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This page describes the protocol of mapping new locations onto the river network, using the example of GloFAS. In this context, ‘new locations’ are usually river discharge observation stations provided by GloFAS users. The locations represent the catchment of the river at their outlet points. During the process of mapping, the ‘best-fit’ of location in the GloFAS model corresponds with the location of the station on the river in the ‘real world’, based on the coordinates of the station from the data provider.
Users should rely on this protocol as a guideline in case they have to extract point time series. To extract point time series, the locations must be mapped onto the GloFAS river networnetwork.
Tools to use
- Google Earth or Google Maps (to verify the station metadata).
- High detail vector river shapefile (e.g. hydroSHEDS at https://hydrosheds.cr.usgs.gov/datadownload.php or http://gaia.geosci.unc.edu/rivers/
- GloFAS river network, represented by the upstream area map (https://cds.climate.copernicus.eu/cdsapp#!/dataset/cems-glofas-historical?tab=form)
- GIS software to display shapefiles and maps (e.g. QGIS at https://www.qgis.org/en/site/forusers/index.html)
- A good enhancement could be to use maps (e.g. Bing or satellite maps) in QGIS. This would provide a more complete workspace in QGIS with the real maps, the high-resolution river layer, and the GloFAS river network in one space overlayed onto each other. Steps to achieve this in QGIS-3:
- Go to Settings/Options/Network and click on "Use proxy for web access".
- Go to plugins and choose QuickMapServices and click install.
- Maps will be available in the Web tab
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In all cases when the provided station is not mapped to the nearest GloFAS model pixel, then a note should be added into the GloFAS station information database about the mapping situation and the nature of the problems or difficulties (i.e. upstream area mismatch, shift of location, GloFAS river network problems, problems with the provided coordinates, difficult area with uncertain rivers, or reservoirs or lakes, etc).
| map_flag | map_flag_comment | Description of issue | Result | Action required by modeller / JRC |
|---|---|---|---|---|
| -1 | synthetic point - no provided coordinates | No coordinates are available from the provider (0,0). | Not a station - not mapped | none |
| 0 | To do. Station has not been checked/mapped yet. | There shouldn't be any 0 flags in the database | ||
| 1 | minor issue or inconsistency / relevant comments about the station | The provided station is in the correct position and can be mapped with High/Very High confidence. There might be minor inconsistency (slightly different upstream area, station not on the river). The comment specifies any minor inconsistency. | Station mapped successfully with high confidence. | none |
| 2 | incorrect metadata "duplicate of station GXXXX" | Station metadata is misleading and the station is mapped with Low/no confidence. In the comment is specified which metadata does not allow to map the station with higher confidence. The station is a duplicate, specified in the comment. | The station was mapped with low/no confidence and it should not be trusted as it is. The station is a duplicate. It should not be used and should be possibly removed. | Modeller will decide whether to use or not the station. The person in contact with the data provider might have to check the original data. |
| 3 | wrong ldd/ ldd not able to represent network | The station is in the correct place but the ldd does not represent the river system. | The station cannot be mapped into Glofas and should not be used by the modeller. No confidence | The decision whether keep/remove the station or flag it as wrong/useless. |
| 4 | correct metadata and position - obs vs GloFAS does not seem consistent | The station seems to be in the right position but the observed discharge vs GLOFAS discharge plot seems very different. Possible issues: Wrong time series assigned to the station? Wrong metadata? Issues with GLOFAS for that catchment? | Obs vs GloFAS error. Station mapped with moderate confidence. | check against original data if the time series has been assigned to the correct station if the metadata seems correct but it is actually wrong or if there is an issue with the model. |
| 5 | correct metadata - unsure if the station is before or after river confluence | Station seems to be in the correct position with the correct metadata, but unsure of position. In this case, there were no time series associated with the station or the time series is not helpful in locating the station. | Station mapped with low confidence. | check (if possible) with the provider if the station is before or after the confluence. If it is not possible to make a decision the flag can remain as "5" and the modeller can decide what to do. |
| 6 | misleading metadata - specify | Even if the metadata provided is partially misleading the station could be mapped on GloFAS. In this case, is very important to add a comment about the mapping situation and the nature of the problems or difficulties. Possible examples i.e. the station name and the coordinates are correct but the upstream area provided is completely misleading. i.e. the station coordinates are incorrect but the upstream area provided, station name, river name, time series allow the user to place the station in the correct GloFAS position. | moderate confidence. The station can be used by the modeller. | Check original metadata and eventually correct it. |