Agricultural Water-saving Potential for Guanzhong Irrigation Areas under Different Guaranteed Rates of Precipitation

The Agricultural Water-saving Potential (AWP) has important influences on water-saving technology development, regional irrigation water management, agricultural production and water ecological balance protection. The study aims to design a reasonable methodology to calculate the AWP and analysis the AWP of Guanzhong irrigation area, in Weihe River Basin of China. The AWP was divided into resource-based AWP and efficiency-based AWP. The former was calculated according to the coefficient of water transmission in canals and irrigation in the field. The latter was estimated on the basis of the field evapotranspiration. The guaranteed rates of precipitation were chosen as the hydrologic conditions. Under the guaranteed rates of 25%, 50%, 75%, 90% and 95%, the annual total AWPs of the Guanzhong irrigation areas reached 30.69×106 m 3 , 111.67×106 m 3 , 11.75×106 m 3 , 12.52×106 m 3 , and 14.76×106 m 3 respectively. The efficiency-based AWP occupied a proportion of more than 50% in each condition, which indicated that the improvement of water utilization efficiency should be in preference to improvement of water conveyance efficiency in technology innovation. Summer maize, fruit tree and cotton made the largest contribution to efficiency-based AWP while there was not a big difference among the 3 crops in various irrigated areas when it came to the AWP per unit area, and their average values were 9.4, 6.3 and 4.3 mm respectively. Then the study comes up with measures and suggestions to improve the AWP according to the planting structures and features of the 9 irrigated areas. This method takes into account the water consumption during the processes of irrigation and crop growth. It can provide the support for water saving agriculture. The accurate calculation of water dissipation coefficient is the key to the efficiency of the AWP method, and the stability of the measurement coefficient will be improved in the future.