Study on watershed boundary division for unified evaluation of surface water and groundwater resources and environment in karst areas

There are three types of boundary differentiation between surface water basins and groundwater basins in karst areas, that is, the surface watershed and groundwater basin boundary are basically the same in plane distribution;surface watersheds extend beyond the boundaries of groundwater basins.The boundaries of groundwater basins extend beyond surface watersheds.The top boundary of surface water and groundwater coupling basin in karst area is the surface and underlying surface of surface water basin, and the bottom boundary is the top surface of shallow circulating groundwater aquifer or aquifer between aquifer and confined aquifer. In the karst aquifer distribution area with large thickness, the top surface of weak karst development zone can be regarded as the bottom boundary.The secondary boundary between the two sub-systems of surface water and groundwater is the underlying surface of the surface water basin.Combined with the characteristics of specialized (investigation) exploration and regional investigation evaluation, the principle and method of evaluation unit division are put forward.In the new round of natural resources investigation and evaluation, it is helpful to systematically carry out the investigation and evaluation of water resources and environment with watershed as a unit, and implement the unified management of surface water and groundwater resources and environment.