Experimental Study On Water And Salt Transport Characteristics In Stroge Water Of Soil Transition Layer

The lack of land resources is one of main problems which restriction our county's economic development at present.Saline land used as a kind of barren soil, with social progress, it become a precious reserved land resources when treatment technology had acquired ansiderable progress.The previcus treatment mainly with salt washing and salt exclusion in water, it is very difficulty for backward areas where water shortage.This paper combines "LuBoTan" gavemance model, through laboratory simulation test, put forward transition layer theory.It is very impotant for alklaing soil in drought and scare water areas.Based on data from recent study articles, study actuality home and abroad summarize on soil water and salt movement, combined with project of resources department of Shannxi Provice:"The reseaech on harmonious ecological comprehensive treatment model of saline land in LuBoTan, Shannxi Provice". Focus on water and salt movement under the condition of inundation to restrain salt content and water-reserving of soil transition layer with laboratory test method,application HYDRUS-1D model simulation under the condition of water dynamic balance and salt advection-dispersion of soil unsaturated region and soil soil transition layer in evaporation conditions,results were obtained as follows:(1) This text passes by simulation of irrigation.paper records the relation between vertical infiltration distance and infiltration time during the observation period.In the water infiltration process, the last wetting front distance is 128cm. According to the change of wetting front distance,there are three stages:percolation,leakage,infiltration. The vertical infiltration distance and time is a power function, H=3.698T0.344, R2=0.9243.(2) Through simulation irrigation for 20 days,found that infiltration can significantly washing the salt of soil surface. As the passage of time in infilation condition,the total salt content of each soil layer had decreased in of different degree.Based on the variation degree of total salt content,can divided into three layers:0～-45cm rapid decrease layer,-45～-90cm slow reduce layer,-90～-120cm rose slowly layer. (3) By laboratory simulation test in 3 months, found there is a transition layer (10-20cm) in water-reserving condition, transition layer present to-120cm and-105cm peephole when water storage 20cm, the thickness is 15cm; present to-90cm and-75cm peephole when water storage 40cm, the thickness is 16cm; present to-75cm and-60cm peephole when water storage 70cm, the thickness is 20cm.(4) The experiments assurance 3 pool level (20cm,40cm,70cm), the soil initial salt content including inundation to restrain salt content and upper and lower uniformly.Through 3 contrast test, the total salt content of each soil layer of variation trends are similar in differend water-reserving condition,it is stable in saturated layer, it is reduce in transition layer,it is rose in unsaturated region. But whether the content of salt in is high or low in saturated layer,is in relative steady state during the test period.Transition layer have a remarkable isolated effects for salt in lower layer.(5) Soil water content and salt content are simulated using the software of HYDRUS-1D in evaporation conditions when water storage,in order to verification testing result, the average error between simulating data and measuring data is less than 11%,individual is 22%. And the conclusions of the numerical simulation are coherent to the experiment data approximately.(6) Under storge water conditions, through cycle-press the salt can change the distribution of the soil salt in vertical,transition layer as a important theory for change drainage to impoundment model of saline land, it can explain the fate of the soil salt in vertical, transition layer can isolate salt for saturated layer.