Philippe Crouzet EEA With support from Walter Simonazzi (ETC/LUSI) and EEA IDS staff

Rationales for a reference GIS for Hydrosystems. The ECRINS developmentEuropean Catchments and RIvers Network System Philippe Crouzet EEA With support from Walter Simonazzi (ETC/LUSI) and EEA IDS staff

Reference GIS for hydrosystems is prerequisite to producing accurate and representative assessments as well as offering host to legal reporting. • To this end, and considering the strong relationships between land, water and economy the system must consist in: • Calculable and nested catchments. • Drained by relevant, nested and routed rivers, • Completed by standing bodies (lakes, dams), • Related to monitoring and usage points • However rivers lakes, dams and points are geographical objects than can be seen, whereas catchments are concepts that need to be modelled.

River fragmentation (SEBI component): The Loire example (all known dams) • Historical development • Why not applying at the EU level? • Model exists and is validated, • Dams are placed (Eldred2) • Because no calculable river system!

WWTP Sea Dam River Watershed land

Production starts from reality, e.g. rivers from maps • What geographers see and draw is not what is needed for building reference system. Requirements are to: • Clarify conceptual model, mitigated by data source affordability • Identify objects: give usable and unique IDs • Group by logical consistency: set watersheds • Select what is important: choose homogeneous levels, • Relate what relates to what: connect, • Organise dependencies: route • Make it understandable and improvable: document

Conceptual modelling • Goals: • Geometrical accuracy, homogeneous and comprehensive coverage, • Complete topology • “doable” with existing data sets and free of charges • Stepwise model development (foreseeing Inspire implementation) • Designed solution • Operational scale 1/250k • Based on “functional units”: the Functional elementary catchment (FEC) • Made from CCM JRC, by post-processing and assimilation of other sources (ERM, Eldred32, etc.)

Concepts and production method: data source selection

Solving CCM intrinsic problems • CCM is a modelled catchment and network system: • Smallest objects possibly inaccurate because DEM resolution and ArcHydro model, • Being a model, it is fully connected and calculable, but objects are defined by the model, not by the envisaged uses • Being a model it lack gazetting • Being calculable, it can be improved by data processing, provided solutions are defined and implemented and recomputed in an improvement cycle • Completely free of charges

Solving River Basin Districts oddness • Districts are administrative management areas presented as if they were river basins. When used to build a river system • They extend over sea, • They don’t respect basin watershed • They show large “holes” (corrected in further versions) • Hence, adjustments are needed-> Functional RBDs

Building the FECS • Elementary CCM catchments are very small, numerous (~2 millions), and not directly usable because the large range of sizes (few ha to 100’s km2) • FEC making consisted in implementing rules of aggregation into: • Coastal basins and • Continental FECS • by building and populating adequate envelopes: the algorithm is based on Strahler levels, cumulated size, presence of basins and scoring criteria inside larger catchments • Both are then merged into a FEC layer

Clipped (limited by shoreline) international RBDs The Functional RBDs contain the large basins Large basins (the FEC largest envelopes) Aggregation watershedss • Compute ”Functional RBDs” from the reported RBDs: • Collection of FECS belonging to homogeneous basins inside the RBD • Difficult process because high heterogeneity of RBD delineations • Sub-units not ready enough yet • Sub-catchments made to match Functional RBDs where RBDs exist

Sub-basins (largest aggregation catchments) FRBDs reported in violet. Target 10,000 km2, 1470 objects Aggregation watersheds • Target is to cluster FEC (mean size ~100km2) into larger watersheds (~10,000 to 35,000 km2 for example) • Being fully consistent with larges basins AND RBDs, • Having hydrological relevance • Which design and production are affordable • Design algorithm derived from FEC envelopes making, adjusted: • No natural envelopes, • Larger target size makes results more sensitive to tuning

Types of relationships exemplified: lake on the main drain, lake out of main drain, endoreic lake Lakes and dams • Lakes pose serious problems because not linked to the rivers or the watersheds: • CCM source quite homogeneous, locally inaccurate • ERM source extremely heterogeneous and incomplete • A single data set created (~180,000 lakes) by merging and connecting to the outlet river • Experience suggests high difficulty in relating lakes and rivers by nodes, because conflicts between topology and geometry. River segment preferred since more operational.

Dams • Data sources: • No CCM data source, • ERM source heterogeneity beyond imagination and not documented (only point / multi line, no ID, no name, etc.) • Eldred2 data source only for large dams, not totally geolocalised. • Very complex processing carried out to sort out ERM dams into a single feature class and merging with Eldred (with priority to Eldred2) • Available end May • With WFD reporting, source for lake documentation

Documenting and data • Documents are issued with β versions of datasets • Report on the principles and the making of FECS, disseminated with FECs v2 β, • Report on the main drains disseminated with main drains v1 β • Report on aggregation catchments done • Report on lakes and dams under preparation • Disseminated data bases: • CCM Source is 18 databases for catchments, 18 for rivers and nodes, 2 summary databases (40 DB) that require 96 intermediate processing databases (reallocated, export, result and service) plus application. • ERM source is 2 lakes layer, 4 for dams, 2 for rivers • Eldred2 unique source • Results are in 1 database for FECs, 1 for river and nodes and 1 summary (Functional RBDs, aggregation catchments, etc), 1 for lakes and 1 for obstacles (possibly merged if possible), in CIRCA (IG: Water accounts and river fragmentation).

Achievement (16 /05/2009)

Perspectives • The β versions are under processing for making the « broad-brush » water accounts, • Sorting out the whole set of rivers by FEC minus main drain is data source for « Small rivers » assessment, • FECs connectivity and main routing is data source for stratified assessment of water quality, etc.

Immediate applications • WFD “main rivers” are defined as those draining more than 500 km2 (or any other combination). • The response is instantaneous: • And can be use as selection mask to extract data from other layers, if greater precision is required, or complementary attributes

Applications for the next SoER 2010 • Populating data • Population per catchment / per cities withinn catchments • ECVs per catchment (done for summary data ATEAM), on going for MARS data) • Applications • Water asset accounts / water balances underway • Catchment stratification by drivers, altitude, etc. possible -> assessing water quality trends vs. drivers underway, (cf. 2007 methodology) • River fragmentation by dams underway for amphibiotic (SEBI, liaising with hydropower) • Small rivers issue: risks of dry-out • Support for WFD reporting: underway

Envisaged developments • Currently: • Seek for minor errors correction, and process a β3 version end 2009 • Correct errors related to CCM model (e.g. karstic areas) • Planned • Integrate WFD reports to feed-back quality and inform on reporting issues • Stepwise gazette the rivers names and reprocess routes • Prepare a “CCM3” based ECRINS2 in 2011, with systematic input from geographical data at the source of hydro modelling

Pending issues (aggregation watersheds) • When lowering the area target, too large catchments become a problem, • “Too large” catchments are those that cannot be exploded by the simple algorithm used (selecting Strahler levels 6/7) • Supplementary algorithm to cluster differentially Strahler level 5 in underway.

Thanks for your attention Data on CIRCA (ask for IG inscription) mailto:philippe.crouzet@eea.europa.eu

Philippe Crouzet EEA With support from Walter Simonazzi (ETC/LUSI) and EEA IDS staff