City of Helsinki riverbeds, streams and ditches

The dataset includes the water channels of Helsinki, i.e. rivers, streams, ditches, riverbeds and the pipelined sections of the biggest channels. The structure of the data follows the data model of the HSY Hulevesitiedonhallinta (HUTI) project.

The dataset has been produced in 2022 based on spatial data sets. The data sources for the dataset are listed here.

Mainly, banks with a width of more than 2 m have been classified as banks with two contour lines on the hydrograph map and the centreline has been digitized from the hydrograph map. With the exception of Östersundom, which has been completed on the basis of the base map and is classified as over 2 m wide for watercourses collecting water from an area of over 75 hectares based on HSY data. Of the watercourses crossing the Helsinki border, the Mätäjoki River has been digitised on the basis of the Vantaa base map. In the Östersundom area, the Sipoo and Vantaa side streams have been digitised to a coarse resolution based on the base map.

Ditches less than 2 m wide have been copied unedited from the base map, so their timeliness and accuracy varies. Ditches in the Östersundom area have been augmented on the basis of the elevation model.

The data is available for download in a variety of formats, including JSON, KML, CSV, Esri Shape and XML. The available formats can always be found in the outputFormat section of the GetCapabilities query service. For further information and instructions, see the WFS Query Guide.

Previewing the data in the kartta.hel.fi service:

• kartta.hel.fi

Coordinate systems:

• ETRS-GK25 (EPSG:3879). Maintenance coordinate system. The data can also be projected to other coordinates. Other possible coordinates can be found in the GetCapabilities document of the interface service.

API address:

• WMS interface: https://kartta.hel.fi/ws/geoserver/avoindata/wms
• WFS interface: https://kartta.hel.fi/ws/geoserver/avoindata/wfs

Layers:

• Avouomat

Avouomat layer: attributes and translation:

• id: Automatically generated unique identifier.
• uomatyyppi: Type of river bed of the target. River = banks wider than 5m (Vantaajoki and Keravanjoki). Stream = Continuous stream networks with semi-natural sections and a width between 2 and 5 m. Ditch = Streams less than 1 m wide on the base map and streams between 2 and 5 m wide on the base map, which are located outside continuous streams or which, based on map interpretation, have been created as a result of human activity. Noro = A watercourse classified as a noro based on an Ely assessment or nature survey. There is no comprehensive mapping of noros in Helsinki. Some of the noros have been confirmed in the Uhanalaiset- ja silmälläpidettävät luontotyypit(Spatial Data Set of Endangered and Threatened Habitats) (2022).
• keskilevleys: Average width. Based on the classification of the population map. 3 = more than 5 m. 2 = 2-5 metres. 1 = Less than 2 metres. Exceptions are Östersundom , where 2-5m wide is classified as a 2-5m wide channel, which collects water from an area of more than 75 hectares, based on HSY data.
• lisätietoja: Link to the target page of the riverbed in the habitat information system.
• maalaji: Soil type. Based on the new Helsinki soil map (published 2017, updated 2022). Soil type determined for sections of river banks based on spatial data analysis.
• pituus: Length of the section of the riverbed in metres to two decimal places.
• sillanalitus: Bridge analysis. Not applicable to banks less than 2 m wide, based on HSY's data on dams and bridges. The geometry of the open channel coincides with the geometry of the bridge data (snapping). Sections of the bank that pass under the bridge are assigned a value of 1.
• rummussa: Does not apply to pools less than 2 metres wide. Based on the HSY survey data on dams and bridges. The geometry of the pit is consistent with the geometry of the drum data (snapping). Sections of the stream that run in a drum or pipe are assigned a value of 1.
• luonnontila: Natural state. Based on the Endangered and threatened habitats data. Applies only to inventoried sections of stream.