Review of EU-DEM and EU-HYDRO Upgrade Requirements and Options

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1 Framework Service Contract EEA/IDM/15/026/LOT 2 for Services supporting the European Environment Agency s (EEA) implementation of cross-cutting activities for coordination of the in situ component of the Copernicus Programme Services Call for tenders No EEA/IDM/15/026 Lot 2 Spatial data themes Document Code: EG-RPT-EEA-SC1-0020

2 Table of Contents 1. Introduction Service Requirements and Product Specifications Review of Specifications vs. Requirements; Improvement Options Availability of relevant Datasets Review of EU-DEM and EU-HYDRO use by current/future Copernicus projects Conclusions and Outlook List of Tables Table 1: EU-DEM mandatory and optional requirements (taken from [RD10, Appendix] as compiled from [RD8], vertical accuracy corrected)... 9 Table 2: Summary of EU-DEM specifications as accepted in response to Call for Tender ENTR/ 2009/27 (taken from [RD10, APPENDIX] as compiled from accepted Technical Proposal)... 9 Table 3: EU-HYDRO mandatory and optional requirements (compiled from [RD8]) Table 4: Freely available national DEMs in European northern countries (status: Feb. 2017) Legal Notice: The contents of this report were compiled by GAF AG under EEA contract 3436/R0- COPERNICUS/EEA implementing Framework Service Contract EEA/IDM/15/026/Lot 2. Neither the European Environment Agency nor any person or company acting on its behalf is responsible for the use that may be made of the information that is contained in this report. 2

3 [DOCUMENT RELEASE] Name(s) Affiliation Prepared by: Markus Probeck GAF Contributions: Andreas Uttenthaler, GAF Alexander Klaus, Arnd Berns, David Herrmann, Elisabeth Weis, Inés Ruiz Gómez, Birgit Wunschheim Review: Sebastian Carl GAF Endorsement: Sergio Proietti e-geos Approval: Henrik Steen Andersen European Environment Agency Prepared for: Represented by: (Project Manager) Contract No. European Environment Agency (EEA) Henrik Steen Andersen 3436/R0-Copernicus/EEA Implementing Framework Service Contract No EEA/IDM/15/026/Lot 2 [Change Record] Version Date Changes Draft January 2017 First commented outline of the report on EU-DEM and EU- HYDRO Draft February 2017 First complete draft version of report Review of EU-DEM and EU-HYDRO Upgrade Draft March 2017 Minor changes. Henrik Steen Andersen Issue March 2017 First Issue of report Review of EU-DEM and EU-HYDRO Upgrade. Updates to sections 4 and 6. [Applicable Documents] ID Document AD1 Framework Service Contract EEA/IDM/15/026/Lot 2 AD2 Specific Contract No. 3436/R0-COPERNICUS/EEA [Reference Documents] ID RD1 Document Regulation (EU) No 377/2014 of the European Parliament and of the Council of 3 April 2014 establishing the Copernicus Programme and repealing Regulation (EU) No 911/2010 Text with EEA relevance. Official Journal of the European Union L122/44, Vol. 57, 24 April

4 ID Document RD2 Regulation (EU) No 911/2010 of the European Parliament and of the Council of 22 September 2010 on the European Earth monitoring programme (GMES) and its initial operations (2011 to 2013) (Text with EEA relevance). Official Journal of the European Union L 276/1, 20 October 2010 RD3 Directive 2007/2/EC of the European Parliament and of the Council of 14 March 2007 establishing an Infrastructure for Spatial Information in the European Community (INSPIRE). Official Journal of the European Union L108/1-14, 25 April 2007 RD4 Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official Journal of the European Union, L 327/1, 22 December 2000 RD5 Note on Copernicus Reference Data: Proposal for Coordinated Actions with Member States dated 3 rd May 2016, submitted by the French and Spanish representatives to the 10 th Copernicus User Forum on 27 May 2016 (CUF ), 5 pp. RD6 European Commission s Answer to the Note (ES-FR) Copernicus Reference Data: Proposal for Coordinated Actions with Member States (CUF ), 5 pp. RD7 Presentation on Copernicus Reference Data: Proposal for Coordinated Actions with Member States, presented at the 11 th Copernicus User Forum on 6 September 2016, 10 pp. RD8 EC Call for Tenders No ENTR/2009/27: Implementation of an Initial GMES Service for Geospatial Reference Data Access (Lot 1: Implementation of an initial GMES service for geospatial reference data access covering Europe; Lot 2: Implementation of an initial GMES service for geospatial reference data access covering areas outside Europe). Tender Specifications Document Corrigendum, published June 2009 RD9 EEA Call for Tenders EEA/MDI/14/005: Framework service contract for the provision of IT and GIS consultancy services on implementation of Copernicus Reference Data Access (RDA) Component and on supporting EEA in other Copernicus related activities (2 lots)- Tender Specifications Document, published May 2014 RD10 Report on EU-DEM Statistical Validation, prepared by DHI-GRAS, August 2014, 27 pp. RD11 Report EU-DEM Upgrade Documentation EEA User Manual, Issue 1.2, prepared by INDRA, 14 October 2015, 12 pp. RD12 Report EU-Hydro Upgrade User Guide, Issue 3.0, prepared by INDRA, 30 October 2015, 29 pp. RD13 Flyer Copernicus Monitoring Service Reference Data: EU-DEM, EEA, October 2015 RD14 Flyer Copernicus Monitoring Service Reference Data: EU-Hydro, EEA, Oct RD15 Copernicus Space Component Data Access Portfolio: Data Warehouse Issue 2.1 of 1 August 2016 prepared by B. Hoersch & V. Amans, ESA, 84 p. RD16 Download statistics of the Copernicus Land portal ( ), made available by the EEA, February 2017 RD17 Weissteiner, C., Ickerott, M., Ott, H., Probeck, M., Ramminger, G., Clerici, N., Durfourmont, H., Ribeiro De Sousa, A. (2016): Europe s Green Arteries A Continental Dataset of Riparian Zones. In: Remote Sensing, Vol. 8, Issue 11, Article 925: p. 1-27; doi: /rs

