Abstract:
Quantitative relationships describing the nature of surface drainage networks have been used to formulate flood characteristics, sediment yield, and the evolution of basin morphology. Progress has been slow in applying these quantitative descriptors to karst flow systems. Developing geographic information system (GIS) technology has provided tools to 1) manage the karst system’s large, complex spatial datasets; 2) analyze and quantitatively model karst processes; and 3) visualize spatially and temporally complex data. The purpose of this investigation is to explore techniques by which quantitative methods of drainage network analysis can be applied to the organization and flow patterns in the Turnhole Bend Basin of the Mammoth Cave Watershed.

Morphometric analysis of mapped active base-flow, stream-drainage density within the Turnhole Bend Groundwater Basin resulted in values ranging from 0.24 km/km? to 1.13 km/km?. A nearby, climatologically similar, nonkarst surface drainage system yielded a drainage density value of 1.36 km/km?. Since the mapped cave streams necessarily represent only a fraction of the total of underground streams within the study area, the actual subsurface values are likely to be much higher. A potential upper limit on perennial drainage density for the Turnhole Bend Groundwater Basin was calculated by making the assumption that each sinkhole drains at least one first-order stream. Using Anhert and Williams’ (1998) average of 74 sinkholes per km? for the Turnhole Bend Groundwater Basin, the minimum flow-length draining one km? is 6.25-7.22 km (stated as drainage density, 6.25-7.22 km/km?).