Correlating Aquatic Vegetation Growth and Agriculture in Lake Guntersville

Map of the Lake Guntersville area. Credit: DEVELOP

Image Credit: DEVELOP

Authors: Kel Markert, Casey Calamaio

Mentors/Advisers (affiliation): Dr. Jeff Luvall (NASA Global Climatology and Hydrology Center), Dr. Rob Griffin (University of Alabama Huntsville)

Team Location: Marshall Space Flight Center, Huntsville, Alabama

Abstract: There is an inherent relationship between aquatic vegetation growth and water drainage near locations of high agricultural activity. For years, farmers have been made aware of the potential effects of nutrients found in fertilizers on the aquatic ecosystems and water quality in fresh lakes. Aquatic vegetation, classified in Lake Guntersville by the Alabama Department of Conservation and Natural Resources as emergent, submersed, floating, or algal, limit the amount of water readily available for human use. This forces resource management agencies such as the Tennessee Valley Authority (TVA) to attempt eradication using herbicides. Multispectral satellite imagery using the near-infrared and red wavelengths facilitates the creation of vegetation indices for observing aquatic vegetation growth in the lake and seasonal variations for Lake Guntersville in northern Alabama. The Normalized Difference Vegetation Index (NDVI) was used in conjunction with a hydrologic model developed from Shuttle Radar Topography Mission (SRTM) data of 90-meter resolution, displaying the drainage points for locations around the lake in proximity to high agricultural activity. A regression analysis determined the most correlated factors affecting excessive vegetation growth and displayed the impact of nutrient rich runoff from farming communities flowing into Lake Guntersville. These results will lead to more efficient herbicide spraying in areas with high vegetation concentration, which will cut costs, avoid excess spraying and limit human contact to herbicides. Resulting maps outlined the growth of vegetation due to runoff from certain agricultural areas, making farmers more aware of the effects nutrients have on local lake ecosystems.