5 1. INTRODUCTION The EU-DEM and the EU-HYDRO are pan-european reference datasets, which are publically accessible via the Copernicus Land portal ( under the Copernicus full, free and open data access policy. Produced from satellite observations and other ancillary data sources, the two datasets provide spatially explicit digital information on the land surface elevation and the hydrographic network across Europe. Both datasets were initially developed in the frame of the GMES 1 Reference Data Access (RDA) Preparatory Action in , and have been undergoing several improvement steps since. The EU-DEM is a hybrid Digital Elevation Model (DEM) based on SRTM (Shuttle Radar Topography Mission) and ASTER-GDEM (Advanced Space-borne Thermal Emission and Reflection Radiometer - Global Digital Elevation Model) data, fused by a weighted averaging approach. For areas north of 60 northern latitude, also publically available Russian topographic maps were incorporated. It is predominantly a raster-based Digital Surface Model (DSM) of the EEA-39 countries 2, representing the first surface as seen by satellite sensors, i.e. including the aboveground height of objects such as built-up areas and forests. 3 It provides elevations at one arc second (approximately 30m) postings. The EU-DEM is currently available as updated version The EU-HYDRO provides an EEA-39 wide cartographic representation of hydrographic vector datasets of surface water bodies, i.e. lakes and the river network. This information had initially been photo-interpreted from High-Resolution (HR) optical satellite imagery of the reference year 2006 and in a 2 nd step been updated from Very High Resolution (VHR) optical satellite imagery of the reference year Beyond the upstream limits of interpretability of the imagery, the dataset was complemented with parts of a modelled drainage network with catchments, drainage lines and nodes, as derived from EU-DEM v1.0. The product is currently available as public beta version 0.9, with validation currently ongoing. Main targeted users of the EU-DEM and EU-HYDRO products are the operational Copernicus services, particularly the Land Monitoring Service that typically is in need of freely available, continent-wide consistent information layers. Both datasets intend to address a need for gap filling in those areas for which no national or geospatial regional reference data can be accessed (because they don t exist at the required scale or quality, or available only commercially), or in cases where homogeneous data specifications are required over the full geographic coverage in EEA39 countries. 5 Digital Elevation Models (DEMs) provide information required for a broad range of applications with different technical requirements and use cases in the various fields of earth observation, whereas the hydrographic network is typically associated with use in hydrology (such as assessment of water resources on a European level, run-off modelling and flood forecasting) and ecological applications. In September 2016, the French and Spanish representatives to the Copernicus User Forum presented a note on Copernicus Reference Data: Proposal for Coordinated Actions with Member States [RD5] to the 11 th Copernicus User Forum meeting of 6 th September 2016, addressing 1 GMES (Global Monitoring for Environment and Security) was the previous name of Copernicus 2 Comprising the 33 member countries of the European Environment Agency (i.e. the 28 European Union member states together with Norway, Switzerland, Liechtenstein, Iceland and Turkey) and the six cooperating countries Albania, Bosnia and Herzegovina, the Former Yugoslav Republic of Macedonia, Montenegro, Serbia as well as Kosovo under the UN Security Council Resolution 1244/99. More information at the EEA website: 3 in contrast to a Digital Terrain Model (DTM), which would provide information on the height of the real earth s surface 4 The previous version 1.0 had been validated and found to overall conform to the requested specifications, see [RD10] 5 Taken from product description at the Copernicus Land portal: 5

