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This study examines the qualitative and quantitative effects of urban development on watersheds, focusing on the case of Upstate South Carolina. It analyzes changes in land use, water quality, erosion and sediment control, and the biological effects of flow. The results highlight the negative impacts of urbanization on watersheds and the importance of proper planning and management to mitigate these effects.
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What’s Mud Got to Do With It? Stephen J. Klaine, Ph.D. Department of Biological Sciences Clemson University sklaine@clemson.edu
Co-authors • J.A. Smink, K.L. Sciera, J.W. Pike, M.A. Goddard, W.R. English,C.J. Post, M.A, Schlautman, T, Karanfil, J.M. Hur, B.A. Powell, J.C. Morse, J. Allen and J.C. Hayes Departments of Biological Sciences, Forestry and Natural Resources, Entomology, Soils and Plant Sciences, Agricultural and Biological Engineering, School of the Environment, Strom Thurmond Institute, and the Clemson Institute of Environmental Toxicology, Clemson University, Clemson, SC
Outline • Introduction • What happens when we develop watersheds • Qualitatively • Quantitatively
Upstate SC Urban Growth 1990 - 2000 Urban Area Increase 78% 1990 - 2000 Population Increase 15% Growth Ratio 5:1
Lost Creek Development Site • 286 acres – 4 phase plan • zoned R-15 • 40’ stream easement (20’ either side) • 30’ easement for the roads
Permanent Water Quality Sample Station • Housed Unit Automatic Water Sampler Cellular Phone/Modem Battery Power Work Bench • Rain Gage • Solar Panel • PVC Housing for sample lines
Feb, 2004: Lost Creek: 15% developed Knight Creek: 0% developed Sept, 2004 Lost Creek: 40% developed Knight Creek: 0% developed Feb, 2005: Lost Creek: 60% developed Knight Creek: 0% developed Feb, 2006: Lost Creek: 75% developed Knight Creek: 10% developed Feb, 2007: Lost Creek: 75% developed Knight Creek: 10% developed
March 2003 August 2005 March 2004 Lost Creek Time Series Looking upstream March 2006 March 2007
April 2003 March 2004 April 2006 November 2003 September 2005 Lost Creek Time Series Looking downstream
Erosion and Sediment Control ???? April 2006
Lost Creek Runoff Event • Channel scour • Bank scour • Fine sediment deposition After a runoff event During a runoff event
15% developed O% developed
Runoff Event Summary February 5, 2004 Lost CreekKnight Creek • Rainfall (mm) 23.1 27.4 • Peak Flow (cfs) 4.7 1.5 • Event Volume (cf) 168,617 74,358 • TSS EMC (mg/L) 326 116 • Nitrate EMC (mg/L)0.71 0.11 • Total Phosphorus0.140 0.08 EMC (mg/L)
Paired WatershedDeveloped Watershed versus Undeveloped WatershedKnight Creek is undevelopedLost Creek is undergoing development (~20% as of Sept, 2004)
8000 mg/L 80 mg/L
Runoff Event Summary September 1, 2004 Lost Creek Knight Creek • Rainfall (mm) 31.7 31.7 • Peak Flow (cfs) 18.8 0.37 • Event Volume (cf) 88,316 440 • TSS EMC (mg/L) 2,884 41.9 • Nitrate EMC (mg/L)1.39 0.37 • Total Phosphorus0.23 0.07 EMC (mg/L)
Dry Weather Period: Lost Creek and Knight Creek Discharge Per Acre • Lost Creek: 50% Development • Period rainfall 1.08 in. • Discharge increases significantly with little rain • Knight Creek: 5% Development • Period rainfall 1.12 in. • Event peak discharge 50% less • Rainfall has slight impact on base flow • Discharge moderated
Wet Weather Period: Lost Creek and Knight Creek Discharge per Acre • Lost Creek: 75% Development • Period rainfall 5.43 in. • Event peak discharge increases • Ground water recharge decreases • Flash flood frequency increases • Knight Creek: 10% Development • Period rainfall 4.61in. • Event peak discharge 1/10th Lost Creek • Flash flooding not observed • Ground water recharge
Runoff or Recharge: Lost Creek and Knight Creek • Wet Period • Lost Creek 5.43 inches • Knight Creek 4.61 inches • Lost Creek higher % runoff per acre • Lost Creek lower % recharge • Dry Period • Lost Creek 1.08 inch/25 days • Knight Creek 1.12 inch/25 days • Knight Creek higher base flow per acre
Biological Effects of Flow • Flow variables were correlated with total invertebrate density (Clausen and Biggs 1997) • Biomass of periphyton decreased with increasing flood frequency (Clausen and Biggs 1997) • Rivers with maximum flows >20x median flow had lower median taxonomic richness, density, and biomass (Quinn and Hickey 1990) • Flood frequency (>3x median flow) was the strongest ecological predictor (Clausen and Biggs 1997) • Flows can affect ability of fish to maintain position and insects to remain colonized
Ephemeroptera Plecoptera Trichoptera ephemenoptera plecoptera trichoptera
Summary Data 6% developed 20% developed
CTL LC MN KN 1 mm Scale: • Pictures taken at test completion - 168 hr
Development Monitoring Use graded scale: 0=open lot 6=cleared 5=foundation 4=framed 3=construction ongoing 2= exterior construction complete 1=complete with landscaping, no bare soil
Habitat Methods • EPA’s Rapid Bioassessment Protocol (RBP) • Uses Score Sheets for Parameters • Do multiple assessments and average results • Too Subjective???
Lost Creek: Development vs. Habitat 75% developed No Significance
Knight Creek: Development vs. Habitat <10% developed * Significance at =0.05
Conclusions • Small changes in land use can cause large changes in aquatic ecosystem health • Hydraulic, chemical and biological changes • Aquatic ecosystems are impacted quickly during development • Current BMPs may not be adequate
Acknowledgements • USDA-NRCS • SRWC • Clemson University PSA