Risk Assessment Of Soil Salinization And Regulation Of Water And Salt In Songyuan Irrigation District

Soil salinity has become one of the world's most serious and the most attention environmental geological disasters, its adverse impact of society, the environment and the degree of harm on human health and economic development is difficult to measure with economic losses, the result of Soil salinity is often with disastrous consequences of broad, potential, stability and durability, therefore, the task for disaster prevention and mitigation of such disasters is urgent. Carry out risk assessment of soil salinity and regulation of water and salt is an important way and disaster prevention and mitigation measures, it is not only the risk of disaster evaluation system expansion and refinement, but also for the development of measures to mitigate soil salinization hazards provide a scientific basis and support .This paper comprehensively summarized and reviewed domestic and foreign soil desertification, soil salinization and seismic hazards, landslides, debris flow, meteorological disastersr natural disasters risk assessment, regulation of water and salt latest research progress and development. To disaster theory, earth science ideas, systems theory, risk theory, focused on the soil salinization disaster itself and the risk of soil salinization theory, theory of risk evaluation system, Construction of the gray system theory Entropy-based Grey soil salinity disaster risk assessment model, Carry out risk assessment and regulation of water and salt case study in Songyuan Irrigation District Western Jilin Province, for risk assessment results use three dimensional numerical model for groundwater flow control of water and salt, and achieved the following results:(1) From the perspective of Disaster proposed the concept of soil salinity hazards, systematic analysis of the formation process of soil salinity hazards and factors, the formation process of soil salinity hazards consist of modern salt formation, the residual salt and alkali soil formation process; The environment system to Soil salinity hazard is divided into natural environmental to hazards subsystem and human activities environmental to hazards subsystem, this research rich theoretical system of soil salinity hazards.Put forward soil salinity and its risk systems for disaster risk definition and analysis of its content, features, constructed a system to clarify among the soil salinity hazard systems, soil salinity disaster risk systems and disaster risk assessment of relationships conceptual model The model framework, clear structure, clear physical meaning, is a useful exploration to promote disaster theory and risk theory crossover study.(2) Established the overall concept model of Soil salinity disaster risk assessment, model interpretates of the meaning of Soil salinity disaster risk assessment, given the content and evaluation of its evaluation process. Based on the analysis of Soil salinity disaster risk systems, taking into account the formation and evolution of soil salinity hazards and the damage object and scope, Tertiary structure was established with a covering of soil salinity hazards and the basic conditions for the formation of Disaster in exposure, vulnerability, disaster prevention and mitigation capabilities and other factors, including 4 factors,12 sub-layers and 28 evaluation factors. Soil salinity indicators of disaster risk evaluation index system.Characterization of the indicator system is comprehensive, clear and easy-to-disaster significance to quantify can provide effective and reliable disaster risk assessment support to soil salinity disaster risk assessment, is also a theoretical system of the expansion and refinement.(3)The gray system theory and information entropy used in risk assessment, established based on the entropy of Grey Evaluation Risk Assessment Model of soil salinity hazards and based on risk theory, established a disaster risk index of soil salinity model.In this paper soil salinity disaster risk is as a gray system and to determine the weight of entropy, combined with disaster risk index of soil salinity model, achieve soil salinity disaster risk quantitative evaluation in Songyuan Irrigation District and the results in good agreement with the irrigation truth and strong objectivity, indicating That the model can be used to for the purpose of disaster prevention and mitigation of disaster risk evaluation of soil salinity. Based on this, disaster economic losses in 2007 estimated results show that the damage to Songyuan Irrigation District caused by soil salinity up to 22.157 billion yuan in economic losses.(4)This paper conmbines re-planning of land use regulation and regulation of water & salt numerical model to soil salinity disaster risk.Land use regulation would extend the area of paddy fields 1.59 million mu , dry land area reduced to 0.958 million mu, 0.3 mu million of grassland area and is the original flat. Under this premise, carried out three-dimensional numerical model (Visual Modflow model) of hydrogeology as a means of regulating water and salt simulation research, design, three different irrigation programs were designed, analyzed and compared before and after the effect of regulation. The model can of provide decision support for Songyuan Irrigation District soil salinity disaster control soil salinity, and for other Irrigation District where soil salinity disasters is heavy also have reference value.The final irrigation on yield of grain output accounts showed that the increase of grain yield caused by up to 3.378 billion yuan in direct economic benefits after regulation, indicating that the benefits are obvious, control scheme is feasible.