Research on Characteristics of Groundwater Recharge in the Weishan Irrigated District Based on a Bromide Tracer

Bromide was used as tracer in the Weishan Irrigated District to determine the groundwater recharge as well as to evaluate the impacts of different irrigation basin locations, irrigation regimes, and crop types on the recharge. The comprehensive recharge coefficient and the Kriging Spatial Interpolation methods were used to distinguish the effects of precipitation and surface water irrigation on the groundwater recharge rate. The results show that the recharge rates ranged from 85.8 to 243 mm/a, with an average of 168 mm/a. The average recharge rate in the upstream district is greater in the downstream and the average recharge rate of irrigated land (193 mm/a) is greater than non-irrigated land (110 mm/a). The recharge rates in fields of winter wheat-summer maize and cotton with irrigation are 210 mm/a and 140 mm/a, respectively, while they are 115 mm/a and 94.1 mm/a under no irrigation conditions. The comprehensive recharge coefficient of groundwater in the upstream irrigation area is larger than that in the downstream. By comparing the spatial distribution of the groundwater level and the comprehensive recharge coefficient, it is found that there is a positive relationship between the groundwater level and the comprehensive recharge coefficient. The results of this study can provide reference and guidance to a water resources analysis of the Weishan Irrigated District.