Project 0 4193 regional characteristics of unit hydrographs
This presentation is the property of its rightful owner.
Sponsored Links
1 / 17

Project 0-4193 Regional Characteristics of Unit Hydrographs PowerPoint PPT Presentation


  • 79 Views
  • Uploaded on
  • Presentation posted in: General

Project 0-4193 Regional Characteristics of Unit Hydrographs. David B. Thompson, Texas Tech, RS George R. Herrmann, TxDOT, PD William H. Asquith, U.S. Geological Survey, Co-PI Xing Fang, Lamar University, Co-PI Theodore G. Cleveland, University of Houston, Co-PI. Background.

Download Presentation

Project 0-4193 Regional Characteristics of Unit Hydrographs

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


Project 0 4193 regional characteristics of unit hydrographs

Project 0-4193Regional Characteristics of Unit Hydrographs

David B. Thompson, Texas Tech, RS

George R. Herrmann, TxDOT, PD

William H. Asquith, U.S. Geological Survey, Co-PI

Xing Fang, Lamar University, Co-PI

Theodore G. Cleveland, University of Houston, Co-PI


Background

Background

  • Substantial progress on the “Texas” hydrograph method has been made over the past 7 years or so ...

    • Design storm depth and temporal distribution--DONE

    • Weakness in Curve Number method documented--DONE

    • Unit hydrographs--almost DONE

    • Time parameters--almost DONE

  • What is left? A temporal loss rate model=excess rainfall

    • Complete the loop: Rainfall --> Excess Rainfall --> Runoff

    • Motivation for 2-year extension request . . .


Primary 0 4193 objectives

Primary 0-4193 Objectives

  • Is the NRCS dimensionless unit hydrograph representative of Texas hydrology? SORT OF (at times)

  • If not, can alternative methods be developed? certainly YES

  • Can an alternative loss model to NRCS curve number method be developed from the existing database and resulting UH? Can a loss model “tuned” to the UH procedures that will result from 0-4193 to date? (Requested modification)


0 4193 approach

0-4193 Approach

  • Common database (93 watersheds and 1,600 events)

  • Joint but INDEPENDENT data processing . . .

    • Assumption of differing LOSS-MODELS--A necessary step

  • Unit Hydrograph Computations

    • Gamma UH fit to Qp and Tp (USGS): Shape and Tp parameters

    • Rayleigh IUH fit by error minimization (Univ. of Houston)

    • Linear programming fit by error minimization (Lamar Univ.)

    • Traditional method (Texas Tech Univ.)


Gugas shape parameter

GUGAS SHAPE PARAMETER

NRCS


Comparison of guh to nrcs dimensionless uh

Undeveloped watershed DUH is more symmetrical and peaky than developed watershed DUH and the NRCS DUH.

COMPARISON OFGUH TO NRCS DIMENSIONLESS UH


Time to peak

Time to Peak

  • Equation to estimate time to peak from main channel length, main channel slope, and development classification has been developed.

  • Measure of equation applicability

  • Measure of equation prediction accuracy.

  • Handy nomograph

UNDEVELOPED WATERSHEDS


Comparison of guhs

Comparison of GUHs


Comparison of guhs1

Comparison of GUHs


Estimation of time to peak from time of concentration

ESTIMATION OF TIME TO PEAK FROM TIME OF CONCENTRATION


Two methods for time to peak

TWO METHODS FOR TIME TO PEAK


0 4193 implications

0-4193 Implications

  • Watershed development influences UH shape and time scale.

  • GUH of same order of NRCS GUH.

  • GUH shape can be predicted and uncertainty computed.

    • K = function(L,D)

  • GUH Time-to-Peak (Tp) can be predicted without Time-of-Concentration (Tc) and uncertainty computed.

    • Tp = function(L,S,D)

  • GUH Tp can be predicted with Tc and uncertainty computed.

    • Tp= function(Tc, D)

  • THE TWO TpMETHODS COMPLIMENT EACH OTHER!


Temporal loss rate functions

Temporal Loss-Rate Functions

  • Potential candidate models

    • Initial loss, constant loss-rate, runoff coefficients

    • Green-Ampt, and other phenomenological models

Work to Do

  • Modify existing analytical tools to accommodate search for optimal loss-rate function given a UH.

  • Apply to database to estimate parameters

  • Analyze results from parameter estimation

  • Synthesize and regionalize


Unit hydrographs

Unit Hydrographs

  • A unit hydrograph (UH) is the hydrograph of runoff that results from a unit pulse of effective precipitation (runoff) distributed evenly over a watershed over a specific duration of time.

  • UHs are used for drainage designs for watersheds with drainage areas with a wide range of sizes.


Process model

Process Model


  • Login