Georgia Water Resources Conference

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Georgia Water Resources Conference

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https://hdl.handle.net/1853/70886

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Georgia Water Resources Institute

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Cash crop land suitability analysis using environmental spatial information through automated geospatial model

(Georgia Institute of Technology, 2013-04) Panda, Sudhanshu Sekhar

Georgia's agricultural industry plays a huge role in the state's economy, contributing billions of dollars annually. The agricultural production may increase with proper site specific crop management (SSCM). One of the basic SSCM approach is to grow crops in the best suitable locations for higher production. As we know, crop production would increase with favorable soil types, topography, land-use and climate, especially precipitation. The goal of this study was to develop a production suitability map of Georgia's three main cash crops: corn, cotton, and peanuts using geospatial technology in four agriculture rich counties of South Georgia, Seminole, Decatur, Colquitt, and Mitchell. High resolution SSURGO data, very high resolution (1/9 arc second) DEM raster, and 1 m resolution NAIP imagery were collected from the USDA-NRCS geospatial data gateway and precipitation data were collected from GA--AEMN weather stations and the NWS stations in those four counties. Suitability rasters were created from each spatial data layers for the individual crops using the attributes available with the data and personal decision making scenario development. Once all suitable rasters were created they were combined into one suitable map (raster) using weighted sum analysis. For three crops, three suitable rasters were created. All three crop suitable rasters were finally analyzed to suggest suitable locations for growing those cash crops in the four counties. This study is an important eye-opener for agricultural decision makers for high crop production with zero to little extra investment but by just managing the environmental factors properly through geospatial decision making. Above all, the study developed an automated geospatial model that can be easily replicated in other study areas with only little data tweaking.
U.S. Geological Survey Site-Specific Water Use Database (SWUDS)

(Georgia Institute of Technology, 2013-04) Lawrence, Stephen J.

The U.S. Geological Survey’s site-specific water use database (SWUDS) is designed to store permitted and non-permitted surface and groundwater withdrawals from source waters, water deliveries among water suppliers, and return flows to receiving waters for individual public and private water suppliers and water-use entities. Industrial, thermoelectric, commercial, and residential water use from surface and groundwater sources can be compiled at the county and hydrologic unit levels; SWUDS also has the ability to account for interbasin and inter-county deliveries among water suppliers. This presentation will graphically show the accounting capabilities of SWUDS to network the complex interdependencies of water withdrawal, treatment, distribution, finished-water deliveries, wastewater treatment, and return flows to a receiving water body for a typical public water supplier. The Augusta-Richmond County water system will be used as an example.
Modeling nitrogen in on-site wastewater treatment systems

(Georgia Institute of Technology, 2013-04) Radcliffe, David E. ; Bradshaw, J. K.

State regulatory agencies set standards for minimum lot size for homes on onsite wastewater treatment systems (OWTS) based on the expected nitrogen (N) load to groundwater. However, the data to support these standards are sparse. In a recent field study on a clay soil, we developed a two-dimensional model for N treatment. Our objective was to use this model to predict the N treatment for 12 soil textural classes using two years of weather data from the field experiment. We found that soil texture had a strong effect on OWTS performance. Denitrification losses varied widely among soils, from 1% in the sand class to 75% in the sandy clay class. This was due to the effect of water content on denitrification. Leaching losses to groundwater ranged from 27% in the sandy clay class to 97% in the sand class. It was important to consider differences in recharge among soil textural classes in estimating the minimum lot size to protect groundwater. The lot sizes ranged from 0.26 to 1.13 ha and were largest for mediumtextured soils where denitrification and recharge were intermediate.
Revised hydrogeologic framework of the Floridan aquifer system in Florida, and parts of Georgia, Alabama, and South Carolina

(Georgia Institute of Technology, 2013-04) Williams, Lester J.

The hydrogeologic framework for the Floridan aquifer system has been revised throughout its extent in Florida and parts of Georgia, Alabama, and South Carolina. The updated framework generally conforms to the original framework established by the U.S. Geological Survey in the 1980s except for adjustments made to the internal boundaries of the Upper and Lower Floridan aquifers and the individual permeable zones that comprise these aquifers. The revised boundaries of the Floridan aquifer system were mapped by taking into account results from local studies and regional correlations of geologic and hydrogeologic units. Additional high and low permeability zones have been incorporated into the framework to allow for finer discretization of permeability variations in the two regional aquifers or within the same aquifer of a local or subregional area. These additional units can be used to progressively divide the system into discrete hydrologic units that may be important for assessing groundwater and surface water interaction, saltwater intrusion, and offshore movement of groundwater. The extent and altitude of the freshwater/saltwater interface in the aquifer system has been mapped to define the freshwater part of the flow system that will be a focus for future groundwater availiabilty assessments.
Changing Our Perspective to Increase Our Understanding of Basic Aquatic Ecosystem Function

(Georgia Institute of Technology, 2013-04) Flite, Oscar P. ; Rosenquist, Shawn E. ; Moak, Jason W.

