make carving optional

grass/hydrology.html

@@ -108,6 +108,7 @@ <h3>Create map of DEM depressions</h3>
 
 
 <h3>Derive contributing area for a given outlet</h3>
+
 Set region to the high resolution study area and zoom to it,
 compute flow accumulation, flow direction and basins with 15000 cells threshold:
 
@@ -122,15 +123,16 @@ <h3>Derive contributing area for a given outlet</h3>
 <pre><code>
 d.erase
 d.rast ortho_2001_t792_1m
-d.rast accum_5K values=1000-1000000
+d.rast accum_15K values=1000-1000000
 </code></pre>
 
 <p>
 Delineate contributing area (watershed) associated with an outlet located 
-on the extracted stream and convert it to vector format:
+on the extracted stream and convert it to vector format.
+Import coordinates of the outlet to include it in the map in the next step.
 
 <pre><code>
-r.water.outlet input=draindir_5K output=basin_A30 coordinates=638845.52,220085.26
+r.water.outlet input=draindir_15K output=basin_A30 coordinates=638845.52,220085.26
 r.to.vect -s basin_A30 output=basin_A30 type=area
 v.in.ascii input=outlet_point.txt output=outletA30 separator=space
 </code></pre>
@@ -152,39 +154,10 @@ <h3>Derive contributing area for a given outlet</h3>
 <span class="question">What is the delineated watershed area [ha] ?  </span><br>
 Optional: How would you compute average slope of this contributing area?
 
-<h3>Assess and mitigate impact of the road on flowrouting</h3>
-Compare the extracted streams (accum > 1500) with official stream data:
-
-<pre><code>
-d.rast ortho_2001_t792_1m
-d.rast accum_5K values=1500-1000000
-d.vect streets_wake color=red
-d.vect streams color=green
-d.out.file streamcompare
-</code></pre>
-
-<p>Carve a pre-defined channel given by the stream data into DEM</p>
-
-<pre><code>
-r.carve raster=elev_lid792_1m vector=streams width=2 depth=0.8 output=elev_lidcarved_1m
-r.colors elev_lidcarved_1m raster=elev_lid792_1m
-d.rast elev_lidcarved_1m
-</code></pre>
-
-<p>Extract streams from the carved DEM and compare with the official streams map.<br>
-<span class="question">What is the difference between accum_5K, accumc_5K1m and streams?<br>
-Explain the advantage and disadvantage of carving.</span>
-
-<pre><code>
-r.watershed -as elevation=elev_lidcarved_1m accumulation=accumc_5K1m
-d.rast accumc_5K1m values=1500-10000000
-d.vect streams
-d.out.file streamcarved
-</code></pre>
-
 <h3>Compute refined flow pattern using D-inf</h3>
 Compare upslope and downslope flow lines:
-<span class="question">On what type of landform (ridge, valley) they converge?</span>
+<span class="question">On what type of landform (ridge, valley) do the upslope
+and dowslope flowlines converge?</span>
 
 <pre><code>
 g.region raster=elev_lid792_1m -p
@@ -193,7 +166,7 @@ <h3>Compute refined flow pattern using D-inf</h3>
 </code></pre>
 
 <p>
-Display maps along with contours to see relation to terrain:
+Display maps along with contours to see the relation of flow pattern to terrain:
 
 <pre><code>
 d.erase
@@ -207,20 +180,25 @@ <h3>Compute refined flow pattern using D-inf</h3>
 d.out.file flowlines
 </code></pre>
 
-<h3>Compare the multiple flow direction result with D8 and Dinf</h3>
-<span class="question">Compare the results of r.watershed:  accum_5K and accum_mfd_5K1m. Why are they different,
-which is more accurate and why?</span>
+<h3>Compare the multiple flow direction flow accumulation with the D8 and Dinf</h3>
+
+Compute flowaccumulation using the default MFD method and display the 
+flowaccumulation maps from MFD and SFD (the Dinf maps flowacc_1m was displayed above):
+
 <pre><code>
-r.watershed -a elevation=elev_lid792_1m threshold=5000 accumulation=accum_mfd_5K1m
-d.rast accum_mfd_5K1m
+r.watershed -a elevation=elev_lid792_1m threshold=15000 accumulation=accum_mfd_15K
+d.rast accum_mfd_15K
 d.vect streams
 d.out.file stream_mfd
 d.erase
-d.rast accum_5K
+d.rast accum_15K
 d.vect streams
 d.out.file stream_sfd
 </code></pre>
 
+<span class="question">Compare the MFD and SFD results of r.watershed. 
+Why are they different, which is more accurate and why?</span>
+
 <h3>Compute wetness index</h3>
 
 <pre><code>
@@ -231,8 +209,8 @@ <h3>Compute wetness index</h3>
 d.out.file wetness
 </code></pre>
 
-Compute the wettness index using the formula in the lecture (hint: you will need
-to compute slope using elev_lid792_1m and use accum_mfd_5K1m as contributing area.
+Optional: Compute the wettness index using the formula in the lecture (hint: you will need
+to compute slope using elev_lid792_1m and use accum_mfd_15K as contributing area.
 Check the values by comparing your output with wetness_1m computed with r.topidx.
 
 <p>Display elev_lid792_1m in 3D and drape over wetness_1m as color.<br>
@@ -253,6 +231,40 @@ <h3>Create a map of flooded area</h3>
 area maps at these two levels. Include the maps of flooded areas 
 at these water levels in your report.
 
+<h3>Optional: Assess and mitigate impact of the road on flowrouting.  </h3>
+
+<p>
+Compare the extracted streams (accum > 1500) with official stream data:
+
+<pre><code>
+g.region rast=elev_lid792_1m -p
+d.rast ortho_2001_t792_1m
+d.rast accum_5K values=1500-1000000
+d.vect streets_wake color=red
+d.vect streams color=green
+d.out.file streamcompare
+</code></pre>
+
+<p>Carve a pre-defined channel given by the stream data into DEM</p>
+
+<pre><code>
+r.carve raster=elev_lid792_1m vector=streams width=2 depth=0.8 output=elev_lidcarved_1m
+r.colors elev_lidcarved_1m raster=elev_lid792_1m
+d.rast elev_lidcarved_1m
+</code></pre>
+
+<p>Extract streams from the carved DEM and compare with the official streams map.<br>
+<span class="question">What is the difference between accum_5K, accumc_5K1m and streams?<br>
+Explain the advantage and disadvantage of carving.</span>
+
+<pre><code>
+r.watershed -as elevation=elev_lidcarved_1m accumulation=accumc_5K1m
+d.rast accumc_5K1m values=1500-10000000
+d.vect streams
+d.out.file streamcarved
+</code></pre>
+
+
 <!--
 r.lake elevation=elev_lid792_1m wl=113.7 lake=flood2 coordinates=638728,220278
 r.lake elevation=elev_lid792_1m wl=114.0 lake=flood3 coordinates=638728,220278