Nicolas Flipo Pierre Labadie Laurence Lestel Editors

Time trajectories of key environmental issues, from the original organic and microbial contaminants of the past to today's emerging contaminants, are covered. Some of the identified trajectories within the Seine basin will be presented in section 3 of this chapter.

The Hydrological Features of the Seine River Basin

The main tributaries of the River Seine are the River Yonne, River Marne, and River Oise. 1 The hydrological network (Strahler orders 3–7) of the Seine and the main pilot sites studied.

Fig. 1 The hydrological network (Strahler orders 3 – 7) of the Seine and the main experimental sites that have been studied

Evolution of the Basin Population

The PIREN-Seine program focuses mainly on the Seine river basin upstream of its estuary, the latter also studied by the long-term program Seine-Aval, which started in 1995 [36]. The main experimental sites studied in the Seine basin and the etching sites presented in Ayrault et al.

Fig. 3 Population density of the Seine basin in 1901, 1954, and 2015

The Land Cover

Industries and Navigation

This work is complex, as both water and river systems are at the same time a resource, an economic good and a cultural and symbolic asset, subject to different regulations according to these different functions. Each function generates distinct actors or sets of actors and is perceived differently by each of these actors according to multiple and changing reading networks over time.

Circulation of Material Within the Basin

The opening of the biogeochemical cycles due to several factors has led to more systemic approaches that combine the following pathway components: (1) condition indicators; (2) controlling factors and pressure indicators, generally economic; and (3) a set of social indicators, such as scientific knowledge and social awareness, inclusion of issues on the political agenda, environmental studies, and regulatory and technical responses. Mass balances at the size of the Seine river basin were carried out for nitrogen [58], non-ferrous metals [59] and polycyclic aromatic hydrocarbons (PAHs) [60].

Fig. 5 Schematic circulation and storage of material within an impacted river basin: material ﬂ ow within the river basin territory and its leaks into the aquatic system (based on [53, 54])

Multiple Long-Term Trajectories of River Control FactorsFactors

Thanks to the archives of the Ponts et Chaussées engineers [48], a cartographic database of the river course and its corridor has been established, showing its evolution since the end of the 18th century. Comparison of pressure/response trajectories shows a time lag, sometimes several decades, characteristic of each problem [42].

Trajectories of River State and Societal Response to River IssuesIssues

The next phase is a period of accelerated deterioration of the aquatic environment and of water resources (AB, stage 2), often faster than population growth in the catchment, which first reaches the level of water quality (WQC1) where water resources are impaired, often followed by a very poor level of water quality (WQC2). The duration of the moderate environmental degradation (ED1) from the societal perspective is defined here as more than WQC1, and the duration of severe degradation (ED2) as more than WQC2 (Fig.7).

Evolution of Main Research Themes

Present Structuration of the PIREN-Seine Research ProgrammeProgramme

Lestel L, Eschbach D, Meybeck M et al (2020) The evolution of the water bodies of the Seine basin through historical maps. Gateuille D, Gaspery J, Briand C et al (2020) Mass balance of PAHs at the scale of the Seine Basin.

Fig. 10 Main research themes mobilized to describe, understand, and model the Seine River basin and its social interactions, presented in a spatio-temporal diagram

Transformations of Seine Water Bodies in the Early 1800s and Their Drivers

In the rest of the basin, other ponds had been constructed since the Middle Ages, mostly for fish production [25]. In the alluvial plain of stream orders 3-4, an artificial network of ditches was used for centuries to flood grasslands when necessary [25].

Fig. 1 Schematic presentation of the Seine River basin and its main tributaries (orders 6 – 7) with zooms on speci ﬁ c man-made physical transformations

Current State of the Seine River Water Bodies

Finally, their analysis provides quantitative information on the condition of the river and its associated watersheds and their dynamics over the past two centuries (Fig. 2). A brief overview of the history of the cartographic documents of the Seine River and their critical analysis is given first.

