The wide application of drip irrigation under mulch in semi-arid agricultural regions in China not only improves agricultural water efficiency, but also affects formation of groundwater and the mechanism of water infiltration to a certain extent. This paper takes the typical semi-arid agricultural region in China as the research object. The movement of soil water under the three types of underlying surface was simulated by the Hydrus-2D model for the quantitative analysis of groundwater recharge. The influence of drip irrigation under mulch on groundwater infiltration depth and cumulative infiltration amount under different level years was simulated. Taking a normal flow year as an example, the simulated results showed that the maximum infiltration depth of drip irrigation under mulch reached 250 cm, which was greater than that of border irrigation (138 cm) and bare area (158 cm). The cumulative infiltration amounts of drip irrigation under mulch at 80, 120, 140 and 200 cm were respectively 1,484.8 m3/hm2, 686.3 m3/hm2, 554.1 m3/hm2 and 238.1 m3/hm2, which were greater than that of border irrigation and bare land at the same depth. The results proved that drip irrigation under mulch could increase the infiltration depth and cumulative infiltration amount, which is beneficial to groundwater recharge in semi-arid agricultural regions of China.

The imbalance between exploitation and recharge and the yearly decline in water tables is a common water resource problem in semi-arid areas in China. To ensure the sustainable use of groundwater and the stability of the regional hydrological cycle, a reasonable groundwater control table need to be determined to achieve a balance between groundwater exploitation and recharge. Based on the characteristics of the vertical hydrological cycle in semi-arid irrigation areas, this paper used a combination of in situ field experiments and software simulations to calculate the groundwater infiltration recharge under three types of subsurface conditions, namely, drip irrigation under mulch, border irrigation, and bare area, and to analyze the relationship between groundwater infiltration recharge and groundwater table. Based on the relationship between groundwater recharge and discharge, the critical groundwater depth of maintaining exploitation and recharge balance (CGDM) for drip irrigation under mulch was calculated to be 131.52-187.15 cm, and the critical groundwater depth of disrupting exploitation and recharge balance (CGDD) was 307.66-363.67 cm. For border irrigation, the CGDM was 80.00-84.34 cm and the CGDD was 198.87-248.44 cm. It also proposed a groundwater table management strategy to address the risk of imbalance in regional groundwater exploitation and recharge. The critical groundwater depth of controlling risk management (CGDC) can be used for regional groundwater management and guidance for agricultural irrigation, providing technical support for achieving regional groundwater exploitation and recharge balance and maintaining a stable hydrological cycle.