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Georgia Water Resources Conference
Georgia Water Resources Conference
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ItemPhosphorus and Sediment in Headwater Streams Draining Poultry Operations in the Upper Etowah River Basin, Georgia(Georgia Institute of Technology, 2007-03) Romeis, Josh ; Jackson, C. Rhett ; Radcliffe, David E. ; Risse, L. Mark ; Bryant, J.A 1.5-year monitoring program was initiated in January 2005 to support a University of Georgia study aimed at evaluating nutrient trading opportunities for phosphorus (P) in the upper Etowah River basin in Georgia. Twelve first-order streams were instrumented with hydrologic monitoring equipment and automated samplers. Nine streams drain agricultural (AG) watersheds predominated by poultry operations but different in terms of land use history, best management practices, soil test P (STP) concentrations, and other factors. Three streams drain forested (FORS) watersheds. The monitoring program consisted of biweekly grab sampling coupled with stormchasing. From preliminary results, median low-flow and stormflow concentrations of total P (TP) in astreams were 0-1 and 1-3 orders of magnitude greater, respectively, than in FORS streams. The 3 highest median stormflow TP concentrations in AG streams were observed where 3 of the 4 highest STP concentrations were observed. Median low-flow total suspended solids (TSS) concentrations in AG streams were 0-1 order of magnitude greater than in forested streams. Median stormflow concentrations of TSS between the two land use types were within the same order of magnitude. Streamflow, STP, event mean concentrations, and other variables may be important for estimating P loads from agricultural watersheds monitored for the study.
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ItemModeling Phosphorus Loading to Lake Allatoona: Implications for Water Quality Trading(Georgia Institute of Technology, 2007-03) Radcliffe, David E. ; Lin, Z. ; Risse, L. MarkLake Allatoona, a large reservoir north of Atlanta Georgia that drains an area of about 2870 km2, is threatened by excessive algal growth and scheduled for a phosphorus (P) TMDL. In this paper, we use the Soil Water Assessment Tool (SWAT) computer model to estimate the total P load to Lake Allatoona during the periods 1992-1996 and 2001-2004. We also use the model to estimate the contribution from different sources in the watershed. The total P load to Lake Allatoona increased by 20% between the two time periods. The contribution from point sources decreased from 30% to 13% of the total load due to permit restrictions on P for poultry processing plants. The largest nonpoint source of P was estimated to be forest land use in 1992-1996 accounting for 31% of the load and urban land use in 2001-2004 accounting for 50% of the load. Poultry/cattle land use accounted for 18% in 1992-1996 and 15% in 2001-2004. The implications for a program to trade P credits are: 1) point sources and poultry/cattle operations account for similar percentages of the current load, 2) urban development accounts for most of the current P load and should be brought into a trading program, 3) poultry processing plants that have not upgraded to better P removal technology might trade their current load to wastewater treatment facilities that accept their wastewater, 4) cattle in streams and row crops are not large sources according to our model, and 5) there is little net loss of P to streams during transport to Lake Allatoona so distance of a source from the lake may not be important in a trading scheme.
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ItemPhosphorus, sediment, and e. Coli loads in unfenced streams of the Georgia Piedmont, USA(Georgia Institute of Technology, 2005-04) Byers, Harris L. ; Cabrera, Miguel L. ; Matthews, Monte K. ; Franklin, Dorcas H. ; Andrae, John G. ; Radcliffe, David E. ; McCann, Mark A. ; Kuykendall, Holli A. ; Hoveland, Carl S. ; Calvert, Vaughn H., IIContamination of unfenced streams with phosphorus, sediments, and pathogenic bacteria from cattle activity may be affected by the availability of shade and alternative water sources. The objectives of this study were to evaluate water quality in two streams draining tall fescue/ bermudagrass pastures with different shade distributions, and to quantify the effects of alternative water sources on stream water quality. Loads of DRP, TP, and TSS were measured during storm flow, and loads of DRP, TP, TSS, and E.coli were measured every 14 d during base flow in two streams located in the Piedmont region of Georgia. Our results showed that grazing cattle in pastures with unfenced streams contributed significant loads of DRP, TP, TSS, and E. coli to surface waters (p<0.01). Although storm flow was similar in both streams, loads of DRP, TP, and TSS were larger (p< 0.08) in the pasture with the smaller amount of non-riparian shade. Water trough availability significantly decreased (p< 0.08) base flow loads of TSS and E. coli in both streams. Our results indicate that possible BMPs to reduce P, sediment, and E. coli contamination from beef-cattle-grazed pastures may be to develop or encourage non-riparian shade and to provide cattle with an alternative water supply away from the stream.
