1. Runoff Processes Environmental Hydrology Lecture 10

2. Photo: B. Wemple

3. Why predict runoff? Estimate water supply (seasonal, annual) Estimate flood hazard, flood flows (event- based) Design infrastructure – detention basins, culvert sizing (“design storm”) Understand system behavior

4. The Hydrograph Source: U.S. Geological Survey, 2007 http://water.usgs.gov/

5. The Hydrograph Ward & Trimble, Fig. 5.11

6. The Hydrograph Source: U.S. Geological Survey http://water.usgs.gov/ Ranch Brook at Ranch Camp, near Stowe, VT USGS 04288230

7. Runoff Production Horton overland flow time Infiltration rate, i (mm/hr) Precipitation rate, p (mm/hr) p > i  overland flow Robert E. Horton Image source: American Geophysical Union

8. Runoff Production Horton Overland Flow R5 Catchment, Oklahoma. Photo: K. Loague, Stanford Univ.

9. Runoff Production Variable Source Area model John D. Hewlett From: Jackson et al., 2005. Hydrologist : John D. Hewlett (1922-2004), Hydrological Processes 19: 2093-2095. Ward & Trimble, Fig 5.3

10. Runoff Production Variable Source Area model Source: Taiwan Forestry Research Institute http://oldpage.tfri.gov.tw/book/2000/23e.htm

11. Geochemical indicators of runoff production Source: Burns et al., 2001. Quantifying contributions to storm runoff through end- member mixing analysis and hydrologic measurements at the Panola Mountain Research Watershed (Georgia, USA). Hydrol. Process. 15, 1903–1924 (2001)

12. Factors affecting runoff Precipitation- –Type, duration, amount, intensity Watershed Characteristics –Size, topography, shape, orientation, geology, soils Land use

13. Effect of development on runoff Ward & Trimble, Fig. 5.13

14. Lab: Measuring runoff Depart 11:15 a.m. kiosk on Carrigan Drive (east side of Aiken). Bring lunch, shorts, sandals. Return by 5:30pm. Read “How Streamflow is Measured” http://ga.water.usgs.gov/edu/measureflow.html Read Wemple et al., 2007 http://www.uvm.edu/~envhydro/Resources/Private/Readings/Wemple-etal-HP.pdf