme has been on rainwater harvesting which is being promoted for water conservation particularly in semi-arid and arid regions. The papers have attempted to quantify potential hydrological and economic impacts of rainwater harvesting. Kahinda et al. examined the likely impacts of rainwater harvesting on runoff on river basins in South Africa. The study assumed that increasing the spatial coverage of rainwater harvesting within a basin will cause changes to values of the Pitman rainfall–runoff model relating to interception, soil moisture storage capacity, and minimum absorption rate. The study assumed that specific increases in the spatial coverage of rainwater harvesting will result in specific changes in values to the Pitman model. The estimation of the hydrological impact of rainwater harvesting was therefore based on comparing simulations based on different model parameter values. What is uncertain is whether the assumed changes in the Pitman model parameter values realistically represent the effect of rainwater harvesting. The study by Ndirutu has shown that physical interpretation of some of the Pitman model parameter values is questionable. Further studies aimed at understanding hydrological impacts of rainwater harvesting are therefore called for.
Zimmerman et al. compared in monetary terms using the discounted cash flow method the performance of rainwater harvesting with that of the public water reticulation system in rural northern Namibia. The study estimated the average annual volume of water which can be harvested from roofs per homestead. Using the price of water from local vendors, the study established that the investment in roof harvesting is amortised within the fifth year at a discount rate of 3%. The roof harvesting technique was considered to be the most economically efficient. The rainwater harvesting system also offered opportunities for engaging in vegetable gardening. Studies that investigate both the hydrological and economic impacts of water conservation techniques that are popularly promoted should be encouraged so that those adopting these approaches will fully understand both the benefits and costs. 5. Water for People Sub-Theme Papers under this sub-theme cover four areas, namely groundwater treatment, treatment of contaminated mining effluent, removal of disinfection by-products in drinking water, and microbial health risks at water abstraction points. Pritchard et al. investigated the potential of using plant extracts for purification of water from shallow wells in Malawi. This is an innovative approach since there has been very little scientific research work into the use of plant extracts to purify groundwater. Water from shallow wells is commonly used throughout Africa and in some cases is contaminated and consumed untreated. The study investigated some of the most promising plant extracts, namely Moringa oleifera, Jatropha curcas and Guar gum. The results showed that the addition of M. oleifera, J. curcas and Guar gum considerably improved the quality of water from shallow wells. Overall, M. oleifera powder produced superior results, seconded by Guar Gum and lastly J. curcas. There is a need to explore other plants that are readily available in different countries. To ensure public safety, further research could also focus on investigating any toxic effects of these plant extracts. Contaminated mining effluent remains a major problem in Africa. Fosso-Kankeu et al. investigated the reduction of metal loads in surface waters around mining areas using indigenous microorganism strains in South Africa. The experiments aimed to achieve acceptable minimum concentration levels of excess calcium, iron and magnesium in surface waters around mining areas using indigenous strains of Shewanella sp., Bacillus subtilis sp. and Brevundimonas sp. B. subtilis and Shewanella sp. absorbed the highest amount (14% Ca, 8% Mg and 8% Fe) of each of the three metals recorded from solutions containing the metals at 30 ppm concentration, with calcium being the most easily removed metal species. Metal removal from solution decreased when their concentrations in solution was at 50 ppm. The studies revealed that the combination of these metals in one solution affected the microorganisms’ affinity for the metals thus reducing their removal efficiency. There was also a tendency for microorganisms to release the absorbed metal into solution after a certain period of time, most probably due to an efflux transport mechanism. On a related topic Mamba et al. also investigated heavy metal removal from contaminated small-scale mining effluent using clinoptilolite and bacteria. The removal of As, Ni, Mn, Au, Co, Cu and Fe was investigated on mine water samples using original and HCl-activated (in 0.02 M and 0.04 M) natural clinoptilolite and bacterial strains. Both clinoptilolite and bacteria demonstrated capabilities of removing Cu2+, Co2+, Fe2+, Mn2+, As3+ and Au from solution which augurs well for metal recovery from mining and mineral processing solutions, as well in water decontamination. In yet another paper, Mamba et al. investigated the biosorptive removal of copper and cobalt from aqueous solutions by Shewanella sp. At optimum concentration (0.002 M/ 3.86 g l 1), biosorbent dosage (150 104 CFU/ml) and solution
Editorial / Physics and Chemistry of the Earth 34 (2009) 707–710