6 primarily the two Copernicus in-situ component s pan-european reference data products EU-DEM and EU-HYDRO. The document raises concerns about duplication of efforts between Copernicus and national reference data sets as well as over inconsistencies especially in terms of geometry, creating difficulties for national use of Copernicus services and products and the setting-up of related downstream applications. The note specifically makes reference to Article 5 in the Copernicus Regulation [RD1], and asks for a change in the current practise of producing Copernicus reference data (i.e. EU-DEM and EU-HYDRO datasets); moving away from a currently centralised generation of services to a mix of (i) bottom-up provision and re-use of (appropriately generalised and harmonised) existing national data towards defined technical specifications, and (ii) maintaining the current centralised approach for those Member States which [ ] do not express the will to collaborate in generating Copernicus reference data. In their presentation to the 11 th Copernicus User Forum meeting on 6 th September 2016 [RD7], the French and Spanish representatives further underlined that the EU-DEM and EU-HYDRO datasets exhibit lower data quality than some national level datasets as well as inconsistencies therewith, and that separate maintenance efforts for national and Copernicus reference data are needed. The presentation acknowledged that in case of a bottom-up approach, the data sharing provisions of INSPIRE 6 [RD3] only would not be sufficient to ensure that data can be shared under the Copernicus data and information policy. Furthermore, an example of ES-FR cross-border selection of riversegments intends to highlight that INSPIRE provisions would be insufficient for ensuring pan- European data homogeneity (in terms of geometry and attribution) and consistency with nationallevel data as well as meeting the Copernicus services needs 7. In conclusion, the French and Spanish representatives proposed to establish a convergence mechanism towards consistency between European and national reference data at least for voluntary Member States (MS), and a coordinated bottom-up production process as a second step. In response to the note by France and Spain and subsequent interventions by Member States, the European Commission (EC) provided a reply [RD6], welcoming the note as a valuable source of recommendations for the entity that is entrusted with the cross-cutting in situ coordination, i.e. the European Environment Agency (EEA). Amongst others, the document confirms the importance of the delivery and sharing of INSPIRE compliant national reference data and information, encouraging Member States to further increase efforts for speeding up the process, rather than going beyond the INSPIRE level of ambition on specifications at a stage where Member States are still far from reaching the baseline. Such improved sharing of data would then naturally ease and facilitate the necessary consistency between the national reference data and the Copernicus reference data, reducing the need to make use of other sources. The EC further recommended that the EEA analyses the note and its recommendations to enhance Copernicus access to and application of existing European and national assets including the INSPIRE compliant data and services. This investigation should be taking into account the main criteria for the Copernicus reference data sets: 1) full open and free access; 2) full EU28 coverage (extended coverage: EEA39); 3) harmonised specifications, fit for spatial analysis; 4) timely delivery. 6 Infrastructure for Spatial Information in the European Community 7 The example requires further analysis, as it may be the consequence of applying different thresholds in the hierarchy of river systems, rather than flaw in the INSPIRE provisions.. 6

7 The EC concluded that in case fulfilment of these four criteria would be recognised by EEA at a certain time, national reference data could then feed into the improvement of EU-DEM and EU- Hydro. To prepare this report, the EEA has been supported by a dedicated expert consortium contracted in June 2016 for various issues related to spatial reference data, producing, amongst others, in-situ newsletters, fact sheets, State of Play reports and further analyses on Copernicus service component level. 8 It is important to state that neither the author nor part of the expert consortium have been involved in the production process of the EU-DEM or EU-HYDRO datasets. The mandate and objective of this report is to provide a comprehensive, independent and objective analysis of the EU-DEM and EU-HYDRO requirements, specifications and further upgrade options, for enabling an informed discussion between involved stakeholders. Since there is a considerable legacy of reviews and validations for both datasets, the present report focuses mainly on synoptically evaluating the publically available information from the various reports, documentations and previous analyses 9. This is complemented by further own analyses where required, as well as by information gathered through interviews with relevant stakeholders, Copernicus projects, etc. In essence, this report aims to contribute to answering the question to which extent the current versions of the EU-DEM and EU-HYDRO products could benefit from further upgrade, and whether for such purpose an integration of existing space, in situ and reference data and capacities in Member States would (at least partially) be technically feasible, cost-effective or possible in a timely manner in the sense of the Copernicus Regulation [RD1]. For that purpose, this report focuses on analysing: the service requirements specified for the EU-DEM and EU-HYDRO products, the undertaken product upgrades, as well as the products resulting actual technical and quality specifications (section 2); the level of matching between requirements and specifications, identifying existing issues and improvement options (section 3); the availability of relevant national-level and EEA-39 wide datasets and their specifications as well as their suitability for further product upgrade (section 4); the actual and expected future use of the EU-DEM and EU-HYDRO products by Copernicus services and the broader public (section 5); resulting conclusions and an outlook to the future (section 6). This first complete draft version of the Requirements and Options report is provided as basis for further discussion between main stakeholders. 8 More information at the Copernicus in-situ portal: 9 All direct quotations in this report are marked by text in italics. All reference documents are indicated as [RD..] as listed on p.3/4. Other reference documents except the indicated have not been used for this report. 7

8 2. SERVICE REQUIREMENTS AND PRODUCT SPECIFICATIONS This section provides a comprehensive inventory of the service requirements specified for the EU-DEM and the EU-HYDRO products, the measures undertaken to upgrade them further, and the resulting actual technical and quality specifications. The EU-DEM and EU-HYDRO datasets were initially created between 2009 and 2012 under an EC contract following the open Call for Tender ENTR/2009/27 on Implementation of an Initial GMES Service for Geospatial Reference Data Access [RD8] as part of the GMES Preparatory Actions phase. The general objective of that phase was to support the uptake of GMES services and to prepare the ground for a future legislative proposal on a GMES Programme and associated budget, 10 with a particular view to implement a European initial GMES service for a geospatial reference data service element cross-cutting the different GMES services (Land, Emergency, Security in particular). This had been identified as necessary for taking a step up of the R&D results and GMES precursor activities towards fully operational services, under an open and free access scheme [RD8]. The two datasets, which had been identified as most crucial, were hydrological networks and elevation data for which there is a need to improve both access and quality at European level [RD8]. According to the EC, this need was based on clearly identified gaps: (i) areas for which no national or geospatial regional reference data could be accessed because they were not existing at the required scale or quality or available only commercially; (ii) cases where homogeneous data specifications are required over the full geographic coverage in EEA39 countries [RD6]. In this context, it is worth noting that specifically the INSPIRE Directive [RD3] aims at overcoming such gaps by establishing common specifications, enabling data interoperability and allowing, amongst others, bottom-up data sharing approaches by European Member States. Since the Call for Tender had however been launched in an early stage of the implementation phase of the INSPIRE Directive, and exactly because of the gaps identified, a mitigating approach had to be applied. In essence, this meant the creation of top down reference datasets, in combination with decentralised access to national/regional data where possible taking into account the main criteria for the Copernicus reference data sets: 1. full open and free access, 2. full EU28 coverage (extended coverage: EEA39), 3. harmonised specifications, fit for spatial analysis, 4. timely delivery. [RD6]. EU-DEM The initial Call for Tender [RD8] identified the urgent need for an EU-DEM with continent-wide consistent elevation data, since it was realised in previous consultations that at that time, and following the conclusions from the workshop on European Elevation Data 11, no single data source can provide a fully consistent and complete pan-european coverage, which was considered a sufficient reason to consider the possibility of setting up a GMES DEM service as part of the GMES core Land Monitoring services portfolio. The related tender specifications had therefore requested production of the EU-DEM as a mid-scale digital elevation model along a set of mandatory and optional requirements as summarised in Table 1. Additionally, the tender specifications asked for the elevation data are focussing on the actual bare ground height, meaning, excluding object heights as typically included in a Digital Surface Model (DSM). [RD8]. 10 as was subsequently realised through the establishment of the GMES Initial Operations (GIO) in October 2010 [RD2], succeeded by the establishment of the operational Copernicus Programme in April 2014 [RD1] 11 EU-DEM workshop, Stresa, May 2009 (back to back w. ISRSE-33) 8

