gross and effective drainage area delineation in the prairie provinces
DESCRIPTION
A. g. r. i. c. u. l. t. u. r. e. a. n. d. A. g. r. i. c. u. l. t. u. r. e. e. t. A. g. r. i. -. F. o. o. d. C. a. n. a. d. a. A. g. r. o. a. l. i. m. e. n. t. a. i. r. e. C. a. n. a. d. a. - PowerPoint PPT PresentationTRANSCRIPT
Gross and Effective Drainage Area Delineation in the Prairie Provinces
Presentation at PPWB Prairie Hydrology Workshop
January 29, 2013
AgricultureandAgri-FoodCanada
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Overview
Concepts Why is this of concern to the PPWB? Background Manual Process Migration to GIS Environment Recent Changes What Does the Future Hold?
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Concepts
Stichling and Blackwell (1957) presented a paper proposing the concept of fluctuating drainage area by year, by season, by event
Godwin and Martin (1975) presented a paper refining the concept of gross, effective and dead drainage areas
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Gross Drainage Area
“The gross drainage area of a stream at a specified location is that plane area, enclosed by its drainage divide, which might be expected to entirely contribute runoff to that specified location under extremely wet conditions. The gross drainage boundary is the drainage divide (i.e. the height of land between adjoining watersheds).”
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Effective Drainage Area
“The effective drainage area is that portion of a drainage basin which might be expected to entirely contribute runoff to the main stream during a flood with a return period of two years. This area excludes marsh and slough areas and other natural storage areas which would prevent runoff from reaching the main stream in a year of ‘average runoff’.”
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Dead Drainage Area
“Drainage is considered dead if there is no outflow from an area even under very wet conditions. This situation is common on the Canadian Prairies where major depressions having sloughs and shallow lakes with no outlets are usually associated with dead drainage. A dead drainage basin includes all of the area tributary to such a depression.”
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AgricultureetAgroalimentaireCanada
Why is this of concern to the PPWB?
• Need drainage areas that are acceptable to all member agencies
• For purposes of apportionable flow determination, only projects within the effective drainage area are considered as depletions to the natural flow
Background
1970 - PFRA, as part of an IHD Study, undertook task of delineating drainage areas (543 stations)
Early 1970s - Need for standardization 1975 - at PPWB’s request, PFRA accepted
responsibility for delineating areas on streams; covered by Master Agreement on Apportionment; commitment reaffirmed in June 2003
1978 - Hydrology Memorandum #25 (1191 stations) and 3 subsequent addendums
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1983 - Hydrology Report #104 (1687 stations) with 8 subsequent addendums (Addendum #8 published in 2001 included 2689 stations)
1994 - Decision made to migrate data base and process to a GIS environment
Late 1990s - digitizing lines and developing a GIS process
2001 - Completed migration from manual to GIS environment
2008 - Current GIS version (8) includes entire Prairie Provinces area (3312 stations)
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Manual Process
Time consuming and resource intensive Difficult to update data base Limited product usability
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Index Cardsand Summary Reports
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Migration to GIS Environment
Process
- digitize delineated boundaries
- develop gross & effective polygons
- develop linkage network
- compare manual & GIS tabulations to check/confirm linkages
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Migration to GIS Environment
Benefits
- data base easy to update/maintain
- quick automated revision of areas
- easy access of data base by users
- unlimited application potential
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Recent Changes Association of all dead drainage areas
with a drainage basin Addition of “artificial” stations to give
complete coverage of Prairies
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Ongoing Enhancements
Continue to refine delineations- use 1:20,000 scale coverage where available- check delineations using digital NTS maps
(DEMs) Incorporate local information provided by users
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Current (Version 8, 2008) Product
http://www.agr.gc.ca/nlwis-snite/index_e.cfm?s1=data_donnees&s2=details&s3=lc-ct&page=wb-bv_plus
What Does the Future Hold?
?????? – PFRA no longer exists, and there is no mandate in the current organization to continue drainage area delineation activities
International Harmonization of Watershed Boundaries and Hydrographic Features (IJC)
Development of Watershed Delineation Tool – for specific projects, not for drainage area database maintenance
Features of the Watershed Delineation Toolhttp://www.agr.gc.ca/watersheddelineation
Delineate watershed boundaries anywhere within the Canadian Prairies
Produce maps and hydrology reports containing standard watershed information
Delineated watershed boundary and area
Contributing and non-contributing areas
Longest flow path, stream length and slope, draiange density
Location of WSC gauging stations
Download watershed boundaries to standard geographic formats (KML or shape file)
Easy to use and interactive
QUESTIONS???
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