Groundwater Response To Climate Change In Guanzhong Basin Based On SWAT

Water is the source of life. It is essential to human survival and development of resources, while China’s freshwater resources per capita is far lower than the average level in the world. In recent years, due to the impact of global warming and human activities in the water resources quantity decreased dramatically, river flow reduced or even stop, the water environment began to deteriorate, and direct threat to human survival and development. The Guanzhong basin is resource shortage region, and the temperature, precipitation, evaporation, runoff, groundwater levels and other elements of the water cycle by climate change undergone significant changes, water supply and demand become more prominent, water resources security situation is more serious. So it is especially urgent and important fully analyses and research the Guanzhong basin groundwater response to climate change.In this paper the impact of climate change on groundwater as the main line, the change of temperature and precipitation characteristics nearly 60 years of the Guanzhong basin is studied. Precipitation and temperature of Guanzhong basin was analysed by using MK and Morlet wavelet methods. According to the long-term observation data of groundwater for nearly 30 years, analyzes the characteristics of spatial distribution and dynamic change of groundwater level of the Guanzhong basin. Using DEM digital elevation data, land use type data, soil property data, rainfall and temperature data, SWAT hydrological distribution model is established, and set the climate change scenario model, calculate the surface runoff under climate change scenarios and the change of groundwater recharge. Finally, the following conclusions:1. The annual precipitation of the Guanzhong Basin from around 1960 began a decrease trend, but the downward trend was not significant until after 1995, annual precipitation showed a significant decreasing trend. Annual precipitation in different regions of Guanzhong Basin has different mutations time. Wugong, Xi’an and Huashan mutations time was in 1961, 1966 and 1986. Annual precipitation in Guanzhong basin existence for 3 years and 5 years, 20 years, 35 years periods, of which 20 years and 35 years of the cycle is the most significant. In recent years, the Guanzhong basin precipitation in the autumn and spring decrease trend obviously, does not change significantly during the winter and summer.2.The annual average temperature of Guanzhong basin, from 1990 began to rise, to the upward trend after 2000 began even more significant. The annual average temperature mutations time was 1995 years of Baoji and Xi’an and Huashan, but the temperature mutations time was 1990 years of Wugong. Annual average temperature of the Guanzhong basin existence for 15 years and 30 years cycles, the cycle of 30 years is the most significant. Winter and autumn temperatures of Guanzhong basin increased significantly since 1995 the spring temperature since 2003 has increased significantly, and summer temperatures change is not obvious.3.Guanzhong Basin groundwater level is consistent with the distribution of terrain contours. Groundwater flows from both sides of the basin to basin center. The Guanzhong basin water level in the 1980 s with basic precipitation changes in volatility stage, into the ninety s, the groundwater in slow decline, by 1995, the underground water level began to drop, dramatically until 2000, the groundwater decline eased, parts of water also rebound.4.Using digital elevation data, land use data, soil data, meteorological data and so on, SWAT hydrological models for the entire watershed established the Guanzhong basin. The groundwater recharge and runoff will increase with the increase of precipitation be calculated with the model. When the temperature is constant, precipitation decreased by 10%, the groundwater recharge decrease 29.83%, precipitation increased by 10%, groundwater recharge increased 34.52%. When precipitation constant temperature increase groundwater recharge little effect, when the temperature increases 1℃, the amount of groundwater recharge decreased by 1.1%.5.Coupling SWAT and MODFLOW model to calculate the change of groundwater level under the different climate change scenarios. When precipitation increased or decreased by 10%, the groundwater level is also a corresponding increase or decrease 0.6-1.5m. Temperature changes have little effect on the groundwater table. Climate change directly affects the water table by relatively small, mainly indirect influence groundwater level changes.