II. The use of the DSSIPM in the Alentejo region of southern Portugal

Agricultural Water Management 51 (2001) 203±215

II. The use of the DSSIPM in the Alentejo region of southern Portugal L. Mira da Silvaa,*, J.R. Parkb, J.D.H. Keatingec, P.A. Pintoa a

SeccËaÄo de Agricultura, Instituto Superior de Agronomia, 1349-017 Lisboa Codex, Portugal b Department of Agriculture, The University of Reading, Reading RG6 6AT Berks, UK c International Institute of Tropical Agriculture, Ibadan, Nigeria Accepted 23 February 2001

Abstract DSSIPM is a decision support system that was developed to improve planning and management in large irrigation schemes. Paper I provided a description of the system, including its structure, databases and procedures. Here, the application of DSSIPM to the Odivelas irrigation scheme is described, a case study in the Alentejo region of Portugal. The results obtained suggest that the introduction of irrigation is likely to increase crop diversity and the income of farmers. Analysis indicates that the performance of irrigated areas will be affected by such diverse factors as crop prices, subsidies, the availability of water, land taxes and the price of water, the existence of markets for non-traditional crops, the size of ®elds and the technological skills of farmers. The development priorities for improving the economic performance of agriculture in the Odivelas region were identi®ed. They include developing marketing and processing facilities, reformulating water prices and land taxes, improving water distribution, developing extension services, providing irrigation equipment and farm machinery to rent, and modifying land tenancy legislation. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Irrigation schemes; Planning and management; Decision support systems; Alqueva; Alentejo; Portugal

1. Introduction Alentejo is an administrative region in the south of Portugal which covers about one third of the total area of the country. The region has been facing serious social and economic problems, the most visible being the decrease and ageing of its population. *

Corresponding author. E-mail address: [email protected] (L. Mira da Silva). 0378-3774/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 - 3 7 7 4 ( 0 1 ) 0 0 1 2 5 - 1

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The problems are worse in rural areas, which are characterised by high unemployment rates and the abandonment of land by farmers. Agriculture is usually the most important economic activity in these rural areas. However, the potential productivity under rainfed conditions is low due to soil and climatic factors. Thus, irrigation seems to provide a strategy to diversify crop production and potentially increase incomes. This, in turn, may overcome some of the existing problems of land abandonment and population decrease. Despite the potential for irrigation of the Alentejo region, the existing irrigation schemes in the area are characterised by low adoption of irrigation by farmers and lack of crop diversity (Daehnhardt, 1990, 1993, 1996). In many of these schemes, water shortage in dry years has been the most important constraint on the adoption of irrigation by farmers. Nevertheless, there are other issues which have acted as limiting factors, from the low potential of the soils for irrigated crop production to the lack of marketing facilities for irrigated crops. Most of these limitations arise due to inadequate planning and management (Caldas, 1994; Ferreira, 1989; MAI-CCRA, 1982). Planning has often been restricted to the design of the water conveyance infrastructure, sometimes complemented by broad economic and financial appraisals of the projects. Operational management, in almost all of the schemes, has been limited to issues such as the control of water distribution. Alqueva is a large irrigation project that is under development in Alentejo. The project is expected to provide water to irrigate a further 110,000 ha in the region. However, the project has many critics who say that the project is too big, is not economically or social justifiable and that the environmental impact will be high. Further, it is suggested that the water will not be sufficient to irrigate the whole area, will be of low quality and that the soils are unsuitable and the slopes too steep for irrigation (Feio, 1988; LeitaÄo, 1988, 1989). The most recent assessments, however, contradict these critical views (COBA, 1995; DR-CCRA, 1993; LNEC, 1994; SEIA, 1995). Alqueva may, if there is water available and farmers adopt irrigation, be the best alternative to avoid the increasing socio-economic problems of the region. Despite the benefits the project may bring to the region, it is unlikely to achieve satisfactory performance without adequate planning and management. In fact, the scenarios proposed in recent assessments for the future irrigated areas seem too optimistic, since they have yet to be achieved in the existing irrigation schemes in the region (Daehnhardt, 1990, 1993, 1996). These include high utilisation rates, unusual levels of crop diversity, and high incomes to be obtained from irrigated agricultural activities. While such outcomes are not impossible, the poor performance of some of the existing large schemes in the region suggest that there are still major problems in these irrigated areas. In order to avoid similar situations in the future there is a need to improve decision-making, namely in relation to crops, crop production techniques and irrigation methods selected by farmers, and to identify efficient policies and actions to support the introduction of irrigation. The field work involved in the development of the DSS has been described in previous papers (Mira da Silva et al., 1997, 1998) and the design and potential output from the DSS has been described in Paper I. This paper outlines the analysis and the results that can be obtained with the help of DSSIPM.

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2. The second phase of the Odivelas irrigation scheme The second phase of the Odivelas irrigation scheme Ð Odivelas(II)1 Ð is a potentially irrigable area to be developed within the Alqueva project that is expected to provide water for 4520 ha. The scheme was selected as a case study because it will be the first part of the Alqueva project to be implemented. In addition, the institution responsible for the development of Alqueva (EDIA) selected Odivelas(II) as a pilot study to provide information for other areas within the scheme. By working in close contact with EDIA, it was possible to gain access to most of the data available on the scheme, including maps (e.g. fields, soils), aerial photographs, and a list of the owners of the proposed fields to be irrigated. The information necessary to characterise the Odivelas(II) scheme was collected from different sources, but mostly from published material (CCE-DGPR, 1992; CPU, 1991; ABORO, 1996; IESE, 1997), soil, topography, and land use capacity maps (scale 1:50,000 Ð SROAa, 2001; Cardoso, 1965; 1:25,000 Ð SCE, 2001; 1:50,000 Ð SROAb, 2001), aerial photographs (1:30,000 in large field zones; 1:10,000 in small field zones) and a comprehensive series of interviews with farmers. Thus, the overall analysis included a general description of the scheme (land use, crop production, etc.), an assessment of the climate and soils in the future irrigated areas, an overview of the socio-economic and structural environment, an analysis of some social and structural aspects of the farmers and their farms and a description of the fields to be irrigated in terms of size and ownership. The experience of farmers with respect to irrigation (i.e. water sources, crops, irrigation methods) and their main sources of information were also considered. This information was then used to characterise soils, farmers, zones within the scheme, and irrigated fields, classifying data into groups to be matched with the crops, crop systems and irrigation methods requirements. The matching process forms the basis of the application of the DSS, allowing the selection of possible crop systems for each field and the estimation of their yields (as described in Paper I). The major source of agronomic, socio-economic, and structural data was obtained from interviews with farmers. A total of 76 farmers within the Odivelas region were interviewed. The sample farmers managed 46.1% of the fields in Odivelas(II) scheme (312 in a total of 677), corresponding to 67.4% of the potentially irrigable area (3047 of 4520 ha). The information was focused on farmer characteristics, their farms, the crops they cultivate and the potentially irrigable fields located within the scheme. Most questions were pre-coded, but respondents were given the freedom to express their opinions. Thus, the information obtained from the interviews was both quantitative and qualitative in nature. The Odivelas(II) scheme is in a pre-project stage. The most recent information available on the scheme is a broad assessment of the Alqueva project (CCE-DGPR, 1992). According to this report, the water will be distributed under pressure in order to allow sprinkler irrigation methods to be used without further investment at field level. 1 In order to distinguish the first phase of the Odivelas irrigation scheme, which started irrigating in 1974, from the second phase of the Odivelas irrigation scheme, which is a project that is expected to start irrigating in a few years, the latter is called, in the context of this paper, the Odivelas(II) irrigation scheme.

