JWSS - Journal of Water and Soil Science

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Limitations of rainfall and surface water resources farmers have to use both surface and subsurface resources for growing different crops. In this study optimal management of irrigation water allocation and cropping pattern utilizing conjunctive use of surface and subsurface water resources is studied. Also the effect of reducing water consumption in different growth stages with different irrigation strategies for major crops (wheat, barely, corn, sugar beet, rice) in Fars province was studied. The results of the study showed that optimal cropping pattern for the first season would be mainly wheat and in the second season would be corn and rice. Also in this model different policies for decreasing water demand were studied. Since crop water requirement in the second season is higher than the first season, therefore restriction on including high water consuming crops in the second season would be the best choice in the cropping pattern.

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Studying the sustainability of farming systems entails the integrated assessment of the strong interdependence between their environmental, economic and social attributes. Optimum allocation of water resources in a farming system improves the conservation and sustainability status of resources in addition to reducing the socio-economical damages. In order to analyze and assess the different aspects of farm management and agricultural systems planning, a number of mathematical programming models have been developed in recent decades. The purpose of this article was to assess and analyse the sustanability and determine the appropriate pattern of cropping in a rural farming system, namely, south Baraan located in the east of Isfahan city. In order to incorporate environmental, economic and social dimentions, two criteria of maximum net return and employment creation per unit of agricultural water consumption were defined as system’s sustainability indicators. Thus, the ratios “net return / water consumption” and “employment / water consumption” were optimized by using single and multiple objective fractional programming models. The economic and social efficiency of each unit of agricultural water consumption was computed and compared in several single and multiple objective scenarios of linear and fractional programming models, and finally the most appropriate patterns of cropping for the region were determined based on the available land, water and human resources of the region.

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At the river catchments, different strategies at the whole or different parts of the basin can be applied for water resources management. One of these strategies is optimal water allocation and crop pattern. In this study, an optimization model for water allocation and cropping pattern is presented based on the cooperative game theory. To measure the performance of the developed model, the cultivated area of Ordibehesht Canal in the Doroodzan irrigation network has been studied. First, using a fuzzy model and considering the fuzzy coefficients values in the objective function and constraints, the optimal crop pattern and allocated water has been determined for each crop. Second, benefits of stakeholder’s coalitions have been determined by developing a cooperative game model and based on the structure and properties of the irrigation water distribution network and water rights of each part. Then, the total net benefit has been reallocated to the different stakeholder in a rational and equitable way using Least Core games. The results show that by allocating more water to the sectors with more potential production, more profits are generated and water productivity increases. For example when players cooperate together and form the grand coalition, the net benefit increases from 8.906 billion Tomans to 9.724 billion Tomans that show an increase in the economic productivity of water.