[GIS] Calculating distance of sites to riverways using ArcGIS Desktop

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How do you calculate the distance of about 10 sites scattered across a region to bodies of water (rivers and lakes) using ArcGIS 10.1?

I have the lat/lon coordinates of the 10 sites as a point feature class and I have downloaded the Surface Water Area (polygon shapefile) for the study area from the UK Ordnance Survey webpage.

I want to determine the easiest route-ways that are available in the study area by taking into account slope and proximity to rivers. I understand that I can achieve this by running a cost path analysis if I have a dem raster, slope raster and distance rasters to rivers and valley floors. But I am not sure how to create distance rasters to rivers and valley floors using Spatial analyst tools.

Best Answer

If you have the Spatial Analyst extension, it sounds like you may be able to make use of the Path Distance tool. You will need an elevation raster to serve as input. The tool will output a raster with a value in each cell that represents the shortest distance to one of your points from that cell, taking the topography into account in its calculations.

Of course this is assuming you're looking for overland and not hydrologic distance.

Related Solutions

[GIS] Performing Cost Path analysis in ArcMap

In order to perform this task in ArcGIS 10.1, you will require the Spatial Analyst Extension which can perform analysis on rasters including Least-Cost Path.

ESRI has created a series of tutorials to get you started with Spatial Analyst. The last of which creates the optimal route to a site. If you follow the tutorial you should be on your way to finding the optimal route for all ten of your sites. The results will look something like this:

enter image description here

It sounds as if the rasters you're missing are the slope raster as well as the distance rasters to rivers and valley floors (wouldn't valley floors usually contain some sort of waterway?) You should be able to easily create these with Spatial Analyst.

If you don't have access to Spatial Analyst, you should be able to create them and perform the analysis using open source GIS such as QGIS or GRASS. The tools needed are available in those, and you could just adapt the tutorial for use in those programs.

[GIS] Creating Cost Surface Raster for Least Cost Path Analysis

Choose a range of values for costs (e.g. 1 = low costs, 10 = height costs).

Reclasify each input data to a cost raster.

e.g.:

reclassify elevation:

altitude > 1000 m --> cost 10
altitude 900 to 1000 m -> cost 9
…
altitude < 100 m --> cost 1

reclassify proximity to rivers:

distance < 10 m --> cost 1
distance 10 to 200 m -> cost 2
…
Distance > 2000 m --> cost 10

Combine all cost raster to a single cost raster. If a factor is more important than others you can use a different weight for each factor. Use Raster Calculator tool to calculate total costs. E.g. if elevation is more important than proximity to rivers you can use:

“cost_elevation” * 0.8 + “cost_rivers” * 0.2

In ArcGIS Help you find more information.

Best Answer

Related Solutions

[GIS] Performing Cost Path analysis in ArcMap

[GIS] Creating Cost Surface Raster for Least Cost Path Analysis

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