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The specific characteristics of the water conveyance infrastructure, such as the water pressure in the outlets, have not yet been defined. A large irrigation zone has already been selected based on soil and topographic characteristics, but it is seen only as a general indication of the future irrigated areas. The final delimitation of the irrigated area will be based on more detailed and updated information. The DSS is, therefore, expected to make an important contribution in subsequent planning stages. 3. General characterisation of the Odivelas(II) scheme 3.1. Bio-physical aspects The climate in the Odivelas(II) region is characterised by dry, hot summers and wet, cold winters. The dominant soils are, in general, suitable for irrigation. The major soil limitation is drainage. 3.2. Regional socio-economic and structural aspects The analysis focused on population, roads, marketing and processing facilities and bank credit. As in the rest of the Alentejo, the population in the region is decreasing and getting older. The roads are generally in good condition. There is a lack of marketing and processing facilities, especially for non-traditional crops. Incomes from traditional crops have decreased in recent years and it is doubtful that they can provide the basis for profitable production in the future. There is extensive use of bank credit and it appears that many farmers are willing to invest in new or changing technologies. 3.3. Farms and farmers: social and structural aspects Issues considered here included land tenancy, farm size and structure, infrastructural investment, the age and education of farmers, their sources of income, seasonal labour use, and rented farm machinery. There are few young farmers in the region and the older farmers are not well educated. Renting land is not common, mostly due to unfavourable legislation. There are a large number of small farms often with geographically dispersed fields. The diminishing availability of seasonal workers is a problem although the renting of farm machinery is common. 3.4. Farmers and irrigation experience Most of the farmers interviewed have experience with irrigation and many cultivate large irrigated areas. This explains, at least in part, why they are so enthusiastic about Odivelas(II), and suggests that they will irrigate if there is water available. However, the range of crops grown in the region is limited. Most farmers have only used gravity irrigation methods, whilst in Odivelas(II) the water will be distributed under pressure. Farmers stated their preference for pressurised water, although many have not considered the additional costs that are associated with this method of irrigation.

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3.5. Land use and crop production Current land use in the potentially irrigable area of Odivelas(II) is dominated by arable production. The most important crops are wheat, sunflower and forages. Rainfed crop rotations include wheat followed by 1 or 2 years of sunflower, forages, pastures or fallow. It is not possible to identify typical irrigated crop rotations, but wheat and sunflower are often irrigated. There are also several non-traditional crops (e.g. flax, broccoli). With respect to crop yields farmers suggested that lack of water in the summer, late frosts, and excess of water in the winter were their major production concerns. 4. Application of the DSS to the Odivelas(II) scheme: methods The interviews with farmers provided important information on current crop production in the Odivelas region and the potential for change in the future. The objective of the application of the DSS to Odivelas(II) was to integrate this socioeconomic information with the existing biophysical information in the region to identify and quantify the major constraints which might affect the performance of the Alqueva scheme and to establish priorities for development. Specific actions and policies to improve the performance of the future irrigated areas can be diverse, including such aspects as improvement of drainage, implementation of effective extension services, and selection of the most appropriate fields to include in potentially irrigable areas. The application of the DSS here considers the options available to overcome two important issues: the decrease in farmers' incomes, which has been the main factor responsible for land abandonment and population decrease in the Alentejo region; and the low adoption of irrigation by farmers. The analysis was undertaken for a target date of 2005, which was assumed to provide a representative situation after the implementation of the Odivelas(II) scheme (the project is expected to start irrigating at the end of 2001). Both the situation with the project and without the project were analysed. Together, these two scenarios provide a clear illustration of the potential impact of introducing irrigation. A major part of the information used as input for the DSS was obtained directly from the Odivelas(II) assessment. This included technical (crop requirements, field characteristics, farmer attributes) as well as economic data (prices of crop products, production factors, tractors, other machines, and labour). The crops, crop systems and crop systems operations had to be carefully selected and defined, to ensure the validity of the output provided by the DSS. A total of 18 crops were included in the analysis (Table 1). In four cases, these crops were divided into two different sub-groups (maize, potatoes, sunflower and wheat). For each crop/crop type, two different crop systems were considered. They were defined according to several criteria, such as the level of inputs and outputs (low/high; e.g. nitrogen application/crop yields), the level of mechanisation (90 hp/120 hp tractors) and the irrigation methods used (drip/sprinklers/ centre pivot). This resulted in a total of 44 different crop systems being included in the analysis …18 crops ‡ 4 crop types ˆ 22 crops  2 crop systems per crop ˆ 44 crop systems†.

