Environmental Science 102
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 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
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
Extended periods of precipitation
Rapid melting of snow or ice
Short bursts of extremely heavy precipitation
Saturation of the ground
Destruction of Wetlands
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: