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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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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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175 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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25 views

Setting connectivity between cells in raster? [closed]

I am trying to follow the methodology of Poulter 2008 for raster modelling of coastal flooding due to sea level rise paper found here He shows quite dramatic differences in flooding area due to the ...
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1answer
19 views

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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2answers
69 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
147 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
64 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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0answers
56 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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19 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
88 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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1answer
33 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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1answer
109 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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0answers
100 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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0answers
32 views

Hazus MH Error Adodb.connection

I'm a new user to Hazus 4.0 and I'm trying to run a Quick Look flood model and am running into the following error. Error Source Adodb.Connection Description: Provider cannot be found. It ...
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2answers
136 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
122 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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0answers
58 views

Accessing FEMA's server for WMS? [duplicate]

I have been trying access this dataset in QGIS: https://hazards.fema.gov/gis/nfhl/rest/services/public/NFHL/MapServer also available at these three links: 1. https://hazards.fema.gov/femaportal/...
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1answer
27 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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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
134 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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0answers
258 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
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
130 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
411 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
562 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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2answers
697 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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0answers
35 views

How to separate overlapping rasters in ArcGIS?

I'm currently building a flood modelling map for a uni assignment in ArcGIS 10.3.1. I have three flood rastercalc layers, 2m, 5m, and 10m flood levels. Each has been made translucent so the basemap is ...
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1answer
214 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
121 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
65 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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1answer
88 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
65 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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1answer
1k views

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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1answer
431 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
290 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
59 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
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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1answer
273 views

Extracting features from raster data using ArcGIS Desktop?

I want to extract flood related pixels from my imagery. I calculated mLSWI(Modified Land Surface Water Index). According to the literatures, mLSWI >= 0.5 is flood pixels. How do I identify the ...
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0answers
673 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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1answer
110 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 ...
1
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1answer
829 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
322 views

Getting flood depth grid values for road segments?

I have a 2 features, the first contains values for flood depth (Raster, GRID). the other is a road network (vector, polyline) that has been clipped to the boundary of the depth grid. I am racking my ...
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0answers
52 views

Where can I obtain data on flood sites, land sewage systems, and property value?

I am a college student trying to obtain this data for a class project. If anyone can help that would be great. Basically, my hypothesis for this project is that land sewage systems that have not been ...
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0answers
971 views

How to make an inundation map?

My task is to calculate the area available for specific plant species in a natural reserve that has been reconnected to the tidal influence. First step is to create an inundation map for a natural ...
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0answers
90 views

What is the background processing of rainfall thresholding?

I want to create a flood map using Quantum GIS. First of all I create catchment area (flow accumulation). Then, I delineate a Channel Network by applying a threshold to flow accumulation. So I want to ...
2
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1answer
735 views

map flood inundation risk QGIS

I am using RADAR data to create a map of biomass estimates. I want to mask out all land susceptible to flooding because water-logged soils affect the backscatter ...and will have an impact on ...
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0answers
502 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
177 views

What is the process for identifying a 20 year flood zone?

I am currently working on an assignment where I need to model flood risk areas. Firstly I was asked to identify potential flood risk zones based on the following criteria: identify areas that I would ...
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0answers
1k views

Assessing Flood Hazard Risk Zones using DEM

My Question: 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....
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1answer
190 views

Urban Hydrology Using With GIS

I'm researching how can I create a model urban floodplain depending on rainfall. And Which programme should I use? I want to show floodplain depending on temporal and spatial distribution on study ...