WIT Press

Considering Salinity Effects On Crop Yields In Hydro-economic Modelling – The Case Of A Semi Arid River Basin In Morocco


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WIT Press


C. Heidecke & A. Kuhn


Agricultural production, especially date palm cultivation, is the major food and income source for people in the Drâa basin in Southern Morocco. However, the semi-arid river basin faces very low rainfalls and has suffered from a continuing drought over the last years. River water, as the principal source for irrigation, has been increasingly substituted by groundwater mining. This has led to an unsustainable downing of the groundwater table, increased salinisation problems, and has posed further constrains on the agricultural production potential. Without targeted water resources management, water available for irrigation will soon be depleted or too saline to be used for most crops. Consequently, farmers will not be able to maintain their production levels, and subsequently lose an important source of family income. The relationship between water use and agricultural production is represented using an integrated hydro-agro-economic simulation model with a spatial water distribution network of in- and outflows, balances and constraints. The model results are driven by profit-maximising water use by agricultural producers which are primarily constrained by both water availability and quality. Crop yields are influenced by quantitative irrigation water application deficits and by the salinity of irrigation water. Results show considerable differences depending on whether salinity is incorporated or not. When salinity is considered, yields tend to be much lower despite increased irrigation water needs to enable a reduction of soil salinity through leaching. Keywords: nonlinear programming, water allocation, water quality, salinity.


nonlinear programming, water allocation, water quality, salinity.