Mihir Agrawal
Civil/Environmental
- Jun 25, 2024
- 1
Hello,
I am a university student and I am working on a university project very important for my master's degree. In my project I am mainly working on HecRAS 6.
I am badly struck in obtaining the expected results from my project. I really really really need help
Please help me out.
Below, I have explained the setup and main goal of the project.
Setup:-
The core idea of the project is to recreate the 2021 floods which happened in Germany and compare the impacts of man-made obstructions in the river flow path to know the difference in the inundation depths in the flooded regions. For that I have prepared a 2 separate 2D Flow model in HecRAS.
In my first model, I have not included any man-made obstructions in the flow path and let the water flow freely in the river and let it flood naturally on the banks and surroundings. I was able to nearly get the same level of flow in CMS and water depth which was recorded by the government gauges at the time of floods there.
In my second model, I added the bridges in the flow path depicting its exact location as they existed in reality during the time of floods.
I expect the results to have some kind of water blockage on the upstream of bridges, which in turn increases the inundation upstream of the bridges.
For preparing the models, I have used a 10m resolution DEM with buildings raised on their original location and with multiple inputs like global meteorological input of Precipitation raster files and flow hydrographs of the incoming river and tributaries in the study area.
I used the exact same model for both models, with the only difference being that in the second model I added the bridges inside the flow path and nothing else.
After running both models, I wanted to see some high water depths upstream of the bridges and then a partially blocked flow of water passing through the piers of the bridge downstream of them. But I did not get that.
I went further and exported the depth layers of the results for the maximum depth. And I went to QGIS to subtract the layers from each other to see the results. Here, I expected to see a very slight difference in the water flowing depth in the river (up to 1 meter) and also a difference in the inundation areas.
But the results that I am getting are not like these, I am NOT observing any kinds of water blockages on the upstream of the bridges (no difference in depths in the river flow path), but there is some difference at the border of the flow path (a thin line like), and at the downstream boundary condition, there is an enormous depth difference of around 5 metres, which is not possible as there is not change anywhere around that area in the models, the water depth should be the same there.
I subtracted the max depth layer from my second model, i.e., with bridges, from the max depth layer from my first model, i.e., without bridges (subtraction = model 1 minus model 2). I am getting a water depth layer range of -6 m to +4 m. This is very huge in comparison to the inundations in the surroundings.
I feel that there is some error in modelling my bridges, and my second model is not properly taking the bridges into account while running the simulation.
I am not sure what to do, and I really require some assistance to point out mistakes in my model and help me correct them.
Please help me.
Thanks a lot in advance!!!
I am a university student and I am working on a university project very important for my master's degree. In my project I am mainly working on HecRAS 6.
I am badly struck in obtaining the expected results from my project. I really really really need help
Please help me out.Below, I have explained the setup and main goal of the project.
Setup:-
The core idea of the project is to recreate the 2021 floods which happened in Germany and compare the impacts of man-made obstructions in the river flow path to know the difference in the inundation depths in the flooded regions. For that I have prepared a 2 separate 2D Flow model in HecRAS.
In my first model, I have not included any man-made obstructions in the flow path and let the water flow freely in the river and let it flood naturally on the banks and surroundings. I was able to nearly get the same level of flow in CMS and water depth which was recorded by the government gauges at the time of floods there.
In my second model, I added the bridges in the flow path depicting its exact location as they existed in reality during the time of floods.
I expect the results to have some kind of water blockage on the upstream of bridges, which in turn increases the inundation upstream of the bridges.
For preparing the models, I have used a 10m resolution DEM with buildings raised on their original location and with multiple inputs like global meteorological input of Precipitation raster files and flow hydrographs of the incoming river and tributaries in the study area.
I used the exact same model for both models, with the only difference being that in the second model I added the bridges inside the flow path and nothing else.
After running both models, I wanted to see some high water depths upstream of the bridges and then a partially blocked flow of water passing through the piers of the bridge downstream of them. But I did not get that.
I went further and exported the depth layers of the results for the maximum depth. And I went to QGIS to subtract the layers from each other to see the results. Here, I expected to see a very slight difference in the water flowing depth in the river (up to 1 meter) and also a difference in the inundation areas.
But the results that I am getting are not like these, I am NOT observing any kinds of water blockages on the upstream of the bridges (no difference in depths in the river flow path), but there is some difference at the border of the flow path (a thin line like), and at the downstream boundary condition, there is an enormous depth difference of around 5 metres, which is not possible as there is not change anywhere around that area in the models, the water depth should be the same there.
I subtracted the max depth layer from my second model, i.e., with bridges, from the max depth layer from my first model, i.e., without bridges (subtraction = model 1 minus model 2). I am getting a water depth layer range of -6 m to +4 m. This is very huge in comparison to the inundations in the surroundings.
I feel that there is some error in modelling my bridges, and my second model is not properly taking the bridges into account while running the simulation.
I am not sure what to do, and I really require some assistance to point out mistakes in my model and help me correct them.
Please help me.
Thanks a lot in advance!!!