GEOSPATIAL ANALYSIS OF SINKHOLES TO DELINEATE KARST CATCHMENT, KAIBAB PLATEAU, GRAND CANYON NATIONAL PARK

The Kaibab Plateau is home to over 1,000 known sinkholes located on the north rim of Grand Canyon National Park (GRCA). These sinkholes act as the primary recharge points for many springs below the North Rim of the Grand Canyon, including Roaring Springs—the sole water source for the park and the 5.5 million annual visitors and employees. Roaring Springs is believed to have a large catchment centered within GRCA’s Kaibab Plateau boundaries. However, a recent dye trace indicates that the karst network supplying this, and other major springs, is far more complex than previously assumed. New tracer results indicate that the complexity of the Roaring Springs catchment requires considerably more hydrologic monitoring and analysis than previously planned. This study examined the morphology and distribution of sinkholes on the Kaibab Plateau at GRCA using geospatial and field data to further delineate the variability in sinkhole recharge dynamics. Field measurements and observations were used to verify LIDAR-derived spatial models at both landscape and site scales. Although preliminary results suggest size, orientation, and distribution of sinkholes may be influenced by the structural geology of the region, formation of sinkholes does not appear to be limited to areas of known faults and fractures. Size and density may instead be indicative of the size of subsurface conduits feeding into fault and fracture-driven drainages. These results provide an important step towards understanding the complex groundwater dynamics of the Kaibab Plateau. Identifying the catchment that serves as the primary source to Roaring Springs and other major springs within GRCA is a necessary step towards assessing the vulnerability of the groundwater system and protecting GRCA’s water supply from possible contamination.