Water RunoffBy: Kori Howell

Overview

Water Runoff defined

Importance

Type of water erosion

Effects on the Environment

Flooding

Causes of runoff

Prevention methods

Overview video

What is Water Runoff?

• The flow of water that occurs when excess storm water, melted water or other sources flows over the earth’s surface.

• The primary agent of soil erosion by water.

•When the soil is infiltrated to full capacity and excess water flows.

• Similar to a sponge

Why is Water Runoff important?

• It can cause water erosion

• It affects the environment

• It can cause flooding

Four Types of Water Erosion

• Splash erosion

• Sheet erosion

• Rill erosion

• Gully erosion

Splash Erosion

• The impact from massive amounts of raindrops that can damage the soil surface.

• Detaches the soil particles and destroys the soil structure

• Affects plant growth and crop production

Sheet Erosion

• The overland transportation of sediment through water runoff without a well defined channel.

• The movement of soil particles downslope by water movement.

Rill Erosion

•Water runoff through well formed channels known as rills

•Concentrates the water runoff into narrower flow paths

Gully Erosion

• Transportation of large amounts of eroded material

•Can damage underground utilities

Water Runoff Effects on Environment

•Water pollution

•Risk to aquatic lifeforms

•Contaminates drinking water

Primary Pollution Agents to Groundwater

• Pesticides

• Herbicides

• Insecticides

• Oil

• Algae

• Fertilizer

Affects on Aquatic Life

oAlters metabolic process of aquatic speciesoDisrupts animal mating and spawningoAlters genders in fish, changing male fish to female fishoIncreased growth rate of algae plants, which reduces amount of oxygen in the wateroDeath

Contaminated Drinking Water

• Leakage of pesticides, herbicides, fertilizer, etc… into water systems can contaminate drinking water. This increases the chances of health risk in humans and animals.

• Bacteria can also contaminate drinking water aquifers if it seeps through cracks in the bedrock.

• There have been cases where E Coli bacteria has entered into our water systems and killed several people.

Flooding Caused by Runoff

• Water runoff is the primary cause of flooding in urban communities.

• Can be devastating to a community

• The return period is the frequency that the flood may occur.

What Causes Runoff to Occur

•Meteorological factors

• Physical characteristics of land

•Human activities

Meteorological Factors

• Rainfall intensity

• Rainfall amount

• Rainfall duration

• Distribution of rainfall over the drainage basin

• Direction of storm movement

• Precipitation that occurred earlier and resulting soil moisture

• Other meteorological and climatic conditions that affect evapotranspiration, such as temperature, wind, relative humidity, and season

Physical Characteristics of Land

• Land use

• Vegetation

• Soil type

• Drainage area

• Basin shape

• Elevation

• Topography, especially the slope of the land

• Drainage network patterns

• Ponds, lakes, reservoirs, sinks, etc. in the basin, which prevent or delay runoff from continuing downstream

Human Activities

•Urbanization

•Overuse of fertilizers

• Population growth

• The more buildings and structures that are built reduces infiltration of water into the ground and accelerate runoff to ditches and streams

• As a result, the peak discharge, volume, and frequency of floods increase in nearby streams.

Prevention Methods for Water Runoff

1.Follow best management practices

2.Capture and Store Runoff

3.Redirect runoff

4.Develop inspection and maintenance program

General Best Management Practices

• Seeding with grass and fertilizing to promote strong growth provide long-term stabilization of exposed surfaces.

• Seeding with grass and overlaying with mulch or mats is done to stabilize cleared or freshly seeded areas.

• Wildflower cover has been successfully used by many state and county highway departments to provide attractive vegetation along roadways and erosion control.

• Sodding with established grass blankets on prepared soil provides a quick vegetative cover to lessen erosion.

Capture and Store RunoffRain Barrel Rain Garden

Capture and Store Runoff (cont.)

Terraces Dry Well (Infiltration Trench)

Redirect Runoff

Swale French Drain(Underground Drain)

Develop Schedule and Maintenance Program

• Schedule and periodically inspect and maintain permanent erosion and runoff controls. This should include a periodic visual inspection of permanent best management practices during runoff conditions to ensure that the controls are operating properly. Clean, repair, and replace permanent erosion and runoff control best management practices when necessary.

Water Runoff Overview Video

• https://www.youtube.com/watch?v=kyH02NjyfPA

References

• Swanson, Abbie. "What Is Farm Runoff Doing To The Water? Scientists Wade In." NPR. NPR, 5 July 2013. Web. 03 May 2015.

• "Surface Runoff - The Water Cycle." , from USGS Water-Science School. N.p., 15 Apr. 2014. Web. 03 May 2015.

• "Erosion, Sediment and Runoff Control for Roads and Highways." EPA. Environmental Protection Agency, 13 Jan. 2010. Web. 03 May 2015.

• "Control Heavy Runoff - Solving Drainage and Erosion Problems - Fairfax County, Virginia." Control Heavy Runoff - Solving Drainage and Erosion Problems - Fairfax County, Virginia. Fairax County Virginia, n.d. Web. 03 May 2015.