Questions tagged [flood]

A flood is an overflow of water that submerges land which is usually dry. Within GIS we often want to model a flood with terrain models.

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18 views

Will Polygon Volume work if my polygon does not represent a constant plane height?

I am working on calculating flood inundation volume in ArcMap. I have polygon layers that represent flood inundation at specific recurrence intervals. My layers do not have a constant plane height ...
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1k views

Assessing Flood Hazard Risk Zones using DEM? [closed]

What is the best effective way to quickly estimate flood hazard risk areas using DEM data? Ideally I am looking for guidance to move forward and perform this process over large areas (i.e. entire ...
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Explanation of HAND (height above nearest drainage) model procedure

i tried to follow this procedure Spatial Analysis - Calculate a cells elevation (height) above the nearest stream cell but i have some problem to understand everything. I mean the 2th answer in the ...
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36 views

Creating cumulative friction map

I am looking at bottom friction (Manning's n) values in relation to storm surge as large volumes of water flow over a surface. In order to calculate total head loss occurring as water passes from the ...
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20 views

GRASS GIS: Time series of overland flow from r.swim.water

I am trying to perform an overland flow routing on a large area using r.sim.water in GRASS GIS. I've looked at other answers and made sure to set my computational region to the elevation raster I'm ...
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2answers
51 views

Creating contours based on polyline using ArcMap?

I would like to create a simple floodplain map. I have LiDAR data with 1 meter accuracy. I have clipped it to a small area of interest that my computer can handle processing the LiDAR. I want to ...
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116 views

Multi-Spectral High Resolution Satellite images for flood events

I'm searching for multi-spectral high resolution satellite images for flood events. I found a database of flood events from this link with dates and approxiamte locations (polygons) and I used the ...
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22 views

Editing DEM file

I'm currently working on a small town flood inundation mapping , the DEM file i am using for simulation contains a breakwater built after a recent flood event. My question is if it is possible to edit ...
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1answer
54 views

Assigning XS Cut Line Attributes like River/Reach Name, Stationing, Bank Lines, etc?

I'm working on a flood inundation project as my research study of my course. I am now assigning XS Cut Line Attribute (after constructing the XS Cut Lines) in HEC-Georas > RAS Geometry > XS Cut Lines ...
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1answer
14 views

ArcHydro Point to Stream WSE DEM error

I have been trying to figure out how to make a flood delineation map, and the tool runs, but I'm getting this error "001003: Datum conflict between input and output." I thought this would be as simple ...
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3k views

Generating floodplain generation given river section polylines, flood level elevation points and DEM of land surface? [closed]

I am looking to generate flood plain polygons to represent 20 and 100 year flood zones, in the most accurate and efficient way possible, given the following datasets: River cross section polylines ...
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689 views

How to visualize inundation using Sentinel 1 SAR Data?

I am trying to visualize flooding after hurricane Harvey that made landfall on August 25-26 2017. Based on this video, I've been able to obtain the basics of Sentinel-1 SAR imagery. Sentinel 1 comes ...
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Seeking vector file of extent of flood plain of 2010 Pakistan Floods?

I am looking to locate a shapefile or any vector file that can be used for analysis I am conducting of change in size of cropland in the Punjab region of Pakistan. The file of interest would reflect ...
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1answer
511 views

Flood records/database in Europe

Anyone knows where I can find a complete* database with the historic flood occurrence in Europe, at least since the 70's ? I am looking for some information on the date, number of floods*, amount ...
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2answers
98 views

Determining flood extents based on a daily flow? [closed]

I have a DEM raster and daily average flows (e.g., 50Ml/day). And I want to determine how far the water extent goes when the flow accumulates for 7 days based on 50 ml per day?
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1answer
282 views

Showing overland flow route on DEM in QGIS?

