基于MOD16数据的渭河流域地表实际蒸散发时空特征

基于流域水量平衡法,利用水文数据和气象数据对渭河流域MOD16-ET(实际蒸散发)数据进行精度验证; 利用2000-2012年MOD16-ET数据和GIS技术定量分析了渭河流域(分为干流、泾河、北洛河3个子流域)地表实际蒸散发年际和年内的时空变化特征。结果表明:(1) 3个子流域的实测降水空间插值结果与MOD16-ET估算结果比较,相对误差平均值为8.36%,渭河干流误差较小,其他2个子流域误差相对较大; (2) 3个子流域上游至下游的ET剖面线变化不同,明显受地表覆盖类型影响; (3) ET值年内分布大致呈单峰型格局,季节变化特征为夏季(177.14 mm)> 秋季(105.22 mm)> 春季(92.97 mm)> 冬季(77.50 mm); (4) 基于栅格尺度的ET值年际变化特征空间分布,各子流域下游以降低趋势为主,渭河中游和上游以升高趋势为主,北洛河、泾河中游和上游以基本不变趋势为主,具体影响因素的定量分析仍需MODIS资料的时间累积。

Spatial and Temporal Characteristic of ET in the Weihe River Basin Based on MOD16 Data

Based on the water balance model in the Weihe River basin, this paper versified the accuracy of MOD16-ET by using hydrological and meteorological data. Under the support of GIS technology, this paper studied the spatial and temporal characteristics of ET in the Weihe River basin during 2000-2012. The findings are as follows: (1)The average relative error was 8.36% between spatial interpolation results based on measured rainfall and estimates based on MOD16-ET. The error was smaller in the mainstream basin of Weihe River, while it was relatively larger in other sub-catchments of the Weihe River basin. (2)The profile lines of ET showed different changes from upstream to downstream in the sub-catchments of the Weihe River basin, which apparently affected by the land cover type. (3)The monthly variation of ET roughly showed a unimodal pattern. The seasonal variation of ET showed that the maximum value was in summer (177.14 mm), then autumn (105.22 mm), spring (92.97 mm), winter (77.50 mm). (4)The spatial distribution of annual variation of ET showed different characteristic in the scale of grid. The ET mainly showed a increasing trend in the downstream at each sub-catchment, while it mainly showed a decreasing trend in the midstream and upstream basin of Weihe River and basically unchanged trend in the midstream and upstream basin of the Beiluohe River and the Jinghe River. Quantitative analysis of specific factors still needed the accumulation of MODIS data.