Definir a ferramenta de Profundidade e Extensão de Inundação baseada em HAND (Arc Hydro)

kat_h

Olá, <\/P>

Estou tentando delimitar uma planície de inundação de um pequeno riacho no ArcGIS Pro 2.9 com Arc Hydro. <\/P>

Tenho seguido o fluxo de trabalho apresentado no webinar recente: Arc Hydro: Flooding and Forecasting.<\/P>

1. Preenchimento de depressões no DEM baseado em LiDAR
2. Direção do Fluxo e Acumulação do Fluxo
3. Distância do Fluxo para criar um raster HAND 
4. Ferramenta ArcHydro: Definir Profundidade e Extensão de Inundação baseada em HAND<\/P>

Como você determina qual deve ser o parâmetro 'Input Flood Depth'?
O webinar menciona que é o limiar vertical, mas não tenho certeza do que isso significa. É a profundidade máxima do riacho?<\/P>

Eu só tenho dados LiDAR, o DEM e a linha/raster do riacho disponíveis. <\/P>

Qualquer conselho sobre esta ferramenta é apreciado, obrigado! <\/P>

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DeanDjokic

When using HAND method for "flooding", the "Input Flood Depth" is the depth above stream centerline that you want to "flood" with. 

What that specific value is, is up to you.  For example, if you use the "max depth of the creek", that is the equivalent of the "bankfull" and most of the resulting flood polygon should be contained within the channel.  Anything higher should start spilling into the overbanks and you should get "flooding".

So where do you get that number?  Depends on what you are doing.  It can come from the observations (e.g. high water mark or a stage from a gage) or through flow modeling and rating curve to convert flow to depth.  If you are doing the rating curve approach, make sure that the rating curve is based on the same resolution data you used to derive HAND with (or is adjusted accordingly).

And remember that inherent assumption in HAND flood modeling approach is that your water surface is uniform (constant) and parallel to the bottom of the channel.  For each channel segment.  So if you expect that the depth will change (significantly) as you go downstream, you should partition the overall stream into multiple segments that have uniform (but variable from segment to segment) depth and then use "Define HAND-based Flood Depth and Extent from Table" tool to get the floodplain.  More work but might give you better results.

If you stream segment is short, then first follow the approach you have presented (single reach), see if you like the results, and if not, then use the "table" approach.  Note that you will have to reprocess the input data and partition the streams and get their catchments before you can use the "table" approach.

Hope this helps.