Study On The River-groundwater Interreaction Of Yuxi River Upstream

Water temperature can characterize groundwater activity, as a tracer of groundwater circulation, which is mainly used in two aspects at present, that are river and groundwater circulation and the detection of groundwater seepage of the project. In the area of the small scale, groundwater temperature is mainly influenced by supply water temperature and the human activity in the short term. The selected five test points in upper reaches of Yuxi River have not been affected by human activities. As a result, the groundwater temperature data of the experiment measured in the field is mainly affected by temperature of river and groundwater. The analysis results of groundwater temperature data show that the groundwater temperature changes with buried depth, the smaller the buried depth changes, the greater the temperature affects, and vice versa. The greater the buried depth changes, the greater the temperature influences. When the interaction of river and groundwater achieves stability, the stable groundwater temperature of the points 1 and 2 is close to river temperature. Therefore, we deduced that the groundwater is recharged by river. The stable groundwater temperatures of the points 3, 4, and 5 are close to groundwater temperature, which is higher. We deduced that groundwater recharge river. At the same time, according to piezometric head analysis results measured by nilometer, the head of points 1 and 2 are reduced in turn. Therefore, the two points are determined that the river recharge groundwater. The heads of points 3, 4, and 5 increase by degrees, they are determined that groundwater recharge river.SEAWAT software is applied for simulating the influence of different hydraulic gradient between rivers and groundwater and the influence of different permeability coefficient on the temperature transport. We understand that the temperature varies with time and buried depth under different conditions. According to simulation results, under the condition of the same water temperature and groundwater temperature, temperature profile curve changes gradually with time, towards the direction of the high temperature, and the range of temperature variation increases gradually with the reduction of buried depth no matter what both in the condition of the same permeability coefficient and the different head or the different permeability coefficient and the same head. The head difference and the permeability coefficient get bigger, exchange capacity of the yield of groundwater becomes larger, the impact on the model layer is greater, the temperature changes faster, and vice versa. Small permeability coefficient and head difference, water exchange capacity of groundwater is little, the temperature change is slow. In the same head and the same permeability coefficient, but different in the relationship between river and groundwater, exchange capacity of the yield of groundwater is the same when flow model reaches a steady state. In winter, the temperature of the river is lower, and groundwater temperature is higher. When the river recharge groundwater, the overall temperature is at the low side, closing to the river temperature; When the groundwater recharge river, the overall temperature is at the high side, closing to groundwater temperature.