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Table 1 Crops considered in the analysis Crop

Crop use

Rainfed/irrigated

Barley Broccoli Carrots Green peppers Lettuce Maize

Industry Fresh consumption Fresh consumption Fresh consumption Fresh consumption Industry Silage Fresh consumption Industry Hay Fresh consumption Industry Fresh consumption Silage Silage Industry Industry Industry Industry Industry Industry Industry

Rainfed Irrigated Irrigated Irrigated Irrigated Irrigated Irrigated Irrigated Rainfed Rainfed Irrigated Irrigated Irrigated Rainfed Irrigated Irrigated Rainfed Irrigated Irrigated Rainfed Rainfed Irrigated

Melons Oat Oat/comm. vetch Onions Potatoes Ryegrass Sorghum Sugar beet Sunflower Tomatoes Triticale Wheat

Some of the crops and crops systems included in the analysis were identified by farmers in the questionnaires and are well known in the region. Others, such as carrots, green peppers, lettuce, onions, potatoes (industry and fresh consumption), ryegrass, sorghum and tomatoes (fresh consumption) are not common but have been grown in the region before (albeit in small areas), or were mentioned by farmers. 5. Application of the DSS to the Odivelas(II) scheme: results 5.1. Without project situation The total number of fields and the area selected by the DSS (i.e. cultivated) under this scenario indicate the potential for rainfed crop production of the soils within the Odivelas(II) scheme. Only 17 fields, corresponding to 9 ha, are not cultivated (Table 2), and this is mostly because of their small size. All the other fields are able to produce incomes under rainfed conditions (average 27,209 Esc ha 1).2 The only crop selected under these conditions is sunflower. However, it must be emphasised that the DSS selects the crop, and not the crop rotation, which maximises the income for a particular field in the given year. As a consequence, some of the crops which exist in real rotations are not 2

1 Euro ˆ 200:482 Esc.

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Table 2 Crop systems selected by the DSS; future situation without project %

Potentially irrigable area (ha)

Crop system

Number of fieldsa

Sunflower high level rainfed Sunflower low level rainfed Cultivated Not cultivateda

28 294 322 17

8.3 86.7 95.0 5.0

1429 1609 3038 9

Total

339

100.0

3047

a

%

Average potentially irrigable area per field (ha)

Average income (Esc ha 1)

46.9 52.8 99.7 0.3

51.0 5.5 9.4 0.5

30687 24124 27209 0

100.0

9.0

27127

No crops are selected (i.e. no generated income) in these fields.

selected by the DSS because they generate lower incomes than others which are also included in the analysis. In the region of the Odivelas(II) scheme, for instance, triticale is cultivated in some areas but is usually integrated in rotations with wheat and sunflower, which provide higher incomes. If sunflower is excluded from the analysis, the DSS suggests the number of fields cultivated would be reduced to 22 (6.3% of the total number of fields), the area to 1055 ha (34.6% of the potentially irrigable area) and the average income to 2716 Esc ha 1. These 22 fields are occupied by rainfed crops that are predicted to provide low incomes in 2005 (e.g. triticale and oats). This analysis shows how critical the situation can be under rainfed conditions. Sunflower production is dependent on subsidies and thus on the future developments within the Common Agricultural Policy. If subsidies are reduced, it will become increasingly difficult to obtain a profitable income from rainfed crop production within the Odivelas region. 5.2. With project situation The results obtained for the situation with project (i.e. under irrigated conditions) are distinct from those obtained under rainfed conditions. The fields and area that are not cultivated are still the same (17 fields, 9 ha), but the crops and crop systems selected (8 crops, 16 crop systems) and the average income from cultivated fields (238,944 Esc ha 1) are considerably different (Table 3). These results not only suggest that the introduction of irrigation may improve crop diversity but also indicate that the availability of water can substantially increase the incomes obtained by farmers. However, there are still 119 fields (35.1% of the total number of fields), corresponding to 784 ha (25.7% of the potentially irrigable area) which would be cultivated with rainfed crops even if there was water available (Table 3). The average income in these fields is only 17,873 Esc ha 1, and the only crop selected is sunflower. The reasons why irrigated crops are not selected are diverse. Sprinkler irrigated maize, for instance, was not selected due to steep slopes, which prohibit this method of irrigation. Potatoes, sugar beet, carrots, broccoli and green peppers cannot be cultivated (i.e. are not selected) by low technology, non intensive, non innovative farmers. Crops irrigated by centre pivots can only be cultivated in large fields, in which it is possible to install these systems. In this scenario,

