Schlumberger Soundings ,And Sand-Column Resistmty Testing For Determining Stream-Aquifer Connection Great Sand Dunes Natl. Monument., Colorado

The Great Sand Dunes National Monument, located in south-central Colorado, is comprised of<br>approximately 4002 Km of Holocene eolian sand dunes together with several surface streams and their<br>associated riparian ecosystems. The dune field and its two major physiographic boundaries, i.e. Sand<br>Creek on the north and Medano Creek on the south, together form a complex and unique system for the<br>study of eolian transport and recycling, including an unusual streamflow phenomenon known as bedform<br>dependent pulsating flow. Federal officials perceived that a very large ground-water pumping<br>project proposed for an area less than ten miles north of Sand Creek threatened its flow, and thus its<br>associated physical transport phenomena andriparian ecosystem, as well as Federal reserved water rights<br>decreed to the National Monument. The magnitude of the threat depends upon the degree of hydraulic<br>connection between the surface flow in Sand Creek and the underlying aquifer system.