Watershed Effects on Streamflow Quantity and Quality in Six Watersheds of Gwinnett County, Georgia

Landers, Mark N.; Ankcorn, Paul D.; McFadden, Keith W.

doi:10.3133/sir20075132

Cited by 16 publications

(15 citation statements)

References 18 publications

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“…In 2006, 2007, and 2008 the mean annual regional discharge was 6, 21, and 50% lower than the 10‐year average. Similar results were observed by Landers et al (2007), where the annual sediment yield estimates (1998–2003) for six watersheds in the Georgia Piedmont varied substantially between years owing to differences in precipitation.…”

Section: Resultssupporting

confidence: 88%

Channel stability and sediment source assessment in streams draining a Piedmont watershed in Georgia, USA

Mukundan¹,

Radcliffe²,

Ritchie³

2010

Hydrological Processes

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Abstract:Streams can be classified as stable or unstable, depending on the stage of channel evolution. Many streams of the southern Piedmont in United States have high sediment loads and are listed as impaired under the total maximum daily load (TMDL) program and may be unstable. It is not clear as to what the target (reference) load or remediation measures should be for unstable streams. The objective of this study was to determine the relative channel stability for a typical southern Piedmont stream using rapid geomorphic assessments (RGAs) and sediment yield analysis. The results were supported through a sediment fingerprinting analysis. RGAs were performed along 52 reaches on the North Fork Broad River (NFBR) main stem and two tributaries. Annual sediment yields were calculated and compared with yields in the southern Piedmont for stable streams that are resilient to degradation or aggradation and unstable streams that are susceptible to such disturbances. Majority of the NFBR main stem was found to be unstable with signs of geomorphic instability in the form of degradation and aggradation. The estimated average annual sediment yield was 0Ð78 T ha 1 year 1 . By comparison, the median annual yield is 0Ð20 T ha 1 year 1 for stable streams and 0Ð48 T ha 1 year 1 for unstable streams in the Piedmont ecoregion with comparable drainage basin size. We conclude that the NFBR is in an unstable stage of channel evolution. Sediment fingerprinting proved that majority of the stream-suspended sediment emanated from eroding stream channels. The methods outlined in this study have implications for the reference condition and remediation efforts related to stream turbidity and stream channel restoration.

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Section: Resultssupporting

confidence: 88%

Channel stability and sediment source assessment in streams draining a Piedmont watershed in Georgia, USA

Mukundan¹,

Radcliffe²,

Ritchie³

2010

Hydrological Processes

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“…The TP ECs from urban land uses represent only urban nonpoint sources of TP. The TP ECs simulated by SWAT are comparable to the results from our field studies (Romeis et al, 2008) and to values reported in the literature (e.g., Beaulac and Reckhow, 1982; Loehr et al, 1989; McFarland and Hauck, 2001; Landers et al, 2007; Lin, 2004; Pierson et al, 2001a; Vervoort et al, 1998).…”

Section: Resultssupporting

confidence: 90%

“…The mid‐interval method assigns the elevated concentration to the entire 2‐wk interval — or even longer — surrounding a storm, while the SWAT simulations predict that elevated concentrations last only a few days. Our discussion assumes TP concentrations are greater during storms than baseflow (Frick et al, 1998; Landers et al, 2007).…”

Section: Resultsmentioning

confidence: 99%

Modeling Phosphorus in the Lake Allatoona Watershed Using SWAT: II. Effect of Land Use Change

et al. 2009

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Lake Allatoona is a large reservoir northeast of metropolitan Atlanta, GA, threatened by excessive algal growth. We used the calibrated Soil and Water Assessment Tool (SWAT) models developed in our companion paper to estimate the annual P load to Lake Allatoona in 1992 and in 2001 after significant changes occurred in land use. Land use data in 1992 and 2001 from the Multi-Resolution Land Characteristics (MRLC) Consortium showed that forest land use decreased during this period by about 20%, urban land use increased by about 225%, and pasture land uses increased by about 50%. Simulation results showed that the P load to Lake Allatoona increased from 176.5 to 207.3 Mg, which were 87.8% and 103.1%, respectively, of the total P (TP) annual cap (201 Mg) set by the Georgia Environmental Protection Division (GAEPD) for discharge into Lake Allatoona. In the early 1990s, the greatest sources of the TP load to Lake Allatoona (and their percentages of the total load) were pasture (33.6%), forest (27.5%), and point sources (25.0%). Urban land uses contributed about 6.0% and row-crop agriculture contributed about 6.8%. A decade later, the greatest two TP sources were pasture (52.7%) and urban (20.9%) land uses. Point-source P loads decreased significantly to 11.6%. Permit limits on poultry processing plants reduced the point-source P loads, but increasing urban and pasture land uses increased nonpoint sources of P. To achieve further reductions in the P load to Lake Allatoona, contributions from pasture and urban nonpoint sources will need to be addressed.

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“…Landers et al . () showed that watersheds with IAs within a 25‐foot stream buffer ranging from 1.6 to 4.4% of watershed area appeared to affect base flow and storm flow. Shuster et al .…”

Section: Introductionmentioning

confidence: 99%

“…Landers et al . () and Joiner et al . () have shown that variations in hydrologic response and water quality between 12 of the county watersheds are related to both their watershed percent EIA and basin slope.…”

Section: Introductionmentioning

confidence: 99%

Effects of Impervious Area and BMP Implementation and Design on Storm Runoff and Water Quality in Eight Small Watersheds

Aulenbach

Landers

Musser

et al. 2017

J American Water Resour Assoc

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The effects of increases in effective impervious area (EIA) and the implementation of water quality protection designed detention pond best management practices (BMPs) on storm runoff and stormwater quality were assessed in Gwinnett County, Georgia, for the period 2001‐2008. Trends among eight small watersheds were compared, using a time trend study design. Significant trends were detected in three storm hydrologic metrics and in five water quality constituents that were adjusted for variability in storm characteristics and climate. Trends in EIA ranged from 0.10 to 1.35, and changes in EIA treated by BMPs ranged from 0.19 to 1.32; both expressed in units of percentage of drainage area per year. Trend relations indicated that for every 1% increase in watershed EIA, about 2.6, 1.1, and 1.5% increases in EIA treated by BMPs would be required to counteract the effects of EIA added to the watersheds on peak streamflow, stormwater yield, and storm streamflow runoff, respectively. Relations between trends in EIA, BMP implementation, and water quality were counterintuitive. This may be the result of (1) changes in constituent inputs in the watersheds, especially downstream of areas treated by BMPs; (2) BMPs may have increased the duration of stormflow that results in downstream channel erosion; and/or (3) spurious relationships between increases in EIA, BMP implementation, and constituent inputs with development rates.

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Watershed Effects on Streamflow Quantity and Quality in Six Watersheds of Gwinnett County, Georgia

Cited by 16 publications

References 18 publications

Channel stability and sediment source assessment in streams draining a Piedmont watershed in Georgia, USA

Channel stability and sediment source assessment in streams draining a Piedmont watershed in Georgia, USA

Modeling Phosphorus in the Lake Allatoona Watershed Using SWAT: II. Effect of Land Use Change

Effects of Impervious Area and BMP Implementation and Design on Storm Runoff and Water Quality in Eight Small Watersheds

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