pH 6.5, Shewanella sp. recorded maximum copper and cobalt uptakes of 38% and 27%, respectively. The kinetic data obtained at different concentrations suggested that the biosorption rate was fast and in most cases the biosorption took place within 8 h followed by a slow attainment of equilibrium and the Langmuir sorption model fitted the data well with very high correlation (>0.95). These studies showed that there is a potential to use microorganisms and other low-cost chemical methods to treat contaminated waters, thus giving an effective and environmentally friendly way of remedying contaminated sites in Africa. It would be interesting if further studies could be spread to heavy metals and other chemicals related to contaminated sites in the mining industries. Other critical elements in groundwater are fluorine as discussed by Musonda et al. (2007) in the case of Malawi, coliforms in Malawi (Mkandawire, 2008; Pritchard et al., 2008), and iron in Zimbabwe (Hoko, 2008). Mhlongo et al. monitored the prevalence of nitrosamines, especially N-nitrosodimethylamine (NDMA), in three South African water supply systems and investigated their removal using cyclodextrin polyurethanes. A disinfection by-product and potent carcinogen, NDMA has recently been detected in many drinking water supplies internationally (Richardson, 2005). Trace amounts of NDMA were detected at one of the water treatment plants and in the distribution network in South Africa. The application of water-insoluble cyclodextrin (CD) polymers in the removal of nitrosamines and potential amine precursors from the water samples was tested. Quantitative removal of NDMA (based on peak area) from the water samples was achieved. Findings from this study show that there is a need to explore other less costly and environmentally safe methods of disinfection such as solar disinfection (Murinda and Kraemer, 2008), and plant extracts as discussed by Pitchard et al. in this issue and Nkurunziza et al. (2009). The occurrence of various disinfection by-products of chlorine such as trihalomethanes (THM) and haloacetic acids presents a potential health hazard. Abdullah et al. examined the relationship between water quality parameters in raw water with chlorine demand and the formation of disinfection by-products in a water treatment system in Malaysia. They developed statistical models for the prediction of chlorine demand and the THM formation. The models developed have the potential to be used for managing quality of drinking water and operation of water treatment systems. The treatment of runoff rarely receives attention yet it is a major source of drinking water in rural areas. Rianawati and Balasubramaniam presents a simple and rapid solid-phase microextraction (SPME) method coupled with gas chromatography–mass spectrometry (GC–MS) for the quantitative determination of 16 polycyclic aromatic hydrocarbons (PAHs) in rainwater and stormwater samples. The method developed has the potential to reduce the costs of analysing critical elements in drinking water. The evaluation of microbial health risk at water abstraction points in rural Kenya with the Observed Adverse Effect Level (OAEL) approach was conducted by Yillia et al. They applied models for recreational water quality to characterize the potential health risk (PHR) of infection with gastroenteritis (GI) and highly credible gastroenteritis (HCGI) illnesses from single exposure at several water abstraction points (WAP) along the Njoro River in rural Kenya. The contamination levels were quite high and this would necessitate treatment of drinking and implementation of comprehensive catchment management measures to protect WAPs and the entire stream. 6. Water and Society Sub-Theme Papers within the Water and Society Sub-Theme are focusing on access to water for irrigation (Kemerink et al.), wetland resources
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(Magole and Magole) and potable water (Makoni et al.). Kemerink et al. investigated the socio-political and biophysical factors affecting access to water by farmers at small-scale irrigation schemes established during the 1930s within the Makanye River basin in Tanzania. Membership to the irrigation scheme and water allocation was initially decided through traditional rules by the chief during the colonial period, then by government as part of the socialist system, and after the introduction of the multi-party system during the 1990s by elected representatives. Upstream irrigation schemes were found to be abstracting water without taking into account the needs for the downstream schemes. However, conflicts over water allocation between upstream and downstream schemes were minimized through some farmers having plots on both the upstream and downstream schemes. Within each of the schemes, water allocation to specific zones was decided by elected representatives. Well connected farmers were found to have an advantage during water allocation. Kemerink et al. established that despite the existence of a water allocation committee which was supposed to solve any disputes relating to water allocation, other structures such as traditional elders and factors like gender influenced the composition of water allocation committees and dispute resolution. Kemerink et al. therefore advocate for the consideration of the different social structures and factors in developing mechanisms for water allocation and resolving disputes that may arise. Magole and Magole examined the views of different stakeholders towards the ownership and benefits arising from the Okavango Delta in Botswana. The Okavango Delta region was in 1964 wholly under communal tenure, but this had decreased to 41% by 2008. The decrease was through land being allocated to a game reserve and wildlife management areas. Inhabitants of areas under communal tenure derive their livelihoods from the delta through flood recession cultivation, fishing, harvesting of aquatic plants and veld products, livestock watering and grazing. The reduction in the area under communal tenure has therefore decreased their access to natural resources within the delta. The land that has been set aside for the game reserve and wildlife management is being used for tourism which Magole and Magole contend that this benefits mostly the private sector, particularly internationally owned companies. Although local communities are involved in tourism in some parts of the delta as part of the community based natural resources management programme, most of the enterprises that the communities engage in are in partnership with the private sector. The views of the stakeholders with regards to ownership and benefits from the Okavango Delta were analysed by Magole and Magole from outputs of a public debate. Representatives of government were of the view that the Okavango Delta belonged to all the stakeholders comprising local inhabitants, and all citizens of Botswana. Representatives of local inhabitants had no clear answer to this issue as they considered themselves to be the primary stakeholders, but they perceived that they are being marginalized from utilizing the delta. The study by Magole and Magole raises fundamental questions regarding the sustainability of measures for managing the Okavango Delta. If those who have historically lived on valued ecosystems such as wetlands perceive that they are being marginalized by measures aimed at conserving these ecosystems, can these measures be considered to be sustainable. Kgathi et al. (2007) established that the Okavango Delta provided opportunities for inhabitants of this region to cushion themselves from natural shocks such as droughts and dessication of channels. What is not known is how these management measures have affected the resilience of local communities to these shocks. The growth of tourism in Botswana is a national objective for diversification of the economy. Issues that need further studies are the impacts of tourism on livelihoods at the local level. Management of future development of the Okavango Basin will benefit from information on how
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Editorial / Physics and Chemistry of the Earth 34 (2009) 707–710
nationally, regionally and internationally justifiable measures for managing ecosystems impact on rural livelihoods at the local level. 7. Conclusions Presenters of papers during the 9th WaterNet/WARFSA/GWPSA Symposium were invited to submit their papers to be peer reviewed for possible publication in this issue. In comparison to previous symposia, there has been a decrease in the number of papers which were submitted for possible publication in this issue. Van der Zaag (2007) analysed the growth in both the number of papers presented during the WaterNet/WARFSA/GWP-SA symposia, and published in the Physics and Chemistry of the Earth. The number of papers published grew from 33 in 2001 to a peak of 52 papers in 2007. However, this current issue of the Physics and Chemistry of the Earth has 23 papers which is a major decline. The decline in the number of papers is most probably due to a reduction in research being carried out in some of the countries in the east and southern Africa region. This reduction is due to WARFSA having been non-operational during the last 4 years. WARFSA had become a major source of funds for researchers within the Southern Africa Development Community (SADC) region, and was funding over 70 research projects (van der Zaag, 2007). With the exception of South Africa, other SADC countries do not have research funds specifically dedicated to water issues. WaterNet and WARFSA were conceived as being complementary, with WaterNet concentrating on training, but part of the training in research was facilitated through WARFSA funding. We strongly recommend that funding agencies, the SADC Secretariat and the SADC Council of Ministers responsible for water to revive WARFSA since research is an integral part of capacity building within the water sector. The development of innovative and relevant solutions to water resources management in the SADC region should be based on research outputs that have been peer reviewed to international standards. References du Pleiss, W.P., 1999. Linear regression relationships between NDVI, vegetation and rainfall in Etosha National Park, Namibia. Arid Environments 42, 235–260. Grist, J., Nicholoson, S.E., Mpolokang, A., 1997. On the use of NDVI for estimating rainfall fields in the Kalahari of Botswana. Arid Environments 35, 195–214. Hoko, Z., 2008. An assessment of quality of water from boreholes in Bindura District, Zimbabwe. Physics and Chemistry of the Earth 33, 824–828. Kgathi, D.L., Ngwenya, B.N., Wilk, J., 2007. Shocks and rural livelihoods in the Okavango Delta, Botswana. Development Southern Africa 4, 289–308.
