Study On The Effect Of Human Activity On Water Cycle In Plain Of Manas River Basin

The oasis plain area of Manas River Basin is a typical ecological fragile zone and irrigated agricultural area in Xinjiang. The contradiction between supply and demand of water resources is very serious. In recent years, unreasonable exploitation of groundwater has caused the deterioration of the ecological environment gradually. To some extent, water saving measures in large area has changed the water cycle of river basin. Groundwater is an important part of the water cycle in the plain area. To a certain extent, the water level of the water cycle reflects the sustainable development of the water cycle in the river plain area. Therefore, analyzing on the influencing mechanism of human activities in the water cycle of the river basin is of great significance to master the transformation rules of precipitation, surface water and groundwater. Maintaining the rational exploitation and utilization of water resources in arid areas and the sustainable development of regional ecological environment are important.Based on the summary of the literature and the results of previous studies, the oasis plain area of Manas River Basin is choosed as an example. The Effect of Human Activity on Water Cycle in Plain of Manas River Basin is studied. Firstly, the characteristics of human activities were determined. And the main factors which affect the water cycle, such as farmland irrigation, groundwater exploitation and other factors are generalized. Meanwhile, rainfall, snow melting, evaporation, surface, vegetation and groundwater and other factors are generalized comprehensively. The water transport model of one dimensional unsaturated zone in the river basin was constructed. The migration and transformation process of the vertical input aeration zone in the surface water was calculated by HYDRUS-1D simulation. We have had water leaching process at the bottom of the unsaturated zone. And it provides basic data for the initial input of aquifer model. On this basis, watershed boundary and hydrogeological parameters are generalized. The groundwater numerical model is constructed. The effects of different irrigation modes and different groundwater exploitation on the water quantity and water level were analyzed. The research results show that the model has better simulation results. The coupling between the model calculation results of the unsaturated zone and the aquifer model can be well applied to the study area. Thus the coupling calculation of the simulation of the ground surface, the aeration zone and the aquifer system is realized.On the basis of model building and theoretical analysis, coupling of the model of the unsaturated zone and the aquifer model is utilized. The supply and drainage of groundwater in the study area were analyzed by the method of water balance. The results show that the vertical infiltration at the bottom of the aeration zone is the main source of the groundwater in the study area. In the simulation period, the surface infiltration capacity is 55932.73×104m3, 44.92% of the total recharge. Followed by the supply of river, the surface infiltration capacity is 20247.81×104m3, 23.5% of the total recharge. In addition, the upstream side supply is 9981.06 × 104m3, accounted for 11.58%. The main methods of excretion were artificial exploitation and evaporation and transpiration. The groundwater run off exchange in the study area is from the south to the north. In order to further explain the impact of human activities in the future, under the condition of current parameters, simulation and analysis of the water cycle characteristics of the future planning year is done. Predicted results show: current situation of irrigation mode(195m3/ mu), the traditional furrow irrigation mode(235 m3/ mu) and high efficiency water saving irrigation mode(155 m3/ mu) compare with the baseline year, by 2020, the ground water level and quantity both have a certain degree of change. In the study area, the change of plane infiltration are 1091.4×104m3 decrease, 4224.11×104m3 increase and 3584.73×104m3 decrease. The maximum variation of groundwater level in the study area respectively were 0.23 m decrease, 2.1m increase and 0.8m decrease. Drip irrigation under film can not only guarantee the requirement of crop water requirement, but also can effectively save water resources in the inland arid area. Under different mining conditions, the three schemes are in a negative equilibrium state, and scheme two is the more reasonable through general analysis, that is the adjustment of planting structure. The amount of groundwater exploitation is the main discharge, which directly affect the change of groundwater dynamics. The research results provide reference for the development and utilization of regional water resources.