Identification of saline risk area and sustainable optimum water allocation for Irrigated farmland in arid region

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(1)A model which can estimate evaporation only by maximum and minimum ground surface temperature (MST model) was developed. Spatial distribution of evaporation of Hetao Irrigation District, Inner Mongolia, China was estimated by satellite image and MST model and the results were validated.(2)Relationship between spatial distribution of saline area in the District and topological, geographical conditions was analyzed.(3)Based on the relationship between seasonal change of annual average and deviation of NDVI (Normalized Vegetation Index) obtained by MODIS image and the estimated evaporation, saline risk area was identified.(4)As constraints of linear programming, water balance based on estimated evaporation and salt balance of each sub region was considered, and drainage water quality of each sub region was specified by a leaching efficiency coefficient. Applying linear programming, optimal sustainable water allocation was determined. The results showed that improvement of conveyance efficiency is effective as measures for improvement of the irrigation and drainage system.