MULTIDISCIPLINARY KARST RESEARCH ON A MILITARY RESERVATION: CAMP BULLIS, TEXAS

Federal support and funding of karst research at the Camp Bullis Military Training Site, Texas has proved a role-model for karst investigations and been key to the discovery of hydrogeological and biological relationships for improved management of karst resources in the central Texas region. Nearly 100 caves and 1,300 karst features have been located to date on the 113.3-km² reservation. Their study has redefined concepts of groundwater movement in the area by demonstrating groundwater flow between formations previously believed hydrologically separate, identifying modes of cave development distinctive to particular lithologies, delineating flowpaths in units once thought impermeable, and using the information to identify zones of contaminant movement, and endangered and rare species distribution. Specific examples follow.

The upper 39 m of the Glen Rose Formation, regionally the lower confining unit for the Edwards Aquifer, are highly permeable and hydrologically continuous with the Edwards. Groundwater has been traced in the Glen Rose at rates of 300-600 m/day. Detailed surveys, exceeding state standards, have found one to two orders of magnitude more caves and karst features than in geologically identical neighboring properties, prompting review of existing survey requirements. The Dolomitic Member of the Kainer Formation in particular forms topographically subdued features that often appear insignificant, but if excavated, prove hydrologically and biologically important caves. Federally listed endangered karst invertebrates have been found in 23 caves, and their distribution is defined by continuity of lithologic units. Fourteen endangered species caves in the Dolomitic were discovered or their known extents substantially expanded by excavation.