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Table 3 Crop systems selected by the DSS; future situation with project Crop system

Number of fields

Potatoes high level industry Potatoes low level industry Sugar beet high level Sugar beet low level Carrots high level Carrots low level Broccoli high level Broccoli low level Sunflower high level rainfed Sunflower low level irrigated Sunflower low level rainfed Maize high level industry Maize low level industry Green peppers high level Tomatoes high level industry Tomatoes low level industry With irrigated crops With rainfed crops Cultivated Not cultivateda

1 22 10 35 2 6 2 2 6 59 113 2 56 1 1 4 203 119 322 17

0.3 6.5 2.9 10.3 0.6 1.8 0.6 0.6 1.8 17.4 33.3 0.6 16.5 0.3 0.3 1.2 59.9 35.1 95.0 5.0

32 370 390 340 180 77 150 47 374 189 410 89 150 131 9 99 2254 784 3038 9

Total

339

100.0

3047

a

%

Potentially irrigable area (ha)

%

Average potentially irrigable area per field (ha)

Average income (Esc ha 1)

1.1 12.2 12.8 11.2 5.9 2.5 4.9 1.5 12.3 6.2 13.5 2.9 4.9 4.3 0.3 3.3 74.0 25.7 99.7 0.3

32.0 16.8 39.0 9.7 90.0 12.9 75.0 23.5 62.3 3.2 3.6 44.5 2.7 131.0 8.8 24.8 11.1 6.6 9.4 0.5

308285 214695 211593 133320 865784 575249 979704 730137 19324 34034 16552 50304 30584 634250 209634 127507 315876 17873 238944 0

100.0

9.0

238225

No crops are selected (i.e. no generated income) in these fields.

59.9% of fields are irrigated and the utilisation rate is 74.0%. This scenario was based on a subsidised price of water (10 Esc m 3), no individual water restrictions and no marketing constraints. The price of water in the future irrigated areas is an issue of primary importance. If water is not subsidised, the price could be extremely high. According to some pessimistic views, it could reach 50 Esc m 3 (Feio, 1988). The results obtained with the DSS suggest that the adoption of irrigation by farmers can be severely affected by the price of water, particularly for changes between 5 and 15 Esc m 3 (Fig. 1). When the price reaches 15 Esc m 3, only 25% of the total number of fields and 60% of the potentially irrigable area are irrigated. Further increases in the price of water, within the likely range, do not seem to affect substantially the adoption of irrigation by farmers. The incomes from irrigated crops can help to explain the effects of changing the price of water. Indeed, the average income from the area irrigated (i.e. for which the DSS selects irrigated and not rainfed crops) increases within the range between 5 and 15 Esc m 3 (Fig. 2). This results from the decrease in the total area irrigated (see Fig. 1). When the price of water reaches 15 Esc m 3, only high value crops (e.g. vegetables for fresh consumption, tomatoes for industry) are selected. The average income from the area irrigated increases because the fields that can only be cultivated with low value irrigated

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Fig. 1. Effects of changes in the price of water: percentage of potentially irrigable fields that are irrigated and percentage of potentially irrigable area that is irrigated (utilisation rate). Source: DSS.

crops (e.g. irrigated sunflower) are excluded (i.e. are converted or remain as rainfed crop production). This, in turn, affects the average income from the total area cultivated (i.e. with irrigated and rainfed crops), which decreases steadily with the increase in the price of water. These results suggest that there are three options available for the future irrigated areas within the Odivelas(II) scheme:  the price of water can be subsidised in a similar way to that in some of the existing irrigation schemes in Alentejo (i.e. less than 10 Esc m 3); the percentage of fields

Fig. 2. Effects of changes in the price of water: average income from area irrigated (area with irrigated crops) and average income from area cultivated (area with irrigated crops plus area with rainfed crops). Source: DSS.

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irrigated and the utilisation rate can then be expected to be above 60 and 75%, respectively;  the price of water is not subsidised (i.e. values above 15 Esc m 3); it will not be possible to cultivate traditional low value crops; the percentage of fields irrigated and the utilisation rate can be expected to be very low (under 25 and 60%, respectively); similar rates characterise some of the existing irrigation schemes in Alentejo;  the price of water is not subsidised but regional strategies are implemented to allow the selection of high income crops in the majority of the fields and potentially irrigable area; this is a very optimistic scenario. The scenario under irrigation (with project) was also used to evaluate the effects of changing other external conditions (i.e. the DSS input) on the performance of the future irrigated areas (i.e. the DSS output). The most important results obtained are listed below:  Prices and subsidies (crops): if crop prices and subsidies are lower than those assumed in the DSS, the performance of the scheme will be affected; if the direct subsidies which are currently given to sunflower, maize and wheat are reduced, for instance, the percentage of fields irrigated and the utilisation rate will be lower;  Water availability: the analysis of the effects of imposing limitations on the volume of water that farmers are allowed to use suggest that the utilisation rate and the incomes are not affected if values are higher than 4000 m3 ha 1; for values under 4000 m3 ha 1, the percentage of fields and area irrigated and the incomes can be severely affected;  Soil and field characteristics: three fields were identified as unsuitable for irrigation due to steep slopes; the best alternative seems to be their exclusion from the scheme; in addition, some fields have drainage problems; drainage should therefore be a priority in the development of Odivelas(II); soil salinity can also be a constraint in the future irrigated areas, reducing the crop options available to farmers and the incomes they are able to obtain;  Crop marketing and processing facilities: this is likely to be one of the major limitations in the future irrigated areas; vegetables and crops for industrial processing are particularly affected; the average incomes from the area irrigated can be severely reduced; if marketing and processing facilities are not developed, it will only be possible to grow traditional low value crops in most of the fields;  Field size: the results suggest that the percentage of fields and area irrigated and the incomes obtained by farmers decrease with field size; however, more detailed analysis indicates that the reasons for poor performance in small fields may be due to other limitations (e.g. farm structural characteristics); the complex nature of this issue, together with the large number of small fields in Odivelas(II) and the cost of implementing irrigation infrastructure in these fields, emphasises the need for further assessments;  Farmers' knowledge and extension services: the lack of knowledge among farmers is likely to reduce the adoption of new crops and production techniques; nevertheless, the results show that the most important constraints are restricted to a small group of farmers who are unlikely to adopt irrigation without external help; this suggests that the most urgent needs in terms of technical advice might be overcome with inexpensive solutions, such as the provision of an agronomist by the association of farmers.

