用经验径流系数推算全球径流深度分布场

Global Distribution Fields of Runoff Depths Calculated by Empirical Runoff Coefficient

通过回顾110 a的全球径流量估算历史,以中国为样本区域,通过求算样本区域的径流系数,利用最小二乘法回归得出了径流系数经验公式。基于径流系数经验公式和高分辨率降水深度图,利用地理信息系统绘制了全球水资源的高分辨率空间分布场,计算得出全球（不含南极洲）径流量为47 884 km^3,平均径流深度为359 mm;内流区径流量为1 663 km^3,平均径流深度为58.4 mm。将31个内流区径流量的计算结果与有关文献进行比较,发现下垫面蒸发和人类利用耗散对地下径流及地下水增量变化在水资源核算中的重要性,计算得出的内流区径流量与实际值较为接近。

In this paper,the 110-year history of the estimated global runoff volumes was reviewed. The land slope and aridity index were taken as the independent variables,the method of Ordinary Least Squares（ OLS） regression was employed to estimate the runoff coefficients in typical regions,and the empirical formula of runoff coefficient was used to calculate the runoff volumes in China. Based on the empirical formula and high-resolution precipitation grid data,the Grid and Spatial Analysis module in Geographic Information System（ GIS） was applied to calculate the high resolution spatial distribution fields of global water resources. Main calculated results were that the total runoff volume in the world（ excluding the Antarctic Continent） was 47 884 km^3,the average runoff depth was359 mm,and the average runoff coefficient was 0. 462; the runoff depth in Africa was 230 mm,the runoff coefficient was 0. 345,and both were the lowest in the 6 continents; the runoff depth in South America was 770 mm,the runoff coefficient was 0. 507,and both were the highest; the runoff depth in Asia was 313 mm,which was lower than the average in the world,and the runoff coefficient was 0. 495,which was higher than the average in the world. The results were compared with the relevant literatures. This study emphasized the importance of groundwater runoff and groundwater increment in arid and semiarid regions,and the estimated runoff depths in these regions were increased significantly. The calculated runoff volumes in Africa and Australia were 6 944 km^3 and 3 026 km^3 respectively,which were obviously higher than the average of 24 estimations between 1973 and 2014 in literatures. Moreover,the authors also calculated the runoff patterns of all the 31 interior drainage areas in detail in the world. The total area of the interior drainage areas in the world was 28. 47 × 106 km2,the total runoff volume was 1 663 km^3,the average runoff depth was 58. 4 mm,and the average runoff coefficient was 0. 252. The runoff depth in the interior drainage areas in Oceania was 35 mm,the runoff coefficient was 0. 129,and both were the lowest in the world. Case studies in the interior drainage areas showed that the runoff depth fields calculated by the empirical formula were in accordance with the actual runoff distribution patterns in Africa,Oceania and 4 regions in Asia,including the Nura River in Kazakhstan,Hexi Corridor and west Inner Mongolia Plateau in China,southeast Mongolia and China＇s central and eastern Inner Mongolia Plateau,and the interior drainage areas in Arabian Peninsula. The theoretical hypothesis was confirmed for the interior drainage subregions,and the higher the spatial resolution was,the larger the calculated runoff value would be. Main conclusions of this study are as follows： the spatial resolution of this study was 0. 166 7 degrees,and it was 3 times of the major resolutions used in the runoff calculation; the runoff volumes were calculated from the high spatial resolution runoff fields in this study,including the runoff volumes in interior drainage basins and the runoff volumes consumed in the exorheic drainage basins before flow inflowed into the oceans; the differences between the runoff volumes in this study and the actually measured runoff volumes at the debouchures to the oceans or inland lakes should be the interruptive consumption of the evaporation from natural water surface and wetlands,the net water consumption of agricultural irrigation,and the net dissipation of artificial water usage in urban and industrial regions in watershed; the groundwater runoff and the increment of groundwater and of soil available water are the main forms of runoff in arid and semiarid climate zones. In available literatures,the underestimation of water resources was mainly the ignored evaporation from natural waters and wetlands as well as the net dissipation of artificial water usage.