The cultivated field received not only its own share of rainfall but all of the runoff from the catchment.耕地不仅获得它自己那份雨水而且还接受集水区的全部径流。For the relief of drought, the rains will have to fall into the catchment area.雨必须要下在集水区才能对解除旱灾有用。The river's catchment is a key transit point for migrating birds.这条河的汇水处是候鸟的重要落脚点。