Investigation of groundwater flow in karst aquifer and application of geomorphologic karst model.

摘要

Karst aquifers are extremely heterogeneous systems, in which conduits are indeterminate, and recharge is spatially variable. Developing a physically-based numerical model of karst systems is difficult at best. As an alternative several analytical geomorphologic karst models were developed based on the concept of a geomorphologic structure model for surface basins. These new models express the hydrologic response of a karst basin in terms of calibrated conduit Horton numbers and mean flow velocities. The geomorphologic karst flow models were validated against a numerical model MODFLOW-DCM. Geomorphologic karst models of different orders and complexity were compared. In addition, analytical relationships were derived from governing equations that explicitly express karst basin hydraulic response times to rainfall inputs as a function of conduit Horton number RL and a mean basin velocity.;One of the several geomorphologic karst models developed in this dissertation was calibrated and validated to simulate the spring discharges at Blue Spring near Deland, Florida. Time series analysis techniques were used to analyze observed data for rainfall, groundwater levels and spring discharge in the Blue Spring area in Volusia County, Florida. Results indicate that multiple flow components might exist in the karst aquifer, and recharge conditions appear to influence the hydrodynamic characteristics of the karst aquifer. Temporal lag interval results generated from the time series analysis are consistent with response times estimated from the calibrated geomorphologic model.