Vulnerability of shallow ground water and drinking-water wells to nitrate in the United States: Model of predicted nitrate concentration in U.S. ground water used for drinking (simulation depth 50 meters) -- Input data set for semiconsolidated sand aquifers (gwava-dw_semc)

This data set represents the presence or absence of semiconsolidated sand aquifers in the conterminous United States. The data set was used as an input data layer for...本数据集表征了美国本土范围内半固结砂含水层（aquifer）的有无分布情况。该数据集曾被用作……的输入数据图层。