analysis of hydrological erosion risk
DESCRIPTION
MSc thesis in GIS "ANALYSIS OF HYDROLOGICAL EROSION RISK FOR THE ST. MARY BASIN, MONTANA, USA"TRANSCRIPT
ANALYSIS OF HYDROLOGICAL EROSION RISK FOR THE ST. MARY BASIN, MONTANA, USA
Silvia Vittozzi
Master di 2° Livello in “GIS e telerilevamento per la pianificazione Geoambientale”
UNIVERSITA’ DEGLI STUDI DI ROMA “ROMA TRE”
30 Giugno, 2008
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THE PURPOSE OF RESEARCH
IS TO ESTIMATE
THE MOST EXPOSED AREAS TO SOIL EROSION
IN THE UPPER ST. MARY BASIN, MONTANA,
USA
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Source: www.wikipedia.org
WATERTON-GLACIER INTERNATIONAL PEACE PARK
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Hydrology
Upper Old Man River watershed; in the South of the map, the affluent St. Mary river. Source: www.uoguelph.ca
Saskatchewan River watershed. Source:www.wikipedia.org
St. Mary River Km 200Oldman River Km 362South Saskatchewan Km 1,392 kilometers
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THE SOIL
• Is basic for all life’s form.
• Encloses elements:
– biological
– mineral
• Is a natural resource
• it need long time to be created (geological ages!)
• It need to be conserved
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Soil erosion by waterRAINFALL causes rills and sheet erosion
Fonte: Marco Acutis DiProVe, [email protected], www.acutis.it
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SOIL LOSS CAUSED BY WATERDepend on:
• amount and intensity of rainfall and runoff.• land cover which reduce the direct forces of rainfall• susceptibility to erosion (texture, composition,…)• topography of the landscape as described by slope length,
steepness and shape.• Artificial conservation practices (terracing, canalizations)
and land use.
THE GIS IS A POWERFUL TOOL WHICH CAN MANAGE
TOGETHER ALL THESE ELEMENTS
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DEM resolution 10 m
Fonte : USGS
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USLE
= UNIVERSAL SOIL LOSS EQUATION• Long terms (annual)• In a determinate area
• In this case: Upper St. Mary watersheed
• A standard method to map the potential risk and erodibility of soil
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USLE
It was conceived:– In USA – In 1978 – Wischmeier and Smith (USDA)– For the field. Subsequently was applied also at not only agricoltural areas
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USLEA = R * K * LS * C * P
• A = potential mean annual soil loss
• R FACTOR = rainfall factor• K FACTOR = soil erodibility factor• LS FACTOR = topographic factor• C FACTOR = land cover factor• P FACTOR = conservation practices (terracing)
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THE USLE MAP
• It show:– The Potential erosion– The areas where rise RILL EROSION and SHEET
EROSION
• UNITA’ In English Units: tons /hectar/year
• DATUM: NAD83
10/04/2023 17Shape file ottenuto dalla classificazione del data set: Vegetation Map - Waterton-Glacier International Peace Park Vegetation Mapping Project. USGS-NPS 1999 Glacier National Park-
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DATA SOURCES of rainfall data:
United States Mean Annual R-factor, 1971-2000 spatial grid
•Unità di misura : (100’s ft-tons in h-1 ac-1 yr-1) * 10 •DATUM : WGS72 •PRISM Group (Parameter-elevation Regressions on Independent Slopes Model) climate mapping
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DATA SOURCES soil
USDA State Soil Geographic (STATSGO) Data Base for Montana
•Coverage•NAD1927
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DATA SOURCES Land useUSGS-NPS 1999 Glacier National Park Vegetation Map - Waterton-Glacier International Peace Park Vegetation
Mapping Project. Shape file, NAD 83 .
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