Mazvimavi, D., Meijerink, A.M.J., Savenije, H.H.G., Stein, A., 2005. Prediction of flow characteristics using multiple regression and neural network: a case study in Zimbabwe. Physics and Chemistry of the Earth 30, 639–647. Musonda, K.W.M., Masamba, W.R.L., Fabiano, E., 2007. A case study of fluoride groundwater occurrence in Nathenje, Lilongwe, Malawi. Physics and Chemistry of the Earth 32, 1178–1184. Mkandawire, T., 2008. Quality of groundwater from shallow wells of selected villages in Blantyre District, Malawi. Physics and Chemistry of the Earth 33, 807–811. Murinda, S., Kraemer, S., 2008. The potential of solar water disinfection as a household water treatment method in periurban Zimbabwe. Physics and Chemistry of the Earth 33, 829–8232. Nkurunziza, T., Nduwayezu, J.B., Banadda, E.N., Nhapi, I., 2009. The effect of turbidity levels and Moringa oleifera concentration on the effectiveness of coagulation in water treatment. IWA Water Science and Technology 59 (8), 1551–1558. Nyabeze, W.R., 2005. Calibrating a distributed model to estimate runoff for ungauged catchments in Zimbabwe. Physics and Chemistry of the Earth 30, 625–633. Parida, B.P., Moalafhi, D.B., Kenabatho, P.K., 2006. Forecasting runoff coefficients using ANN for water resources management: the case of Notwane catchment in eastern Botswana. Physics and Chemistry of the Earth 31, 928–933. Pritchard, M., Mkandawire, T., O’Neill, J.G., 2008. Assessment of groundwater quality in shallow wells within the southern districts of Malawi. Physics and Chemistry of the Earth 33, 812–823. Richardson, S.D., 2005. New disinfection by-product issues: emerging DBPS and alternative routes of exposure. Global NEST Journal 7 (1), 43–60. van der Zaag, P., 2007. The impact of regional water resources capacity building: citations of the published proceedings of the annual WaterNet/WARFSA/GWPSA symposia in Southern Africa, 2001–2005. Physics and Chemistry of the Earth 32, 971–975.
Dominic Mazvimavi Department of Earth Sciences, University of the Western Cape, Private Bag X17, Bellville, 7535 Cape Town, South Africa Tel.: +27 21 959 2871; fax: +27 21 959 2438 E-mail address: [email protected] Innocent Nhapi WaterNet Secretariat, P.O. Box MP 600, Mount Pleasant, Harare, Zimbabwe Tel.: +263 4 336 725/333 248/2917028; fax: +263 4 336 740 E-mail address: [email protected] Available online 14 August 2009
Contents lists available at ScienceDirect
Physics and Chemistry of the Earth journal homepage: www.elsevier.com/locate/pce
Editorial
9th WaterNet/WARFSA/GWP-SA symposium: Water and sustainable development for improved livelihoods
1. Introduction
2. Hydrology Sub-Theme
This special issue contains selected and peer reviewed papers which were presented during the 9th annual symposium organized by WaterNet, Water Research Fund for Southern Africa (WARFSA), and Global Water Partnership Southern Africa (GWP-SA), and held in Johannesburg, 29–31 October 2008. This symposium attracted participants from east and southern Africa, and other parts of the world, and had ‘‘Water and Sustainable Development for Improved Livelihoods” as the theme. The symposium has become an annual event providing researchers, policy makers, and water resources planners and managers opportunities for sharing ideas on capacity building in implementing integrated water resources management approaches. Papers in this special issue have been grouped following the sub-themes of the symposium which were:
Papers in this sub-theme are mainly investigating models or modelling approaches for overcoming limitations arising from lack of adequate hydrological data for water resources analysis. Lack of adequate hydrological data for water resources planning and management is a major problem in the east and southern Africa region. The WaterNet/WARFSA/GWP-SA Annual Symposium has had each year a special session on the Predictions in Ungauged Basins, which is a research agenda of the International Association of Hydrological Sciences. Previous papers in this journal have also investigated possible solutions for overcoming this problem (Mazvimavi et al., 2005; Nyabeze, 2005; Parida et al., 2006). Satellite imagery has the potential to provide much needed data for water resources planning and management. Two papers in this sub-theme, Onema et al. and Munyaneze et al. are investigating the potential for quantifying hydrological variables using data derived from satellite images. Onema et al. investigated use of the normalized difference vegetation index (NDVI) to estimate monthly rainfall on the Semliki Basin located in the humid equatorial region between the Democratic Republic of Congo and Uganda. On a month to month basis, NDVI was weakly correlated to monthly rainfall on some of the sub-basins. A high correlation existed between monthly rainfall and NDVI with a 1-month lag. This reflects that the state of vegetation is a reflection of the influence of rainfall during the previous month. The strength of the relationship between NDVI and rainfall was found to vary in space. Basins at different elevation levels had different correlation between NDVI and rainfall. It is likely that topography has an influence on the NDVI – rainfall relationship due to the variation of vegetation type with altitude and soil types (Grist et al. 1997; du Pleiss, 1999). Munyaneza et al. related satellite derived lake levels to those obtained from bathymetric studies of Lake Kivu which is located between the Democratic Republic of Congo and Rwanda. Both ENVISAT and ER-2 derived lake levels were positively related to gauged lake levels with the coefficient of determination being 0.86 and 0.77, respectively, while the standard error was 0.642 m and 0.701 m, respectively. This study demonstrated that satellite altimetry can be used for monitoring changes in available water in lakes. A major problem in rainfall–runoff modelling is estimating model parameter values that are physically meaningful. Some
Hydrology Water and Environment Water and Land Water for People Water for Society Water Resources Management There are however no papers that were considered for publication under the Water Resources Management Sub-Theme. The Editorial highlights important findings of the papers in this issue and attempts to point out some of the research gaps. Where the name of the author appears in this Editorial without the year of publication, this means the paper being referred to is in this special issue. There is an increasing number of papers investigating the potential for using satellite imagery for water resources planning. This is a welcome development particularly in the east and southern Africa region where there is generally inadequate data to accurately represent temporal and spatial variations of aspects of water resources. Contamination of water due to lack of sanitation and mining operations is a major problem in the east and southern Africa region, and this is reflected by several papers in this issue exploring methods for removing some of the contaminants. Understanding issues that affect access to water and water-related resources especially in rural areas is another topical issue examined by some of the papers.
