미국
Stream, Ditch or Canal as an Irrigation Source on Agricultural Land in the Conterminous United States, 1992: National Resource Inventory Conservation Practice ISO03
This data set represents the estimated percentage of the 1-km grid cell that is covered by or subject to the agricultural conservation practice (CPIS03), Stream, Ditch or Canal as an Irrigation Source (SDCIS) on agricultural land by county. Stream, Ditch or Canal as an I rrigation Source is described as: "Stream : A flow of water in a channel or bed, as a brook, rivulet, or small river. Ditch : A long, narrow trench or furrow dug in the ground, as for irrigation. Canal : An artificial waterway used for irrigation." (U.S. Department of Agriculture, 1995) This data set was created with geographic information systems (GIS) and database management tools. The acres on which SDCIS's are applied were totaled at the county level in the tabular NRI database and then apportioned to a raster coverage of agricultural land within the county based on the Enhanced National Land Cover Dataset (NLCDe) 1-kilometer resolution land cover grids (Nakagaki, 2003). Federal land is not considered in this analysis because NRI does not record information on those lands.