Interaction between Surface Water and Groundwater in Yinchuan Plain

Abstract

The interaction of surface water (SW) and groundwater (GW) is becoming more and more complex under the effects of climate change and human activity. It is of great significance to fully understand the characteristics of regional SW–GW circulation to reveal the water circulation system and the effect of its evolution mechanism to improve the rational allocation of water resources, especially in arid and semi-arid areas. In this paper, Yinchuan Plain is selected as the study area, where the SW–GW interaction is intensive. Three typical profiles are selected to build two-dimensional hydrogeological structure models, using an integrated approach involving field investigation, numerical simulation, hydrogeochemistry and isotope analysis. The SW–GW transformation characteristics are analyzed with these models, showing that geological structure controls the SW–GW interaction in Yinchuan Plain. The SW–GW flow system presents a multi-level nested system including local, intermediate and regional flow systems. The runoff intensity and renewal rate of different flow systems are evidently different, motivating evolution of the hydro-chemical field; human activities (well mining, agricultural irrigation, ditch drainage, etc.) change the local water flow system with a certain impacting width and depth, resulting in a variation of the hydrological and hydro-chemical fields. This study presents the efficacy of an integrated approach combining numerical simulation, hydrogeochemistry and isotope data, as well as an analysis for the determination of GW-SW interactions in Yinchuan Plain.

Assessing the Influences of Land Use Change on Groundwater Hydrochemistry in an Oasis-Desert Region of Central Asia

“…Meanwhile, the vertical infiltration of agricultural irrigation water promotes the leaching and dissolution of mineral and soil salt, which could thus transfer the soluble salt downward into phreatic water, causing the higher salinity of groundwater in summer (Figure 11) [48]. Previous studies reported that evaporites and saline soil were widespread in the irrigated district of the Tarim Basin, due to the irrational irrigation, inefficient drainage, and violent surface evaporation [15,33]. Wang et al found that groundwater salinity was significantly correlated to soil salinity in saline-alkaline land in an arid oasis [14].…”

“…The cultivated land area has markedly expanded from 2000 to 2020 (increasing by 732.38 km 2 (121.8%)) in the study region (Table 1 and Figure 4), and agricultural irrigation relies on stream water and pimped groundwater, thus leading to irrigation return flow as a dominant source of phreatic water [16]. That is, agricultural irrigation and groundwater extraction play an important role in the seasonal change of groundwater quantity and quality [15,27]. For the cultivated land, the vertical infiltration of irrigation water could cause the groundwater level to rise, but groundwater extraction leads to groundwater level decline in the growing season (Figure 11).…”

“…Water 2022, 14, 651 15 of 19 widespread in the irrigated district of the Tarim Basin, due to the irrational irrigation, inefficient drainage, and violent surface evaporation [15,33]. Wang et al found that groundwater salinity was significantly correlated to soil salinity in saline-alkaline land in an arid oasis [14].…”

“…Groundwater dynamics have been closely related to human activities, while the natural factors are secondary [5]. Cultivated area expansion easily causes greater groundwater extraction in the arid oasis-desert region due to limited surface water resources, and strengthens the coupling among river water, soil water, groundwater, and ecological environment [15]. This in turn threatens groundwater and downstream ecosystems, causing a series of hydrological and ecological problems [50].…”

“…However, large-scale farmland expansion has led to groundwater overexploitation for irrigation, thus noticeably altering groundwater hydrochemical cycling (e.g., groundwater salinization) in arid regions, in turn affecting public health, groundwater resource renewability, soil fertility, and vegetation growth [13,14]. Groundwater hydrochemistry is crucial for biogeochemical cycling because it could impact water utilization and the ecological function of groundwater [15,16]. Therefore, a deep understanding of groundwater hydrochemistry and groundwater-surface water interactions impacted by land use change is essential for effective groundwater management for ecological and human requirements in oasis-desert regions [17].…”