Potential map accuracy of groundwater nitrate load from agricultural activities in Shimabara City, Nagasaki Prefecture, Japan

Abstract

The potential map for nitrate load in groundwater was produced using statistical data from agriculture and forestry for Shimabara City, Nagasaki Prefecture, Japan. Observed distribution of high nitrate loads corresponded well with the locations of high nitrate loads from the detailed potential map using land-use from aerial photographs. It was confirmed that polluted groundwater is typically located in the downstream of the high potential nitrate load area in this map. The findings indicate a high accuracy of the potential map. We also examined the distribution-change of nitrate loads using the potential map based on the old municipalities. The distribution of high potential areas was drastically changed after 1985.