University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 52 4 2021 06 22 Investigation of the Effect of Adjustment of Estimation of Agricultural Water Demand on the Performance of Water Distribution System in Irrigation Districts (Case Study of Roodasht Irrigation District, Esfahan) Investigation of the Effect of Adjustment of Estimation of Agricultural Water Demand on the Performance of Water Distribution System in Irrigation Districts (Case Study of Roodasht Irrigation District, Esfahan) 1149 1161 81851 10.22059/ijswr.2020.309273.668723 FA Habib Karimi Avargani Department of Irrigation Engineering, College of Aburaihan,University of Tehran, Pakdasht, Iran 0000-0003-1574-606X Mehdy Hashemy Department of Irrigation Engineering, College of Aburaihan,University of Tehran, Pakdasht, Iran 0000-0001-9962-1437 Abdolmajid Liaghat Department of Irrigation and Reclamation Engineering, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. 0000-0002-3224-6529 Seyyed Ebrahim Hashemi Garmdareh Department of Irrigation Engineering, College of Aburaihan,University of Tehran, Pakdasht, Iran 0000-0003-3727-0111 Journal Article 2020 09 08 The poor performance of irrigation districts led to the unreliable distribution of surface water among farmers. Therefore, it is necessary to improve the water distribution in the irrigation district. For this purpose, there are two practical solutions, improve operational method and adjustment of estimation of agricultural water demand, each of which has been researched separately. In this study, for the first time, the effect of improving the adjustment of estimation of water demand was investigated by developing and combining AquaCrop model and ICSS hydrodynamic model for Roodasht irrigation district under a water shortage scenario in the status quo. For this purpose, the daily agricultural water demand was estimated for each of the secondary irrigated units based on the cultivation pattern by using the AquaCrop model. After calculating the average daily flow rate to each off-take (the output of the water distribution simulator model in the main canal) the adequacy index was calculated for two conditions, 1) with considering the amount of requirements specified by the network administrator  (available condition) and 2) adjustment of water demand. The results showed that the performance evaluation indicator improved from 3% to 16% for all off-takes by adjustment of agricultural water demand. This improvement has been achieved by reducing the amount of water right in the upstream and middle of the main canal and increasing the amount of water right for downstream. Also, the equity of water distribution has improved among water users by adjustment of agricultural water demand. The poor performance of irrigation districts led to the unreliable distribution of surface water among farmers. Therefore, it is necessary to improve the water distribution in the irrigation district. For this purpose, there are two practical solutions, improve operational method and adjustment of estimation of agricultural water demand, each of which has been researched separately. In this study, for the first time, the effect of improving the adjustment of estimation of water demand was investigated by developing and combining AquaCrop model and ICSS hydrodynamic model for Roodasht irrigation district under a water shortage scenario in the status quo. For this purpose, the daily agricultural water demand was estimated for each of the secondary irrigated units based on the cultivation pattern by using the AquaCrop model. After calculating the average daily flow rate to each off-take (the output of the water distribution simulator model in the main canal) the adequacy index was calculated for two conditions, 1) with considering the amount of requirements specified by the network administrator  (available condition) and 2) adjustment of water demand. The results showed that the performance evaluation indicator improved from 3% to 16% for all off-takes by adjustment of agricultural water demand. This improvement has been achieved by reducing the amount of water right in the upstream and middle of the main canal and increasing the amount of water right for downstream. Also, the equity of water distribution has improved among water users by adjustment of agricultural water demand. https://ijswr.ut.ac.ir/article_81851_c2b00869b78ac7a80a4cf5f60dd728e2.pdf