Hydromet January 2001 -- AMS Short Course on Instrumentation

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Hydrometeorological Hydrometeorological MeasurementsMeasurements

Melanie A. Wetzel Desert Research Institute

University of Nevada, Renoand

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Components of the Hydrologic Cycle

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Processes of Transport and TransformationWater resources distribution is controlled by the radiation balance, movement of air masses with contrasting temperature and moisture contents, terrain features and local airflow patterns

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Primary Elements of Hydromet Monitoring

Atmospheric Vapor Cloud Water Rainfall Snowfall Snowpack Groundwater Streamflow Water Quality

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Atmospheric Humidity

Ground-based temperature/humidity monitoring Rawinsondes to provide vapor transport Role of wind-driven evaporation Impact of soil type and other surface parameters

Hydromet January 2001 -- AMS Short Course on Instrumentation

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EvapotranspirationLysimeters measure the loss of water by mass balance from a surface layer usually containing soil and vegetation

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Evaporation

Water loss from open water is a large source of atmospheric moisture. Evaporation from snow in dry or high altitude zones also causes significant loss.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Measurement of Cloud Water Content

Hot Wire SensorsOptical ProbesImpaction CollectorsCloud Sieves

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Tipping Bucket Raingages

Calibrated per-tip volume is converted to equivalent depth per unit area. Errors due to sticking of snow on sides of funnel, debris, and unrepresentative capture at collection aperture.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Weighing Bucket and Snow Gages

Use of heating, anti-freeze solutions and apparatus for wind screening improve the measurement of total rain and snow equivalent depths.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Snow Depth Sensors

Applications which require monitoring of physical snow depth (such as at ski areas) can utilize acoustic snow depth sensors. Amounts are under-represented when snow has a low density due to sound transfer into the snowpack.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Measurement of Snow Water Equivalent

Snow pillows monitor mass of overlying snow, and snow cores provide column water amount.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Fuel (Vegetation) Moisture

Fuel Rod devices are designed to simulate moisture content of trees within forest environments, for monitoring fire potential. Fuel moisture is a direct function of atmospheric humidity, precipitation and soil moisture.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Streamflow Monitoring

Stream discharge is estimated from measurements of the stream stage height.

Stage height instruments:Staff gage

Stilling well / floatBubblerPressure TransducerAcoustic Sensor

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Stream Cross-Sections

Flumes and weirs control flow into a known cross-section, so that river stage height can be monitored visually or automatically. Stage height is related to volumetric discharge using stream profile measurements.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Current Meters and Profiles

Stream velocity follows a vertical profile similar to boundary layer winds, and measurement depths are selected to according to this profile.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Discharge Calculations

Number and location of current measurements across the channel are determined from stream width and depth.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Flood Recurrence Interval

Numerical ranking of peak streamflow is used to estimate the probability of flood conditions.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Water Quality

Contaminants include sediment, bacteria, metals, aerosols, biogenic chemicals and many others.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Water Chemistry and Turbidity

Sample collection and automated sensing are used to monitor sediment and pollutant

concentrations.

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Networks of Hydrometeorological Sensors

Hydromet January 2001 -- AMS Short Course on Instrumentation

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Effects of Local ChangesAlterations of the stream channel, soil and vegetation are analogous to modification in the airshed due to construction and urbanization

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ReferencesNathanson, J.A., 1997: Basic Environmental Technology. Prentice

Hall, New Jersey, 440 pp.Ward, A.D., and W.J. Elliot, 1996: Environmental Hydrology.

Lewis, Boca Raton, 496 pp.Watts, S., and L. Halliwell, ed., 1996: Essential Environmental

Science: Methods and Techniques. Routledge, New York, 512 pp.