Mulched drip irrigation for maize cultivation has been widely implemented in the Xiliao River Plain in Northeast China in recent years. However, the effects of the change in irrigation method on soil water content and groundwater recharge in this area still remains uncertain. In this study, soil water content under mulched drip irrigation and flood irrigation was measured through field experiments. Soil water movement in the entire growing season under the two irrigation methods was simulated for the quantitative analysis of groundwater recharge by the Hydrus-2D model. Results showed that soil water content under mulched drip irrigation was generally larger than that of flood irrigation in the initial growth stage. However, an opposite trend was observed in the main growth stage. The simulated results indicated that the cumulative water fluxes of flood irrigation were greater than the values of mulched drip irrigation. Moreover, while infiltration depth under flood irrigation reached the maximum simulated depth (400 cm), infiltration depth under mulched drip irrigation was only 325 cm. The results of this study showed that mulched drip irrigation reduced the infiltration depth and groundwater recharge to some extent in the Xiliao River Plain. Such results are helpful in determining the influence of mulched drip irrigation on groundwater and can be a reference for the maintenance of the sustainability of regional groundwater in the large-scale promotion of mulched drip irrigation.

Due to the effects of global warming, the vapor pressure deficit (VPD) will inevitably and continuously rise in future, which is a fact that must be faced when discussing the sustainable development of vegetation ecosystems. Understanding the response of vegetation to changes in the atmospheric moisture state is necessary for minimizing the adverse effects of climate change. Using the leaf area index (LAI) and meteorological data in the Yellow River Basin collected over nearly 40 years, we explore the spatiotemporal variations in VPD and vegetation within the growing season and the differences in the effects of VPD on vegetation in different climatic zones. The results show the following: (1) both VPD and LAI in the Yellow River Basin show an increasing trend, in which VPD increases radially outward centered on the arid regions, while the vegetation develops favorably over almost the whole basin; (2) at the whole-basin scale, the area of VPD positively correlated with vegetation growth is greater than the area of negative correlation, and this overall trend is increasing significantly; (3) the VPD exerts heterogeneous effects on different vegetation in different climatic zones, and these heterogeneity findings suggest that the effects of VPD on vegetation are more influenced by differences among the climatic zones of the vegetation than by differences in the vegetation types themselves. Our results provide insights into the effects of atmospheric moisture on vegetation growth and provide references for the sustainable development of vegetation ecosystems and future safeguarding strategies of vegetation over large spatial scales.

Irrigated areas are major vectors of agricultural development and components of ecosystems. The groundwater level maintains the irrigated areas’ ecology safety and sustainable development. Under the influence of irrational irrigation practices—such as flood irrigation or extreme water saving without consideration of ecological impact—different areas within an irrigation district may experience anomalies in groundwater levels (either too deep or too shallow). It is of great significance to carry out research on water resource allocation and future water-saving strategies, taking into consideration groundwater depths. In this study, a method for the optimal allocation of irrigation water resources that considered groundwater level was used to regulate irrational irrigation practices and to reveal the future direction of water saving. Helan County in Ningxia province, an ecologically fragile and arid irrigated area, was selected as a case study. Multiple scenarios of different water use and different degrees of water-saving were analyzed. The results showed that non-engineering water-saving measures (such as adjusting the planting structure and controlling the amount of irrigation for rice) had better benefits compared to engineering measures (such as efficient water-saving irrigation and channel lining). When implementing only one water-saving measure, the strategy of replacing 75% of the rice area with corn yielded the best results. This approach can reduce the irrigation water shortage rate to 11% and increase by 4.58% the acreage where the groundwater level is reasonable. When multiple water-saving measures are implemented together, the most effective strategy for future water-saving efforts involves the joint implementation of several measures: replacing 75% of the rice area with corn, limiting irrigation for rice to no more than 11.85 thousand m³/ha, adopting high-efficiency water-saving irrigation in 90% of the pump-diverted water irrigation region and 40% of the channel-diverted water irrigation region, and maintaining the channel’s water utilization coefficient at 0.62. This strategy can keep the irrigation water shortage below 3.66% and increase the acreage where the groundwater level is reasonable, by 4.58% per year. The conclusions and research approaches can provide references for the formulation of water-saving measures for irrigated areas’ sustainable development.

In order to comprehensively evaluate the degree of satisfaction of ecological flow in rivers, an evaluation system was constructed based on the daily average flow, monthly average flow, and the lowest monthly flow data of the Kushui River in Ningxia from 2017 to 2019, including indicators such as flow changes, flow satisfaction at different levels, ecological water demand guarantee, and monthly average ecological water demand suitability, to assess the health status of the Kushui River. The results showed that the minimum runoff of the Guojiaqiao hydrological station in the Kushui River during the dry season was relatively small, with a large gap compared to the annual average daily flow, but the degree of ecological flow guarantee was high, reflecting the seasonal and uneven distribution characteristics of the Kushui River. It is recommended to strengthen the research on the dispatching of water storage reservoirs, rationally allocate water, and gradually improve and improve the sustainable guarantee degree of ecological flow in the Kushui River.