Fig. 2 Schematic steps of the analysis of historical cartographic documents on water bodies to quantify the their morphology, uses and water works as well as aquatic habitats and their dynamics

The Inventory and Critical Analysis of River Maps

These processed documents related to the rivers of the Seine basin have been stored in an open access database (ArchiSeine) (Box 2), which complements the digitized open access historical maps Geoportail established by the IGN (Institut Géographique National). The law of 19 July 1837 to improve the navigation of the Seine led to the planning of the Seine by the Ponts et Chaussées engineers and the construction of the first set of six locks on the Seine.

Fig. 3 Main sources of historical cartographic documents on the Seine River used in quanti ﬁ ed trajectory analyses

General Use of Maps to Document River Environmental Changes

The Seine River Basin is covered by a large variety of maps (Fig.3), in terms of spatial coverage, from local to basin-wide (65,000 km2) spatial scales, spanning the last 200 years. The deepening of the river and the re-profiling of the bank seen on bathymetric maps (C) (e.g. Vuillaume, Fig.4e) leads to the loss of habitat areas and diversity of fish.

Fig. 4 Examples of ﬂ uvial elements represented on historical maps and listed in Table 1 (A – Q)

Stream Network Modi ﬁ cation on the Versailles-Saclay Plateau (1670 – 1860)

Man-Made Heterogeneity of the Floodplain

In the 1970s, the hydrological dynamics of the Bassée were also influenced by the operation of two large reservoirs (Aube and Seine Reservoirs; see Fig.1): the low Fig. Only patches of the original riparian forest remain between the sand pits and the agricultural areas [©La Pérouse 2005].

Fig. 6 Aerial photograph of the Bassée ﬂ oodplain, upstream of the Seine-Yonne con ﬂ uence, showing the multiple sandpits, generally ﬁ lled by groundwaters, and the straightened, deepened and dredged navigation channel with its levees and dikes

Simpli ﬁ cation of Seine River Channel and Loss of Islands

In line with this work, a first reconstruction of the former hydrological trajectory of the Seine basin was proposed by Bonnet [21]. The operation of the water system of the Seine is currently simulated with CaWaQS (CAtchment WAter Quality Simulator).

Fig. 2 Two statistical features of the Seine discharge data recorded at the Pont d ’ Austerlitz (Paris, France) gauging station since 1885

Implementation of the Seine Basin Model

Calculated discharges in each river cell of the hydrographic network result from both stream aquifer fluxes and contributions from subsurface runoff. Anthropogenic pressures on water resources are taken into account through water withdrawals in each aquifer.

General Two-Step Calibration Strategy of Hydrosystem Models

The first step is crucial in our approach, as the second step depends on the aquifer recharge estimated by the first step. River discharges are well simulated by the CaWaQS model over 1993–2010 at different stations of the watershed (Table 3).

Average Water Budget 1993 – 2010

Heavy pumping removes 10 m3s1 from alluvial plains connected to the downstream part of the river network (Strahler recommends . >3). Both overflows and direct exchanges at the stream-aquifer interface of aquifers contribute to 55% of the discharge of the river network at the outlet of the watershed (Fig. 5).

Estimating Land Cover Changes

Thus, these spatial distributions were considered stable during the period 1900–1950, with negligible variations in the first half of the twentieth century [102]. In both cases, adjustments to the forested and urban areas were made at the expense of or in favor of the share of agricultural land in the entire area.

Estimating Anthropogenic Water Uptake

This additional step aims to incorporate as accurately as possible the significant expansion of the urban area over time and its implications for local water budget calculations. In relation to the 1900 simulation, it is assumed that most withdrawals were taken from surface water in the early twentieth century.

Climate Scenarios

7 Magnitude scalograms of daily precipitation time series in the Beauce sector for the five climate model products and for the SAFRAN data used as a reference. For example, the low-frequency variability found in BCC-CSM does not have the same scales as in the SAFRAN reanalysis (i.e., 5–7- and 16–19-yr scales), and the magnitudes associated with the annual cycle are overestimated.

Fig. 7 Magnitude scalograms of daily precipitation time series in the Beauce sector of ﬁ ve climatic model products and for the SAFRAN data, used as the reference

Water Resources Trajectory from the 1900s to the 2100s

Rousset F, Habets F, Gomez E et al (2004) Hydrometeorological modeling of the Seine basin using the SAFRAN-ISBA-MODCOU system. Massei N, Laignel B, Deloffre J et al (2010) Long-term hydrological changes of the Seine river flow (France) and their relation to the North Atlantic Oscillation over the period 1950-2008.