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ItemLand use effects on suspended sediment yield in six small Georgia watersheds(Georgia Institute of Technology, 2005-04) Bradshaw, J. Kenneth ; Radcliffe, David E. ; Lichtenstein, Karin ; Bakker, Mark ; Jackson, Rhett ; Markewitz, Daniel ; Risse, L. MarkIn Georgia, over 600 stream segments are scheduled for TMDL development due designated use. Seventy-seven stream segments are listed for excessive sediment. The state does not have quantitative standards for the regulation of sediment concentration. The development of sediment yields using appropriate reference streams with minimum development may be a way to determine what the maximum daily sediment loading should be for impaired streams. This study was initiated to compare water quality in six streams with differing land use. This paper focuses on suspended sediment comparisons among the six streams. Two streams drain areas that are entirely forested and these represent reference streams for the purpose of this study. Two streams drain areas that are predominately agricultural (one dairy and the other a combination of poultry and cattle), and two streams drain areas that are in subdivisions with septic systems. Suspended sediment concentrations (SSC) and stream stage were measured during base flow and storm flow conditions. Annual sediment and water yields were calculated and for each stream for the years 2003 and 2004. Average SSC ranged from 155 to 720 mg/L and was lowest in one of the forested steams and highest in the dairy stream. Sediment yield ranged from 0.91 to 10.11 Mg/ha/yr and was lowest in one of the forested steams and highest in the dairy stream. In general, the forested streams had the lowest sediment yields, the agricultural watersheds had the highest sediment yields, and the suburban streams were intermediate.
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ItemAutomatic calibration and predictive uncertainty analysis of a semi-distributed watershed model(Georgia Institute of Technology, 2005-04) Lin, Z. ; Radcliffe, David E.A two-stage routine has been developed for automatic calibration of the Soil Water Assessment Tool (SWAT, a semi-distributed watershed model) that finds the best values for the model parameters, preserves the spatial variability in essential parameters, and leads to a measure of the model prediction uncertainty. We calibrated the stream flow in the Etowah River measured at Canton, GA (a watershed area of 1,580 km2) for the years 1983-1992 and used the years 1993-2001 for validation. Calibration for daily and monthly flow produced a very good fit to the measured data. Nash-Sutcliffe coefficients for daily and monthly flow over the calibration period were 0.60 and 0.86, respectively; they were 0.61 and 0.87 respectively over the validation period. Regardless of the level of model-to-measurement fit, non-uniqueness of the optimal parameter values necessitates uncertainty analysis for model prediction. The nonlinear prediction uncertainty analysis showed that caution must be exercised when using the SWAT model to predict short-term (7-day average) flows, especially under low and high flow conditions.
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ItemThe Effects of Stream Fencing and Water Troughs on Cattle Movement Patterns and Stream Water Quality(Georgia Institute of Technology, 2003-04) Matthews, Monte K. ; Cabrera, Miguel L. ; Franklin, Dorcas H. ; Radcliffe, David E. ; Andrae, John G. ; Calvert, Vaughn H., IIInformation about cattle impact on streams is limited in the southeastern United States. This study is being conducted to determine the effects of stream fencing and use of water troughs on stream water quality in the Georgia Piedmont. Base flow and storm flow samples are taken and analyzed for N, P, E. coli, total sediments, turbidity, dissolved oxygen, and temperature. Global Positioning System collars are used to track cattle and determine the amount of time spent within the stream riparian area. Results from the first year of the study showed that the amount of time cattle spent in riparian areas (over 10%) was positively correlated with daily maximum air temperature (r2 =0.92). Additional results reveal that the concentration of E. coli in base flow samples was higher in unfenced than in fenced streams, and also showed a positive relationship with the time cattle spent in riparian areas. Maximum dissolved reactive P concentrations in storm flow were higher in unfenced than in fenced streams. Removing water troughs from the pasture resulted in an immediate increase in the amount of time cattle spent near the streams.
