Study On Groundwater Simulation And Water-salt Balance To Irrigation And Drain System In Arid Area

With the development of human civilization, reduction of arable land, and soil degradation has become a major threaten to humanbeing. Especially in arid area of northwest in China, alkalization and soil secondary salinization have been paying great attention by government and scientists. Especially in the irrigated area which has high-water level and grave soil secondary salinization. In order to improve and use saline land, and control soil secondary salinization, it is awfully necessitated to combine the groundwater numerical model and water and salt balance model. So to find the groundwater and salt movement law. And then we can analyze and estimate its condition of water and soil resources, and realize the sustainable utilization of water and soil resources, and the sustainable development of agriculture.The paper summarizes the basic situation of the project area for supplying water to farm in 58 group of Nongsanshi, Xinjiang. And analyze the groundwater system and causes of saline formation. Then based on dynamic features of groundwater system in study area, it is easier to calculate and identify elementary every parameters using the pumping test data. Based on putting groundwater numerical model and water and salt balance model combined, it is awfully necessitated to simulate and comparative analyze in study area and typical area. At the same time, it predicts and analyses the environmental change under five different projects of the basin. And the main conclusions of this paper are:1) the simulation model of groundwater shows that in intensive exploitable area, with the enlarging of mining and continuing of mine time, it makes partial-area flow concentration phenomenon, with enlarging of mining and continuing of mine time; The area of depth of groundwater between3 to 5 meters increased and stabilized at last, and the area of depth of groundwater above five meters increased continuly; Groundwater drawdown by disturbance is between 2 to 6 meters in phreatic area. And drawdown by disturbance is between 7 to 9 meters in intensive exploitable area; Lateral inflow which mining of groundwater draw is main aspect. But with the increase of mining, the vertical inflow also enlarged.2) According to the calculation results of water and salt balance in study area: after actualizing measure such as well irrigation and well drainage, it takes on desalinization in whole study area; the movement of salt is mainly affected by Vertical water exchange. And with increase of mining, vertical infiltrated water increase, and the total ionic concentration of groundwater rise continued, up to 5.73g/L. Water-quality deteriorated day by day.3) the optimum plan is surface water indraught is 20321×104m3/a, groundwater yield is 1289×104m3/a, water displacement is 2434×104m3/a.