Section 7

• How do you know when a river has reached flood stage?
Water levels in a channel exceed bank. (The stage at which the river will overflow its banks)
• What land use and channel zone changes may increase flooding and/or flood damage?
Agriculture, straightening, bank failure, removal of roughness. Urbanization, loss of riparian zone…
• What are three different types of drought?
?Agriculture Drought: Soil moisture insufficient for plant needs.
?Hydrological Drought: Extended period of low flows.
?Meteorological Drought: Extended period of low precipitation.
• Explain how each of the following land uses affect watershed function: agriculture, grazing, timber harvest, urban, mining
?Agriculture: Increases erosion, decrease infiltration, change albedo, ET, change drainage, modifies nutrients, NPS from fertilizers and pesticides, affects water supply, population, food supply.
?Grazing: Increased infiltration, soil compaction.
?Timber Harvest: Increased erosion and overland flow (if clearcut), ther is more water flow/yield from the lack of transpiration from trees.
?Urban: Increased runoff, loss of roughness.
?Mining: Metals getting into water area.
• If a channel is straightened and loses its riparian zone, how does this affect flood susceptibility?
Means loss of roughness/riparian zone can perhaps increase flood zone because there is nothing around to soak up the water?
• What are some of the main objectives of watershed management?
?Maintain High Water Quality
?Sustaining Water Quantity
?Limit Erosion
?Sustaining Habitat, Biodiversity
• What methods can be used to limit overland flow and maximize infiltration in an urban area? In areas with other types of land use?
Decrease impermeable surface area, promoted infiltration and decreased overland flow, increased roughness and complexity of drainage channels.

Areas with other Types of Land Use: GIS evaluation of watersheds forest health, slope steepness, soil erodibility, controlled burns, forest thinning, more vegetation for high erosion.

• What may be the benefit of constructing a sediment basin in an area with high overland flow and erosion?
Benefit of Construction a Sediment Basin in an area with High Overland Flow and Erosion: Acts as a temporary pond built to capture eroded or disturbed soil that is washed off during rain storms and protect the water quality.
• What are some of the main objectives of channel zone management?
Maintain water quality, aquatic habitat, minimize susceptibility to flood damage.
• What may be the benefits of vegetated buffers surrounding channels?
Lowers water temperatures, source of woody debris, improve habitat, reduce sediment, organic material, nutrients, pesticides and other pollutants migrating to the stream. Also reduces erosion.
• Give examples of best management practices.
?Agriculture: Planting along contours, filter strips, nutrient management.
?Forestry: Streamside and road management, fire management, revegetation.
?Urban: Detention ponds, vegetated swales, infiltration basins, permeable pavement.
• Why must watershed and channel zone management be integrated?
To sustain watershed function. Promote infiltration/decrease overland flow, protect from erosion, allow space for channel migration, riparian zone buffer.