Abstract
Abstract. A scheme describing the process of stream–aquifer interaction was combined with the land model CLM4.5 to investigate the effects of stream water conveyance over riparian banks on ecological and hydrological processes. Two groups of simulations for five typical river cross sections in the middle reaches of the arid-zone Heihe River basin were conducted. The comparisons between the simulated results and the measurements from water wells, the FLUXNET station, and remote sensing data showed good performance of the coupled model. The simulated riparian groundwater table at a propagation distance of less than 1 km followed the intra-annual fluctuation of the river water level, and the correlation was excellent (R2 = 0.9) between the river water level and the groundwater table at the distance 60 m from the river. The correlation rapidly decreased as distance increased. In response to the variability of the water table, soil moisture at deep layers also followed the variation of river water level all year, while soil moisture at the surface layer was more sensitive to the river water level in the drought season than in the wet season. With increased soil moisture, the average gross primary productivity and respiration of riparian vegetation within 300 m from the river in a typical section of the river increased by approximately 0.03 and 0.02 mg C m−2 s−1, respectively, in the growing season. Consequently, the net ecosystem exchange increased by approximately 0.01 mg C m−2 s−1, and the evapotranspiration increased by approximately 3 mm day−1. Furthermore, the length of the growing season of riparian vegetation also increased by 2–3 months due to the sustaining water recharge from the river. Overall, the stream–aquifer water interaction plays an essential role in the controlling of riparian hydrological and ecological processes.
Highlights
Water is indispensable for ecohydrological system (Milly et al, 2005; Ouyang et al, 2003; Shen and Chen, 2010; Zhao and Cheng, 2002)
The groundwater table depth near the river channel is significantly reduced as the river water level increases. This is because, as Eq (1) shows, the higher river water level induces a greater hydraulic gradient, which enhances lateral recharge to the riparian aquifer
The effect of Kr is significant over the short-term simulation (Fig. 4i–l): as the Kr ranged from 3 to 24 m day−1, the time spent by the nearest grid to get the equilibrium state is shortened from 2 to 0.5 days
Summary
Water is indispensable for ecohydrological system (Milly et al, 2005; Ouyang et al, 2003; Shen and Chen, 2010; Zhao and Cheng, 2002). Among a variety of water resources, aquifer water and stream water, which constitute more than 30 % of the freshwater storage, are key factors in hydrological cycle (Chen and Xie, 2010; Schär et al, 1999; Xie et al, 2014; Yu et al, 2014). Aquifer water can store the excess rainfall, and in the arid season, it reversely recharges the wet, root-zone soil and sustains the ecosystem above by upward capillary flux (Nepstad et al, 1994). The stream is very important in the ecohydrological system It continuously transports water from the humid region to the arid region and supports the ecosystem in the lower-reach area (Contreras et al, 2011; Jobbagy et al, 2011)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