I've been asked to produce a risk map at work which will show the possible flood route from sewers that surcharge (flood) during heavy rainfall. This is basically where I know the x-y coordinate (OS ...
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2answers
80 views

Issue with FEMA OGC Web Feature Service returning HTTP 400 error when attempting to download GML file

I'm trying to use an OGC web feature service in some software I am involved in developing. The service is described at the bottom of this page: https://hazards.fema.gov/femaportal/wps/portal/NFHLWMS ...
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717 views

Flood mapping in QGIS 2.4

I am trying to delineate flood-prone areas using QGIS. I have a vector layer of the river and a DEM of the same area. I have used the GRASS Module to get watershed by using r.watershed and I have ...
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90 views

ArcGIS Calculate flooding area based on input amount of water

I have created a DEM based on historical maps from 1816. I'm supposed to calculate the flooded area for certain amounts of water (in m³/s). I intended to do it with ArcHydro - however, as far as I ...
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2answers
828 views

Flood Inundation Mapping In HEC-RAS?

I'm getting this output as a result of discharge values while doing flood inundation mapping. In some areas there are breaks as indicated by red arrows. If this result is correct what would be the ...
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20 views

Measuring flood mitigation effectiveness in river at different time using ArcGIS Desktop?

I am trying to measure the effectiveness of flood mitigation in a river using ArcGIS 10.2. Data available to me are the left and right bank polyline of 4 years , settlement data and point data where ...
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1answer
149 views

Maximum water extent JRC dataset [closed]

I am trying to map the maximum water extent in a certain area. Therefore I thought to use the JRC dataset by using the 'max_extent' band. The code however gives me the following error: "max_extent" is ...
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1answer
37 views

Converting a point file, into a smoother set?

I am currently attempting to show how a coastal area was flooded from the 2010 Mentawai Ocean tsunami on the Pagai Islands. I currently have a DEM and a DEM which I have sourced from a point data set, ...
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137 views

Spatial prediction in GIS [closed]

I have a number of images, (these could be vectorised) that are label classifications. There are only 2 classes, 1 or 255. Each image is from a different date. For each date I also have data that can ...
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1answer
149 views

Flood Plain Mapping using HEC-GeoRAS and ArcMap?

How can I get complete bounding polygon of XS CutLines for flood plain mapping (Flood Inundation Mapping) using HEC-GeoRAS and ArcMap 10.3? When I tried to perform this task, the bounding polygon ...
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1answer
160 views

HEC-RAS limitation on cross sections?

For every cross-section profile, Manning's value is assigned. There are numerous values in a single cross-section profile but HEC-RAS allows only 20 values per cross-section. How can I deal with ...
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2answers
188 views

Increasing Flood Plain

I am doing a project where we are attempting to determine how many more buildings would flood if the FEMA flood plain increased by 1',2' and 5'. I have the elev of the flood plain rasters from lidar ...
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1answer
2k views

Generate flood map using qgis [closed]

How can I generate a flood inundation map and flood depth using QGIS within 3 hours?
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1answer
146 views

How to approximate the elevation of a shapefile in any pixel of a grid using a digital terrain model?

Introduction I am working on some flood maps of a given region. As the data is confidential, I will try to stay as general as possible without any loss of relevant information. The truth is, my ...
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1answer
888 views

How to extend a (river water level) raster, transfering its values to the added area?

Exploring the raster tools in QGIS and related software, I found raster buffer functions to surround existing rasters. The values of the raster buffer are restricted to be distances from the interior ...
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1answer
71 views

Solving computing time problem when grid size element increases in flood model?

I want to create high resolution and high accuracy "area of inundation" map using FLO-2D Model. I have high resolution Digital Elevation Model (DEM) and I must show small topographic details on my ...
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2answers
3k views

Converting polyline to polygon in ArcGIS Desktop for floodplain map?

I'm using ArcGIS Desktop 10.5 and working with a flood map from FEMA, which uses polylines with distinct attributes for each hazard zone (1%, 0.2%, floodway, etc). I'm trying to convert these ...
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1answer
28 views

Finding Vector data that is in the area of a specific value of Raster data

I am doing a flooding analysis and would like to know how many roads would be flooded at certain elevations. The roads are in vector data format, while the elevation information is in raster. What ...
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302 views

Using Python to extract flood hazard info from National Flood Hazard Layer (NFHL) using any given lat/long point? [closed]

Can Python be used to extract flood hazard classifications from National Flood Hazard Layer (NFHL) site using any given lat/long point? Specifically the following seven classifications: 1% Annual ...
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1answer
439 views

Locating flooded area by creating buffer with elevation around points using ArcGIS Desktop?

