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--- wiki:site-protecting_forest [2018/07/12 09:41] – eurac
+++ wiki:site-protecting_forest [2018/07/13 15:14] (current) – eurac
@@ Line 3: / Line 3: @@
 ==== General description: ====
- The following model is an approach to delineate areas where the biotic ecosystems (forests) contribute to the mitigation of natural hazards and the protection of human assets from hazardous natural processes. At the Alpine-wide scale, this has been done by combining separate regional models for avalanches, rock-falls and water channel relevant processes. The models use topographical information derived from the 25m EU DEM and statistically derived threshold values identified by earlier projects and assessments (performed in all Alpine countries) to model potential avalanche and rock-fall release and transition zones. ** Figure ** ** 1 ** describes in detail the calculation procedure to derive the developed indicators per local administrative units (LAU2) of the Alpine Space.
+The following model is an approach to delineate areas where the biotic ecosystems (forests) contribute to the mitigation of natural hazards and the protection of human assets from hazardous natural processes. At the Alpine-wide scale, this has been done by combining separate regional models for avalanches, rock-falls and water channel relevant processes. The models use topographical information derived from the 25m EU DEM and statistically derived threshold values identified by earlier projects and assessments (performed in all Alpine countries) to model potential avalanche and rock-fall release and transition zones. **The flowchart below** describes in detail the calculation procedure to derive the developed indicators per local administrative units (LAU2) of the Alpine Space.
 ==== Input data ====
-  * <font 14px/inherit;;windowtext;;inherit>DEM (slope, slope-length, flow direction, watershed, plan curvature, contour lines)</font>* <font inherit/inherit;;windowtext;;inherit>Land Cover</font>* <font inherit/inherit;;windowtext;;inherit>River Network</font>* <font inherit/inherit;;windowtext;;inherit>Land Cover</font>
+  * DEM (slope, slope-length, flow direction, watershed, plan curvature, contour lines) * Land Cover * River Network * Land Cover * River Network
-  * <font 14px/inherit;;windowtext;;inherit>River Network</font>
 ==== Calculation processes ====
@@ Line 26: / Line 24: @@
 <font inherit/inherit;;windowtext;;inherit>In Arc GIS the calculation of the Energy Line Angle can be done with the following steps:</font>
-  * <font inherit/inherit;;windowtext;;inherit>Creating an integer raster with the elevation of the release areas.</font>* <font inherit/inherit;;windowtext;;inherit>Running the tool Euclidean Allocation and Distance with the integer raster as Input (to speed up the calculation, a maximum distance of 2000m should be set).</font>* <font inherit/inherit;;windowtext;;inherit>Using the Raster Calculator, subtract the result from the DEM. The value you get is the elevation difference from every pixel to the release zones Δh.</font>* <font inherit/inherit;;windowtext;;inherit>The Euclidean Distance calculated in step (b) represents Δl.</font>* <font 11.0pt/11;;inherit;;inherit>The energy line angle can than simply be calculated with ELA = atan( Δh/Δl) (</font><font 11.0pt/11;;inherit;;inherit>→</font><font 11.0pt/11;;inherit;;inherit>Arc GIS calculates angles in radians to get a result in degrees you have to multiply it with 57.2958)</font>
+  * <font 14px/inherit;;windowtext;;inherit>Creating an integer raster with the elevation of the release areas.</font>
+  * <font 14px/inherit;;windowtext;;inherit>Running the tool Euclidean Allocation and Distance with the integer raster as Input (to speed up the calculation, a maximum distance of 2000m should be set).</font>
+  * <font 14px/inherit;;windowtext;;inherit>Using the Raster Calculator, subtract the result from the DEM</font><font inherit/inherit;;windowtext;;inherit>. The value you get is the elevation difference from every pixel to the release zones Δh.</font>* <font 14px/inherit;;windowtext;;inherit>The Euclidean Distance calculated in step (b) represents Δl.</font>
+  * <font 14px/inherit;;inherit;;inherit>The energy line angle can than simply be calculated with ELA = atan( Δh/Δl) (→Arc GIS calculates angles in radians to get a result in degrees you have to multiply it with 57.2958)</font>
 **(****5) Limit avalanche Paths with energy line angle:**<font inherit/inherit;;windowtext;;inherit>Knowing the avalanche path, the energy line angle allows a rough estimation of maximal runout distance. The previously measured events occurred at an ELA of 17° - 47° with the mean 28°. Events with ELA 17° are very improbable. We used this threshold for our approach to consider all possible events. (Bauerhansel et al. 2009, PARAmount Project 2012).</font>
@@ Line 33: / Line 34: @@
 **(6) Calculate potential rock-fall start zones:**<font inherit/inherit;;windowtext;;inherit>Similar to the avalanche release areas, this can roughly be done by selecting all areas with bare-rock land-cover and a slope steeper than 43°. In the Alpine-wide approach we had to use CORINE Land Cover as the input dataset where most rock surfaces are not delineated (because of resolution and minimum mapping width). For that reason, we also included all the areas without vegetation. Depending on the DEM resolution, different slope thresholds should be applied (Berger et al 2010).</font>
+|DTM resolution/cell size [m]|Threshold slope gradient [º]|
+|1|55|
+|5|49|
+|10|46|
+|25|43|
 **(7) Create Cost Raster:**A cost raster represents the theoretical costs a falling rock would have to overcome from one area to the next (pixel to pixel). These costs depend on the slope length and the land-cover/surface roughness. The highest costs are found in flat, forested areas and low costs exist in steep areas without forest-cover. A single raster can be created by combining two reclassified slope rasters (one for forest areas and one for all other surfaces). The reclassification should occur with the following values:
+^Slope^Costs no forest^Costs in forest|
+|<5º|10|30|
+|>5-10°|9|27|
+|>10-15°|8|24|
+|>15-20°|7|21|
+|>20-25°|6|18|
+|>25-30°|5|15|
+|>30-35°|4|12|
+|>35-40°|3|9|
+|>40-45°|2|6|
+|>45°|1|3|
 **(8) Calculate energy line angle for every start zone:**Energy line angle is calculated using the same methodology as in step 4.
@@ Line 59: / Line 78: @@
 **(15) Backlink intersections of hazard potential and damage potential to release areas:**In the case of avalanches all the transition zones that intersect with infrastructure have to be traced back to the corresponding release area. Using Raster in ArcGIS, this can be done by inverting the DEM and performing a new cost path analysis starting from the intersected damage potential areas. Finally, by combining the avalanche release and transition zones as well as rockfall transition zones that possibly harm infrastructure we are able to identify Object-protecting forest.
+<font 26px/inherit;;inherit;;inherit>**Protection Forest**</font>
+{{:en:protection_forest_flowchart_f1.jpg?nolink&1643x2001}}
+{{:en:biomassproductionfromgrassland_page_12_1_.jpg?nolink&500x300}}
+<font 18px/inherit;;inherit;;inherit>**Flowchart depicting the procedures used to derive the supply, flow and demand indicators**</font>
+\\