Category: Research

Principal Investigator: Terry W. Sturm (Georgia Tech)

Sponsor: GWRI
Start Date: 1999-03-01; Completion Date: 2000-02-29;
Keywords: Climate and Hydrologic processes, Geomorphological and Geochemical processes, Sediments, Models

Problem and Research Objectives:

Continued development in urban watersheds without adequate controls on sediment production from construction activities contributes sediment load to urban streams that may affect its sediment regime. Subsequent deposition of the sediment chokes the benthic aquatic habitat, and affects storage in the channel and floodplain and thus the flooding potential of the stream. In addition, urbanization creates a greater volume of runoff and higher peak flows with a different timing than exists prior to urbanization. These higher flows may contribute to bank erosion in some stream reaches and deposition further downstream. The result is again a change in geometry and sediment regime of the natural stream with consequent adverse affects on aquatic habitat and stream water quality. Furthermore, the deposited finer-grained sediments from urbanized areas may carry with them attached contaminants that are subject of resuspension during subsequent flood conditions. While much work has been done on urban hydrology to predict changes in runoff characteristics due to urbanization, much less attention has been paid to the closely related sediment effects and the changes that they cause in flooding potential and water quality of the recieving stream over the entire watershed. The research project provides a case study of an urban stream to distinguish sediment contributions from watershed development and bank erosion, resultant changes in floodpain and channel storage, and the final effect on flood routing and thus flooding potential as well as movement of sediment-bound contaminants through the watershed system. In addition, a methodology has been developed that can be applied to other urban streams to predict the effects of urban development not just on the hydrology of the watershed, but on its sedimentology as well. As a result of the study, recommendations will be made on the relative efficacy of specific control measures such as best-management practices on contruction sites to limit sediment yield, artificially-created wetlands for aditional floodplain and sediment storage, streambank stabilization, vegetative buffer zones along the stream, and strict constols on development of the floodplain. This methodology allows decision makers to make more informed watershed-wide decisions rather than piecemeal approval and disapproval of particular development projects.

Principal Investigator: David Wenner (University of Georgia)

Sponsor: GWRI
Start Date: 1999-03-01; Completion Date: 2000-02-29;
Keywords: Groundwater Flow and Transport, Geomorphological and Geochemical processes, Groundwater, Nitrate Contamination

Problem and Research Objectives:

The presence of nitrate in groundwater in the Floridan Aquifer near Albany Georgia has prompted an investigation using nitrogen isotopic data to identify the source contamination. It is thought that the contamination originates from a farm and that nitrates were transported by groundwater flow to an adjacent residential community. This community’s water supply comes from homeowner wells, some of which exceed the MCL for nitrate in drinking water. A variety of materials capable of producing this contamination, such as cattle manure, biosolids (sewage sludge), and synthetic inorganic fertilizers are present or have been used on this farm. Biosolids were utilized as fertilizers over a twelve year period from 1984 to 1996 and a cattle feed lot was in operation from 1980-1984. Synthetic inorganic fertilizers were used prior to 1984. A hydrogeologic study conducted by the Georgia Geological Survey indicated that the most probable source of groundwater contamination is a disused cattle feed lot on the suspect property. To further assist in identifying the source of contamination, d15N values were measured for dissolved nitrate from nine wells both on the farm and within the residential community. The data from the contamination plume ranged from +5.5‰ to +2.3‰. This range is consistent with the idea that the major source of contamination stems from synthetic inorganic fertilizers. This conclusion is predicated on numerous studies indicating that different nitrate sources produce different ranges of d 15N values for dissolved nitrates. Typically, nitrates derived from inorganic fertilizers range from -5‰ to + 3.5‰, soil organic material from + 3.5‰ to +7.5‰, and manure and septic system effluent from +10‰ to +20‰. There are no known study of the d15N values of nitrates derived from biosolids. To reinforce this conclusion, d15N values were measured for grasses at sites where only cattle manure and biosolids were present. Analysis of plants serve as proxies for dissolved nitrate in soils because there is little or no isotope fractionation between plants and the dissolved nitrate that they uptake. The aim of this investigation was to directly assess the d15N values of dissolved nitrates in soils derived from decomposition of cattle manure and sewage sludge. A second investigation was initiated in order to constrain the age of nitrate contamination by measuring the tritium concentration of groundwaters within the area.

Principal Investigator: Aris Georgakakos (GWRI/Georgia Tech)      About…

Sponsor: GWRI
Start Date: 1998-07-01; Completion Date: 1999-12-31;
Keywords: Climate and Hydrologic Processes, Hydrology, Management and Planning
Problem and Research Objectives:

Climate variability and change pose both challenges and opportunities for the US. To be better prepared, the United States has developed a national assessment process to identify and analyze the potential consequences of climate variability and change.

Principal Investigator: Aris Georgakakos (GWRI/Georgia Tech)

Sponsor: GWRI
Start Date: 1998-12-01; Completion Date: 1999-07-31;
Keywords: Hydrology, Management and Planning, Drought

Problem and Research Objectives:

This project intends at developing a state-of-the-art river basin planning and management system that can (a) assess the potential of the ACF basin to meet various water uses, and (b) quantify the trade-offs associated with various water allocation scenarios and policies. The purpose of this system is to assist the ongoing tri-state (Alabama, Florida, and Georgia) water allocation negotiation. The project is co-sponsored by citizen groups in Georgia.

Principal Investigator: Aris Georgakakos (GWRI/Georgia Tech)

Sponsor: GWRI
Start Date: 1997-08-01; Completion Date: 1999-06-30;
Keywords: Climate and Hydrologic processes, Hydrology, Management and Planning
Problem and Research Objectives:

This project aims at demonstrating the value of climate and hydrologic forecasts on the operation of multi-purpose reservoirs in the US.

Short Course

Instructor: Huaming Yao (GWRI/Georgia Tech)
Instructor: Aris Georgakakos (GWRI/Georgia Tech)

Sponsor: GWRI