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6. Establishing priorities for the future irrigated areas The priorities for the future irrigated areas of the Odivelas(II) scheme depend on the objectives to be accomplished. In the case of this research, the objectives initially proposed were to increase the adoption of irrigation and the incomes obtained by farmers. The results obtained for the situation with project, however, are not promising. There is still a large fraction of the potentially irrigable fields and areas that are not cultivated with irrigated crops. The analysis described in this section investigates how the adoption of irrigation and the incomes in these fields could be increased. The identification of the variables that determine the exclusion of all irrigated crops was based on a sub-scenario of the situation with project. In this sub-scenario, only the fields which had not been originally selected for irrigation were included (136 fields; see Table 3). In addition, only three crop systems were considered: potatoes (low level industry), tomatoes (low level) and sugar beet (low level). These crop systems were selected because they are not very demanding in terms of farmer attributes and farm characteristics (i.e. do not require high technological, innovative, structural or intensification attributes), whilst at the same time are able to provide high incomes. The results obtained suggest that the major limitations are related to the technological, innovative and intensification level of farmers, the potentially irrigable area, drainage conditions, accessibility and slope of fields, and the depth and pH of soils. The specific actions and policies that can be used to overcome these limitations are extremely diverse. They include modifications in land tenure legislation, changes in farm taxes, development of marketing activities, improvement of drainage and accessibility conditions, exclusion of fields with steep slopes, and reassessment and improvement, or exclusion, of areas with poor soils. A final scenario was simulated with the DSS to evaluate the effects of some of the actions and policies proposed. The results indicate that the performance of the Odivelas(II) scheme can be substantially improved in terms of the percentage of fields and area irrigated and the incomes generated by farmers in the fields which were not originally irrigated. 7. Conclusions Irrigation has the potential to increase the incomes of farmers in the Alentejo region of southern Portugal. The construction of irrigation infrastructure, however, does not necessarily mean that farmers will use the water available. Indeed, if nothing is done to stimulate the adoption of irrigation by farmers in the Alqueva, it is likely that the future irrigated areas will remain dominated by traditional crops and crop production techniques. Incomes from agriculture will remain low and the socio-economic developments forecast as part of the Alqueva project will be unlikely to materialise. This is the scenario that has characterised many of the existing schemes in Alentejo. There is no reason to believe that the situation will be different in the Alqueva project, unless new tools and methods are used in the planning and management process. The performance of both existing schemes and future irrigated areas can only be improved if

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structures, agencies and policies are put in place to help farmers to make the best use of the water available. The application of the DSS to the Odivelas(II) scheme suggests that the following actions should be given priority if the adoption of irrigation by farmers is to be increased:  development of marketing and processing facilities;  subsidisation of water costs and imposition of restrictions on water use;  reassessment of soil conditions (i.e. drainage, salinity and pH) and exclusion of unsuitable fields before infrastructures are developed;  reassessment of the limitations related to field size and modification of land tenancy legislation to encourage renting;  development of extension services and provision of irrigation equipment and farm machinery to rent. The results discussed in this paper indicate that the DSS is able to explore a wide range of scenarios, integrating bio-physical and socio-economic data to establish priorities, in terms of specific actions and policies to improve performance within irrigated areas. The DSS is already being used to help in planning and management activities in the Odivelas(II) scheme, confirming its value as a decision support tool with the objective of increasing the incomes of farmers in Alentejo and improve the overall status of the agricultural sector in the region. References ABORO AssociacËaÄo de BeneficiaÂrios da Obra de Rega de Odivelas. RelatoÂrio e Contas do ExercõÂcio de 1996. Ferreira. Caldas, J.C., 1994. BenefõÂcios Sociais dos Projectos HidroagrõÂcolas. Jornada TeÂcnica da ComissaÄo Nacional Portuguesa de IrrigacËaÄo e Drenagem. ComissaÄo Nacional Portuguesa de IrrigacËaÄo e Drenagem, Lisbon. Cardoso, J.C., 1965. Os Solos de Portugal: sua CaracterizacËaÄo e GeÂnese. Secretaria de Estado da Agricultura, MinisteÂrio da Economia, Lisbon. CCE-DGPR ComissaÄo das Comunidades Europeias Ð DireccËaÄo Geral das PolõÂticas Regionais 1992. Empreendimento de Fins MuÂltiplos de Alqueva. Estudo de AvaliacËaÄo Global. Lisbon. COBA Consultores de Engenharia e Ambiente 1995. Recursos HõÂdricos do Rio Guadiana e sua UtilizacËaÄo.  gua, Lisbon. Instituto Nacional da A CPU, 1991. Plano Director Municipal de Ferreira do Alentejo. CPU Consultores, Lisbon. Daehnhardt, E., 1990. PerõÂmetros de Rega em ExploracËaÄo. Algumas CaracterõÂsticas e Elementos EstatõÂsticos ate ao ano de 1989. MinisteÂrio da Agricultura, Pescas e AlimentacËaÄo. DireccËaÄo-Geral de HidraÂulica e Engenharia AgrõÂcola, Lisbon. Daehnhardt, E., 1993. PerõÂmetros de Rega em ExploracËaÄo. ActualizacËaÄo de Algumas CaracterõÂsticas e Elementos EstatõÂsticos ate ao ano de 1991. MinisteÂrio da Agricultura, Pescas e AlimentacËaÄo. DireccËaÄo-Geral de HidraÂulica e Engenharia AgrõÂcola, Lisbon. Daehnhardt, E., 1996. PerõÂmetros de Rega em ExploracËaÄo. ActualizacËaÄo de Algumas CaracterõÂsticas e Elementos EstatõÂsticos ate ao ano de 1995. MinisteÂrio da Agricultura. Instituto de Estruturas AgraÂrias e Desenv. Rural. DireccËaÄo de ServicËos de HidraÂulica AgrõÂcola, Lisbon. DR-CCRA. Dossier Regional Ð ComissaÄo de CoordenacËaÄo da RegiaÄo Alentejo 1993. Empreendimento do Alqueva. EÂvora. Feio, M., 1988. Alqueva. Um regadio com maÂs condicËoÄes. Vida Rural, Vol. 11, Lisbon, pp. 54±64. Ferreira, J.F.F., 1989. A problemaÂtica actual do projecto de Alqueva Ð Alternativas. Revista de CieÃncias AgraÂrias, Vol. XII, No. 1. Lisbon, pp. 5±15.

