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GEOMORPHOLOGY COMPONENT RESULTS |
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What story do the geomorphology results tell?The combined geomorphology scores reveal a pattern of lower scores along the eastern and western borders of Minnesota with the steep slopes of eastern Minnesota, and the dry climate pattern of western and northwestern Minnesota being the primary drivers. Why is the mean score important?The mean score is the average of the three geomorphology index scores for each watershed. Comparing mean results across Minnesota reveals statewide health trends. The mean can also be used to compare results in similar watersheds, such as upstream or downstream within the same basin or across an ecoregion. Why is the minimum score important?The minimum is the lowest of the three geomophology index scores calculated for each watershed. This may indicate an area of vulnerability to consider before taking action, or a resource concern to consider when protecting watershed health. |
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| CREATING RESULTS | SCORES AND PATTERNS | THE HEALTH STORY | NEXT STEPS |
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What geomorphology information was
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What story do the geomorphology results tell across Minnesota?
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Soil Erosion Susceptibility Data Layers: Ssurgo Soils Database; K-Factor (NRCS, 2009) Statsgo Soils Database Digital Elevation Model (National 10 Meter DEM)
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Groundwater Contamination Susceptibility Data Layers: Groundwater Contamination Susceptibility model (Portschel, et al, MPCA, MN DNR 1989)
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Climate Vulnerability Data Layers: Precipitation - Evapotranspiration 30 Year Trend (MN Climatology, 1961-1990)
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The three geomorphology index values were combined into one mean (average) geomorphology score for each watershed. This mean value masks some of the variation found in each individual index, but serves to illustrate an overall gradient in results by basin and region.
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Of the three geomorphology index values, the index with the lowest value was identified and mapped across the state. The map on the left shows the lowest geomorphology index value in each watershed. The map on the right identifies which index scored the lowest in each watershed.
Both the mean and minimum geomorphology index results show a pattern of lower scores in eastern and western Minnesota, with higher scores on a north-south line through central Minnesota. The three indices represent a different kind of vulnerability to change in natural resource systems.
The Soil Erodibility index uses a scale based on soil type and slope; therefore, shows the soils that are most naturally vulnerable to erosion are in the northeast and the southeast. This index does not measure factors that can displace soils such as wind, water or land use practices.
The Groundwater Contamination Susceptibility index scores show that groundwater is very susceptible to contamination in the southeast, with fairly high vulnerability existing throughout much of Minnesota. Only the northern tier of watersheds showed consistently lower vulnerability.
The Climate Vulnerability index has a pattern of scores based on the precipitation-evaporation 30 year climate trends in Minnesota. Lower scores are found in western Minnesota where there is a trend toward moisture deficit. Lower scores are also found in northeastern Minnesota where there is a trend toward moisture excess. The highest scores are in central Minnesota where there is a closer balance between precipitation and evaporation.
The Geomorphology indices are context indices. They measure existing, inherent vulnerability to degradation based on the geology and geographic location of a watershed.
The Geomorphology mean and minimum scores follow the same pattern of low scores (high vulnerability) along the western and eastern borders of Minnesota. This result is largely driven by the Climate Vulnerability Index which scores the range of moisture balance conditions across the state on a scale of 0-100. It is likely that the influence of this index is over-stated given the large range of values, and the lack of information available on the relative importance of this index.
The Groundwater Contamination Susceptibility results follow the pattern of vulnerable soil types and geologic formations on a general line from southeast to north central Minnesota. The lowest scores fall in the karst region of the southeast blufflands. A more detailed pattern of groundwater vulnerability can be viewed on the index page; which shows that northwestern watersheds have a narrow band of very vulnerable geologic area that is not well represented by the major watershed scale results.
The geomorphology story is incomplete. The current three indices reveal areas of vulnerability across the existing landscape, so should be used as a health context to be considered before taking action. To refine this component, a condition index could be added. The index being considered would measure stream and valley type, which would assess stream stability by evaluating stream shape in relation to valley type.
In addition, the existing index values could be refined in several ways:
