基于作物缺水指数的土壤含水量估算方法

Estimation of soil moisture based on crop water stress index

为研究江苏省徐州市的土壤水分时空分布及动态变化,基于MODIS数据和站点气象数据,利用蒸散发双层模型和考虑土壤水分可供率的改进双层模型分别计算实际蒸散发量,利用Penman-Monteith模型计算区域潜在蒸散发量,计算获得作物缺水指数(crop water stress index,CWSI),并与2010年7月和11月的土壤相对含水量实测数据分别进行回归分析建模,得到了土壤含水量分布图。结果表明:基于蒸散发双层模型的土壤含水量估算结果与实测值的决定系数分别为0.53和0.72,平均相对误差分别为5.89%和9.6%;对双层模型进行改进后,土壤含水量估算结果与实测值的决定系数都为0.84,平均相对误差分别为3.47%和6.03%,利用改进后的双层模型对土壤相对含水量进行估算效果更好。

In this paper, the authors calculated the amount of the actual evapotranspiration based respectively on double layer model and improved double layer model in consideration of the available water rate of soil with MODIS data and meteorological data so as to investigate the temporal and spatial distribution of soil moisture and dynamic changes in Xuzhou City, Jiangsu Province. The amount of the potential evapotranspiration was calculated by using Penman- Monteith formula. Models were built to estimate the relative content of water of Xuzhou in July and November 2010, by crop water stress index （CWSI） obtained by the actual evapotranspiration and the potential evapotranspiration. The result shows that the relative error of the estimated data based on the improved double layer model and that of the measured data are 3.47% and 6.03% respectively, with the correlation coefficient being 0.84 and 0.84, which are better than the results obtained by the model based on the double layer model, whose relative error is 5.89% and 9.6% , and whose correlation coefficient is 0.53 and 0.72.