Drought Early Warning System Of Irrigation District In Western Guanzhong Plain

Study area located in the western of Guanzhong Basin, is a traditional irrigation district with a long history of irrigation. On account of water shortage, uneven distribution of rainfall in-year, vulnerable ecological environment and Weihe River runoff decrease, drought has become the bottleneck of agriculture and socio-economic development of the region. Therefore, based on a comprehensive analysis of water resources, drought characteristics and socio-economic conditions, this article established an applicable drought early warning system. The main research findings are as follows:(1) Based on the data of historical drought events in the study area, the study analyzed the time-space evolution characteristics of drought disaster in terms of drought affected rate and drought disaster rate. From the analysis results, from 1990 to 1994, the drought affected rate and drought disaster rate showed a rapid upward trend and declined after 1994 which reflecting the people’s disaster prevention and mitigation with economic development has improved. The average drought affected rate in the study area is 21.63%, the average drought disaster rate is 7.09%.(2) Trends of precipitation and runoff in the study area were analyzed with Mann-Kendall trend test method. The exceedance probability curves of monthly precipitation and monthly runoff were drawn to estimate the frequency of the different hydrological conditions in the future. According to the data of groundwater monitor wells in the study area, the annual and monthly variations of groundwater were discussed. Groundwater flow numerical simulation model was established to simulate and predict the groundwater level.(3) Fuzzy comprehensive evaluation was adopted to establish the drought watch index evaluation system with precipitation, runoff and groundwater as the drought influence factors. Analyzed the supply-demand relationship between water demand(irrigation water use, domestic water use, ecological water use) and water supply(available diversion water, available groundwater) in the future. Then, the drought early warning system was established based on the above.(4) The drought early warning system was verified according to the data in 2007, the result indicate the drought early warning result was consistent with the actual drought condition.(5) The situation is not optimistic in 2020 according to the drought early warning system. With the current development and utilization of water resources, different degree of drought events will occur throughout the year. Water shortage and irrational way of development and using water resources are still the key restricting factors of agricultural development.