From 2D/1D simulations for Wadi and surface water modeling (including road embankments, culverts...etc), how does the two compare in terms of capabilities and features? We do have HEC-RAS but not the other (yet)?
From a 1D/2D water cycle perspective, I can synthetize how the processes are modeled:
You can use OpenFlows FLOOD as a single tool to implement an integrated modeling solution capable of imposing spatially and temporally varying rainfall (using direct rain-on-grid). We can impose the rainfall from a constant value, from one or more timeseries (hydrographs) or from a meteorological model. Once the rainfall hits the surface, rainfall water is converted in 2D overland flow (based in topography), and FLOOD can estimate losses by infiltration and evapotranspiration (both variable in space and time). The infiltration / flow through porous media (saturated and unsaturated) to the ground can also be modeled (in 3D) with variable layer thickness. There is also interaction with the (1D) drainage network through rivers and canals.
Water moves through all the mediums (atmosphere, porous media, soil surface, and river network) based on mass and momentum conservation equations. The interactions between the different processes (like water exchange between aquifer and river) are calculated dynamically by the model, using the hydraulic gradients. MOHID Land can model the whole system described above, however the 1D surface drainage network can also be modeled using SewerGEMS (SWMM engine), with the advantage of this solver including a wide panoply of hydraulic structures (including culverts, etc.), among other features and capabilities.
If stormwater drainage network exist, OpenFlows FLOOD can also integrate this subsurface network, dynamically interacting with both 2D surface runoff and (1D) surface drainage network system. Bidirectional interaction between surface runoff and stormwater drainage network is done through manholes or inlets / storm drains.
FLOOD can also be used for modeling coastal flooding, including storm surges and tsunamis.
Finally, on top of all this, FLOOD can be used for modeling water quality (nutrient cycles) and water contamination (microbiology or other contaminants) and sediments transport.
Now, compiling some of the main differences that we believe you can find in terms of features comparing to HEC-RAS, I would enumerate the following:
I hope I had helped.
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just a small note on features in HEC RAS where precipitation on grid is now possible and you can add geometry directly in RAS Mapper including bringing in Esri shape files ..etc (started to look more of a GIS platform) ... but yah the rest especially integration... for a single job I am running between HEC RAS, HEC HMS and then Civil Storm.. would be nice to do all in one place!!!