夹砂层状土壤潜水蒸发特性及计算模型

针对西北地区农田土壤常见的砂土夹层土壤结构，通过室内土柱实验，研究了浅层地下水埋深条件下夹砂层状土壤的潜水蒸发特性。研究结果表明：砂层对水分蒸发既有促进也有抑制作用，相同厚度时潜水蒸发强度随砂层层位的升高以及级配的变差而降低。以砂层的相对层位和相对有效粒径作为砂层的量化指标，建立了适用于不同层位和质地夹砂层土壤稳定蒸发强度的修正模型，并对其进行了验证。该实验为定量研究夹砂层状土壤潜水蒸发提供了新思路。

Characteristics and calculation model of phreatic evaporation of sand-layered soil

Phreatic evaporation characteristic of sand-layered soil with a shallow water table was analyzed according to laboratory experiments. Results show that the sand layer has positive and negative effect on the water evaporation. At the same soil layer, the phreatic evaporation decreases with the increase of sand positions and the decrease of sand particle sizes. Taking relative sand position and sand particle size as quantitative indices, correct model of steady phreatic evaporation with different sand positions and sand particle sizes was established. Parameters test of steady phreatic evaporation model was analyzed. The research supplies a new method for quantitative study of steady phreatic evaporation of sand-layer soil.