Water Hydrologic cycle p The hydrologic cycle is

Water

Hydrologic cycle p. The hydrologic cycle is a summary of the circulation of Earth’s water supply p. Processes involved in the hydrologic cycle p Evapotranspiration p Condensation p Precipitation p Infiltration p Runoff

The water cycle

Distribution of Earth’s Water

Running water p Begins as sheetflow p. Infiltration capacity depends on § Intensity and duration of rainfall § Prior wetted condition of the soil § Soil texture § Slope of the land § Nature of the vegetative cover p. Sheetflow develops into tiny channels called rills

Running water p. Changes from upstream to downstream p. Profile §Cross-sectional view of a stream §Viewed from the head (headwaters or source) to the mouth of a stream

Longitudinal profile of a stream

Changes from upstream to downstream p. Factors that increase downstream §Velocity §Discharge §Channel size

Changes from upstream to downstream p. Factors that decrease downstream §Gradient §Channel roughness p. Base level is the lowest point to which a stream can erode

Adjustment of base level to changing conditions

Running water p. Stream valleys are the most common landforms on Earth’s surface p. Types of stream valleys §Narrow valleys V-shaped § Downcutting toward base level § Features often include rapids and waterfalls §

Running water p. Stream valleys p. Two general types of stream valleys §Wide valleys Stream is near base level § Downward erosion is less dominant § Stream energy is directed from side to side forming a floodplain §

Features of wide valleys p. Floodplains p. Meanders § Cut bank and point bar § Cutoffs and oxbow lakes

Meandering Channel

Drainage patterns

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Define: wetlands pa low-lying area of land that is saturated with moisture. For example: Marshes, swamps, and bogs are examples. www. google. com/url? sa=X&start=17&oi=define&q=http: //www. thehenryfo

Define: wetlands p “those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions” www. google. com/url? sa=X&start=1&oi=define&q=http: //www. epa. gov/OC

Wetlands p High diversity n p Transitional zone to upland Classification – Cowardin system n n n Marine wetlands – coral reefs, rocky shorelines, salt water Estuarine wetlands – tidal salt marsh, mangrove swamps, strong tidal influence Riverine wetlands – transitional area to upland, high species diversity, high productivity Lacustrine wetlands – lakes, ponds Palustrine – bogs, fens, peatlands

Wetlands are transition zones

Wetlands are transition zones

Wetlands are transition zones http: //www. pbase. com/roamer 8/image/57048104

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Who cares about wetlands? p Hydrologic processes Intercept runoff and store it to reduce flooding p Stabilize streambanks p Contribute to recharge and discharge of groundwater p p Water quality improvement p p Remove sediment, toxins, nutrients from water Wildlife habitat High primary productivity (abundant plant life) p Abundant and diverse wildlife p

Wetland protection p Gradual recognition of values n Wetland removal sequence 1980’s No net loss policy p Heavy regulation of wetland management p

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Lakes p Littoral zone – shallow, rooted vegetation dominated margin of a lake n p Key wildlife habitat area Thermal stratification n Winter p n Spring p n Mixing of water (agitated by wind) Summer p n Ice formation – creates zone for fish life Thermocline (most oxygen in upper layers Fall p Temperature unifies as air cools, mixing of water

http: //www. fishsniffer. com/guest/images/041103 lakezones. gif