9 Table 1: EU-DEM mandatory and optional requirements (taken from [RD10, Appendix] as compiled from [RD8], vertical accuracy corrected) Mandatory requirements Optional requirements Coverage EU27 Extended coverage of EEA38, EEA38 + international river basin districts according to the requirements as set out by the Water Framework Directive, or full wall to wall pan- European coverage Consistency / homogeneity Resolution Accuracies Projections Access conditions Cross border consistency (countries, different data sources etc.) Consistency both with the geometry of the hydrographical pattern and Consistency with the hydrological modelling of (continuity of water flow) Water surfaces burnt in the DEM Horizontal: 1 arc sec (+/-30 m) posting (consistent with 1: scale for other (topographic) data themes); Vertical units: integer meters Horizontal: better than 5 m Vertical: overall accuracy of 5 m RMSE 12 WGS84, ETRS 89 and EVRF2000; geographic coordinates (Lat/Long) Full, open and free access. Minimum variation in Z between 2 adjacent posting values should be properly described in DEM values according to following differentiation (95% confidence): lowland plains: 2m (<10% slopes) ; midlands: 5m (10 30 % slopes); mountains: 10m (> 30% slopes). Vertical differentiated accuracies, corresponding with the differential resolution categories: lowlands: 1 m absolute RMSE; midlands: 2,5 m absolute RMSE; mountains: 5 m absolute RMSE the INSPIRE compliant European projection systems(lcc, LAEA, UTM) national projections/datums As outcome of the tendering process, alternative specifications were accepted by the EC, as summarised in Table 2 below. Specifically the dataset s character, being composed of predominantly DSM data sources, and the lower vertical accuracy, are noticeable modifications compared to the initial tender requirements. Table 2: Summary of EU-DEM specifications as accepted in response to Call for Tender ENTR/2009/27 (taken from [RD10, APPENDIX] as compiled from accepted Technical Proposal) Product Coverage Data Sources Resolution Vertical Accuracy Access EU-DEM EEA38 SRTM & ASTER GDEM (+ topomaps north of 60 N) 1 arc-second (~30 m) +/- 7.0 m RMSE Unrestricted The EU-DEM was produced by the selected commercial service provider as a hybrid DEM, composed through a weighted averaging approach of SRTM 3 arc sec and ASTER-GDEM in combination with Russian topographic maps. The EU-DEM has been additionally edited to ensure that water features are adequately represented. Version 1.0 was released to public upon completion of the GMES Preparatory Action on Reference Data Access (RDA), together with the EU-DEM Statistical Validation Report [RD10]. 12 The EU-DEM Statistical Validation Report [RD10] erroneously lists in the text and in the Appendix, Table A.1 2m RMSE as overall vertical accuracy requested by the Call for Tender ENTR/2009/27, whereas the final (corrigendum) version of the Call [RD8] had actually requested 5m overall vertical accuracy. It had been updated from 2m to 5m during the tendering phase, following a respective Request for Clarification. 9

