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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QGIS - How to split and display Population Data according to District/Province?

I'm a complete beginner in QGIS, currently self-teaching myself through Youtube. Current Problem: To split and display population data according to district/province Project Background: To measure ...
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1 answer
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Creating a layer showing difference before/after flood (raster)

I ran a supervised classification on two satellite images - (i) before and (ii) after a flood. Now even before the floods, there were pre-existing water bodies which obviously don't count as flooded ...
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1 answer
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Should I re-scale all the dataset to one scale before running them into model?

I have been working on the Flood susceptibility modelling and also have identified, collected and generated data of around 26 controlling factors(indicators). Furthermore, i'm going to put them into ...
1 vote
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Generate topographical index from a digital surface model (DSM) to generate a flood susceptibility map [closed]

I'm performing a random forest model to generate a flood susceptibility map, I have LiDAR data from the study area where I generated Digital Surface Model (DSM) and Digital Terrain Model (DTM) raster ...
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1 vote
1 answer
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Layer error: Image.rename: The number of names (1) must match the number of bands (10)

I am using Landsat 7 data (ee.ImageCollection("LANDSAT/LE07/C01/T1_TOA")) for flood mapping. I am trying to write the code but I'm stuck at a line where it says "Layer error: Image....
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How do I calculate high water extents?

Could someone suggest the right path to follow if I were looking to calculate the high water extents or potential flooding that could occur on a tidal river. I am working in ArcGIS Pro and have ...
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Is it possible to query using an attribute in Digital Earth Africa?

Am doing flood mapping in Digital Earth Africa(DEA), wondering if there is way to query using an attribute say water body to determine the built up areas that are prone to floods. Or is there another ...
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2 answers
54 views

Delete geometries based on intersection with another layer

Working on QGIS, I have two layers 1. buildings (polygons) 2. flood area (polygons) I want to get rid of the building located in flood plains. In other words, I need to find where those layers ...
3 votes
1 answer
148 views

Calculating area in QGIS, defined as zone with relative elevation compared to a river

I’m trying to do the following in QGIS. When creating a 3D map, I want to follow a line or area of interest, such as a river, and create an area which is measured perpendicular to the line of interest,...
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How to check hydrological connectivity in flood fill techniques in QGIS?

I have a set of polygons (include their elevation levels), representing geographical areas. I want to check which polygons will be inundated if a flat flood level is given. Lets say 1m flood from sea ...
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131 views

Creating a Cross section of a river

I am using QGIS and HEC-RAS for my project. HEC-RAS needs a file for the river bathymetry. Since I do not have data for river bathymetry, I decided to use the Profile Tool in QGIS to create a river ...
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1 answer
252 views

Flood Analysis in QGIS

I am trying to use QGIS to assess what areas will flood if the river floods a specific height. I have a DEM of the area as well as a vector file of the lines of the river of interest. I cannot get a ...
1 vote
2 answers
136 views

Offset raster boundary by elevation

I've been given a raster with flood elevation limits along a river, it's not a constant flood level so elevations range by ~35m. I need to do an analysis of the impacts if these elevations were 2m ...
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Raster manipulation in ArcGIS - Flood Mapping with HAND

I am trying to create flood maps using the height above nearest drainage (HAND) method using data from the continental flood inundation mapping (CFIM) project. I have the following data: A raster map ...
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Measuring the intensity of raster pixels within buffers

I need to create a variable ranging between 0 and 1 to compute the intensity of a flood. I have the raster file for the flood and the layer with the coordinates of the households that have been ...
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1 answer
89 views

Generating extent of 1 ft rise in floodplain using ArcMap

I have a polygon layer that represents the max inundation extent along a stream for the one-year storm event (generated in hec ras). If this floodplain was theoretically raised by one foot, what would ...
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1 answer
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What does "slope.lt(5)" do in Google Earth Engine?

Can someone explain what ".lt" is in the code below, and how it works? var hydrosheds = ee.Image('WWF/HydroSHEDS/03VFDEM'); var terrain = ee.Algorithms.Terrain(hydrosheds); var slope = ...
2 votes
1 answer
285 views

How to find out which areas are affected by flooding due to heavy rain?

I'm working on a little project to visualize affected streets of flooding due to heavy rain. I already got a DEM for my study area and filled the depressions with r.fill.dir. Since I never worked on ...
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1 answer
244 views

Using WofE (weight of evidence) in ArcMap

I need to use "weight of evidence" in a project about floodrisk I heard that this model can be implemented in ArcMap but I did not find any videos in YouTube. Can anyone help me?
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Editing TIN surface by polygon using ArcMap

I'm doing a 2D hydraulic flood study of rivers in a 63 km2 basin. I have a raster of the topography (1x1 meters) that I have passed to TIN using ArcMap. Giving a z=0.3 meters, I get a TIN network with ...
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How do I "flood" a terrain in Cesium to represent a high water level

I am thinking about using a plane object to represent a water level by rendering it as a certain height above ground using Cesium. Is there any example code that
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1 answer
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Spatial join - allocate values from joined polygon based on input polygon

I'm trying to determine population inside Special Flood Hazard Areas. To do this I'm doing a spatial join of census shapefiles with the FEMA National Flood Hazard Layer, using the Boolean field ...
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Creating local copy of an online Potential Flood Inundation Map

I am completely stuck, usually I can figure out how to create a local copy of hosted services, but this one I can't seem to get anything to work and any suggestions would be great. Currently I can ...
0 votes
1 answer
309 views

Google Earth Engine - Blend Sentinel-1 SAR Images?

Does anybody know why I am getting these strips across my Sentinel-1 images and how to fix it? I am using multiple images over Mozambique between January 1st and January 13th. I want to use this ...
2 votes
1 answer
103 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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GRASS GIS: Time series of overland flow from r.sim.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 ...
3 votes
2 answers
281 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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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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1 answer
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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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7 votes
2 answers
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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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1 answer
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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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2 answers
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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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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 ...
1 vote
2 answers
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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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2 votes
0 answers
177 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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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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1 answer
202 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 ...
1 vote
1 answer
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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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1 answer
297 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 ...
1 vote
0 answers
204 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 ...
3 votes
2 answers
311 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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2 votes
1 answer
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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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-1 votes
1 answer
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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 ...
2 votes
2 answers
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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 ...
1 vote
1 answer
312 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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1 vote
0 answers
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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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1 answer
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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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1 answer
179 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 ...
2 votes
1 answer
599 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 ...
2 votes
2 answers
1k 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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