Surface Drainage-Main or Lateral on Agricultural Land in the Conterminous United States, 1992: National Resource Inventory Conservation Practice 608

This data set represents the estimated percentage of the 1-km grid cell that is covered by or subject to the agricultural conservation practice (CP608), Surface Drainage, Main or Laterals (SDML) on agricultural land by county. Surface Drainage, Main or Laterals are described as "an open drainage ditch constructed to a designed size and grade. [As] part of a water management system to collect and convey excess surface or subsurface water.

本数据集记录了各县域范围内农用土地上，由农业保护措施（CP608）——地表排水干管及支管（SDML）覆盖或受其影响的1公里网格单元的预估占比。其中，地表排水干管及支管被定义为"依照设计尺寸与坡度修建的开放式排水明渠，作为水管理系统的组成部分，用于收集并输送过剩的地表或地下积水"。