Merge pull request #1341 from lucalanteri/patch-1

Update convergenceindex.rst

Author: pcav

python/plugins/processing/algs/saga/help/convergenceindex.rst

@@ -3,6 +3,11 @@ CONVERGENCE INDEX
 
 Description
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+It calculates an index of convergence/divergence regarding to overland flow. 
+By its meaning it is similar to plan or horizontal curvature, but gives much smoother results. 
+The calculation uses the aspects of surrounding cells, i.e. it looks to which degree surrounding cells point to the center cell. 
+The result is given as percentages, negative values correspond to convergent, positive to divergent flow conditions. 
+Minus 100 would be like a peak of a cone, plus 100 a pit, and 0 an even slope.
 
 Parameters
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@@ -18,7 +23,8 @@ Outputs
 
 See also
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-
+Koethe, R. / Lehmeier, F. (1996): 'SARA, System zur Automatischen Relief-Analyse', Benutzerhandbuch, 2. Auflage 
+[Geogr. Inst. Univ. Goettingen, unpublished]
 
 Console usage
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