I have a shapefile with points, that each have an elevation in their attribute tabel, based on how high the water level is, at a given return period. I need to create a buffer around these points at ...
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2answers
797 views

Creating flood area based on connected pixels of DEM in ArcGIS Desktop?

I am trying to show the area of flooding that occurs when bodies of water increase by different increments, like 0.5, 1, 1.5 meters, etc.. for all of Tanzania. I have a DEM with all of the bodies of ...
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1answer
4k views

Calculating flood volume using LiDAR DEM and HEC-RAS floodplain polygon?

I’ve got a vexing GIS analysis problem which is conceptually fairly straightforward, but in reality more challenging to figure out…. Basically, I need to calculate the VOLUME of floodwater within a ...
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509 views

Simulating flood without flooding whole area and covering surface structures (with DEM)? [closed]

I have a high resolution DEM and want to do a flood simulation starting at a river. My hope is that the water runs into historical (now dry) river channels (in which I'm interested in) at first and ...
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1answer
237 views

Exporting complete river profile from hec-ras into ArcMap?

Whenever i import the data from hec-ras the result is the same, what mistake am i making here?
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2answers
137 views

Substracting rasters using ArcGIS Raster Calculator?

I need to adjust a DEM (raster) and I was wondering if the Raster Calculator is the right tool to use, and how? I’m modelling floods in Xochimilco (Mexico) and via OpenStreetMap I have acquired the ...
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1answer
91 views

DEM showing areas in the ocean to be greater than 0m (my MSL in my project)

I am a new GIS student currently working on a coastal flood model in arc map, where I intend to create flood polygons at various heights above 0m contour (MSL)to represent the extent of area flooded ...
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1answer
73 views

What Algorithms to use for Levee breach Analysis?

I have a (relatively) High resolution DSM of the Country side, and want to figure out the extent of area that will be flooded if the Embankment/levee fails at a a given point. Something like this: ...
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2answers
762 views

Storm Water flooding [closed]

Is there a method in Arc Gis for mapping storm water runoff in an urban environment assuming that the sewers are at full capacity. I just want to map roughly where the water will flow over the land ...
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1answer
531 views

How to design a flood with water elevation on a specific point?

Actually I have to know the flooding area caused by a rise of the water level due to the implementation of a dam. So I would like to know if there is an extension or any tool in QGIS or GRASS which ...
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1answer
334 views

Estimating population in flood zones?

I have a census tract shapefile with the population of a minority group and total population. I am trying to analyze this group by high and low risk flood zones. The problem is that not all of the ...
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1answer
61 views

How to add hypothetical values to a raster?

I have to create Non-Regulatory Products for a few FEMA regions. Right now I am working on the 'Increased Flooding Scenarios' where you add a hypothetical value to the existing Base Flood (1', 2', and ...
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1answer
114 views

Advice on Flood mapping of village area [closed]

This is my first attempt to do a study on this topic. I would like to get some advice on what data are required for doing flood mapping. The area I have selected for this is a village which faces ...
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2answers
493 views

Belgium Flood And Precipitation Mapping

Similar to Free sources of mapping data for France, does any one know a source for free downloadable flood and precipitation maps for Belgium?
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1answer
2k views

Calculating Flooded area / Inundation in ArcGIS for Desktop?

I was tasked to create a layer with the flooded areas if the sea / river level was to go up by X feet. There is no requirement to take Flow and Pour Points into account, just a simple raise in water ...
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2answers
2k views

Simplified flood “model” / estimation from elevation data

The goal is to present an estimation of potential flooded area. But still keeping it simple. I know this will not be accurate. The question is: will it be good enough for at gestimate / rough ...