Research Of The Influence From The Development Of Songyuan Irrigation Area To Soil Salinization

Songyuan irrigation area is located in the plains in western jilin province, and the southwest of Songnen plains, is the key projects of ten billion jins of commodity grain in jilin province yield capacity planning, to develop land resources, improve grain production in west jilin, meet the production and living water, reform saline-alkali land, protect the regional ecological environment. Transforming a large area of saline-alkali and wasteland into paddy field, and introduce the second songhua river water for irrigation are the basic measures. But the introduction of a large amount of surface water and the dramatic changes of land utilization way may cause region ground water level rise considerably, bring certain secondary salinization risk for irrigation area. This paper revolves around the influence of Songyuan irrigation area development the soil salinization problem.Irrigation area of soil salinization is closely related to the characteristics of the groundwater table in the area. This paper is on the basis of fully understanding the natural geographic and geological and hydrogeological conditions in the study area and irrigation land use planning and the design of irrigation scheme, build groundwater flow numerical model of diving. Using models to predict space-time change law of underground water level in the irrigation area in 5 years after the implementation of project. The results showed that irrigation underground water level has an overall rise, and the water level rising range between 0.2—0.6 m, the rising extent in the west is larger than the east, and paddy field have larger change than dry land area and undeveloped area, and in first year there is a maximum rising height of water level, then decreases year by year, and finally the water level tend to be stable.Using the numerical model of groundwater can get the change trend of groundwater evaporation after water irrigation. The groundwater evaporation rise greatly than before as the underground water level rising, total growth rate of each irrigation groundwater evaporation within 5 years is between 20%- 80%, and rising range reach to the maximum value and decreases year by year consistenting with the law of underground water level rise.According to the irrigation area of soil salinization degree distribution data, with the aid of GIS spatial analysis technology calculate out the average soil salinization in irrigation piece. On this basis, according to the soil salt equilibrium theory, predict the soil salt content of paddy field, dry land, grassland, feed and non-agricultural land respectively, evaluate the trend of soil salinization of different land use areas.Compared with previous studies, this article uses the dynamic variation of groundwater evaporation in counting, and land in the study area can be divided into three categories to evaluate respectively, especially considering the non-agricultural land scattered in irrigation area, make evaluation result more scientific and reliable.According to the calculation results, in the planning of land use scheme and design of irrigation quota, the soil of each irrigation area will be generally in a state of desalination within five years, salinization degree will be mitigated, soil salt content will be reduced by 18%- 50%,meanwhile, soil salinization degree of the dry land, grassland and feed area will remain constant, and the degree of soil salinization of non-agricultural land use in irrigation area will increase year by year.With regard to possible soil salinization risk in Songyuan irrigation area, the paper put forward practical and feasible prevention measures, emphasizing to build perfect drainage ditches to control the underground water level and reduce the evaporation of groundwater, ultimately achieve the purpose of preventing soil salinization.