swat land phase of the hydrologic cycle l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
SWAT – Land Phase of the Hydrologic Cycle PowerPoint Presentation
Download Presentation
SWAT – Land Phase of the Hydrologic Cycle

Loading in 2 Seconds...

play fullscreen
1 / 10

SWAT – Land Phase of the Hydrologic Cycle - PowerPoint PPT Presentation


  • 135 Views
  • Uploaded on

SWAT – Land Phase of the Hydrologic Cycle. Kristina Schneider Kristi Shaw. Surface Water Runoff. Calculates surface runoff volumes and peak runoff rates using daily rainfall amounts Runoff volume estimated using a modification of the SCS Curve Number Technique.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'SWAT – Land Phase of the Hydrologic Cycle' - fisk


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
swat land phase of the hydrologic cycle

SWAT – Land Phase of the Hydrologic Cycle

Kristina Schneider

Kristi Shaw

surface water runoff
Surface Water Runoff
  • Calculates surface runoff volumes and peak runoff rates using daily rainfall amounts
  • Runoff volume estimated using a modification of the SCS Curve Number Technique.
  • Two options for estimating the peak runoff rate:
    • The modified Rational formula
    • The SCS TR-55 method
surface runoff volume
Surface Runoff Volume
  • Selected modified SCS method for the follow reasons:
    • Reliable and has been used for many years in the US
    • Computationally efficient
    • Required generally available inputs
    • Relates runoff to soil type, land use, and management practices

R is rainfall & Q is daily runoff

  • The modification deals with how Soil Water content is calculated.
peak runoff rate
Peak Runoff Rate
  • Rational Method:
    • A stochastic element is included to allow for a realistic runoff rate.

tc can be estimated by adding the surface and channel flow times.

Alpha is a dimensionless parameter that expresses the proportion of total rainfall that occurs during tc.

Q is a daily runoff.

A is the drainage Area.

peak runoff rate6
Peak Runoff Rate
  • The SCS TR-55 method
    • The peak runoff rate is dependent on the rainfall distribution and amount, the runoff curve number, and the time of concentration

qp = peak rate

qp*=peak rate per unit of rainfall

    • There are a set of curves are available (USDA-SCS, 1986) for estimating qp* given rainfall distribution (SCS Type I, IA, II, or III), the runoff curve number, and the watershed time of concentration.
pond reservoir outflow
Pond / Reservoir Outflow
  • Three alternative estimation schemes:
    • The input is measured outflow.
    • Specify water release rate
      • Volume > emergency spillway is released within one day
      • Primarily used for small uncontrolled reservoirs.
      • Reservoir volume > storage extra water is released at a specified rate
    • User specified monthly target volumes for the reservoir
lateral subsurface flow
Lateral Subsurface Flow
  • Streamflow contribution, which originates below the surface but is above the zone where rocks are saturated with water.
  • Calculated simultaneously with redistribution in the soil profile (0-2m).
  • Kinematic storage model is used to predict lateral flow in each soil layer:
    • Accounts for variation in conductivity, slope and soil water content
    • Allows for flow upward to an adjacent layer or to the surface
return flow
Return Flow
  • Volume of streamflow originating from groundwater
  • SWAT partitions groundwater into two aquifer systems
    • shallow, unconfined aquifer which contributes return flow to streams within the watershed
      • storage water may replenish moisture in the soil profile in very dry conditions or be directly removed by plant uptake (trees)
      • water may also seep into the deep aquifer or be removed by pumping
    • deep, confined aquifer which contributes return flow to streams outside the watershed (water may be removed by pumping)