子牙河流域蒸散发时空变化及其影响因素分析

Temporal and Spatial Variation of Evapotranspiration and Its Influencing Factors in Ziya River Basin

蒸散发是水文循环和水量平衡的关键要素,研究其时空变化规律对流域水资源优化配置等方面具有重要意义。利用SEBAL模型结合参考蒸发比对子牙河流域2001—2020年蒸散发进行模拟,采用Mann-Kendall趋势检验和变异系数法对时空变化特征进行分析,并通过相关性分析、偏相关分析与通径分析探讨蒸散发变化的影响因子。结果表明:(1)SEBAL模型模拟的子牙河流域蒸散发,与涡动相关系统实测蒸散发数据相对误差为-7.5%,与子流域水量平衡计算结果相对误差为-9.6%。(2)子牙河流域多年平均蒸散发量为520.3 mm/a,年际变化中春季、夏季、秋季表现为上升趋势,冬季总体变化不大,年内蒸散发变化表现为单峰型,主要集中于5—7月份。(3)流域蒸散发空间分布特征整体表现为西高东低,不同下垫面类型下,水体多年蒸散发量最大,其次为林地和草地,农田和城镇最低。(4)流域蒸散发变化受净辐射与空气温度的直接影响最大,受气压的间接影响最大。

Evapotranspiration is a key element of hydrological cycle and water balance.It is of great significance to study the spatial and temporal variation law for the optimal allocation of water resources of river basins.The SEBAL model combined with the reference evaporation ratio was used to simulate the evapotranspiration in the Ziya River Basin from 2001 to 2020.The MannKendall trend test and the coefficient of variation method were used to analyze the temporal and spatial variation characteristics.The correlation analysis,partial correlation analysis and path analysis were used to explore the influencing factors of evapotranspiration change.The results show:(1) The relative error between the evapotranspiration simulated by the SEBAL model and the measured evapotranspiration data of the eddy correlation system is-7.5%,and the relative error with the water balance calculation result of the sub-watershed is-9.6%.(2) The annual average evapotranspiration of Ziya River Basin is 520.3 mm/a,which shows an upward trend in spring,summer and autumn,with little overall change in winter,and the annual evapotranspiration shows a single peak,mainly concentrated in May to July.(3) The overall spatial distribution characteristics of evapotranspiration in the basin are high in the west and low in the east.Under different underlying surface types,the annual evapotranspiration of water body is the largest,followed by forest land and grassland,and farmland and urban land are the lowest.(4) The change of evapotranspiration in the basin is directly influenced by net radiation and air temperature,and indirectly influenced by air pressure.