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 Jorge Ramirez (Jorge) posted on Friday, September 28, 2007 - 12:22 pm
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Just to mention a few minor updates that will be available in the next release:
-A "begin" time will be available for google earth animations.
-Georeferencing problem for google earth options has been corrected, but GE functionality continues to only work for UK
The following options are available in the current version, but haven't been mentioned, they are useful when splitting a catchment and adding contaminant exiting an upper catchment into a lower catchment:
-The generate tracer output option hourly collects the amount of contaminant exiting the catchment or reach. This option only records contaminant in the smallest 2 grainsizes.
-The contaminant tab allows you to add contaminant at a single location, the input file should be in the format of a tracer output file, previously mentioned.
If you encounter any problems with these changes, please contact me, j.ramirez@hull.ac.uk |
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Made many small changes - really will release in version 6 - but have found an issue with the recirculation button - have to now restrict sediment being input to prevent too large amounts landing and leading to buildups of sediment on input pixels.
Tom |
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Some really lazy notes - really to myself about some recent updates....
Some model development notes, whilst away in Canada
Been trying to sort out the flow routing and lateral erosion system.
Previous methods of erosion and dep erode full amount then divide up amongst cells according to either bedlslope, discharge slope or edge slope.
First versions of CAESAR used bedslope to calc tau to calc erosion in all eight directions if possible.
Tried with erode_w2 calculating tau in all eight directions using discharge – works OK. But hard to integrate lateral, Also found error that allowed negative discharge values to be calculated in calc_flow direction, which allowed really high Tau values to be calculated (c.10000 ) which gave some crazy values and may have led to some of the more erroneous erosion hotspots. Fixed that
Now, instead of eroding totoal amount then dividing and moving according to tau gradient and edg etc.. now its all routed according to discharge gradient, then can add an amount/volume thats moved laterally. So basically disaggregate lateral and downstream components – and then can calc tau for both.,..
But found that in order to deposit on inside needed to have higher lateral tau than downstream tau.
Experimented with having bedload routed only due to steepest direction of Tau. Found worked kind of, but led to very narrow and 90deg bend style channels. However, reasonable assumption to make more of flow go in steepest direction. So added exponent to calc_max_flow_direction – which has a less extreme effect.
Also stopped tau being able to be calculated in all 8 directions – which resulted in too great tau being calculated for an individual cell. Now in calc_max_flow_dir there are lines so only use positive of balances between left and right discharges. Also experimented with slightly different ways of calculating discharge in route functions. Really found that there was not a better way.
If calculated lateral tau according to the edge[x,y] gradient, then total tau for a cell is/was much greater than the downstream component – but if I only used lateral tau in the steepest direction (of edge gradient) then this meant I could start to get lateral movement of sediment without having massively over calculate the lateral Tau.
So presently running with discharge tau – calculated in all 8 directions. Then lateral tau is calculated on one direction only according to:
50/radius of curvature * ci * 1000 * vel^2 (here velocity is that calculated from the main discharge (max_flow[x,y,0]) |
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OK,
found that I was getting 'lumps' of sediment created on the inside of bends. Tracked down to the smooth discharge function. Removed it, seems to cure things and model works fine without it |
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