copyright © 2005 esri. all rights reserved. h&h using arcgis introduction to nss

Copyright © 2005 ESRI. All rights reserved. H&H Using ArcGIS

Introduction to NSS

2-2H&H Using ArcGISCopyright © 2005 ESRI. All rights reserved.

Stream Statistics Background


Regression Equations

Used to estimate streamflow statistics for ungaged sites (in uncontrolled flow environment)

Relate streamflow statistics to measured basin characteristics

Developed by all 48 USGS Districts on a State-by-State basis through the cooperative program (usually sponsored by DOT)

Often not used because of large efforts needed to determine basin characteristics

Users often measure basin characteristics inaccurately


Need for Streamflow Statistics

Water resources planning, management, and permitting by Federal, State, local agencies

Instream flow determinations for controlling pollution and protecting habitat

Designing and permitting facilities such as wastewater-treatment plants, hydropower plants, and water-supply reservoirs

Designing structures such as roads, bridges, culverts, dams, locks, and levees


Example Regression Equation

Regression equations take the form:

Q100 = 0.471A0.715E0.827SH0.472

where:

A is drainage area, in square

miles

E is mean basin elevation, in feet

SH is a shape factor, dimensionless


Basin Characteristics Used for Peak Flows

Basin characteristic# of States using

this (including PR)Drainage area or contributing drainage area (square miles) 51

Main-channel slope (feet per mile) 27

Mean annual precipitation (inches) 19

Surface water storage (Lakes, ponds, swamps) 16

Rainfall amount for a given duration (inches) 14

Elevation of watershed 13

Forest cover (percent) 8

Channel length (miles) 6

Minimum mean January temperature (degrees F) 4

Basin shape ((length)2 per drainage area) 4

Soils characteristics 3

Mean basin slope (feet per foot or feet per mile) 2

Mean annual snowfall (inches) 2

Area of stratified drift (percent) 1

Runoff coefficient 1

Drainage frequency (number of first order streams per sq. mi.) 1

Mean annual runoff (inches) 1

Normal daily May-March temp (degrees F) 1

Impervious Cover (percent) 1

Annual PET (inches) 1 … and many others


Problems in Providing Statistics

Published streamflow statistics for data-collection stations are scattered among hundreds of reports nationally

Many publications are out of date and/or out of print

Labor cost for information requests is high

Streamflow statistics are not available everywhere they are needed


Manually Determining Basin Characteristics

A 10-square mile basin takes an hour to a few days, depending on characteristics measured and source material

The required time increases exponentially with increasing watershed area because of the increasing dendritic patterns and logistical problems when matching between map sheets

The manual process is not completely repeatable

The error introduced by determining basin characteristics probably is as large as the uncertainty in the regression models


Teamwork !

USGS:

Data development, server hosting, parameter extraction

methodology, equations, UI design

Aquaterra:

NSS – regression calculator

ESRI:

GIS WEB and desktop implementation, integration,

application and system design


StreamStatsDB/NSS

StreamStatsDB – database (MS Access) with all the data that were used for derivation of regression equations, and their coefficients (cca. 5,200 gaging stations) Heavily normalized

All regression equation coefficients

Separate application for database editing

NSS - VB application for computing regression for known input parameters (regression calculator) – peak/low flows, rural/urban (if available) Uses data from StreamStatsDB so the application does not have

to change when the underlying data and equations change


StreamStatsDB

… and many others


NSS


Role of GIS


Role of GIS

Speedup the process (instead of hours – minutes)

Provide a common (single) access to the methodology (for users and maintenance)

Systematize methodology and datasets used in the process (repeatability)

Provide better tools for deriving characteristics for regression equation determination

Map-based user interface

WEB and desktop implementation based on Arc Hydro


WEB vs. Desktop Implementation

Tradeoffs in each implementation WEB

Centralized location for data and software

End users do not need local software or data

Easy maintenance of the application and data but changes have global scope

Complex hardware and software requirements

Difficult customization

Desktop

Easy local updates to the data (latest and greatest for local area)

Easy modification (full ArcGIS capabilities)

Simpler hardware and software requirements

Can be local (i.e. only local data)

Integrated with other applications


Steps in Implementation

Preprocess data (one time operation) Make sure all parameters can be computed and add functionality

if needed

Select point of interest

Delineate watershed

Display results and confirm validity of the area

Compute required characteristics Determine which characteristics are needed from

StreamStatsDB

Call NSS (in the background) Pass parameters from GIS and save results

Display results


Arc Hydro Tools Role

StreamStats fully implemented within Arc Hydro environment Terrain preprocessing

Local and global watershed delineation

Extracting local characteristics

Assembly of global characteristics

Characteristics developed for StreamStats are available to wider audience (e.g. hydrologic modeling support)

Desktop implementation


Arc Hydro Corollary

Define GIS processes for characteristics extraction

Define nomenclature Characteristics description

Database design (fields names and definitions)

Consistency in development approach


Web Implementation


Main Site (ID)


Main Site - navigationNeed to zoom in before

watershed delineation tool becomes active:

see the stream to snap on


Watershed Delineation - WEB


Results - WEB

Watershed delineation 20-30 seconds, not much

difference with respect to size of the watershed

Parameter computations 10s – 1 minute, depends

on the region (what parameters to get) and somewhat on the size

Careful with concurrent user demand wait and wait and …


WEB Implementation Issues (1)

Size (20 GB and counting - one state)

Speed (WEB) Watershed delineation (30 seconds)

Parameter extraction (40 seconds)

Projection issues (display in one projection, analysis in another)

WEB implementation ahead of time

Preprocessing requirements

User desire for interactive operations Edit resulting watershed before getting characteristics


Inconsistency of parameter extraction techniques between GIS and gage properties (including data sources)

Hefty hardware and software requirements

Multi-state implementation

Implementation support

Implementation on both desktop and WEB

Systematization of data and procedures

Managing scale issues (global delineation)

Cool factor

WEB Implementation Issues (2)


StreamStats Implementation Activities (7/2005)

Source: http://water.usgs.gov/osw/streamstats/ssonline.html

Red – operational; blue – work in progress


Interested in StreamStats for your state?

Contact the USGS Water Resources District Chief for your state:http://water.usgs.gov/district_chief.html

Also, contact the StreamStats Team: [email protected]

For more information, seehttp://streamstats.usgs.gov/

For downloads, see http://water.usgs.gov/software/nff.html

Source: Al Rea, USGS


Desktop Implementation


Watershed Delineation - Desktop

Watershed delineation Use any Arc Hydro

technique


Results - Desktop

Parameter computations Use “NSS Get Parameters”

function from the NSS ArcMap menu (custom toolbar)

Regression computations Batch process - use “NSS

Batch” function from the NSS ArcMap menu (runs NSS)

Interactive - use “NSS Interactive” function from the NSS ArcMap menu (starts Excel)


Interactive Calculator - Desktop

Excel implementation – full flexibility


Desktop Implementation Issues

Size (can be limited to smaller extents – e.g. Wisconsin has 13 regions)

Speed – faster than WEB implementation due to less overhead and more control over preprocessing

Projection issues (display and analysis in the same projection)

Proven technology

Interactive operations More control over the computations (can “play games” –

sensitivity analysis) – can easily implement their own equations on different data

Easy to add more functionality

copyright © 2005 esri. all rights reserved. h&h using arcgis introduction to nss

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