Introduction

The eda model predicts the density of yellow eel using attributes extracted and projected on the river network C. Briand et al. (2018). This model uses then a silvering model to predict the number of silver eels departing from the streams to the ocean Beaulaton, Briand, and Chapon (2015).

In 2012, the second version of EDA has been built on the ccm Vogt et al. (2007) Vogt et al. (2003). One of the main problem using the ccm was that it was not covering the whole water surface Jouanin et al. (2012), and a hack used in Ireland was to raise the estimates of water surface using the water surface of the total river network and waterbodies (including lakes). This let to estimates of biomass close to those estimated by the Irish model de Eyto et al. (2016). However, this raising was done at the EMU (eel management unit) scale which always correspond to very large territories.

In 2018, EDA was built on antoher river network, where the width of the stream is predicted Pella et al. (2012). The lack of inclusion of true water surface in the RHT explains the mismatch betwen productions of silver eels predicted by the model and independant observation obtained from various surveys of silver eel migration. The largest mistach between these two productions has been found in the basins where a large part of the production was stemming from lakes or reservoir such as the Frémur (P. Laffaille et al. (2003), A. Acou et al. (2008)) where part of the catchments is a reservoir enpounded by a large dam or Souston which is a small stream including many large lakes.

This, and the fact that the most productive environment are not covered by EDA L. Beaulaton and Briand (2018) has led us to try to find a way of inserting the water surface bodies. We describe a method to join the river network and the waterbodies using different data sources in the different countries. We also propose a method to remove the surface bodies of the streams when they are overlapped with surface water bodies.

Method

France

The source of data in France is the BD TOPO® Hydrographie which corresponds to the stream, water surface and reservoirs in France. The layers can be downloaded here. Among the attributes of the layer, we find :

  • the hydrographic code of the stream
  • the nature of the layer
Nature Included
Canal (channel) Yes
Réservoir-bassin piscicole (fish pond) No
Réservoir-bassin d’orage (storm surge pond) No
Conduit buse (duct) No
Ecoulement naturel (natural flow) Yes
Retenue-digue (dike reservoir) No
Lac (lake) Yes
Retenue (reservoir) Yes
Glacier, névé (glacier, snow sheet) No
Lagune (lagoon ) Yes
Retenue-barrage (reservoir-dam) Yes
Mare (pond) No
Ecoulement canalisé (channelled flow) No
Retenue-bassin portuaire (reservoir, harbour) No
Plan d’eau de gravière (Gravel pit pond) No
Plan d’eau de mine (Mine pond) No
Inconnue unknown No
Marais (marshes) Yes
Réservoir-bassin (reservoir, pond) Yes
Estuaire (estuary) Yes
  • The salinity
  • the code of the poind
  • the name
  • the Persitence of flow

The french part of the SUDOANG river network database is based on the RHT Pella et al. (2012). In particular the RHT is also built on unit basins, this layer has been used to split the polygons of water surface per basins.

The data are reprojected to the ETRS89-extended / LAEA Europe which can be used at the scale of Europe.

We use the rn and rna tables computed within the sudoang projects. Of particular interest to us are the wettessurfacem2 and wettedsurfaceotherm2 fields. The wettessurfacem2 corresponds to the surface of streams that is not covered by a watebody. The wettedsurfaceotherm2 corresponds to the sum of the areas of polygpons clipped within the unit basins.

Rn table
gid
idsegment
source
target
lengthm
nextdownidsegment
path
isfrontier
issource
seaidsegment
issea
geom
isendoreic
isinternational
country
rna (river network attributes)
idsegment
altitudem
distanceseam
distancesourcem
cumnbdam
medianflowm3ps
surfaceunitbvm2
surfacebvm2
strahler
shreeve
codesea
name
pfafriver
pfafsegment
basin
riverwidthm
temperature
temperaturejan
temperaturejul
wettedsurfacem2 (1)
wettedsurfaceotherm2 (2)
delta
gamma
density
nyellow
pyellow150
pyellow150300
pyellow300450
pyellow450600
pyellow600750
pyellow750
nsilver
nsilver300450
nsilver450600
nsilver600750
nsilver750
turbinemortalitynsilver
turbinemortalityrate
lengthriverm
emu
cumheightdam
riverwidthmsource
DROP TABLE if exists france.surface_hydrographique_bdtopo_unitrht;
CREATE TABLE france.surface_hydrographique_bdtopo_unitrht as
            select  
              surface_hydrographique_bdtopo."ID" as id, 
              surface_hydrographique_bdtopo."CODE_HYDRO" as code_hydro, 
              surface_hydrographique_bdtopo."CODE_PAYS" as code_pays, 
              surface_hydrographique_bdtopo."NATURE" as nature, 
              surface_hydrographique_bdtopo."PERSISTANC" as persistance, 
              surface_hydrographique_bdtopo."SALINITE" as salinite, 
              surface_hydrographique_bdtopo."COMMENT" as commentaire, 
              surface_hydrographique_bdtopo."ID_P_EAU" as id_p_eau, 
              surface_hydrographique_bdtopo."ID_C_EAU" as id_c_eau, 
              surface_hydrographique_bdtopo."ID_ENT_TR" as id_ent_tr, 
              surface_hydrographique_bdtopo."NOM_P_EAU" as nom_p_eau, 
              surface_hydrographique_bdtopo."NOM_C_EAU" as nom_c_eau, 
              surface_hydrographique_bdtopo."NOM_ENT_TR" as nom_ent_tr,
            'FR'||gridid as idsegment,  
            st_intersection(r.geom, the_geom) geom
             from france.bvunitaire3035 r 
            inner join france.surface_hydrographique_bdtopo  
            on st_intersects(the_geom,r.geom) 
            where "PERSISTANC"='Permanent' 
            AND "NATURE" in ('Lagune','Estuaire','Ecoulement naturel','Canal','Retenue-barrage','Réservoir-bassin','Marais','Lac','Retenue');--723627 rows affected, 26:29 minutes execution time

CREATE INDEX  surface_hydrographique_bdtopo_unitrht_geom_gist ON france.surface_hydrographique_bdtopo_unitrht 
 USING gist (geom);
 COMMENT ON TABLE france.surface_hydrographique_bdtopo_unitrht is 'Table issued from bd_topo hydro cut by unit rht basins, the 
 type of water surface considered is permanent surfaces with natures in lagune, estuaire, ecoulement naturel, canal, retenue-barrage,
 reservoir-bassin, marais, lac, retenue';
**River segments from the RHT (yellow dashed line), units basin from rht (in grey), natural stream (écoulement naturel) in blue, canals (in green), and ponds. Marais Poitevin in France.**

River segments from the RHT (yellow dashed line), units basin from rht (in grey), natural stream (écoulement naturel) in blue, canals (in green), and ponds. Marais Poitevin in France.