Development of karst landscape unit maps for Houston County Minnesota, U.S.A.

In karst areas, there is a close relationship between the landscape surface and the bedrock below. Classification of the karst landscape helps identify the groundwater characteristics beneath it. Common indicators of karst, such as springs, sinkholes, and sinking streams, are not always present, therefore karst landscapes were identi-fied through analysis of landscape position and geologic setting. A karst landscape unit describes a unique system that includes the surface and its connections to underlying aquifers. Identifying and mapping these units allows for better water and land resource management and planning. The process began with observations of patterns on the landscape through field observations and Geographic Information System (GIS) reconnaissance. The delineated units were based on geology (bedrock unit); hydrogeology (aquifer characteristics); karst feature type, distribution, and occurrence; spring monitoring; geochemistry; and karst hydrologic characteristics as determined by fluorescent dye tracing including springshed mapping. These elements were combined in a GIS environment, and the unit boundaries were iteratively refined using GIS tools and analysis, Light Detection and Ranging (LiDAR) image review, and field mapping. Karst landscape unit maps were created as part of the products for Houston County for the Minnesota Department of Natural Resources (DNR) County Groundwater Atlas (CGA) program. The process developed can be used to develop karst landscape maps for other counties throughout southeastern Minnesota. The maps were developed to help citizens and government entities identify karst areas so they can deal with the unique myriad of issues that come with karst. The connections to enlarged underground pathways allow for rapid transport of water, creating unpredictable groundwater travel times and flow directions. This makes groundwater in karst settings vulnerable to human activities and complicates remediation efforts for issues like spills or surface applications of chemicals