Project 0 4193 regional characteristics of unit hydrographs
Download
1 / 17

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


  • 102 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.

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

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.)



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 developed watershed DUH and the NRCS DUH.

  • 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 developed watershed DUH and the NRCS DUH.


Comparison of guhs1
Comparison of GUHs developed watershed DUH and the NRCS DUH.


Estimation of time to peak from time of concentration
ESTIMATION OF TIME TO PEAK FROM TIME OF CONCENTRATION developed watershed DUH and the NRCS DUH.


Two methods for time to peak
TWO METHODS FOR TIME TO PEAK developed watershed DUH and the NRCS DUH.


0 4193 implications
0-4193 Implications developed watershed DUH and the NRCS DUH.

  • 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 developed watershed DUH and the NRCS DUH.

  • 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 developed watershed DUH and the NRCS DUH.

  • 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 developed watershed DUH and the NRCS DUH.


ad
  • Login