Simulation of the Relationship between Land Use and Groundwater Level in Tailan River Basin

Groundwater is one of the major water resources in arid areas across the world. Meanwhile, it is widely regarded as the primary water resources to maintain arid oasis ecosystems, and especially socio-economic developments in arid areas. Assessment of the impact of human activities on groundwater system is critical to establish a reasonable utilization strategy of regional groundwater resources. Land use is a major force altering the hydrological processes over a range of temporal and spatial scales. Land use in a watershed can impact water supply by altering hydrological processes such as groundwater recharge, base-flow and surface runoff.

Both land use and groundwater level changes will change the hydrological processes in the region. It is important to understand the hydrological responses to these changes in order to develop sustainable basin management strategies. Excessive groundwater exploitation in the Tailan river basin, located in southern Xinjiang, China resulted in serious eco-environmental concerns. The environment and ecosystem changes have greatly impeded the sustainable development of agriculture and economy in the region.

Prof. ZHAO Chengyi and his student carried out researches about the relationship between land use and groundwater lever in Tailan River basin in order to: (1) develop a numerical model to assess the coupling effects of land use and hydrological process in the extremely-arid inland river basin; (2) incorporate several sink/source factors and the spatial pattern of land use in the numerical simulations using FEFLOW model and use observed data to test the simulations; and (3) identify the effects of the regional land use on two-dimensional groundwater flow.

The results indicated that the amount of irrigation water and pumped groundwater have the most remarkable influences on groundwater level as main source/sink factors. Their variations were simulated according to the irrigation systems with different crops. Other factors including percolation and evapotranspiration of precipitation and condensed water jointly exerted influences on groundwater level. Changes to farmlands had the greatest impact on Tailan River basin for groundwater level, and unused land and Gobi had the least impact on groundwater level. Groundwater level maintained a decreasing trend in the irrigated zone, and increasing groundwater pumping would further intensify the water shortage in Tailan river basin. This coupled effects resulted from land use and extensive groundwater pumping were considered as the major human-induced factors influencing the groundwater system in the extremely-arid inland river basins. The results can provide useful support for land use. Understanding hydrological processes at the watershed level is essential in land use and water resource planning and management, and the proposed approach can be used as a management and planning tool for evaluating the local and overall impacts of land use management on the surface and groundwater flow regimes.

This work has been published on Quaternary International, 2011, 244(2): 254-263. This paper is also archived at http://www.sciencedirect.com/science/article/pii/S1040618210003502.