DISTRIBUTION AND GEOMORPHOLOGY OF LUNETTE DUNES ON THE KANSAS HIGH PLAINS

The High Plains is a vast, low-relief landscape that contains thousands of upland-embedded depressional playa wetlands. Lunettes are isolated dunes that form along the downwind margin of some larger playas. These playa-lunette systems are important landscape elements with a high potential to preserve Native American artifacts and high-resolution records of past environments. While a comprehensive playa wetland geospatial database has been developed for the High Plains, lunettes have only been mapped for the Southern High Plains of Texas and New Mexico.

The purpose of this research was to create a lunette geospatial database and characterize the geomorphology of all lunettes and associated playa depressions in Kansas. Lunettes were mapped in a GIS environment for a 43-county region using 1:24,000 scale digital raster graphics (DRGs) and digital elevation models (DEMs). Potential lunettes were identified by closed or crescentic-shaped contour lines associated with a mapped playa depression on DRGs or as an isolated topographic high associated with a playa depression on DEMs. Morphometric analyses of lunettes and associated playas included position relative to playa, height/depth, perimeter, area, length, width, orientation of long axis, and circularity.

Results indicate 129 lunettes are associated with 104 playas in 20 counties of western Kansas. All lunettes are associated with playas larger than 5 ha, and about 10% of these larger playas have a lunette. Lunette and associated playa perimeter, area, length, width and orientation are all significantly positively correlated indicating playa morphology influences lunette morphology. Lunette height is not significantly correlated with any playa morphometric variables, suggesting larger and deeper playas do not necessarily have more prominent lunettes. Most lunettes (~60%) are located in the four-county region of Finney, Gray, Lane, and Scott counties which have broad, flat uplands with few major drainages upwind of playas and lunettes. While lunette distribution is in part controlled by playa distribution, characteristics of regional uplands also exert a strong control on lunette distribution.