Agricultural water-saving potential in Guanzhong Irrigation Area in different hydrologic years

There has been a rampant water shortage in the Wei River Basin in recent years, significantly affecting the ecological and economic functions of the river and drastically limiting the socio-economic development of the administrative regions within the basin. Although the respective local/national governments have adopted adjustment strategies of the water use structure, agriculture has remained the biggest water user, accounting for over half of total water use in the basin. Meanwhile, agricultural water use efficiency in the basin has been some 1 kg·m^-3, much lower than that in developed countries like Israel and USA. The main reasons for the low agricultural water use efficiency have included low use of advanced technology (e.g., springklers, drop irrigation and mulching), low channel lining rates and high water contamination. In this study, we summarized the current state and trend in agricultural irrigation, calculated the agricultural water-saving potential and then developed a new mode based on current and future crop water requirement. The two main modules of the mode (resource-based water-saving and efficiency-based water-saving) were respectively representative of small-scale and large-scale water analysis. Based on main crops in typical irrigation areas, different water-saving schemes were designed and the water-saving potential of each scheme calculated. The probable water-saving amounts in the nine irrigation districts were analyzed and calculated for different hydrologic years. For instance, in years with water guarantee rates of 25%, 50%, 75% and 95%, agricultural water-saving potentials in Guanzhong Irrigation Area were respectively 30.69 million m³, 111.67 million m³, 117.50 million m³ and 125.21 million m³. Efficiency-based water-saving potential was over 50%, expect for the 25% rate water guarantee condition where it was 42%. Then based on present water-saving technology and planting structure characteristics of the nine irrigation areas, a water-saving mode was put forward which reduced water diversion by 10% and improved agricultural irrigation water use efficiency by 5%. Exploitation of agricultural water-saving potential was the basis for water resources reallocation in the region. This study also laid the base for theoretical and technical support for the development of water-saving irrigated agriculture, planning of water resources reallocation and construction of water-saving society.