Application of Geographic Information System (GIS) Hydrologic Data Modelsto Karst Terrain

Hydrologic data models (HDMs) are GIS-based digital representations of surface drainage networks that are being increasingly applied to address complex water-resources management and protection issues in a variety of topographic and hydrologic settings. However, the application of HDMs to karst terrain is problematic and has not received much prior attention. Using results obtained in a pilot study, this paper discusses the major difficulties and steps involved in creating a HDM capable of incorporating surface and subsurface drainage characteristics of a conduit-dominated karst basin. These include acquiring the necessary geospatial datasets, and the HDM processing techniques used to digitally represent karst features such as internally drained catchments (sinkholes or sinking streams), subsurface conduit flow paths, and temporally-spatially variable flow. A modeling approach is described that uses a combination of manual and automated terrain and HDM processing methods to create an aggregated polygon-and-vector drainage network. The drainage network links internally drained sinkhole catchments, dye-tracer-input sites, and sinking streams (inputs) to karst springs or surface streams (outputs) by way of tracer-inferred flow paths (throughputs). The resulting karst HDM is an effective digital representation of the physical hydrologic framework typical of many well-developed karst basins. Although data input and processing requirements are intensive, and some practical and technical limitations exist, karst HDMs have potential as a valuable new GIS tool, aiding the assessment, management, and protection of karst water resources.