Watersheds - Watersheds Definition: surrounding land from...

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Watersheds Definition: surrounding land from which water flows into a lake, river, estuary or other body of water Most of this water was once precipitation that fell in the watershed
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Watersheds Aquatic habitats reflect the characteristics of their watersheds Important watershed characteristics: soils- type and thickness vegetation- a function of climate, soils, etc. slope of the land- a geological feature human activities- for example, non-point nutrient input
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Watersheds Watershed characteristics largely determine: Aquatic habitats reflect the characteristics of their watersheds aquatic productivity (nutrient input) sensitivity to acidification turbidity flushing rate
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Watersheds Flushing rate (water residence time) large volume small inflow low flushing rate (long residence time) small volume large inflow high flushing rate (short residence time) How long does it take to fill?
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discharge to aquatic habitat fate of precipitation in the watershed precipitation intercepted by canopy drip surface water surface runoff soil water subsurface flow ground water groundwater flow infiltration seepage evapo- transpiration Hydrology above ground below ground
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Stability of water flows (variability over time) surface runoff (flow) subsurface flow groundwater flow not stable (most variable) more stable (less variable) most stable (least variable) permanent streams Watersheds Hydrology
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Surface runoff occurs when precipitation rate exceeds infiltration rate Watersheds Hydrology
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Watersheds The proportion of precipitation that becomes surface runoff depends on: soils- type and thickness vegetation- a function of climate, soils, human activity slope of the land- a geological feature intensity and timing of rain events Hydrology
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Watersheds The proportion of precipitation that becomes surface runoff depends on: soil type particle size small large organic matter infiltration infiltration rate low high clay sand particle type % surface runoff high low Hydrology
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Watersheds The proportion of precipitation that becomes surface runoff depends on: vegetation vegetation desert forest infiltration rate low high dry wet climate % surface runoff high low Hydrology
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Watersheds precipitation rate intensity and timing of rain events Hydrology (declines as soil gets wetter) surface runoff
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Watersheds What does a precipitation rate of 10 mm per hour mean? Hydrology
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Watersheds What does a precipitation rate of 10 mm per hour mean? 10 mm If there was no infiltration. .. Hydrology
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Watersheds Discharge (river flow) = cross-sectional area X current velocity cubic feet per second = square feet X feet per second cfs = ft2 X ft/sec Discharge is the volume of water passing a point in a unit of time. Hydrology
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Watersheds weir measuring discharge Hydrology
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Watersheds weir Hydrology measuring discharge USGS
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Watersheds Discharge = cross-sectional area X current velocity current velocity As discharge increases, any combination of three things can happen: area Hydrology
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Watersheds As discharge increases: depth may increase current velocity Hydrology current velocity current velocity area
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Watersheds As discharge increases: width may increase Hydrology current velocity current velocity area
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Watersheds - Watersheds Definition: surrounding land from...

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