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ItemWatershed model sensitivity to bacteria parameters(Georgia Institute of Technology, 2003-04) Radcliffe, David E. ; Matthews, Monte ; Cabrera, Miguel L.Watershed-scale models can be used to determine the pollutant daily load in TMDL streams, or to test the effect of different scenarios for reducing bacterial load. HSPF (Hydrological Simulation Program – FORTRAN ) is a watershed-scale model distributed as part of the EPA BASINS system. EPA has also developed a Bacterial Indicator Tool for calculating the effect of livestock and septic systems on the bacterial parameters required by HSPF. We used HSPF and the Bacterial Indicator Tool to predict stream flow and FC concentrations in the Little River watershed of the Upper Oconee River basin and test for model sensitivity to bacteria parameters. We calibrated flow and FC concentrations using data from a USGS gaging station at the Highway 16 crossing near Eatonton, GA. The bacteria samples were collected during the period 1990 to 1994. We tested the sensitivity of the model predictions of FC to bacteria parameters by doubling the values of the parameters and calculating the root mean square change in predicted FC concentration. The most sensitive parameters were (in order of decreasing sensitivity): number of beef cattle, number of dairy cattle, time cattle spend in stream, and in-stream first-order decay rate.
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ItemPreliminary Sediment Analysis for the Broad River(Georgia Institute of Technology, 2001-03) Radcliffe, David E. ; Rasmussen, Todd C.Sediment Total Maximum Daily Loads (TMDLs) have been proposed for segments of the North, Middle, and South Forks of the Broad River. Our objectives are to present the sediment data that is available for the Broad River and to use HSPF to make a preliminary analysis of sediment sources. Total suspended solids (TSS) was measured at the USGS gaging station on the Broad River near Bell from 1958 to 1979 and the mean TSS concentration was a relatively high value of 75 mg/L. HSPF was used to predict TSS during the period 1971 to 1979. Land use data was from 1983. Only small adjustments to default discharge parameters were required to calibrate HSPF to the observed discharge at Bell. To calibrate the model for TSS, bed sediment parameters had to be adjusted including reducing the critical shear stresses for deposition and scouring and increasing the initial silt content and depth of bed sediments. These results may indicate that the source of the high suspended sediment levels in the Broad River is legacy sediment.
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ItemNitrogen and Phosphorus Losses from No-till Cotton Fertilized with Poultry Litter in the Southern Piedmont(Georgia Institute of Technology, 2001-03) Endale, Dinku M. ; Cabrera, Miguel L. ; Radcliffe, David E. ; Steiner, Jean L.Adoption of conservation tillage and use of poultry litter as fertilizer in major crops is increasing in the southeastern USA. The water quality impact of these alternative cropping methods needs investigation. In a study near Watkinsville, GA, nitrate loss through drainage was similar between no-till (NT) and conventional tillage (CT) cotton (mean 8.9 vs 8.2 kg ha⁻¹). Cotton fertilized with poultry litter (PL) had higher nitrate loss than that fertilized with ammonium nitrate as conventional fertilizer (CF) (10.3 vs 6.5 kg ha⁻¹). Peak nitrate concentrations reached 30 mg L⁻¹ from CT and 15 mg L⁻¹ from NT. Cotton under PL had about 5 mgL⁻¹ higher peak concentration than CF cotton. Losses of dissolved reactive phosphorus in runoff were: 0.24, 0.25, 0.45 and 0.72 kg ha⁻¹ respectively, for CTCF, CTPL, NTCF and NTPL. There was 48% more total runoff from CT than NT.
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ItemAgricultural Cost Share Programs in Kentucky and North Carolina(Georgia Institute of Technology, 2001-03) Radcliffe, David E.Legislative study committees have been appointed to explore the possibility of establishing a state agricultural cost share program in Georgia. The objective of this paper is to describe the programs in Kentucky and North Carolina and identify the features that might serve as models for the Georgia program. North Carolina established an Agriculture Cost Share Program in 1983 and the current funding level is $6.9 million per year. Kentucky established a Soil Erosion and Water Quality Cost Share Program in 1994. This is a much smaller program with a current funding level of $2.7 million per year. Both programs are administered through local soil and water conservation district offices and cost share best management practices (BMPs) at a rate of 75%. BMPs animal waste storage facilities, lagoon closure, riparian buffers, and nutrient management plans. Part of the funds are used for technical support in both programs. A Georgia cost share program should include many of these features including technical and administrative support, a 75% cost share rate, a focus on a limited number of BMPs, and state-wide application.