Fig. 8 Distribution of average monthly (a) rainfall rate (mm) and (b) actual evapotranspiration rates (mm) over the Seine basin; (c) monthly distribution of mean discharge (m 3 s 1 ) of the Seine River at the basin outlet (Seine at Vernon); (d) distributio

Long-Term Changes in the Structure of the Northern France Agricultural System

The input soil parameters are determined for each soil unit of the geographic soil database in France at scale [19], using local pedotransfer functions [20]. This resulted in an unprecedented opening of nutrient cycles, with increasing environmental losses and increased entry into international markets.

Fig. 2 (a) Gradual specialisation of agricultural systems in the North of France from 1850 to 2015.

Seine watershed, 1955

Seine watershed, 2010-2014

Changes in Land Use and Crop Rotations
Yield-Fertilisation Relationship
Soil Organic Carbon Storage
Agricultural Greenhouse Gas Emissions
Nitrogen Soil Storage and Leaching
Phosphorus Dynamics and Erosion
Aquifer Storage of Nitrogen
Riparian Processes
Point and Diffuse Sources of Nutrients to the River System
N and P Budget of the Water-Agro-Food System
The Importance of Long-Term Storage Processes
The Importance of the Structural Pattern of Agro-Food Systems on the Environmental Imprint

6 (a) Long-term trends of wetted organic carbon inputs in agricultural land of the Seine basin. 12 Long-term variations of point and diffuse sources of N (a) and P (b) in the river network of the Seine watershed.

Fig. 4 Long-term changes in the frequency of (a) permanent grassland (in % of usable agricultural area), (b) legume crops, (c) spring crops (in % of crop rotation), during the 1970 – 2014 period

Phase I

Temporal and Geographical Frame

Thus, during the last two centuries, the perimeter of the union of Paris has changed a lot (Fig. 1). By the 1920s, the union had extended to the surrounding towns of the Seine department, and a third of the department's population was located outside the city of Paris: the population multiplied by 2.5 and reached about 4,550,000 inhabitants.

Methodology

The remaining N is either released into the river as pollution or is denitrified into the atmosphere in the non-reactive form of N2. For households not connected to sewerage, we based our calculations on the fact that 90% of N and 65% of P are excreted in urine and the rest in feces [7].

Intention Without Achievement (1800 – 1868)

In 1852, most of the night soil cultivation was transferred to Bondy (10 km upstream from Paris on the Ourcq Canal), where, in addition to 10,000 m3 of traditional poudrette, three other products were obtained by nitrogen extraction from the liquid phase: 8 t of ammonium muriate (NH4Cl), 40 t of volatile alkali (NH4OH) and 835 t of ammonium sulfate ((NH4)2SO4), which was mostly shipped to England (these the figures are for the year 1852) [27]. The combination of a sharp increase in the amount of night soil, widespread sewage and the declining quality of the river Seine due to sewage disposal led engineers to consider another technique for managing human excrement.

Fig. 2 Map of the voirie de Montfaucon in the beginning of the nineteenth century (Source: Perrot, M

Successful Mutualism (1868 – 1905)

The recovery efficiency of dry collection and treatment (N-DEC) has risen steadily but slowly since the beginning of the nineteenth century. 4 Schematic of atinette filters. Solids are held in the barrel (C) while liquids flow to the sewer (I) [30] (Credit: Gallica).

Fig. 4 Scheme of a tinette ﬁ ltrante. Solids are kept in the barrel (C) while liquids ﬂ ow to the sewer (I) [30] (Credit: Gallica)

The Sacri ﬁ ce of the Seine (1905 – 1968)

The first major wastewater treatment plant, Achères, was not commissioned until 1940 and its size was largely inadequate for a population of more than five million in the 1950s (Fig. 9). 8 Connection of toilets to the sewage system between 1850 and 1960 in the city of Paris and the Paris metropolitan area (see text for data sources).

