Iowa StreamStats Implementation of Design Peak-Flow Determination - Iowa State … · 2014. 4. 30. · U.S. Geological Survey Iowa Water Science Center Iowa City, IA 52240 319-358-3615

U.S. Geological Survey

Iowa Water Science Center

Iowa City, IA 52240

319-358-3615

daeash@usgs.gov

by David Eash

Iowa StreamStats Implementation of Design –

Peak-Flow Determination

Presented at the ASCE Environmental and

Water Resources ConferenceAmes, IA

April 3, 2014

What is StreamStats?

A map-based Web application that provides

information that can be used by engineers,

managers, and planners to make informed

decisions on water-related activities

Primary products are basin delineations, basin-

characteristic measurements, and estimates of

streamflow statistics

Program allows for the analysis of upstream and

downstream relations along streams

How is StreamStats Information Used?

Engineering Design—Bridges, culverts, roads, levees, dams, and other structures along streams; flood-plain mapping

Water and Land Management—Water rights adjudication, in-stream flows, fish passage/habitat studies

Water Quality Regulation—Low flows, perennial vs. intermittent streams (TMDL’s, NPDES Permits)

Sampling Network Design—Cover a range of desired flows

StreamStats Site Capabilities

Provides published streamflow statistics and basin characteristics for USGS streamgages

For user-selected ungaged sites:

• Delineates drainage basin boundaries

• Allows editing of basin boundaries, if necessary

• Computes basin characteristics

• Provides estimates of streamflow statistics based on regression equations

• Allows for download of basin boundary shapefiles

• Allows the printing of maps shown in user interface

StreamStats Implementation for Iowa

74 regression equations from 3 USGS streamflow-

estimation reports will be implemented in StreamStats

StreamStats will allow users to click on any ungaged

or gaged stream site in Iowa and obtain estimates of

30 streamflow statistics

7 low-flow statistics that include 4 annual and 2

seasonal low-flow probabilities and the harmonic

mean

15 flow-duration statistics that include 1% - 99%

exceedance probabilities

StreamStats Implementation for Iowa

8 peak-flow statistics that include 2- to 500-year

recurrence-interval floods

90-percent prediction intervals will be computed for

an ungaged site (for low-flow & peak-flow regression

estimates)

Peak-flow equations were implemented in June 2013

Low-flow and flow duration equations will be

implemented in near future

IA StreamStats app uses peak-flow regional-

regression equations published in SIR 2013-5086

New Iowa Flood Regions

3

3

1

2

2

518 streamgages used for defining six

flood regions

1

3

2

Northwest

Northeast

Southern

Iowa Low-Flow Regions

IA StreamStats app will use low-flow regional-

regression equations published in SIR 2012-5171

Flood Region 1 Regression Equation

Regression equations take the form:

Q1%=DRNAREA0.56610(0.917+0.567 I24H10Y-0.742

CCM^0.55)

where:

DRNAREA is drainage area, in square miles

I24H10Y is maximum 24-hour precipitation that

occurs on average once in 10 years, in inches

CCM is constant of channel maintenance (DRNAREA/

total length of all streams in basin), in mi2/mi

Flood Region 1 Drainage-Area Only

Regression Equation

Regression equations take the form:

Q1%= 102.67 DRNAREA0.524

where:

DRNAREA is drainage area, in square miles

Flood Region 2 Regression Equation

Regression equations take the form:

Q1% = 10(11.1 - 7.92 x DRNAREA^-0.031 -0.002 x DESMOIN

-0.025 x BSHAPE)

where:

DRNAREA is drainage area, in square miles

DESMOIN is percent area of basin within Des

Moines Lobe landform region (percent area)

BSHAPE is a shape factor measure of basin

shape computed as BASLEN2/DRNAREA

Flood Region 3 Regression Equation

Regression equations take the form:

Q1% = 10(6.41 – 3.06 x DRNAREA^-0.097 – 0.009 x KSATSSUR

– 0.035 x BSHAPE)

where:

DRNAREA is drainage area, in square miles

KSATSSUR is the average saturated hydraulic

conductivity of soil (micrometers per second)

BSHAPE is a shape factor measure of basin shape

computed as BASLEN2/DRNAREA

Watershed Delineation from a Point

1. User selects point on stream

2. Point is transferred to a cell in a flow-direction grid derived from a DEM

3. GIS determines boundary from flow-direction grid up to points at which the boundary for the new site intersects boundaries in boundary map layer

