Water Resources Research Act Program

Principal Investigators: Nathan Habana, Leroy Heitz

Abstract: Proper management of a region’s water resources requires water managers and water resources researchers to have accurate baseline information on the geomorphological and ecological health of surface water streams in a region. It is also vital to have a detailed baseline knowledge of potential pollution sources in groundwater recharge areas. Along with this baseline information there is also a need for periodic sampling of water quality indicators to identify changes in the environmental health of streams and groundwater recharge areas. Studies such as surface and ground water supply studies, depend on this kind of long term variable information to develop the best management practices for a region’s water resources. In the past, the only means of visual monitoring of stream and groundwater recharge areas health was either with direct on-ground monitoring or the use of high altitude satellite imagery or LIDAR (Light Imaging, Detection, and Ranging) data. This imagery and data was typically accurate to about 0.5-meter resolution. Because of the expense of data gathering, these resources were not available at intervals that could be used for the continued monitoring of the environmental health of Guam’s streams and recharge areas. Recent advances in commercially available sUAS (Small Unmanned Aerial Systems) technology have made lower cost, highly accurate, sub- meter resolution aerial imagery available. Commercial sUAS drones fly at elevations less than 400 ft., capable of gathering high resolution data used for the development of georeferenced imagery on these low elevation flights. The photographs can be used as detailed high resolution individual photos of streams or groundwater recharge areas or can be composited into highly accurate georeferenced photos of various areas of study. Photogrammetric procedures allow foliage cover removal from the data to develop high resolution composite ground surface digital elevation models of areas of interest. This project involves Five phases: 1. evaluating and choosing which sUAS drones, cameras and analysis software would be most appropriate for the stream and groundwater recharge study areas 2. choosing test stream reaches and groundwater recharge areas to develop the appropriate methodologies for carrying out the aerial data gathering missions 3. aerial data gathering and map development 4. developing a data management scheme for the imagery and other data gathered using the techniques developed by the project 5. continued imagery gathering and processing for various streams and recharge areas on Guam. Federal Aviation Agency (FAA) no-fly zones, military restrictions, site accessibility, and ownership issues will determine which study areas will be selected. Commercial software such as LiMapper and Drone Deploy will be explored as a means of developing georeferenced imagery and digital elevation models of the areas of interest. The detailed georeferenced aerial data will provide baseline knowledge of the location, size, and potential pollution sources in groundwater recharge areas. In Southern Guam, drone data retrieved will accurately plot stream cross sections, determine erosion potential and possible sediment loading, and other sources of environmental contamination. Data management will use WERI’s and the Island's Guam Hydrologic Survey website.