Transport Laws Of Soil Water-Salt In Plain Reservoir Downstream In Xinjiang

With water level rises after plain reservoir stores water, backwater area increases, voidsin the stratum in the bottom and brim of reservoir are filled with water, groundwater levelaround reservoir rises therewith, which brings about some eco-environment problems aroundthe reservoir and downstream, such as soil immersion, swampiness, soil salinization andgroundwater salinization, causes vegetation deterioration around reservoir area, yieldreduction of farmland or desertification, with the result of serious economic losses. there aremany achievements on soil water and salt movement and salination in arid area home andabroad, most of which focused on farmland, while studies on wasteland of no irrigation andvegetation scarceness are rare.This study applied HYDRUS-1D model in salination wastelandsoil around Qiala reservoir in Xinjiang, studied change features of soil salinity in wastelandand simulated salt and water exchange migration law between wasteland soil and groundwater,finally determined parameter of water and salt transport in this area. The results can provideinitial values for salt-water regulation of alkaline land in this area. The main conclusions ofthe study are given below:(1) Without anti-seepage measure or in poor seepage control condition, salination ofdownstream land was accelerated by reservoir water seepage. Seepage influence range inQiala reservoir is at least beyond1000m which enlarges the area of salination of downstreamland.(2) The key to reduce adverse effect of plain reservoir to soil and water environment indownstream is seepage prevention and intercept seepage measure. Seepage preventionmeasure can save precious water resources and develop agriculture and industry better.Cut-off ditch around reservoir is constructed and links to channel, to guarantee leakage waterdrainage of reservoir and prevent and relieve salination and swampiness of land around.(3)There is a significant correlation between top soil salt content and degree ofgroundwater mineralization in salt wasteland, salt in groundwater is the main resource of saltin soil.(4) State of water and salt migration in soil profile in condition of different groundwaterdepth and groundwater mineralization degree were analyzed and predicted usingHYDRUS-1D model. With evaporation intensity approximately identical, when thegroundwater salinity is equivalent, the smaller groundwater depth is, the greater surface saltaccumulation is; when groundwater depth is equivalent, the higher groundwater salinity is,the greater surface salt accumulation is. When groundwater salinity is3g/L, average salinityin topsoil between0~30cm in groundwater depth of0.5m is0.25%which is4.17%higherthan0.24%in groundwater depth of1.0m and56.25%higher than0.16%in groundwaterdepth of2.0m. When groundwater salinity is30g/L, average salinity in topsoil between0~30cm in groundwater depth of0.5m is2.44%, which is42.69%higher than1.71%ingroundwater depth of0.5m and79.41%higher than1.36%in groundwater depth of2.0m.When groundwater salinity is100g/L, average salinity in topsoil between0~30cm ingroundwater depth of0.5m is7.47%which is95.04%higher than3.83%in groundwaterdepth of1.0m and136.39%higher than3.16%in groundwater depth of2.0m. Decliner ofgroundwater depth and salinity can reduce surface soil salt accumulation effectively.