Soil moisture characteristic curve and prediction of available water content of overburden in Xilinhot Mining Area

Topsoil is stripped away by open-pit mining which resulting in large-scale landform changes and vegetation damage.Land reclamation is an effective ways of reconstructing the original ecosystem.The eastern part of Inner Mongolia is fragile and the topsoil is scarce.It is great significance to try to use the overburden to carry out the development of topsoil alternative materials.The water holding capacity of overburden is an important indicator for selecting as topsoil alternative materials， which is useful for guiding the reclamation of the dumping site.However， the direct measurement of soil water characteristic curve is costly and time-consuming.This paper compares the prediction accuracy of soil water characteristic curve and soil available water content in overburden (L1—L5，5 layers) by AP (Arya and Paris model)， MV (Mohammadi and Vanclooster model) and MVVG (MV model with the van Genuchten).The results showed that MVVG had better prediction accuracy for soil water characteristic curve (R2 ＝ 0.940) and effective water content (R2 ＝ 0.7409)， and AP had the best prediction result for soil water characteristic curve (R2 ＝ 0.950)， but it was lower for predicting effective water content (R2 ＝0.490 8) and the predicted results of MV and UNSODA were poorest.The prediction performance of AP model on loamy sand，sandy loam and silt loam in SWCC was better than MV and MVVG， but the prediction performance of all models on sand soil was poor.In addition to the L5 layer， the remaining four layers showed a decreasing trend in field water holding capacity， wilting coefficient and effective water content as the depth of the soil layer increased.Moreover， the effective water content of L2—L4 was lower than L1 (18%)， and L4(8%) ＜L3 (11%) ＜ L2 (15%).Through comparative analysis， this paper considered that the prediction results of MVVG and AP were relatively accurate， and it was suitable for the prediction of soil water holding capacity of overburden.At the same time， the results showed that the L5 layer had the largest effective water content (20%) and had the potential as topsoil alternative materials， and L2—L4 could be used as a material that neutralizes sticky of L5 to bring the soil texture closer to the humus soil (L1).