1474-7065/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.pce.2009.08.002
708
Editorial / Physics and Chemistry of the Earth 34 (2009) 707–710
modellers argue for manual calibration based on an understanding of the structure of the model and hydrological processes dominant on a particular basin. This approach has the risk of being subjective leading in some cases to over- or under-estimation of the importance of some of the hydrological processes. In addition the existence of equifinality of model parameters creates a problem in determining model parameter values that are physically relevant. Ndirutu has compared the performance of automatic and manual calibration of model parameters on basins in South Africa and Zambia. The results of the study did not prove that automatic calibration performed better than manual calibration. Ndirutu recommends a combination of manual and automatic calibration with manual calibration being used to set the physically realistic range of model parameter values followed by automatic calibration. 3. Water and the Environment Sub-Theme The papers in this sub-theme have mainly focused on using satellite imagery for estimating water quality factors in a lake. The motivation of these studies has again been to overcome problems arising from the lack of adequate hydrological data. Chavula et al. (a) investigated the prediction of temperatures of surface waters in Lake Malawi using Advance High Resolution Radiometer (AVHRR) and Moderate Resolution Spectroradiometer (MODIS) imagery. Lake surface temperature was predicted with a coefficient of determination of 0.74 from the Terra/MODIS Ocean Colour data. The study revealed the existence of complex circulation patterns within Lake Malawi. Chavula et al. (b) made a second study to predict chlorophyll concentration in Lake Malawi from MODIS satellite imagery. The predicted chlorophyll concentrations were generally six times more than values obtained through in situ measurements. This poor prediction of chlorophyll concentration could be due to the predictive equation used being inapplicable to oligotrophic lakes such as Lake Malawi. In situ measurements of chlorophyll concentrations were made at a location close to the shore. There is a possibility that the in situ measurements were not representative of chlorophyll concentration at a large scale reflected on satellite imagery. Further studies with data collected at spatially more representative sites need to be carried out to fully explore the feasibility of using satellite imagery for estimating chlorophyll concentration. 4. Water and Land Sub-Theme The main focus of the papers in the Water and Land Sub-Theme has been on rainwater harvesting which is being promoted for water conservation particularly in semi-arid and arid regions. The papers have attempted to quantify potential hydrological and economic impacts of rainwater harvesting. Kahinda et al. examined the likely impacts of rainwater harvesting on runoff on river basins in South Africa. The study assumed that increasing the spatial coverage of rainwater harvesting within a basin will cause changes to values of the Pitman rainfall–runoff model relating to interception, soil moisture storage capacity, and minimum absorption rate. The study assumed that specific increases in the spatial coverage of rainwater harvesting will result in specific changes in values to the Pitman model. The estimation of the hydrological impact of rainwater harvesting was therefore based on comparing simulations based on different model parameter values. What is uncertain is whether the assumed changes in the Pitman model parameter values realistically represent the effect of rainwater harvesting. The study by Ndirutu has shown that physical interpretation of some of the Pitman model parameter values is questionable. Further studies aimed at understanding hydrological impacts of rainwater harvesting are therefore called for.