Aquatic ecosystems are dynamic mixtures of physical, chemical, biological, geological, and meteorological elements. Understanding how that mixture produces the observed water quality at a given location is one of our greatest challenges. To a large degree, our understanding has been limited by the availability of tools and by our research approach. Advances within the last two decades have allowed us to go beyond synoptic sampling (data collection from many sites without regard to travel time) to multiple site, continuous sampling efforts (high frequency data from multiple fixed locations). While those data are important for assessing regulatory water quality, fixed position sampling (Eulerian perspective) falls short of providing a true understanding of aquatic ecosystem function because of the significant spatiotemporal gaps between data collection sites. Continuous data from multiple locations increases data resolution but connecting those data within the context of advective transport requires simulation; this results in far more simulated than measured data. Continuous measurements while following the same parcel of water as it is advectively transported (Lagrangian perspective) is another important approach to understanding aquatic ecosystem function. This approach allows for better spatiotemporal resolution and can lead to better understanding of ecosystem function. The Lagrangian perspective is however limited by the costs and time associated with conducting this type of data collection effort and data sets may be limited in the range of seasonal and stochastic conditions. For six years, Southeastern Natural Sciences Academy has been collecting water quality data with Eulerian data collection methods throughout the Middle and Lower Savannah River Basins. In June 2012, we launched our first Lagrangian research expedition along 233 kilometers (145 miles) of the Middle Savannah River Basin. The goal of this paper is to discuss some of the differences between our Eulerian and Lagrangian data sets and the challenges that lie ahead.
Continued Toxicity in Trail Creek Sediments One Year after the Industrial Fire

(Georgia Institute of Technology, 2013-04) Black, Marsha C. ; Fuller, Scarlett L. ; Jordan, Alexander M. ; Wheeler, Andrew J.

In July 2010 Trail Creek, an urban stream located in Athens, GA was contaminated with runoff from firefighting efforts that contributed nearly 700.000 gallons of water mixed with janitorial chemicals from a burning formulation facility. The effluent contained a dye that turned the creek a vivid blue and toxic chemicals that killed fish and invertebrates along a 9 km reach below the industrial site. Initial assessments of water revealed significant toxicity in Trail Creek that extended nearly 2 km from the spill site. Initial remediation efforts included insitu filtration of creek water with activated charcoal and within 12 months the industrial site was excavated and contaminated soils were removed. By three months after the spill no toxicity was measured in the water column, yet whole sediment toxicity tests conducted in November 2010 revealed significant toxicity remaining in downstream sediments. At 5, 8 and 12 months following the fire we conducted elutriate tests on sediments collected from 4-10 locations downstream from the fire. Elutriates were prepared according to EPA protocol and toxicity of filtered elutriates to the aquatic microcrustacean, Ceriodaphnia dubia, was assessed in acute and chronic tests. Results confirmed significant toxicity in Trail Creek sediments through one year following the spill, with the highest toxicity measured at sites with the highest organic carbon content. All of the toxic sites were located in a wetland located approximately one km downstream of the original spill site. Wetland sediments are highly enriched in organic carbon, and could serve as a sink for the toxic components of the Trail Creek spill, preventing further downstream contamination. Additionally, wetlands also have tremendous biodegradation capabilities and could ultimately degrade the retained toxic chemicals. Further sampling is needed to follow the transport, toxicity and potential remediation of toxic chemicals in Trail Creek.
An update on groundwater conditions in the Clayton and Claiborne aquifers, southwest Georgia, 1994 to 2011

(Georgia Institute of Technology, 2013-04) Peck, Michael F. ; Gordon, Debbie W.

The Clayton and Claiborne aquifers are heavily pumped as sources of water for irrigation, public supply, and industrial purposes in southwestern Georgia. This pumping has led to large water-level declines in the Clayton aquifer, and the Georgia Environmental Protection Division imposed a moratorium on new permits in the Clayton aquifer in the early 1990s. Although the U.S. Geological Survey in cooperation with state and local agencies operates a continuous water-level monitoring network in the two aquifers, the last time an area-wide effort to measure water levels in the aquifers and map their potentiometric surfaces was during October-November 1994. To determine current hydrologic conditions water levels were measured in wells completed in the Clayton and Claiborne aquifers during November 2011 and these data were used to construct potentiometric surface and water level change maps for each aquifer. This presentation will provide an overview of changes in groundwater levels and the configuration of potentiometric surfaces for the Clayton and Claiborne aquifers between October-November 1994 and November 2011.
USGS WaterSMART – providing information and tools for managing water in the Apalachicola-Chattahoochee-Flint river basin, Alabama, Florida, and Georgia

(Georgia Institute of Technology, 2013-04) Hughes, William

Over the last 50 years, the Apalachicola- Chattahoochee-Flint (ACF) Basin in Alabama, Florida, and Georgia has undergone extensive development of water resources for municipal and industrial supplies, power generation, and agriculture. Concurrent with this development, there has been increasing conflict over the use of water in the ACF system, resulting in legal battles over the rights to this valuable resource. The U.S. Geological Survey (USGS) is launching a study in the ACF basin as part of the Department of Interior’s initiative titled “Water: Sustain and Manage America’s Resources for Tomorrow” (WaterSMART) that will provide improved wateravailability information and develop new tools to support water management decisions. This federally-funded, three-year study has three major components that build on USGS data collection and modeling capabilities: estimating water use, modeling surface and groundwater flow, and modeling ecological flow relations. The water use component will develop a site-specific database of water use for the ACF Basin, develop new methods for estimating agricultural withdrawals, and compile available wateruse projections. Calculations of net water use will be improved by obtaining information on interbasin transfers, determining septic-tank return flows, and estimating consumptive use by thermoelectric plants. The hydrologic modeling component will consist of a surface-water model for the entire ACF Basin using the USGS Precipitation- Runoff Modeling System (PRMS) and a MODFLOW groundwater model for the lower Chattahoochee and Flint River Basins. These models will be linked to provide improved simulation of groundwater/surface-water interactions in the lower part of the Basin. The ecological flows component will use multi-state, multi-season ecological models to predict changes in fish and mussel species occupancy based on variations in flow conditions associated with climate change, land-use change, and changes in water withdrawals or discharges.
Financial Risks of Developing New Water Supply Reservoirs in the Southeast, and Elements of a Prudent Path to Securing Water Supplies

(Georgia Institute of Technology, 2013-04) Emanuel, Ben

This paper is based on our July 2012 report documenting the financial and water resource risks tied to developing new water supply reservoirs in the Southeast. Many local governments throughout Georgia are consider-ing significant spending of taxpayer and ratepayer dollars to build new reservoirs. Georgia reservoir proposals as of 2012 could total $10 billion in taxpayer and ratepayer dollars. We outline five financial and water resource risks inherent in the pursuit of new water supply from reservoirs: (1) Reservoirs are highly expensive, usually bringing on debt for ratepayers and taxpayers; (2) a reservoir’s cost is typically a “moving target;” (3) reservoir financing plans often rely on high population growth projections, ultimately leaving existing residents responsible for costs; (4) a reservoir depends on increasingly uncertain rainfall and loses water when high temperatures cause evaporation; and (5) reservoir water is a contested resource subject to competing demands in the river system. We also examine recent projects that provide cautionary tales of communities burdened by borrowing capital to develop new reservoirs. We offer five key recommendations for local leaders who seek to reduce their communities’ risks in planning for enough clean water for the future: (1) Optimize existing water infrastructure first; (2) plan for water use to de-crease as a community grows; (3) pursue flexible water supply solutions; (4) demand accurate assessments of costs; and (5) examine water availability to minimize re-source risks. As communities endeavor to secure water supplies, it is critical that decision-making enhance the community’s flexibility and resilience. Water supply strategies that can respond to unexpected economic and climatic changes place a community in a better financial position when facing an uncertain future. Low-impact supplies rooted in efficiency are best suited to this task.
Chattahoochee-Apalachicola Rivers Water Quality Sampling a Lagrangian Sampling Project

(Georgia Institute of Technology, 2013-04) Fuller, Robert C.

The field work portion of this project began September 22, 2012, with an expected completion date of November 10, 2012. The field work will involve traveling by canoe down the entire Chattahoochee-Apalachicola River system from the source spring near Chattahoochee Gap to the Gulf of Mexico, collecting water quality data, documenting illegal incursions into the river channel, and gathering such other information as may seem to be valuable. As of September 30, 2012, 89.4 miles of the river system has been covered. What makes this project unique and of particular value will be the Lagrangian design of the observations. The purpose of a Lagrangian sampling scheme is to follow an initial mass or “parcel” of water as it moves through its containing channel, tracking changes to the water’s constituents over space and time. Hydraulic modeling work done by others was used to make initial estimates of average river velocities along the length of the system, which were used to calculate doses of a tracking dye sufficient to be detected but not so large as to violate EPA guidelines. Rhodamine WT dye was chosen for tracking and it was detected using a fluorometer. The concept of an initial water mass is used in recognition of the fact that a small mass of water emerging from the source spring will be increasingly dispersed as the mass moves downstream due to the mixing within the channel and the variability of water velocity across the channel. Because of this, it is easier to think of trying to follow the centroid of the dispersing mass than it is to think of predicting the likely position of a single molecule that emerges from the source. Due to low rhodamine WT doses used, the dye is re-dosed at roughly 25 to 50 kilometer intervals along the system.