Analysis of the Transformation Path Between Stream Flow and Groundwater from Dingxin to Shaomaying in Hei River, Catchment West China
WU Yan-qing;MU Fu-qiang; HE Yi-xian;LAN Yong-chao (Cold and Arid Regions Environmental and Engineering Research Institute, CAS. Lanzhou Gansu 730000, China )
Water resources system includes the branch systems of rainfall, surface water, and groundwater. Transformation between surface water and groundwater flow is an important part in water resources researches. Hei River is located in western Gansu Province, West China. It comes from Qilian Mountains and is one of the largest inland rivers in the arid region of the western China. In spite of multiple transformation between surface water and groundwater flow. river water finally flows into the lower reaches, the eastern Juyanhai and the western Juyanhai lakes. When the assessment of water resources was carried out in Hei River catchment, it is difficult to determine transforming relation between streamflow and groundwater flow. The objectives of the study were to ascertain the transformation path between streamflow and groundwater through geophysical exploration and analyzing the relation between eastern Guernai oasis and Hei River. After a site investigation of underground geological structure by using Stratagem EH4 electric conductivity imaging system in Dingxin-Shaomaying valley of the Hei River downstream, it is discovered that there is a fault zone that strikes east- west. This fault zone may be an ancient riverway. Most of streamflow penetrate to subsurface along this fault zone transforming into groundwater flow. The groundwater flow moves toward the eastern Guernai oasis along this fault zone. Then the groundwater flow discharges in the manner of surface evaporation and vegetation evapotranspiration in the eastern oasis of the study area. Thus, there is a close connection between the eastern Guernai oasis and the Hei River. Most of groundwater come from the Hei River in the eastern oasis. Groundwater upward rise is the base of vegetation in the eastern Guernai oasis.