Environmental Science 102
Surface Water

Surface Water

Surface water is water found above the ground surface
This includes streams, lakes, ponds, oceans, seas, and swamps.


Streams are channeled flow of surface water moving downhill under the force of gravity
No size distinction

Stream Flow

Stream flow is the movement of surface water in a channel
A channel is a long, narrow trough (channels can be large or small)

1. Flow Velocity

Flow velocity is a measure of the speed of the flow - typically measured in m/s or ft/s
Greatest velocity in the center of stream and toward the top but not at the surface.

2. Stream Discharge

Volume of water moving through the channel
Discharge equation:

3. Stream Gradient

Stream gradient is the rate of fall in elevation of the stream surface per unit distance - feet/mile, meters/km, % grade, degrees

4. Stream Load

The amount of sediment carried by the stream.
Clay, silt, sand, gravel, and organic material are all moved.
Types of Load:


All streams will flood.
When the volume of water exceeds the channel capacity, the stream will flood.
Water continues to flow in channel
Excess flows in adjacent areas - flood plain
Flood Stage - level at which the stream floods

Causes of Flooding

Excessive Precipitation
Extended periods of precipitation
Rapid melting of snow or ice
Man-made causes
Short bursts of extremely heavy precipitation
Saturation of the ground
Destruction of Wetlands

Flood Prediction

Flood Prediction is stream specific
Dependent on annual precipitation, climate, location, topography, bedrock, man-made alterations
Based on historical records which indicate when flooding is most likely to occur.
Floods are classified according to size of the flood (stream dependent) based on statistical occurrence of flooding

Lakes, Ponds and Wetlands

Bodies of exposed, standing water (includes ponds)

Characteristics of a Lake:

Characteristics of a Pond:

Swamps, bogs, and marshes - wetlands


Short lived features geologically
Formed through tectonic, glacial and erosional processes
To form a lake:
To maintain a lake:
Easily destroyed: