1 / 10

Soil Erosion Processes

Soil Erosion Processes. Richard A. McLaughlin, Ph.D. Soil Science Department North Carolina State University. Water Quality Problems: EPA Ranking. Sediment : widespread problems in surface water. Ruins habitat, clogs waterways, fills lakes and reservoirs.

penda
Download Presentation

Soil Erosion Processes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Soil Erosion Processes Richard A. McLaughlin, Ph.D. Soil Science Department North Carolina State University

  2. Water Quality Problems: EPA Ranking Sediment: widespread problems in surface water. Ruins habitat, clogs waterways, fills lakes and reservoirs. Nutrients: cause algal blooms and ultimately oxygen depletion. Yuck. Pathogens: local problems especially on coast. Many sources and no way to tell them apart! Organic Stuff: degrades and robs oxygen. Heavy Metals: biological impacts Pesticides: mostly a private well problem. R. A. McLaughlin NCSU Soil Science

  3. Non-Point Pollutant Sources: North Carolina Rivers R. A. McLaughlin NCSU Soil Science

  4. But…Construction Sites Have Highest Erosion Rates R. A. McLaughlin Source: US EPA, 1973 NCSU Soil Science NCSU Soil Science

  5. Erosion: Two Phases • Detachment: individual particles are loosened from the soil mass. • Rainsplash > running water > wind • Transport: water or wind carries the detached particles downslope or downwind. • Flow in rills is the most important. R. A. McLaughlin NCSU Soil Science

  6. Factors in Soil Losses • Rainfall: intensity, duration, and energy. • Soil erodibility: texture, structure, organic matter content. • Topography: slope length, steepness. • Surface Condition: vegetation, mulch, bare, etc. • Erosion Control Practices: contours, terraces, silt fences, basins, etc. R. A. McLaughlin NCSU Soil Science

  7. Factors in Soil Losses • Rainfall: intensity, duration, and energy. • Soil erodibility: texture, structure, organic matter content. • Topography: slope length, steepness. • Surface Condition: vegetation, mulch, bare, etc. • Erosion Control Practices: contours, terraces, silt fences, basins, etc. R. A. McLaughlin NCSU Soil Science

  8. Rainfall Factor • Intensity: the volume of water per unit of time e.g. inches/hour. • Records: 1.23” in 1 minute (MD, 1956), 19” in two hours (WV, 1889), 45” in 3 days (FL, 1950). • Duration: how long the storm lasts. • Norfolk has an average of 603 hours of precipitation/year, or 6.9% of the time. Of that, 12 hours exceed 0.5 in per hour. • Energy: droplet size and velocity. • Heavy rain (0.6”/hr) has 30 times more energy than light rain (0.04”/hr). R. A. McLaughlin NCSU Soil Science

  9. 5.5 5.5 5.0 5.5 6.0 6.0 8.0 7.0 6.0 6.5 8.5 7.0 8.0 24-Hour Rainfall Amounts for a 25-Year Recurrence R. A. McLaughlin NCSU Soil Science

  10. Rainfall Erosivity: Duration + Intensity 175 200 225 250 275 175 300 200 350 250 275 300 350 R. A. McLaughlin NCSU Soil Science

More Related