OpenStreetMap
How good (bad) is water represented in OpenSteetMap?
Апублікавана карыстальнікам GenaD 22 Красавік 2015 на мове EnglishA a part of my PhD research, related to the setup of coupled hydrological/hydraulic models using open data at sub-100m resolution and at a global scale, I’m validating how good / bad is water represented in OpenStreetMap. At present, my study area is limited to Murray-Darling River Basin, but eventually it will be rolled-out to the whole Earth. I use Google Earth Engine and a bunch of open-source tools, like PCRaster, GDAL, Fiona. The idea is to perform most of the analysis in the Cloud.
The methodology includes the use of SRTM 30m, Height Above the Nearest Drainage (HAND), 30m resolution, HydroBASINS and LANDSAT 8 datasets.
For more information see my PPT presentation from European Geoscience Union 2015. Abstract: DOI:10.13140/RG.2.1.1514.9601.
Daily routine usually looks like this:
Supported by: Deltares, Earth2Observe and Google.
Абмеркаванне
Каментар ад pizzaiolo у 22 Красавік 2015 у 19:04
Very interesting! Looking forward to hearing more about it.
Каментар ад imagico у 22 Красавік 2015 у 20:24
Nice to see waterbody mapping and use of OSM waterbody data gathering attention outside OSM itself.
Looking at your presentation it seems however your methodology has quite a few issues, both in detail and en large - some of them will likely ‘bite you in the back’ when you try to use that approach in other areas.
The most basic one probably is that the techniques you compare do very different things. In OpenStreetMap we map bodies of water, either standing or flowing. When analyzing Landsat images you map surface water and when analyzing elevation data you map potential drainage lines. It should be obvious that these three methods - even if all of them work perfectly - will produce diverging results.
Your approach to Landsat/SRTM reminds me of something i did several years ago. You are lucky you do not have snow and glaciers or frozen lakes in Australia…
Каментар ад GenaD у 22 Красавік 2015 у 21:52
Thanks for the link, comments and imagico, very useful!
There certainly will be more issues and you’re right about the ‘very different things’. However, all 3 datasets still indicate places with the maximum likelihood of water. With a proper understanding - a nice data fusion should be possible. In any case, I want to analyse the differences pairwise between different dataset after splitting them into areas where different approach can be used to do the analysis. For example:
… OpenStreetMap water based on 1m imagery is still better, but we don’t know that. From what I saw, water centerline for wide rivers is not always a centerline in OSM. I’m not sure if there is an agreement on that, most probably if differs from place to place. For modeling applications it would be actually good to have a geometric centerline and then thalweg.
Based on flow accumulation area it will be possible to estimate approximately how big the river ~actually is. Maybe based on the landuse can estimate the SRTM noise.
About applicability to other areas, I expect the following dataset to come out somewhere soon: Peckel, 2014, so my focus is not to “detect water in the best way using LANDSAT” but rather to focus on the methodology to compare different vector/raster river datasets given watermask based on LANDSAT.
Каментар ад !i! у 30 Красавік 2015 у 20:11
I linked your paper at our list: osm.wiki/Research#Delft
Каментар ад ImreSamu у 24 Верасень 2015 у 14:51
PDF presentation: http://www.unesco-ihe.org/sites/default/files/egu_2015_osm.pdf