Ecological Risk Assessment Of Soil Salinization In Ebinur Lake Wetland National Nature Reserve

Soil salinization may be the most severe eco-environment problem presented to agricultural areas development in semi-arid and arid climatic zones around the globe. Reclaiming salt-affected and salinized soils is a labor- and time-consuming task. The Ebinur lake Wetland National Nature Reserve as the most important nature reserve in Xinjiang,because of the impact of human activities and climate change in recent years,combined with the Ebinur Lake area special geographical location and the characteristics of the monsoon climate,the ecological environment deteriorated sharply and the soil salinization problems become the most important ecological problems in Ebinur Lake Wetland National Nature Reserve.Therefore, it is very important to obtain the information of temporal and spatial variation of soil salinization in real time and accurately to prevent the further deterioration of salinization and the sustainable development of the ecological environment.This paper choice Ebinur Lake Wetland National Nature Reserve as the research area, select the six periods of remote sensing images as the basic data, under the ENVI for remote sensing image pretreatment, combined with RS, GIS and field investigation of soil information to determine the soil salinization formation factor, and extracting salinization information in the study area,then the ecological risk index was use,in order to provide theory and data support for the preventing soil salinization, promote agricultural production and sustainable development of agricultural production and ecological. The results show that:(1)By analyzing the correlation between remote sensing image retrieval salt index and measured surface soil salinity data, we found that the correlation between the two has reached 0.92, indicating that through the remote sensing image of the scope and degree of soil salinization in large range, real-time, dynamic testing is achievable.(2)Combining with the ecological risk comprehensive evaluation model of soil salinization, the weighted sum method to calculate soil salinization ecological risk index of the Ebinur Lake Wetland National Nature Reserve, draw the previous research results,the ecological risk level can be divided into four levels: low risk level, moderate risk level, high risk level and highest risk level.(3)Analysis affects the salinization in the study area of various natural conditions, the ecological risk grade distribution in the study area has a certain regularity, the degree of risk by the lake center water into the surrounding area gradually reduced gradually; Natural factors are the incentive of the regional soil salinization risk, and it is also the decisive role of the occurrence and development of soil salinization.(4)From the spatial distribution characteristic of soil salinization ecological risk level, under the influence of factors such as water areas, the terrain, the ecological risk level of the soil salinization of the Ebinur Lake Wetland National Nature Reserve gradually reduced from around the lake, the level of the area will be increased.Lake district center due to the low, high underground water level, vegetation coverage rate is extremely low ground, harsh natural ecological conditions, thus leading to the great lakes ecological risk level is higher;Peripheral area of Lake District region and the upstream of the Irtysh River, because of the higher terrain, vegetation cover is high, small changes in the terrain,it is not conducive to the accumulation of salt, which make soil salinization ecological risk level low.(5)From the time distribution characteristics of ecological risk level of soil salinization, the Ebinur Lake Wetland National Nature Reserve accounted for the proportion of different risk levels although has certain change, but the overall trend has not changed in 1972-2015,the areas of each ecological risk level were in the order of moderate risk level> high risk level> low risk level> higest risk level. In 1972-2015 years, the area of the moderate risk level of the study area has been reduced, and the other risk level has been increased year by year.