Water body catchment areas (WRRL) Lower Saxony and Bremen

The smallest demarcated hydrological viewing plane of the WFD is the water body. These are primary/direct catchment areas of the water frame straightline water bodies of above-ground waters (WRRL waters, lakes, transitional and coastal waters) on a base scale. Each point in Lower Saxony can be assigned exactly to a water body where the resulting surface water drains according to terrain relief.水框架指令（Water Framework Directive, WFD）所划定的最小水文观测单元为水体。此类水体均为基准比例尺下，地表水体（WRRL水体、湖泊、过渡性水体与近岸海域水体）对应的水框架直线水体的一级直接集水区。下萨克森州内的每一个点位均可被唯一划归至某一水体，该水体即为依据地形起伏完成地表径流汇流的对应区域。