geomatics tools for mapping headwater streams · 2017-10-25 · local slope soil conductivity ......

Geomatics Tools for Geomatics Tools for Mapping Headwater Mapping Headwater

StreamsStreamsAdam HoggAdam Hogg

Inventory Monitoring & Assessment, Ministry of Natural Inventory Monitoring & Assessment, Ministry of Natural ResourcesResources

Headwaters WorkshopHeadwaters WorkshopMay 20, 2009May 20, 2009

Outline

The Challenge

What is a headwater stream?

Mapping history

Map scale

Suggested Methods & Data

Know your data

Data available in Southern Ontario

Two ways to map headwater streams

Accuracy assessment

Case Example – North Carolina

Outline

Current related efforts in Ontario

Ongoing projects involving geomatics

Example of how geomatics can help

Summary

The ChallengeThe Challenge

What is a Headwater Stream?

The furthest point from the watershed outlet from which flowing water is:

measurable year round……… OR

measurable at sometime in the year

First and second-order streams

streams that have no upstream tributaries or only first-order tributaries (Gomi et al. 2002, Meyer and Wallace 2001)

Wetlands?

Represent the transition zone

Where water is channelized

Constructed drainage?

Mapping History

Over the last few decades many agencies and researchers have attempted

Medium scale topographic mapping (~1:10000 – 1:24000)

Sources like OBM, USGS

Past maps:

greatly underestimate # and length

misrepresent flow duration

Unsuitable for identifying streams

Variable scale a problem

Seeing through the coniferous trees

Sources: Morisawa 1957; Hansen 2001; Firman and Jacobs 2002; Heine et al. 2004; Paybins 2002; Colson 2006

1:10 000

Map Scale

A need for large scale (detailed)

Water Resource Information Program (WRIP) & Conservation Ontario large scale hydrology mapping standards

Note: 1:2 000 stream mapping courtesy of Niagara Peninsula CA

111111

1122

2233

1111

11

Stream

1:2 000

Methods & DataMethods & Data

Know Your Data

All spatial data is a model with inherent error

Data search: Province (LIO), CA, engineering firms, your network

Data dictionary, a table including information on:

source, accuracy, scale/resolution, intended use

stream mapping, orthophoto’s, DEM’s.

Data Available in Southern Ontario

Streams & DEM’s

OrthophotosSoilsSurficial Geology

Interpretive

Spring photo’s ideal

Existing stream data

Look for hydrologic indicators

Understand the topography

Stream Prediction Model

DEM upslope contributing area

D-Infinity (Tarboton, 1997)

Topographic Index (Beven & Kirkby, 1978)

flow accumulation

local slope

soil conductivity?

Calibrate model

Interpretively with orthophoto

Other comparative and verified stream data

*In the field

Strengths & Weaknesses

Interpretive & the “human element”:+ Intelligent selection and accurate (time permitted)– A snapshot in time, expensive and time consuming,

random error

Prediction & the “computer element”+ Efficient and more cost effective, can be altered

easily, easy to standardize for large “non- jurisdictional” areas

– Less intelligence and accuracy, difficult to employ intelligent selection

Accuracy Assessment

Purpose of accuracy assessment

Crucial to understanding quality and use

Rules of thumb:

1/3 the total mapping effort

Independently evaluated

Statistically sound (>50 validation samples)

Validation source should be at least 3 times more precise

Report overall accuracy, omission, commission and absolute and/or relative spatial error

Sources:

“Assessing the accuracy of remotely sensed data: principles and practices” (Congalton and Green, 1998)

USGS – NPS Vegetation Mapping Program (USGS Center for Biological Informatics, 1994)

Case Example: North Carolina

Mapping Headwater Streams: Intermittent and Perennial Headwater Stream Model Development and Spatial Application (Russell, 2008)

Use high precision DEM for first and second order stream prediction

Survey grade GPS mapping for calibration and accuracy assessment


Successes:

Spatially accurate, presence absence, length of permanent streams

Challenges:

Commission error, stream length of non-perennial streams, labeling of permanence

Other interesting findings:

Sedimentary areas similar to Southern Ontario 70% of headwater streams were intermittent or ephemeral

Bedrock dominated areas similar to Ontario Shield majority are ephemeral or perennial

Current Related Efforts In Current Related Efforts In Ontario Using GeomaticsOntario Using Geomatics

Existing Projects

Large Scale Mapping Standards

Conservation Ontario and OMNR

Ontario Headwater Restoration Initiative (OHRI)

OMNR led

Identify and map all roadside potential headwater stream and wetland restoration opportunities

Restore a few headwater systems

Oak Ridges Moraine, Lake Simcoe

Wetland loss

Ducks Unlimited Canada led

Estimate wetland loss using current land cover (SOLRIS) and soils

Losses > 10ha

Southern Ontario

CA’s?

Toronto, Niagara ,Grand River, Credit Valley

How Geomatics Could Help

OHRI field data comparison with stream prediction

Standardized mapping

Screening tool

Summary

It is possible to map headwater streams

Mapping and characterization will be challenging and potentially expensive depending project objectives

Know all data available and use a multi-layered approach

Rigorous accuracy assessment is crucial

A few related projects

Questions?

Source: GOES Project, NASA - http://goes.gsfc.nasa.gov

MitigationMitigation

ProtectionProtection

RestorationRestoration

Note: source SOLRIS wetlands

A Possible Decision Support Tool

Note: Source topographic index





Note: source SOLRIS frequently tilled agriculture





Note: Source untilled SOLRIS agriculture





Cyan Ellipse: Development MitigationCyan Ellipse: Development Mitigation

Prevent developmentPrevent development

Magenta Ellipse: ProtectionMagenta Ellipse: Protection Blue Ellipse: RestorationBlue Ellipse: Restoration



Results:

Overall accuracy 83%

Commission 17%

Omission 3%

Length

Over predicted stream length by 24%

Most error in intermittent and ephemeral

Permanency

Low accuracy ~30%

Spatial

70% were within 2.5 meters of actual centerline

geomatics tools for mapping headwater streams · 2017-10-25 · local slope soil conductivity ......

Documents