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IESE. Instituto de Estudos Sociais e EconoÂmicos 1997. Estudo de Impacte Socio-EconoÂmico do Aproveitamento HidroagrõÂcola de Odivelas. EDIA Ð Empresa de Desenvolvimento e Infraestruturas do Alqueva, Lisbon. LeitaÄo, J.D., 1988. Alqueva envolvida por seÂrias razoÄes negativas provenientes de escassez de aÂgua com origem em Espanha. Revista de CieÃncias AgraÂrias, Vol. XI, No. 4. Lisbon, pp. 13±18. LeitaÄo, J.D., 1989. Regar o Alentejo a partir dos recursos proÂprios sem o Alqueva. Revista de CieÃncias AgraÂrias, Vol. XII, No. 1. Lisbon, pp. 43±49. LNEC. LaboratoÂrio Nacional de Engenharia Civil 1994. AnaÂlise do Plano HidroloÂgico Nacional de Espanha. MinisteÂrio das Obras PuÂblicas, Transportes e ComunicacËoÄes, Lisbon. MAI-CCRA. MinisteÂrio da AdministracËaÄo Interna Ð ComissaÄo de CoordenacËaÄo da RegiaÄo do Alentejo 1982. Aproveitamento HidroagrõÂcola da Vigia. Breves ConsideracËoÄes. EÂvora. Mira da Silva, L., Lemon, L., Park, J., 1997. A systems approach to land use planning in irrigated areas. In: Teng, P.S., et al. (Eds.), Applications of Systems Approaches at the Farm and Regional Levels. Kluwer, London, pp. 357±366. Mira da Siva, L., Park, J., Pinto, P.A., 1998. Decision support systems for irrigated zones: an integrated approach to land use planning and management in southern Europe. In: El-Swaify, S.A., Yakowitz, D.S. (Eds.), Multiple Objective Decision Support Systems for Land, Water and Environmental Management. Lewis Publishers, New York, pp. 599±614. SCE. ServicËos CartograÂficos do ExeÂrcito. Carta Militar de Portugal. Lisbon. SEIA. Sociedade de Engenharia e InovacËaÄo Ambiental 1995. Estudo Integrado de Impacte Ambiental do Empreendimento do Alqueva, Vol. I±XI, Lisbon. SROAa. ServicËo de Reconhecimento e Ordenamento AgraÂrio. Carta dos Solos de Portugal. Secretaria de Estado da Agricultura. MinisteÂrio da Economia, Lisbon. SROAb. ServicËo de Reconhecimento e Ordenamento AgraÂrio. Carta de Capacidade de Uso do Solo. Secretaria de Estado da Agricultura. MinisteÂrio da Economia, Lisbon.