I've made a few changes to the Child code, most notably:
I am also working on a way (in 'tStreamNet::RouteFlowArea') to support multiple downstream flows (i.e. flow branching), rather than just along a single edge. I don't know if this will be required for this project, but it sounded like a neat thing to try, and gives me experience mucking with the code. See the end of this page for a preview.
I've run some simple simulations on the grids created last time, as well as a few others:
1. Constant climate on smooth inclined dihedral.
The input file is here. No rainfall or other processes. The run was performed for 1000 years at 1 yr/step, output every 100 yrs. Here are plots of segments 0 and 10 (z is exaggerated by 25x, open boundaries in yellow):
This looks boring and is as expected: nothing happening. To see that there was actually no change (from nothing happening), I wrote a small program to compare the segments in an output file:
5: ~/Projects/Lancaster/Child/Child_CU_STL_2006/Mesh_tests > Tools/CompareSegs.py Mesh009_const/Mesh009.nodes
Segment 0 Segment 10
---------- ----------
0: 0 1000
6: ~/Projects/Lancaster/Child/Child_CU_STL_2006/Mesh_tests > Tools/CompareSegs.py Mesh009_const/Mesh009.z
Segment 0 Segment 10
---------- ----------
0: 0 1000
7: ~/Projects/Lancaster/Child/Child_CU_STL_2006/Mesh_tests > Tools/CompareSegs.py Mesh009_const/Mesh009.q
Segment 0 Segment 10
---------- ----------
0: 0 1000
8: ~/Projects/Lancaster/Child/Child_CU_STL_2006/Mesh_tests > head Mesh009_const/Mesh009.q
0
740
0
0
0
0
0
0
0
0
2. Constant rainfall on smooth inclined dihedral.
The input file is here. Here are plots of segments 0 and 10 (all flows ≥ 1.0e-6 are plotted in blue):
Here are plots for flow thresholds at 1.0e5 and 1.0e6:
Again, this looks as expected. Comparing segments in the output files:
14: ~/Projects/Lancaster/Child/Child_CU_STL_2006/Mesh_tests > Tools/CompareSegs.py Mesh009_rain/Mesh009.nodes
Segment 0 Segment 10
---------- ----------
0: 0 1000
15: ~/Projects/Lancaster/Child/Child_CU_STL_2006/Mesh_tests > Tools/CompareSegs.py Mesh009_rain/Mesh009.z
Segment 0 Segment 10
---------- ----------
0: 0 1000
2: 4.70333209968 4.69767995736
3: 5.10333209968 5.09806152316
4: 5.50333209968 5.49806152757
5: 5.90333209968 5.89806152757
6: 6.30333209968 6.29806152757
7: 6.70333209968 6.69806152757
8: 7.10333209968 7.09806152757
9: 7.50333209968 7.49806152757
10: 7.90333209968 7.89806152757
11: 8.30333209968 8.29806152757
12: 8.70333209968 8.69806152757
13: 9.10333209968 9.09806152757
14: 9.50333209968 9.49806152757
15: 9.90333209968 9.89806152757
16: 10.3033320997 10.2980615276
17: 10.7033320997 10.6980615276
18: 11.1033320997 11.0980615276
19: 11.5033320997 11.4980615276
20: 11.9033320997 11.8980615276
21: 12.3033320997 12.2980615276
22: 12.7033320997 12.6980615276
23: 13.1033320997 13.0980615276
24: 13.5033320997 13.4980615276
25: 13.9033320997 13.8980615276
more...
16: ~/Projects/Lancaster/Child/Child_CU_STL_2006/Mesh_tests > Tools/CompareSegs.py Mesh009_rain/Mesh009.q
Segment 0 Segment 10
---------- ----------
0: 0 1000
It appears that there was some slight erosion of the landscape.
3. Inlet but 'no' rainfall on smooth inclined dihedral.
The input file is here. In this case, it should be noted that an inlet does not produce a source of water, but only a specified drainage area which is different than the actual area of its Voronoi polygon. Without rainfall, the inlet will produce no flow. An inlet can be made to discharge water --without appreciable rainfall on the rest of the landscape-- by giving it a very large area and creating a storm with a very small rain rate. In this example, INDRAREA = 1e18 while ST_PMEAN = 1.0e-12, so that the inlet discharges 1000000 m3/yr while the rainfall on the rest of the landscape is very small. The Child code should probably be changed so that the actual discharge of an input can be set independently of any additional rainfall, although the current workaround may be sufficient for this project.
Here are plots of segments 0 and 10 (all flows ≥ 1.0e-6 are plotted in blue, inlet in white):
Although the inlet appears below the surface of the landscape in 3d, it is actually located at an existing (x, y) node:
Although the discharge from the inlet is appreciable, the (spurious) discharge from other nodes is quite small:
4. Inlet on bumpy inclined dihedral.
In this example, the smooth dihedral has been perturbed by the addition of a uniform random ±1m variation in elevation. The result is to create bends in the flow from the inlet as it seeks the steepest descent:
If some additional rainfall is added (here ST_PMEAN = 1.0e-10 and INDRAREA = 1e16), new streams form in the terrain and join up with the main flow:
This can be seen better if you squint a bit or make the plot smaller:
5. Inlet with branching flows on bumpy inclined plane.
While Child currently supports merging flows, a flow can only leave a node through a single edge (although, as noted above, Child has no flows per se, but only drainage areas which are converted to discharge via rainfall). So, I thought it would be worthwhile to try to allow a flow (i.e. a 'drainage area') to be propagated from a node via several edges, in proportion to the magnitudes of their descending slopes. This is currently experimental, and I hope to have it working better in a few days. I don't know that it will be necessary for this project, but it might be nice to have as an option.
Here are several examples of a flow from an inlet coursing over an inclined plane having a small random variation in elevation. All flows ≥ 1.0e-6 are plotted, although the initial inlet volume (1000000 m3/yr) is distributed over the entire flow, which decreases in volume away from the inlet:
