Pan-European Vulnerability to Pollution: R-Layer - Net recharge

The R layer represents the mean annual net groundwater recharge for the climatic normal period 1961 - 1990, scored (classified) for index values 1...10 according to class breaks proposed by the HOVER project. The recharge caluclation was performed on an averaged montly basis using WORLDCLIM 1.4 climate data (precipitation, temperature, downscaled to 1 km resolution, https://www.worldclim.org/data/v1.4/worldclim14.html) and a temperature-based approach to claculate effective precipitation on a monthly basis after Samani and Hargreaves (1985). Annual diffuse net groundwater recharge was then estimated from effective precipitation using several environmental attenuation factors, as deduced from a scheme by Döll & Flörke (2005). Areas delineated by IHME1500 as "no groundwater" are blanked.R图层代表1961-1990年气候标准期的年均净地下水补给量，依据HOVER项目提出的分级阈值，将其按索引值1至10完成分级赋值。该补给量计算以月均数据为基础，采用WORLDCLIM 1.4气候数据集（包含降水、气温数据，空间分辨率降尺度至1 km，数据来源：https://www.worldclim.org/data/v1.4/worldclim14.html），并参照Samani与Hargreaves（1985）提出的基于气温的月尺度有效降水计算方法完成。随后，参考Döll与Flörke（2005）提出的研究框架，结合多种环境衰减因子，由有效降水估算得到年弥散状净地下水补给量。IHME1500标记为"无地下水"的区域将被留白处理。