Comparison of Allocated Irrigation Water Rights and Irrigation Water Use under Different Precipitation Probabilities: a Case Study in North China

A comparison between gross irrigation water use (GIWU) in fields and allocated irrigation water rights amount (AIWA) is critical for evaluating any system of water rights allocation. GIWU in fields under different precipitation probabilities has been rarely calculated and compared with AIWA using households' survey data. This study developed a method for calculating the GIWU of crops under different precipitation probabilities using field survey data from 391 households and the monitoring data of wells in Chengan County, China. AIWA was compared with the calculated GIWU and irrigation quota. Results showed that AIWA is too small to satisfy the GIWU of the principle crops. The GIWU of main cropping patterns under a precipitation probability of 75% was curtailed between 43 and 77% to fulfill AIWA. AIWA cannot support any cropping patterns when precipitation is lower than the precipitation percentile of 75%. In this condition, farmers are restricted to planting apples, cotton, and sweet potatoes. The uncertainty in precipitation was not fully considered, and the participation of farmers in water rights allocation in Chengan County was limited, which may adversely influence the income and food security of farmers.