Zimmerman et al. compared in monetary terms using the discounted cash flow method the performance of rainwater harvesting with that of the public water reticulation system in rural northern Namibia. The study estimated the average annual volume of water which can be harvested from roofs per homestead. Using the price of water from local vendors, the study established that the investment in roof harvesting is amortised within the fifth year at a discount rate of 3%. The roof harvesting technique was considered to be the most economically efficient. The rainwater harvesting system also offered opportunities for engaging in vegetable gardening. Studies that investigate both the hydrological and economic impacts of water conservation techniques that are popularly promoted should be encouraged so that those adopting these approaches will fully understand both the benefits and costs. 5. Water for People Sub-Theme Papers under this sub-theme cover four areas, namely groundwater treatment, treatment of contaminated mining effluent, removal of disinfection by-products in drinking water, and microbial health risks at water abstraction points. Pritchard et al. investigated the potential of using plant extracts for purification of water from shallow wells in Malawi. This is an innovative approach since there has been very little scientific research work into the use of plant extracts to purify groundwater. Water from shallow wells is commonly used throughout Africa and in some cases is contaminated and consumed untreated. The study investigated some of the most promising plant extracts, namely Moringa oleifera, Jatropha curcas and Guar gum. The results showed that the addition of M. oleifera, J. curcas and Guar gum considerably improved the quality of water from shallow wells. Overall, M. oleifera powder produced superior results, seconded by Guar Gum and lastly J. curcas. There is a need to explore other plants that are readily available in different countries. To ensure public safety, further research could also focus on investigating any toxic effects of these plant extracts. Contaminated mining effluent remains a major problem in Africa. Fosso-Kankeu et al. investigated the reduction of metal loads in surface waters around mining areas using indigenous microorganism strains in South Africa. The experiments aimed to achieve acceptable minimum concentration levels of excess calcium, iron and magnesium in surface waters around mining areas using indigenous strains of Shewanella sp., Bacillus subtilis sp. and Brevundimonas sp. B. subtilis and Shewanella sp. absorbed the highest amount (14% Ca, 8% Mg and 8% Fe) of each of the three metals recorded from solutions containing the metals at 30 ppm concentration, with calcium being the most easily removed metal species. Metal removal from solution decreased when their concentrations in solution was at 50 ppm. The studies revealed that the combination of these metals in one solution affected the microorganisms’ affinity for the metals thus reducing their removal efficiency. There was also a tendency for microorganisms to release the absorbed metal into solution after a certain period of time, most probably due to an efflux transport mechanism. On a related topic Mamba et al. also investigated heavy metal removal from contaminated small-scale mining effluent using clinoptilolite and bacteria. The removal of As, Ni, Mn, Au, Co, Cu and Fe was investigated on mine water samples using original and HCl-activated (in 0.02 M and 0.04 M) natural clinoptilolite and bacterial strains. Both clinoptilolite and bacteria demonstrated capabilities of removing Cu2+, Co2+, Fe2+, Mn2+, As3+ and Au from solution which augurs well for metal recovery from mining and mineral processing solutions, as well in water decontamination. In yet another paper, Mamba et al. investigated the biosorptive removal of copper and cobalt from aqueous solutions by Shewanella sp. At optimum concentration (0.002 M/ 3.86 g l 1), biosorbent dosage (150 104 CFU/ml) and solution
Editorial / Physics and Chemistry of the Earth 34 (2009) 707–710
pH 6.5, Shewanella sp. recorded maximum copper and cobalt uptakes of 38% and 27%, respectively. The kinetic data obtained at different concentrations suggested that the biosorption rate was fast and in most cases the biosorption took place within 8 h followed by a slow attainment of equilibrium and the Langmuir sorption model fitted the data well with very high correlation (>0.95). These studies showed that there is a potential to use microorganisms and other low-cost chemical methods to treat contaminated waters, thus giving an effective and environmentally friendly way of remedying contaminated sites in Africa. It would be interesting if further studies could be spread to heavy metals and other chemicals related to contaminated sites in the mining industries. Other critical elements in groundwater are fluorine as discussed by Musonda et al. (2007) in the case of Malawi, coliforms in Malawi (Mkandawire, 2008; Pritchard et al., 2008), and iron in Zimbabwe (Hoko, 2008). Mhlongo et al. monitored the prevalence of nitrosamines, especially N-nitrosodimethylamine (NDMA), in three South African water supply systems and investigated their removal using cyclodextrin polyurethanes. A disinfection by-product and potent carcinogen, NDMA has recently been detected in many drinking water supplies internationally (Richardson, 2005). Trace amounts of NDMA were detected at one of the water treatment plants and in the distribution network in South Africa. The application of water-insoluble cyclodextrin (CD) polymers in the removal of nitrosamines and potential amine precursors from the water samples was tested. Quantitative removal of NDMA (based on peak area) from the water samples was achieved. Findings from this study show that there is a need to explore other less costly and environmentally safe methods of disinfection such as solar disinfection (Murinda and Kraemer, 2008), and plant extracts as discussed by Pitchard et al. in this issue and Nkurunziza et al. (2009). The occurrence of various disinfection by-products of chlorine such as trihalomethanes (THM) and haloacetic acids presents a potential health hazard. Abdullah et al. examined the relationship between water quality parameters in raw water with chlorine demand and the formation of disinfection by-products in a water treatment system in Malaysia. They developed statistical models for the prediction of chlorine demand and the THM formation. The models developed have the potential to be used for managing quality of drinking water and operation of water treatment systems. The treatment of runoff rarely receives attention yet it is a major source of drinking water in rural areas. Rianawati and Balasubramaniam presents a simple and rapid solid-phase microextraction (SPME) method coupled with gas chromatography–mass spectrometry (GC–MS) for the quantitative determination of 16 polycyclic aromatic hydrocarbons (PAHs) in rainwater and stormwater samples. The method developed has the potential to reduce the costs of analysing critical elements in drinking water. The evaluation of microbial health risk at water abstraction points in rural Kenya with the Observed Adverse Effect Level (OAEL) approach was conducted by Yillia et al. They applied models for recreational water quality to characterize the potential health risk (PHR) of infection with gastroenteritis (GI) and highly credible gastroenteritis (HCGI) illnesses from single exposure at several water abstraction points (WAP) along the Njoro River in rural Kenya. The contamination levels were quite high and this would necessitate treatment of drinking and implementation of comprehensive catchment management measures to protect WAPs and the entire stream. 6. Water and Society Sub-Theme Papers within the Water and Society Sub-Theme are focusing on access to water for irrigation (Kemerink et al.), wetland resources
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(Magole and Magole) and potable water (Makoni et al.). Kemerink et al. investigated the socio-political and biophysical factors affecting access to water by farmers at small-scale irrigation schemes established during the 1930s within the Makanye River basin in Tanzania. Membership to the irrigation scheme and water allocation was initially decided through traditional rules by the chief during the colonial period, then by government as part of the socialist system, and after the introduction of the multi-party system during the 1990s by elected representatives. Upstream irrigation schemes were found to be abstracting water without taking into account the needs for the downstream schemes. However, conflicts over water allocation between upstream and downstream schemes were minimized through some farmers having plots on both the upstream and downstream schemes. Within each of the schemes, water allocation to specific zones was decided by elected representatives. Well connected farmers were found to have an advantage during water allocation. Kemerink et al. established that despite the existence of a water allocation committee which was supposed to solve any disputes relating to water allocation, other structures such as traditional elders and factors like gender influenced the composition of water allocation committees and dispute resolution. Kemerink et al. therefore advocate for the consideration of the different social structures and factors in developing mechanisms for water allocation and resolving disputes that may arise. Magole and Magole examined the views of different stakeholders towards the ownership and benefits arising from the Okavango Delta in Botswana. The Okavango Delta region was in 1964 wholly under communal tenure, but this had decreased to 41% by 2008. The decrease was through land being allocated to a game reserve and wildlife management areas. Inhabitants of areas under communal tenure derive their livelihoods from the delta through flood recession cultivation, fishing, harvesting of aquatic plants and veld products, livestock watering and grazing. The reduction in the area under communal tenure has therefore decreased their access to natural resources within the delta. The land that has been set aside for the game reserve and wildlife management is being used for tourism which Magole and Magole contend that this benefits mostly the private sector, particularly internationally owned companies. Although local communities are involved in tourism in some parts of the delta as part of the community based natural resources management programme, most of the enterprises that the communities engage in are in partnership with the private sector. The views of the stakeholders with regards to ownership and benefits from the Okavango Delta were analysed by Magole and Magole from outputs of a public debate. Representatives of government were of the view that the Okavango Delta belonged to all the stakeholders comprising local inhabitants, and all citizens of Botswana. Representatives of local inhabitants had no clear answer to this issue as they considered themselves to be the primary stakeholders, but they perceived that they are being marginalized from utilizing the delta. The study by Magole and Magole raises fundamental questions regarding the sustainability of measures for managing the Okavango Delta. If those who have historically lived on valued ecosystems such as wetlands perceive that they are being marginalized by measures aimed at conserving these ecosystems, can these measures be considered to be sustainable. Kgathi et al. (2007) established that the Okavango Delta provided opportunities for inhabitants of this region to cushion themselves from natural shocks such as droughts and dessication of channels. What is not known is how these management measures have affected the resilience of local communities to these shocks. The growth of tourism in Botswana is a national objective for diversification of the economy. Issues that need further studies are the impacts of tourism on livelihoods at the local level. Management of future development of the Okavango Basin will benefit from information on how