10 The latter provides the results of an independent validation, undertaken by a GIS consultancy service provider on request of the EEA. The report was published in August 2014, basically confirming the EU-DEM s overall values within specifications, with only a small vertical bias of m and a measured overall vertical accuracy of 2.9 m RMSE, which was in compliance with the agreed specifications (cf. Table 2). More detailed and in-depth findings were obtained under regional, terrain- and LC/LU-related aspects. Due to the relevance for the assessment of the product s current improvement potential, these detailed validation results are discussed more extensively in section 3. The validation report determined improvement potential for the dataset, such as an observed difference in EU-DEM accuracies between the regions north and south of 60 N as the main issue that need to be a target for the planned upgrade of EU-DEM. [RD10]. This has however not yet been implemented and may thus be subject to future upgrade approaches (as further discussed in section 3). Some further upgrade recommendations were subsequently provided by experts from EEA, the EC s Joint Research Centre (JRC), Eurostat and an EEA contractor DHI-Gras, such as for correcting geo-positioning issues, reducing the number of artefacts, improving the vertical accuracy using ICESat as reference and ensuring consistency with EU-HYDRO 2015 [RD11]. Due to these recommendations, the EEA issued a follow-up open Call for Tender during the GMES/Copernicus Initial Operations (GIO) phase as part of the Copernicus RDA activities [RD9], addressing a number of short- to medium-term measures for enhancing the EU-DEM s quality. Several measures were implemented to correct the previously detected issues. A more detailed analysis of the respective improvements of the dataset is given in section 3. The resulting, most recent EU-DEM version 1.1 is publicly available as online viewing service, Web Map Service (WMS) and for download via the Copernicus Land portal. 13 It is provided as contiguous 32-bit (zipped, LZW-compressed) GeoTIFF raster dataset with 25m pixel size and elevation as the only attribute. The dataset is provided for download in tiles of 1000 km x 1000 km size. The EU- DEM version 1.1. has not been separately validated yet. Further improvements, particularly in areas north of 60 northern latitude, are planned to be addressed during the current operational phase of the Copernicus Land Monitoring service [RD13]. Overall, the main areas of use recommended for the EU-DEM by the EEA are [RD13]: Digital Elevation Model of reference in a contiguous dataset for the entire European region. Drainage network generation, river basin, tributary rivers analysis. Flood modelling and flood risk management. Thematic mapping applications for different purposes. Visibility and coverage studies: radio and network coverage, visibility, etc. EU-HYDRO For the EU-HYDRO, the initial Call for Tender [RD8] had requested production of a pan-european hydrographic network, fit to serve as a pan-european reference dataset, along detailed mandatory and optional requirements. It should be composed of line, polygon and node types, constituting a hierarchy of watercourses as a connected and routed network, and including name and key hydrological attribute information (slope, depth, segment length ), at a 1:100,000 (or better) scale resolution for all linear objects and a minimum of 1:250,000 scale resolution for derived polygons such as lakes, catchments, etc. It should encompass rivers, confluences, water surfaces [ ], lagoons and estuaries, dams, cascades, locks, canals and aqueducts, coastlines and shorelines of inland water bodies. In terms of lakes and surface water bodies, virtual centre lines shall connect 13 available at: 10

11 river inlets and outlets. The nodes should consistently indicate river sources, confluences, mouths and endorheic river system ends. Furthermore, [RD8] specified: rivers and canals should be, where relevant, topologically consistent with coastlines, i.e. rivers should end at coastlines. The more detailed specifications for the EU-HYDRO product are summarised in Table 3. Table 3: EU-HYDRO mandatory and optional requirements (compiled from [RD8]) Mandatory requirements Optional requirements Coverage EU27 The EFTA countries (IL, LI, NO, CH) The remaining EEA member state (TR) The 6 EEA cooperating countries (Albania, Bosnia and Herzegovina, Croatia, the former Yugoslav Republic of Macedonia, Montenegro, Serbia ) The other European countries: Andorra, Ukraine, Moldavia, Belarus and the European part of Russia Consistency / homogeneity Resolution Projections Attributes Metadata Topology The continuity of the hydrographic system must be respected in cross border situations (regions, countries ) Underground segments, covered segments or any crossing by artificial constructions shall not provoke in any circumstance an interruption in the network, and shall at least be represented by its virtual centre line, such as to provide the ability of generating a flow network. Typically between 1: and 1: , i.e. a respective spatial accuracy level Between 20 and 50 m. Categorisation of spatial objects may be according to a smaller scale level; however, the geometrical generalisation should rather fit the 1: scale, in order to better fit overlays with ortho -rectified satellite imagery and LC/LU datasets. Usage of ETRS 89 as geodetic datum Usage of spatial data according to following projection systems: o Lambert Azimuthal Equal Area coordinate reference system of 2001 [ETRS-LAEA], for statistical analysis and display. o Lambert Conic Conformal coordinate reference system of 2001 [ETRS-LCC] for conformal pan -European mapping at scales smaller or equal to 1:500,000. o Transverse Mercator coordinate reference systems [ETRSTMzn], for conformal pan-european mapping at scales larger than 1:500,000. Feature Type: River, lake, canal, ditch, coastline, shoreline, spring, confluence, mouth Navigability: Is the hydrographical feature navigable? Origin/creation: Official name( s) in national language(s) Area of length: Area in km2; Length in km The related metadata will be available for distribution via a data catalogue service which will be part of the INSPIRE geo -portal within the Commission, and which will be hosted by JRC/ESTAT. Metadata shall at least fulfil the requirements as defined by the regulation 1205/2008/EC implementing Directive 2007/2/EC of the European Parliament and of the Council as regards metadata The geographic data has polygon, line or point topology, depending on the reference data theme. Data themes that have polygon, line or point topology have an attribute record for each single or multipart polygon, line or point. Topological rules for lines: Smaller scales may be added on top access to national/regional reference data at a higher scale range, in view of ad hoc access for emergency services. the INSPIRE compliant European projection systems(lcc, LAEA, UTM) national projections/datums Drainage type: Perennial, intermittent, episodic Hierarchy: Place in the hierarchy of drainage network (1st, 2nd, 3rd, 4th order) Operational status: In use, planned, abandoned Shore-, coastline construction type Languages: Language of name(s) in ISO 639 code Country Code: ISO 3166 country code of feature 11

