Minimizing runoff and sedimentation by optimizing land use (Case Study: Jajrood watershed)

Proper and organized use of natural resources can help preserve this valuable asset. Land use optimization science can be especially useful in this regard. The main purpose of the present study is to present an appropriate model for optimized allocation of lands with the purpose of gaining the minimizing surface runoff and sedimentation in Jajrood watershed. This watershed is located in the south of Tehran province, Iran. To determine the best land use combination, first the runoff amount in every land use was calculated, and then sedimentation was determined in every land use. Finally, the multi-objective linear programming model was used to solve the optimization problem based on Simplex Method. Results showed that the present land uses area was not optimized and require changes in existence land uses. The optimization results emphasize that the area of irrigated farming lands and rangelands should be reduced and orchards should be increased. The results also indicate that after optimization was employed, surface runoff decreased 73.03 percent and sedimentation decreased about 36.93 percent. The results of sensitivity analysis showed that total surface area of orchards and irrigated farming was the most sensitive factor to changes in runoff and sedimentation. In addition results showed that the most sensitive coefficient in runoff minimizing function is rangeland coefficient and in minimizing sediment function is irrigated farming coefficient, which is due to the high runoff and sedimentation rate of these two kinds of land uses.