Guanzhong Basin Environmental Isotope Distribution Characteristics And Hydrogeological Significance

Guanzhong Basin is located in the center of Shaanxi province. It is also the center of political, economy and culture as one of sixteen key construction regions. But Guanzhong Basin is arid and semi-arid climate zone. The water resources occupation of per person can not reach one sixth of the country. With rapid development of agriculture and industry, coupled with sharp expansion of population in recent years, water demands is adding and water resources becomes lacking. So it is urgent to deeply study water resources.The thesis is selected on the basis of one of the Nation Development and Program Project about Key and Foundamental Researches,"the Study on Groundwater Renewability Law in the Yellow River Watershed"(G1999043606). Through selecting two representative profiles in Guanzhong Basin and by means of environmental isotope techniques, the paper systemically studies the transform relationships of precipitation, stream water and groundwater. According to the environmental isotope dates, the paper establishes the Local Meteoric Water Line (LMWL), analyzes the distribution characteristics of environmental isotope in different water body and its influence factors. On this basis, it also studies the main recharge of groundwater, discusses the relationships between river and groundwater, shallow confined water and phreatic water, northern karst water and quaternary phreatic water as well, and get the recharge percentage which river recharges to phreatic water. In order to recover the tritium concentration in precipitation from 1953 to 2001 for Xi'an area, two methods such as interpolation method and two conference curve method have been employed, and the tritium concentration in precipitation has been recovered. Through calculating the age of shallow and deep groundwater, the velocity of karst water cycle has been obtained. So the paper provides evidences for the transformation studies among rain water, stream water and groundwater in Guanzhong Basin and establishes the foundation for the finish of the National "973" Project "the Study on Groundwater Renewability Law in the Yellow River Watershed".