Fig. 9 Achères wastewater treatment plant in the 1960s (Credit: Barles collection)

Pollution Treatment by Resource Destruction (1968 to Today)

Today, a third of the northern part of the Paris metropolitan area is still discharged into the rivers, mainly in the form of nitrates. Progressive adoption of the "toilet-sewer-sewage treatment plant" combination since the late nineteenth century has created a socio-technical deadlock in human excreta management.

Recovering Circularity Through Source Separation

This paper is a synthesis of the work done in the PIREN-Seine research program on the modeling of pesticide transfer. These studies highlight the difficulty of the spatiotemporal approach to modeling the fate of pesticides in the Seine basin.

Presentation of the Orgeval and Vesle Basins

From a hydrogeological point of view, two thirds of the surface (upper and middle parts) are associated only with the Cenomanian limestone aquifer, while low-permeable Tertiary formations are deposited on top of it in the lower part of the basin. On top of the aquifer, the thickness of the unsaturated zone varies from a few meters in the valley to a few tens of meters below the plateau.

Data Acquisition

In the Vesle Basin, atrazine and DEA concentrations were retrieved for 39 piezometers from the ADES database [15]. Most AI uses are registered for specific crops and often in a particular case (type of pest and/or disease).

The Orgeval Case

As the Orgeval catchment is only about 100 km2, all agricultural practices were monitored for as long a period as possible for the entire catchment. The Vesle catchment is very large and therefore only the use of herbicides has been investigated within a 30-year period for the target practices (vineyard and corn harvesting) for which the use of these AIs has been approved.

The Vesle Case

Pesticides have been studied in the soils, river, groundwater, air, fallout, drainage and wetlands of the Orgeval basin since 1979 [31–36]. These high water flows were associated with higher concentrations, which explains the doubling of the atrazine and DEA flows between 2015 and 2016 (Table 1).

Fig. 3 Surface water ﬂ ow over time (left axis), integrated monthly concentration of atrazine, DEA and DEA/atrazine ratio (DAR) with linear ﬁ tted correlation (right axis)

Pesticide Fate Modelling with the STICS Crop Model

4 Comparison of the accumulated water discharge simulated with STICS-Pest (continuous line) versus observations (circles) at the Orgeval stream outlet. Two aquifers describe the major aquifers of the basin (Cenomanian Chalk aquifer and Tertiary complex multilayered ensemble).

Fig. 4 Comparison of the cumulated water discharge simulated with STICS-Pest (continuous line) versus observations (circles) at the Orgeval catchment outlet

Areas Studied

The outlet considered (Triel-sur-Seine) of the investigated area was chosen far enough downstream of the WWTP exhaust gases to include the emissions from the Paris neighborhood in the Seine River flow. However, it was also set up upstream of the Seine estuary to avoid tidal effects.

Dual-Scale Mass Balance Approach

The annual discharges of water and suspended sediment at the outlet of the studied area were estimated at 1.41010m3yr1 and 3.1105 tonnes yr1, respectively, based on measurements on both the Seine at Paris and the Oise River. A mass balance analysis of the sediment flux taking into account the erosion rate, the deposition rate on the floodplain and in the reservoirs and the sediment flux at the basin outlet gave an estimate of the amount of sediment stored in the river bed: 2.3105 tons year1.

Data Selection and Exploration

In addition, inputs to forest soils through atmospheric deposition (F11a) and the forest ﬁlter effect (F11b) were estimated [19]. In addition, storage in impoundments (F23a), river bed (F23b) and floodplains (F24) and removal associated with sediment dredging (F25a) were assessed.

Flux Estimation Quality

Urban Fluxes

The PAH flow related to runoff on roads and roofs (F12e) was quantified taking into account the amount of runoff collected in the sewer system. However, the quality rating of this flux was reduced to 3 due to the lack of information on the temporal changes in the runoff pollution.

Rural Fluxes

In particular, only a few studies investigated PAH concentrations in sewage systems outside the Paris confluence [ 12 , 63 ]. Consequently, research is still required to accurately quantify the PAH flux in urban parts of the basin other than the Paris confluence.