12 Access conditions Mandatory requirements o Lines must not self intersect or self overlap (exceptions might be allowed for certain feature classes, e.g. roads) o Nodes must be covered by lines, i.e. the position of nodes must be identical with the position of endpoints of lines. Topological rules for polygons: o Polygons may not overlap, i.e. their boundaries may not intersect with boundaries of the same and with other polygons. o Boundaries of neighbouring polygons have the same set of coordinates, within the specified resolution. o Lines must not have pseudo -nodes, the boundaries should not be unnecessarily subdivided. Full open and free access. Optional requirements The EU-HYDRO dataset was produced by the same commercial contractor as the EU-DEM product, through computer-assisted photo-interpretation of HR optical satellite imagery of the reference year 2006, complemented by parts of a modelled drainage network with catchments and drainage lines, as derived from the EU-DEM v1.0. Upon completion of the GMES Preparatory Action on Reference Data Access, a beta version of EU-HYDRO was created, which remained however available only internally at the EEA. 14 In order to address both, remaining technical issues and new user demands, the EEA subsequently asked in a follow-up RDA Call for Tender [RD9] during the GIO phase for upgrade of the EU-HYDRO product alongside the upgrade of the EU-DEM. The purpose of this upgrade was enhancement in quality and enriching of the datasets with new features, within the main objective of providing these reference datasets fit for use by the Copernicus services [RD9]. The upgrade was produced on the basis of VHR optical satellite imagery of the reference year 2012, and upstream, beyond the interpretability of hydrography on satellite imagery, complemented with parts of a modelled drainage network as derived from EU-DEM v1.0. These updates resulted in the most recent EU-HYDRO public beta version 0.9, replacing the previous (non-public) EU-HYDRO beta version. It is made available on a full, free and open basis to the public as online viewing service, Web Map Service (WMS) and for download via the Copernicus Land portal. 15 Data are provided in ESRI File Geodatabase format with 12 feature classes, compatible to shapefile format, with the coordinate reference system ETRS89-LAEA [RD12]. The EU-HYDRO public beta version is currently under validation. The improved river network is recommended to be used at a 1:30,000 scale resolution for linear objects and a minimum 1:50,000 scale resolution for derived polygons [RD14], such as catchments and lakes. The Minimum Mapping Unit (MMU) is one ha (10,000 m²). 14 More information is given at the Copernicus Land portal: 15 available at: 12

13 3. REVIEW OF SPECIFICATIONS VS. REQUIREMENTS; IMPROVEMENT OPTIONS This section provides a review of the level of matching between requirements and actual specifications (including the upgrade improvements implemented) for the most recent versions of the EU-DEM and EU-HYDRO products, as well as an inventory of identified remaining issues and possible improvement options. This assessment is presented for EU-DEM and EU-HYDRO separately: EU-DEM As an outcome of the tendering process, some alternative specifications as compared to the initial requirements formulated in the open Call for Tender [RD8] were accepted by the EC in 2009, specifically for the EU-DEM. Most noticeably, the specifications of vertical accuracy and DTM vs. DSM character were relaxed, with resulting certain limitations in the usability of the EU-DEM for specific land surface modelling and hydrological applications until today, as found e.g. by Weissteiner et al [RD17]. A systematic review of the matching between actual specifications of the EU-DEM (version 1.0) versus the requirements was undertaken by the report on EU-DEM Statistical Validation [RD10] in August 2014, using ICESat measurements as continental-scale reference elevation data. It documented a relatively low bias of m and an overall fundamental vertical accuracy of 2.9 m RMSE (corresponding to an LE95 16 of 5.69 m) in short- or non-vegetated areas with low relief intensity, which meets the accepted general specification of 7m RMSE (cf. Table 2). Particularly high deviations were found for northern countries such as Iceland (9.41 m RMSE), Sweden (7.41 m RMSE) and Norway (5.75m RMSE), which was explained by the lack of SRTM data and hence the heavier reliance on ASTER GDEM and Russian topographic maps in the composition of the EU-DEM north of 60 N. Accordingly, the measured mean vertical accuracy was 2.23 m RMSE (4.37 m LE95) south of 60 N, and 5.19 m RMSE (10.18 m LE95) north of 60 N, confirming the systematic nature of the issue in all areas north of 60 N. The report also investigated the influence of land cover (specifically forest) and slope on the vertical accuracy, observing that the EU-DEM becomes a less reliable measure of ground topography as the terrain slope becomes steeper and the density of the tree cover increases. [RD10]. Specifically slopes were shown to cause significant imprecisions in the vertical accuracy. North of 60 N, samples with slopes < 10% showed a vertical accuracy of 5.53 m RMSE (10.83 m LE95), samples with 10-30% slope 8.45 m RMSE (16.56 m LE95) and samples with > 30% slope m RMSE (21.16 m LE95). The report concluded suggesting, that the observed difference in EU-DEM accuracies between the regions north and south of 60 N is the dominating issue that need to be targeted for the planned upgrade of EU-DEM [RD10]. Subsequent additional investigations of EU-DEM upgrade requirements by experts from, EEA, the EC s Joint Research Centre (JRC), Eurostat and a specialised EEA contractor DHI-Gras identified a need to address also the following issues [RD11]: Ensure proper fixing/alignment of coastline/islands delineation. Fixing river step downs (ensure correct hydro-enforcing). [ ] obtain, use and merge DEM for Scandinavian countries. 16 Linear Error at 95% confidence level 13

