surface water
Technical term used in hydrology, geography, and environmental science for water present on the ground surface, such as in rivers, lakes, and wetlands.
この地域の地表水は農業用水として利用されている。
The surface water in this region is used for agricultural irrigation.
地下水 is water found beneath the ground, while 地表水 is water on the surface such as rivers and lakes.
Compound of 地表 (chihyō, 'earth's surface') and 水 (sui, 'water').