I tried to identify paleochannels using satellite imagery and DEM. I identified the paleochannel and tried to make paleochannel based inundation modeling. What do I need to know to make flood inundation modeling based on paleochannel?
DEM based inundation models can predict flows that are dependent on the time of DEM assessment. If a paleochannel is within a floodplain, often the DEM will not reflect that channel. The best way is to create a broader floodplain model with flows and sediment modeled over a longer period of time. The paleochannel might be picked up by such model at some stage of sediment dynamics.
If such a long-run floodplain model is not of interest, you could modify the DEM to force conditions that allow river to flow through the paleochannel. Such modification need to be based on historical elevation data which might be difficult to get. You need make assumption on relative elevation profile when the paleochannel was active.
Thank you Prof. Timothy O Randhir , how can I create a broader floodplain model with flows and sediment modeled over a longer period of time? What data do I need to create it?
You may check following links for flood modeling, maybe thats what you are looking for:
Hydro-Tools: http://resources.arcgis.com/de/communities/hydro/01vn0000000s000000.htm HEC-RAS http://www.hec.usace.army.mil/software/hec-ras/
Thank you Dr Tobias Ullmann , I know using HEC-RAS can make an inundation modeling but I need a DTM or elevation data. In my case, I need to create an inundation modeling from paleochannels, it means that I need an elevation data that match with the conditions at the time paleochannels are active. So, is that true ?
Yes, HEC-RAS or HEC-HMS models depend on the DEM to predict flows. But for Paleochannels, you need to create a DEM that represents roughly the elevation profile in historic times. You should have the paleochannels as lowest points in a cross sectional profile (Thalweg) to allow flows to match historic conditions. In addition, you might need to recreate elevation changes within the floodplain. This will be tricky as you have to rely on any historic maps form that time.
Prof Timothy O Randhir actually is too difficult to find any historical maps. I think if create a relative elevation model like in the link below, it can be helpful to identify the paleochannels. But, it needs a high-accuracy DTM and the research area is a settlement area. Please, see my proposed research area above.
https://ngmdb.usgs.gov/Info/dmt/docs/DMT16_Coe.pdf
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