14 [ ] rework EU-DEM such that a reasonable match between catchments [ ] and EU-Hydro is achieved. [ ] Additionally, measures for compensating the abovementioned vertical accuracy bias using ICESat, and for generally reducing the number of artefacts were suggested [RD11], since a low number of contained artefacts is commonly considered an important quality factor of DEMs. Artefacts can regularly occur in DSMs due to the sensors physical properties and the related processing techniques, typically in rugged terrain or lowland flat areas, unless specifically corrected. Typical artefacts are so-called pits, spikes, mole runs or step anomalies. The subsequent EU-DEM upgrade to version 1.1 has addressed several of these enhancement recommendations, as summarised in the EU-DEM Upgrade Documentation EEA User Manual [RD11]. More specifically, the following corrections and improvements were made in the frame of that upgrade by the awarded contractor: 17 systematic correction of geo-positioning issues (found and corrected for Malta and Lampedusa islands); elevation bias adjustment with ICESat; 18 screening and removal of artefacts, including the presence of blunders (i.e. negative or positive anomalies); more than artefacts have been detected and corrected; consistency with the upgraded version of EU-Hydro, in order to produce a better river network topology. Ensuring consistency with the upgraded EU-HYDRO product included several further individual aspects [RD11]: Consistency of the coastline with the EU-HYDRO coastline, including the removal of DEM values outside the EU-HYDRO coastline. Use of the EU-HYDRO coastline to smooth the gradient to the coast in flat regions. Burning of EU-HYDRO water bodies to set EU-DEM to the minimum height inside the water body, smoothing the boundaries. Additional to the above corrections, the awarded contractor had actually offered an option for inclusion of national datasets over the Spanish territory and possibly other countries willing to provide access to national datasets [RD6], which would actually have been in line with the more recent suggestions by France and Spain to the Copernicus User Forum [RD5]. However, according to [RD6], this option had to be abandoned for budgetary reasons, and priority had to be given first to a correct fulfilment of the requested core improvement tasks on both, EU-DEM and EU-HYDRO products. Hence, some known issues had to remain un-addressed in the version 1.1 upgrade of the EU-DEM, and should thus be regarded priority for any next upgrade endeavour. Considering the respective impact and effort, a two-stage approach is suggested, fully respecting the principles requested by [RD6] 19, and taking care to maintain and further improve consistency with the EU-HYDRO product and avoid introducing new artefacts: 17 As summarised at the Copernicus Land portal: 18 The ICESat (Ice, Cloud, and land Elevation Satellite) was a NASA satellite mission launched in 2003, for measuring ice sheet mass balance, cloud and aerosol heights, land topography and vegetation characteristics. 19 1) full open and free access; 2) full EU28 coverage (extended coverage: EEA39); 3) harmonised specifications, fit for spatial analysis; 4) timely delivery. 14

15 Mid-term: Integration of meanwhile freely available, better-quality national DEMs (converted to EU-DEM specifications), with first priority given to Scandinavian and northern countries (not precluding further ones if feasible); Long-term: Careful incorporation of further, newly available and European-wide consistent DEM data sources with adequate spatial resolution, in areas south of 60 N. The available respective DEM datasets and their specifications are discussed in section 4. EU-HYDRO Upon completion of the GMES Preparatory Action on Reference Data Access, a beta version of EU- HYDRO was created. Due to unresolved technical issues, this remained however available only internally at the EEA. 20 In order to properly address these technical issues, as well as further, newly emerged user demands, the EEA subsequently asked in the GIO-phase follow-up RDA Call for Tender [RD9] for further upgrade of the EU-HYDRO product, alongside the EU-DEM upgrade. The overall aim was to arrive at a fully consistent database on surface hydrography [ ], fit to serve as a European reference dataset in terms of completeness, consistency, coherence, semantics, topology and metadata [RD9], before issue of the dataset to the public. A detailed list of upgrade requirements was provided in the respective Call for Tender s Technical Specifications document [RD9], which is not reported here at full length. It should be highlighted though that specific emphasis was laid on preserving consistency between the EU-DEM and the EU-HYDRO products through final transfer of the adjustments into the Digital Elevation Model (DEM) and maintaining consistency between river network and corresponding catchment areas [RD9]. The Copernicus Land portal summarises the quality enhancement and thematic enrichment steps that have actually been implemented in this EU-HYDRO upgrade: 21 integration of the relevant information from the drainage network into the river network with the result of one river network containing common properties of both source networks; improvement of the coastline; correction of geometry and topology errors; correction of Strahler codes in certain upstream parts. According to [RD14], significant geometry corrections have been achieved for coastlines, transitional waters, inland waters, dams, culverts, and the general river network. Additionally, the number of river courses, inland water bodies, culverts and islands was increased. Improvements were also reported for topological relationships and consistency. In addition to the initial river network retrieval from 20m spatial resolution satellite imagery and the drainage network modelling from the 25m spatial resolution EU-DEM, the feature data extraction was upgraded through photointerpretation of 2.5m spatial resolution VHR optical satellite imagery, primarily from the reference year 2012 (± 1 year) 22 at scales between 1:30,000 and 1:50,000 [RD14]. Furthermore, codes of the national surface water bodies as reported by Member States under the Water Framework Directive [RD4] were integrated, allowing linkages between EU-Hydro public beta version and the respective national datasets, thus ensuring compliance between the Pan- European and the national datasets, as required by countries. 23 This inclusion of national-level 20 More information is given at the Copernicus Land portal: 21 see 22 ESA Data Warehouse ( CORE_03 dataset, see [RD15] 23 see 15

16 codes of hydrographic bodies is deemed to technically enable a bridging between the spatial data held by or on behalf of the public authorities in the MS for the performance of their public tasks and EU-hydro [RD6], as well as providing a good basis for enabling a future consistent updating of the EU-HYDRO product in that respect, maintaining compatibility with Member States data and avoiding duplication of efforts. At the time of this report s preparation, the quantitative validation of the EU-HYDRO public beta v0.9 dataset was still ongoing. It is currently undertaken by a team of service providers contracted by the EEA under a contract for validation of the GIO/Copernicus Land Monitoring and RDA products. 24 The EU-HYDRO river network and a set of its associated features are validated in a pan- European sampling approach, addressing nearly 2000 sample cells of 1km x 1km size. A visual interpretation and assessment of the EU-HYDRO river network in the sampling cells is performed using Very High Resolution (VHR) satellite imagery from the reference year 2012 (± 1 year) with 2.5m spatial resolution, as provided by the ESA Data Warehouse. Additional topological checks are applied. The validation specifically checks for omission, commission and attribution errors of dataset features, and the assigned Strahler level and attributes of river segments (such as flow direction). Final results are scheduled for end of the first quarter Preliminary partial validation results do however exhibit some trends already: only few feature and attribution errors were found in the river network of this updated dataset, and the positional accuracy, although not explicitly part of the validation, appears to be adequate as compared to the image data basis. However, these findings are to be consolidated and confirmed by the respective final report. Without conducting a detailed assessment (which is beyond the scope of this report), it appears from random visual checks that due to the use of 2.5m VHR imagery indeed an improvement of the feature data extraction and an increase of the number of hydrographic objects has been achieved. Geometric and topological issues seem to have been generally reduced; specifically the coastline issues appear improved. More detailed checks would be needed for assessing e.g. the overall improvement of the river network through incorporation of the modelled drainage network, etc. Except corrections of possible remnant issues and future continuous updating of the established linkage with national-level hydrographic data (as described above), further evolution of the EU-HYDRO dataset appears primarily meaningful in combination with a further upgrade of the EU-DEM, through either: incorporation of better-quality national and/or other, meanwhile freely available consistent DEMs of better spatial resolution (as already stated for the EU-DEM), and/or taking steps for evolving the EU-DEM more towards a DTM (however, this would entail a major reconsideration and reorientation of the EU-DEM nature and specifications). Both options would directly allow improving the spatial accuracy and feature density of derived drainage networks, small river basin delineations, etc., specifically in low-relief regions. The related possible options are discussed in sections 4 and EEA contract no. 3436/R0-COPERNICUS/

17 4. AVAILABILITY OF RELEVANT DATASETS This section provides the results of a detailed investigation of the current availability, specifications and suitability of both, relevant national-level datasets, and other European-wide datasets, for further enhancing the quality of the EU-DEM and EU-HYDRO products. As discussed in section 3, the conducted review of currently available feasible options for further upgrading the two products points actually into the same direction: enhancing the spatial precision and quality of the EU-DEM first, with highest priority. Therefore, this section focusses on reviewing suitable options offered by national-level DEMs and other, European-wide DEMs that have newly entered into the public domain since the creation of the EU-DEM. Suitability in that sense is defined by the previously given overarching conditions of [RD6], interpreted as follows: 1. full, open and free access, including the necessity to pass this access level on to a future (to-be) upgraded EU-DEM; 2. full EU28 coverage (extended coverage: EEA39), understood as being achievable in principle also through consistent combination of some individual suitable data sets towards common specifications (cf. 3.); 3. harmonised specifications, fit for spatial analysis, i.e. fulfilling all the technical specifications of EU-DEM and EU-HYDRO in a consistent and spatially explicit manner, maintaining the products character and preserving the linkage and consistency between the two datasets; 4. timely delivery, basically meaning datasets which are available now. National-level DEMs Substantial quality issues of the EU-DEM are recognised in European areas north of 60 N, i.e. Iceland, Norway, Sweden and Finland. Therefore, an integration of freely available, better-quality national DEMs appears first priority there. Since the first creation of the EU-DEM, these four countries have all made suitable national DEMs freely available. The following Table 4 provides a comprehensive overview of the respective national DEMs characteristics and specifications. Table 4: Freely available national DEMs in European northern countries (status: Feb. 2017) Country Dataset Description Spatial Vertical resolution accuracy Iceland IS 50V Based on topographic map contour lines Norway Sweden Digital terrengmodel Provided by Statens Kartverk GSD- High quality, since Höjddata, grid aggregated from original 1m DSM (from LIDAR & aerial imagery) Character Coverage CRS 25 20m DTM whole Iceland 10 m ± 2.3m - ± 6.4m 50m Finland Korkeusmalli Based on topographic maps contour lines; partially on 2m DEM 10m DTM Standard DTM error 1m (in hilly terrain) 1.4m on average DTM whole Norway whole Sweden whole Finland ISN93/ ISN2004 EUREF89, NN1954 SWREF99T M, RH2000 ETRS- TM35FIN License Open Data Open Data Open Data Open Data License conditions of all four datasets consistently allow full, free and open use of the data. Due to their uniformly better (original) spatial resolution 27 than the EU-DEM, a conversion towards EU- 25 Coordinate Reference System (CRS) 26 Also a 2m-resolution DSM based on laser-scanning data is available, however only under commercial conditions 27 The 50m Swedish DEM exhibits actually much better performance (in terms of characteristics and spatial representation of details) than the 50m aggregated spatial resolution suggest, since the data are derived from an originally 1m-resolution DEM 17