4. GIS accumulates all upstream areas and dissolves internal boundaries

National

Hydrography

Dataset (NHD)

Watershed

Boundary

Dataset (WBD)

National

Elevation

Dataset (NED)

StreamStats Integrates NHD Streams, WBD

Boundaries and NED Elevation in ArcHydro

Burning and Walling of DEM

Forces DEM to agree with stream

network and WBD or locally

digitized drainage boundaries

12-digit HUCs Watershed Boundary Dataset

1

2

3

StreamStats Similar Gages tool estimates

flows at ungaged sites based on flows at

at nearby streamgages for drainage-area

ratios between 0.5 and 1.5

Regional exponents table 15

New Statistical Methodologies included in

the Iowa Peak-Flow Estimation Study

Flood-probability analyses include results of new

statewide regional skew analysis (Bayesian

GLS/WLS regression analysis – constant value -0.4)

New flood-probability analysis method used - EMA

(expected moments algorithm) with new MGB

(multiple Grubbs-Beck) test for detecting low-outliers

New optimization test used for selecting best

transformation for drainage area for the regression

analyses - either a log 10 or a power transformation

QUESTIONS

Iowa Regional Skew Study

Bayesian WLS/GLS Regression

1982 (MSE = 0.302) 2010 (MSE = 0.160)ERL = 17 yrs ERL = 50 yrs

Constant

Regional

Skew Value

for Iowa =

-0.400

240 gages

Effects of including or censoring low

outliers

Figure 5

West Branch Floyd River near Struble

Flood Region 3 transformations of

drainage area for Q1%

Figure 8

Log-10

transformation

of DA

Power

transformation

of DA

DA-0.097

Relative % change between EMA/MGB &

B17B/GB using new skew for Q1%

283 Iowa streamgages – Q1%

Figure 11

RPchange = 100(Qnew-Qold/Qold)Mean 11.8 %

Median 2.0 %

Figure 12

283 Iowa streamgages

Relative % change between EMA/MGB new

skew & B17B/GB old skew for Q1%

Mean 5.0 %

Median -2.1 %

Relative % change between Q1% using

RREs from 2013 and 2001 reports

Figure 13

185 Iowa streamgages

Mean 7.9

Median 6.4

Iowa StreamStats Introductory Page

Lists statistics

estimated

Gives report

referenceLink to Iowa StreamStats

application

Other issues,

cooperative

statement

StreamStats Home Page

http://streamstats.usgs.gov

National Station Statistics Site

Base Layers

Street MapWorld TopoUSA TopoImagery

Streamgage Reports

StreamStats Home Page

http://streamstats.usgs.gov

State Applications

Iowa User Interface

Toolbar

Console

Panel

Banners

Working With Panels

Click on plus (+) sign to

expand list

Display Streamgages

Check box beside layer

name (Stream Gages)

Navigation Panel

Click on points of

compass to move map

center

Overview Map

User Interface at Iowa StreamStats

Startup 1:4,500,000

Zoom-in to Ames area to 1:80,000

Zoom-in to Ames area to 1:10,000

Example Point Selection (1:2,000)

Select Ungaged Site

Scale must indicate

1:24,000 or greater

Click on Watershed

Delineation from a

Point

Watershed Delineation from a Point

1. User selects point on stream

2. Point is transferred to a cell in a flow-direction grid derived from a DEM

3. GIS determines boundary from flow-direction grid up to points at which the boundary for the new site intersects boundaries in boundary map layer

4. GIS accumulates all upstream areas and dissolves internal boundaries

National

Hydrography

Dataset (NHD)

Watershed

Boundary

Dataset (WBD)

National

Elevation

Dataset (NED)

StreamStats Integrates NHD Streams, WBD

Boundaries and NED Elevation in ArcHydro

Burning and Walling of DEM

Forces DEM to agree with stream

network and WBD or locally

digitized drainage boundaries

Example Basin Delineation

Flow Statistics from Regression Equations

Click on Estimate Flows

Using Regression Equations

• Regression equation

estimates assume natural

flow conditions at the

selected site

StreamStats Ungaged Site Report

Multi-Region Basin Calculation

Multi-Region Basin Calculation

Multi-Region Basin Calculation

Multi-Region Basin Calculation

Multi-Region Basin Calculation

Edit a Delineated Basin Tool