Impacts Of Side Evaporation On The Spatial-Temporal Distribution Of Soil Water On Gully Banks In The Loess Plateau

The Loess Plateau is an area which suffer the most serious soil erosion in China, also, it is one of areas which lack of water resource, water resource become the key factor in restraining the ecological recovery. Due to high gully density, side evaporation of the gully cliff and evaporation from soil surface, the soil moisture conditions deteriorate further. Based on field investigation and monitoring, the impacts of side evaporation on the soil moisture spatial-temporal distribution was studied on gully banks in the Loess Plateau, the results indicated that:(1) The soil on gully banks in four types land are extremely dry. The soil moisture on gully banks were KL< KLB< GL< GLB. Double-side evaporation made the soil moisture condition worse than the side evaporation. The side evaporation have significant influence on the soil moisture at the region from 20 cm to the gully cliff, and the influence of side evaporation on soil moisture became weaker as the distance of sample location to gully cliff increased. In double-side evaporation condition, soil moisture is lower in the east than the west. Because of the soil moisture in study areas are much lower than other places, the variability of soil moisture is low intensity. The soil moisture and variation coefficient did not show any correlation.(2) The variation trend of soil water storage on gully bank changed with the rainfall, which means that the higher precipitation is, the higher variation coefficient of soil water storage (SWS) is. Soil water storage change greatly in the soil layer of 0-2 m, and the variation of SWS is decrease as the deeper the soil is. The variation of SWS is different in each land, the relationship is KL< KLB< GL< GLB. Overall, the variation of SWC in rain season is higher than dry season, and upper layer is higher than deeper layer.(3) The alternation of wetting and drying is intense in the areas of 0-2 m to the gully cliff, the correlation between the clay and soil water stability is not significant correlation. The driest sample plots were found where further to the gully cliff in the soil layer of 0-1 m and 2-3 m. this phenomenon indicated that the sample plots near the cliff were not always the driest plots, but must not be the temporal stable plots 。(4) The soil organic matter was increase in the layer of 20-80 cm with the distance to the gully cliff further, but in the layer of 20-80 cm. soil organic matter in 0-20 cm was increased first then declined on the gully banks. In double-side evaporation areas, soil organic matter in wettest parties higher than that in the east. The side evaporation has no significant influence on soil available potassium。(5) There is significant linear relation between surface, side and surface-side evaporation, the relation is:.EA3=0.556EA1+0.489EA2, the accumulate evaporation of the 3 treatments is, side evaporation< surface evaporation< surface-side evaporation. Temperature has significant correlation on all of 3 treatments, precipitation and humidity has significant correlation on soil water storage variation.