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Hydrologic/Watershed ModelingPowerPoint Presentation

Hydrologic/Watershed Modeling

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Hydrologic/Watershed Modeling

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Hydrologic/Watershed Modeling

Glenn Tootle, P.E.

Department of Civil and Environmental Engineering

University of Nevada, Las Vegas

tootleg@unlv.nevada.edu

, Ph.D.

Department of Civil and Architectural Engineering

University of Wyoming

tootleg@uwyo.edu

- Who has used / developed a hydrologic model?
- What model(s) did you use?
- Examples

- Typical Input
- Topography
- Soil Characteristics
- Land cover
- Land use
- Meteorological data
- Typical Output
- Streamflow
- Subsurface Flow
- Depth to water table

- Delineate watershed
- Obtain hydrologic and geographic data
- Select modeling approach
- Calibrate/Verify model
- Use model for assessment/prediction/design

- Area that topographically contributes to the drainage to a point of interest

Natural Watershed

- Points of Interest
- Road crossing
- Stream gage
- Reservoir inlet
- Wastewater treatment plant
- Location of stream restoration

- Digital file that stores the elevation of the land surface a specified grid cell size (e.g., 30 meters)

- Land use

- Land cover

- Soil type/classification

- Meteorological Data
- Temperature
- Precipitation
- Wind speed
- Humidity

- Extrapolation of point measurements
- Theissen Polygons
- Inverse distance weighting

Streamflow

- Hydrologic Data
- Streamflow
- Peak discharge
- Daily flow volume
- Annual flow volume

- Soil moisture
- Groundwater level

- Streamflow

- Hydrologic Budget (In – Out = ΔStorage)

Transpiration (T)

Streamflow (Q)

Evaporation (E)

Groundwater out (GWout)

Reservoir

Precipitation (P)

Groundwater in (GWin)

Infiltration (I)

Watershed

(P + GWin) – (E + T + I + GWout + Q) = ΔStoragereservoir

- It Depends on:
- What time scale are you working at?
- What hydrologic quantity are you trying to obtain?
- What data do you have for your watershed?
- How fast of a computer do you have?

Semi-Distributed

Parameters assigned to each grid cell, but cells with same parameters are grouped

Fully-Distributed

Parameters assigned to each grid cell

Lumped

Parameters assigned to each subbasin

A3

A1

A2

- Physically-based and continuous simulation

- Continuous simulation and physically-based
- Macroscale hydrologic model that solves full water and energy balances

- Typically the model is calibrated against observed streamflow data
- Depending on the model complexity, parameters are adjusted until observed streamflow equals model streamflow
- Which observed value to use:
- Qpeak
- Qvolume
- tpeak

Qpeak

Q

- tpeak

- Qvolume

t

- Precipitation
- Soil parameters
- Hydraulic conductivity
- Soil water holding capacity

- Evaporation (for continuous simulation)
- Flow routing parameters (for event-based)

- Precipitation
- Extrapolation of point to other areas
- Temporal resolution of data

- Soils information
- Surveys are based on site visits and then extrapolated

- Routing parameters
- Usually assigned based on empirical studies

- Assessment
- What happens if land use/land cover is changed?

- Prediction
- Flood forecasting

- Design
- How much flow will occur in a 100 year storm?