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nationally, regionally and internationally justifiable measures for managing ecosystems impact on rural livelihoods at the local level. 7. Conclusions Presenters of papers during the 9th WaterNet/WARFSA/GWPSA Symposium were invited to submit their papers to be peer reviewed for possible publication in this issue. In comparison to previous symposia, there has been a decrease in the number of papers which were submitted for possible publication in this issue. Van der Zaag (2007) analysed the growth in both the number of papers presented during the WaterNet/WARFSA/GWP-SA symposia, and published in the Physics and Chemistry of the Earth. The number of papers published grew from 33 in 2001 to a peak of 52 papers in 2007. However, this current issue of the Physics and Chemistry of the Earth has 23 papers which is a major decline. The decline in the number of papers is most probably due to a reduction in research being carried out in some of the countries in the east and southern Africa region. This reduction is due to WARFSA having been non-operational during the last 4 years. WARFSA had become a major source of funds for researchers within the Southern Africa Development Community (SADC) region, and was funding over 70 research projects (van der Zaag, 2007). With the exception of South Africa, other SADC countries do not have research funds specifically dedicated to water issues. WaterNet and WARFSA were conceived as being complementary, with WaterNet concentrating on training, but part of the training in research was facilitated through WARFSA funding. We strongly recommend that funding agencies, the SADC Secretariat and the SADC Council of Ministers responsible for water to revive WARFSA since research is an integral part of capacity building within the water sector. The development of innovative and relevant solutions to water resources management in the SADC region should be based on research outputs that have been peer reviewed to international standards. References du Pleiss, W.P., 1999. Linear regression relationships between NDVI, vegetation and rainfall in Etosha National Park, Namibia. Arid Environments 42, 235–260. Grist, J., Nicholoson, S.E., Mpolokang, A., 1997. On the use of NDVI for estimating rainfall fields in the Kalahari of Botswana. Arid Environments 35, 195–214. Hoko, Z., 2008. An assessment of quality of water from boreholes in Bindura District, Zimbabwe. Physics and Chemistry of the Earth 33, 824–828. Kgathi, D.L., Ngwenya, B.N., Wilk, J., 2007. Shocks and rural livelihoods in the Okavango Delta, Botswana. Development Southern Africa 4, 289–308.
Mazvimavi, D., Meijerink, A.M.J., Savenije, H.H.G., Stein, A., 2005. Prediction of flow characteristics using multiple regression and neural network: a case study in Zimbabwe. Physics and Chemistry of the Earth 30, 639–647. Musonda, K.W.M., Masamba, W.R.L., Fabiano, E., 2007. A case study of fluoride groundwater occurrence in Nathenje, Lilongwe, Malawi. Physics and Chemistry of the Earth 32, 1178–1184. Mkandawire, T., 2008. Quality of groundwater from shallow wells of selected villages in Blantyre District, Malawi. Physics and Chemistry of the Earth 33, 807–811. Murinda, S., Kraemer, S., 2008. The potential of solar water disinfection as a household water treatment method in periurban Zimbabwe. Physics and Chemistry of the Earth 33, 829–8232. Nkurunziza, T., Nduwayezu, J.B., Banadda, E.N., Nhapi, I., 2009. The effect of turbidity levels and Moringa oleifera concentration on the effectiveness of coagulation in water treatment. IWA Water Science and Technology 59 (8), 1551–1558. Nyabeze, W.R., 2005. Calibrating a distributed model to estimate runoff for ungauged catchments in Zimbabwe. Physics and Chemistry of the Earth 30, 625–633. Parida, B.P., Moalafhi, D.B., Kenabatho, P.K., 2006. Forecasting runoff coefficients using ANN for water resources management: the case of Notwane catchment in eastern Botswana. Physics and Chemistry of the Earth 31, 928–933. Pritchard, M., Mkandawire, T., O’Neill, J.G., 2008. Assessment of groundwater quality in shallow wells within the southern districts of Malawi. Physics and Chemistry of the Earth 33, 812–823. Richardson, S.D., 2005. New disinfection by-product issues: emerging DBPS and alternative routes of exposure. Global NEST Journal 7 (1), 43–60. van der Zaag, P., 2007. The impact of regional water resources capacity building: citations of the published proceedings of the annual WaterNet/WARFSA/GWPSA symposia in Southern Africa, 2001–2005. Physics and Chemistry of the Earth 32, 971–975.
Dominic Mazvimavi Department of Earth Sciences, University of the Western Cape, Private Bag X17, Bellville, 7535 Cape Town, South Africa Tel.: +27 21 959 2871; fax: +27 21 959 2438 E-mail address: [email protected] Innocent Nhapi WaterNet Secretariat, P.O. Box MP 600, Mount Pleasant, Harare, Zimbabwe Tel.: +263 4 336 725/333 248/2917028; fax: +263 4 336 740 E-mail address: [email protected] Available online 14 August 2009