Mean Annual Groundwater Recharge of Germany 1:1,000,000 (GWN1000)

The map shows the average annual groundwater recharge of Germany for the period 1961 - 1990 as a raster image in a cell range of 1 x 1 km. For this purpose, a multi-step regression model was developed (Neumann, J. 2005). In a first step, the baseflow index (BFI = baseflow / total runoff) was determined as the regression target size as a function of slope gradient, drainage density, land cover, available field capacity, depth to groundwater and the ratio of direct runoff to total runoff. Based on this, two different model variants were developed for low-drainage (R < 200 mm/a) and high-drainage regions (R > 200 mm / a). For R < 200 mm/a, groundwater recharge rates were calculated by multiplying the regional grid-based baseflow index and the area-differentiated total runoff according to BAGLUVA. For the higher values R > 200 mm/a, a second regression equation has been used which, in addition to the base flow index, also requires the BAGLUVA total runoff and the depth to groundwater.本数据集以1×1公里栅格单元的栅格图像形式，呈现了1961年至1990年德国的年均地下水补给量。为此，研究人员构建了一套多步回归模型（Neumann, J. 2005）。首先，以基流指数（Baseflow Index, BFI=基流/总径流量）作为回归目标变量，将其作为坡度、排水密度、土地覆被、有效田间持水量、地下水埋深以及直接径流量与总径流量之比的函数，并完成了该指数的测算。在此基础上，研究人员针对低排水区（年值R<200毫米/年）与高排水区（年值R>200毫米/年）分别开发了两种模型变体。对于年值R<200毫米/年的区域，地下水补给速率通过将区域栅格基流指数与依据BAGLUVA划分的分区域总径流量相乘得到；而对于年值R>200毫米/年的高值区域，则采用第二种回归方程进行计算，该方程除基流指数外，还需纳入BAGLUVA总径流量以及地下水埋深两个参数。