西北干旱区农田春小麦蒸散量的空间插值方法

综合运用传统统计分析方法和地质统计分析方法,研究了西北旱区春小麦蒸散量在不同生育阶段的时空变异特征,并分析了试验区表层土壤储水量和叶面积指数对春小麦蒸散量的影响关系,通过分析比较,筛选表层土壤储水量为协同因子,并将其应用到试验区春小麦蒸散量的空间插值研究中。研究结果表明:在所研究的条件下,即使外观较为均匀、面积相对较小的农田,春小麦蒸散量仍具有较高的空间变异(变异系数范围0.328~0.495);当降雨入渗深度小于20 cm时,表层土壤储水量(0~20 cm)是影响研究区春小麦蒸散量变异的主要因子,春小麦不同生育期累积蒸散量与表层土壤储水量变化的相关系数在0.8~0.9之间,远大于春小麦累积蒸散量与叶面积指数的相关系数;基于表层土壤储水量的蒸散量协同克里金空间插值分析与地面实测结果相比,仅42个蒸散量地面采样数据即可保证研究区春小麦蒸散量估计精度高于90%。

Spatial Interpolation Analysis of Spring Wheat Evapotranspiration Measurements in Northwest China

The study investigated spatial variability of spring wheat ET and uses regression analysis to identify the ET main factors. Furthermore, the ET main factors were taken into account in the ET space research. Results showed that the geo-spatial coefficients of variation of spring wheat ET ranged from 0.328 to 0.495 at various growing stages even for homogeneous farm fields. During the spring wheat growing season, the spatial variability of cumulative ET estimates was high at the tillering-shooting stage, and then reduced at the shooting-heading stage. Comparing to leaf area index (LAI), spring wheat ET had a significant relationship with surface soil moisture content change at all the growing stages. When the rainfall infiltration depth was less than 20cm, the soil moisture (0~20cm)was the ET main factor. Compared with the ground-based observations, the ET estimation precision with 42 ET ground sample data was better than 90%.