Make quick inundation maps in QGIS using Open Data

This video shows how to make quick inundation maps using QGIS, SRTM DEM and OpenStreetMap.

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Credits to OpenStreetMap data: © OpenStreetMap contributors

[runcer]

Such an excellent presentation, I have learned so much! thank you.

[joshuasolis]

How do I download the Open Topography Plugin if it’s not in the plugins section and there is no RAR Install option?

[rigzinwilliam]

Hello sir, I have a question.

The method you used here is referred to as a 'bathtub model' and is widely used to predict coastal flooding and land inundation. However, this model does not incorporate hydrological connectivity.

This means that for isolated areas that are inland and show up as 'flooded' in the output, there may actually be no way for the water to get there in the first place (as you can see in your video).

What can you do in QGIS to include hydrological connectivity to your model? I know that you can simply vectorise the raster image of the flooded cells like you've done here and then use the identify features tool to manually delete this, but this may not be feasible for larger areas as it would simply take too much time. I guess what I'm after is more of an expression to enter in the raster calculator, or a tool in the processing tool box rather than manually deleting the vectors and then re-rasterizing it.

[gireeshkrishnan]

if i download in US government site is it any problem in future

[giliasgardenetc]

Thanks for this video it did help but still struggling with the 3D, tables not similar maybe I got the lower version. Still I work my way up to polygonized.

[luposcam]

thank you for this video. do you know if it is possible to apply similar approaches to estimate the (downstream) area impacted by a flood starting from one (or multiple) vector point(s) ? thank you

[arnoldkilaini]

I have used a DEM for 12.5m i get strange results almost half of the city is Flooded) any recommendation???

[ramiramos]

Good morning Sir
I have a question please,
Did Qgis developed new tools that helps for river modelling and flood mapping analysis
And if it is available do you plan to present this tools in the future .

Thank you

[nth]

Thanks bro, its better to spread knowledge to others.

[Vikasa]

where to find the clip extent to the canvas in Qgis 3.16? i can't find it.

[amadougbetnkompetouonchi-p]

Dear Hans thank you for this video. Is it possible to make the inundation map by incorporating the rain data as well?
Best Regards

[oussamahamidat]

thank you so much, that helped me a lot!!!
LOVE U BRO <3
keep going..

[debyshizhi]

Thanks you for this video. I have question, what is the name of the method used in this video ?

[rahmadeenk]

Thanks alot for the video, Would you help me how to get DTM 1 m for Padang West Sumatra Indonesia..?, Thanks..

[tulikamondal]

thank u for this incredible video . just a quick question, how can I share the 3dimensional aspect of the map?

[ahmedwalidmoulahoum]

Hi Hans ! Pretty cool exercise. This can also be used to have a rough estimation of the financial impact of these hypothetical floods if the buildings taken from OSM can be classified according to their value. Do you know of a way how that can be done ?

[brendanpeck]

Many folks here have asked about making this model capable of displaying a flood that begins from a point or from a coastal surge. I am also wondering this and I have an idea.

Remove flooded pixels that are in small groups.

This solution does not require modeling the hydrology nor does it require additional layers. This solution does not consider hydrologic connectivity, but I think it gets the job done. I think that in most cases, these flooded pixels that are outside of hydrologically-connected areas will be in small groups of pixels. Therefor, you could use a tool that removes groups of pixels that are under a set number.

Let me know what you think and please leave your solution. I currently have a project to map tsunami risk areas in Aceh, Indonesia. So, any ideas will be useful.

ps. another idea: Use a tool that creates polygons around pixels, then, select the polygon of interest and delete the rest.