This dataset presents a total of 4817 boreholes that intersect the alluvium at the bottom of the main valleys within the Seine River catchment, mapped based on geological maps at 1:50 000 scale (Pomerol and Monciardini, 1992; Janjou, 2004; Quesnel et al., 2008). The boreholes were extracted from (i) the BSS (Base du Sol et Sous-sol) database available on the French Geological Survey (BRGM) website (http://infoterre.brgm.fr/) and (ii) data available in the literature (Lefebvre et al., 1974; Pomerol and Morciandini, 1992; Krier, 2004; Chourio- Camacho et al., 2024). Each borehole was manually analyzed to ensure consistency between data. This dataset contains the following information: (i) geographic position of each borehole using both WGS84 and the RGF Lambert 1993 projection, (ii) elevation at the bedrock-alluvium interface, (iii) a description of the alluvium such as total alluvial thickness, alluvial facies description, depth and thickness of each individual alluvial facies, (iv) bedrock characteristics such as lithology, geological formation and age, (v) valley location (Chourio- Camacho, 2024) and (vi) total of facies for each borehole, date of drilling, the data provider and the link to data. Our dataset has numerous applications in geomorphology and hydrology. It allows estimating the geometry of the alluvial infill and reconstituting the geometry of the top of the bedrock substrate or quantifying the sediment volume storage along the valley bottoms of the Seine catchment.

Each data point contains the following parameters: X_WGS_84: Geographic X position using the WGS84 projection (unit: decimal degrees; EPSG 4326) Y_WGS_84: Geographic Y position using the WGS84 projection (unit: decimal degrees; EPSG 4326) X_Lambert_93_m: Geographic X position using the projection RGF Lambert 1993 (unit: meters; EPSG 2154) * Y_Lambert_93_m: Geographic Y position using the projection RGF Lambert 1993 (unit: meters; EPSG 2154) Top_Borehole_Elevation_m: Absolute elevation of the top of the alluvial deposits within elevation (unit: meters, vertical reference: NGF–IGN69) * Alluvial_Thickness_m: Total alluvial thickness within the borehole (unit: meters) Alluvial_Bottom_Low_m: Absolute elevation of the bottom of alluvial deposits (unit: meters, vertical reference: NGF–IGN69) Alluvial_Bottom_Up_m : Alluvial bottom elevation (upper part) in meter Alluvial_description: description of the alluvial facies succession from the upper one to the lower one (type, depth and thickness, unit: meter) Sommital_Facies_Layer_1: Lithological facies of the Facies 1 (upper one) Depth_Layer_1_m: Facies 1 layer bottom depth (unit: meters; vertical 0 reference: top of the borehole) Thickness_Layer_1_m : Facies 1 layer thickness (unit: meters) Facies_Layer_2: Lithological facies of the Facies 2 Depth_Layer_2_m: Facies 2 layer bottom depth (unit: meters; vertical 0 reference: top of the borehole) Thickness_Layer_2_m: Facies 2 layer thickness (unit: meters) Facies_Layer_3: Lithological facies of the Facies 3 Depth_Layer_3_m: Facies 3 layer bottom depth (unit: meters; vertical 0 reference: top of the borehole) Thickness_Layer_3_m: Facies 3layer thickness (unit: meters) Facies_Layer_4: Lithological facies of the Facies 4 Depth_Layer_4_m: Facies 4 layer bottom depth (unit: meters; vertical 0 reference: top of the borehole) Thickness_Layer_4_m: Facies 4 layer thickness (unit: meters) Facies_Layer_5: Lithological facies of the Facies 5 Depth_Layer_5_m: Facies 5 layer bottom depth (unit: meters; vertical 0 reference: top of the borehole) Thickness_Layer_5_m: Facies 5 layer thickness (unit: meters) Facies_Layer_6: Lithological facies of the Facies 2 Depth_Layer_6_m: Facies 6 layer bottom depth (unit: meters; vertical 0 reference: top of the borehole) Thickness_Layer_6_m: Facies 6 layer thickness (unit: meters) Bedrock lithology: Lithology of the bedrock (when reached) Borehole_Bottom_Formation_in_French: French name of the Geological formation at the bottom of the well * Period/Epoch: Period/Epoch considering the international chronostratigraphic chart v2023/09 (Cohen et al., 2023) Borehole_Depth_Reached_m: Total borehole thickness (unit: meters) * Borehole_Name: Borehole name using the BSS nomenclature or the bibliographic reference * Valley: name of the river valley in which the borehole is located Total_facies: Total number of described facies Date_of_drilling: Date of drilling of the considered borholed when available* Provider/Reference: Data provider or references * Link to data: link to the borehole page on the BSS website Acknowledgements: This work is part of the RGF: Bassin de Paris programme supported by the BRGM. It benefited from financial support from the Agence de l'Eau Seine Normandie. We thank Le Port de Rouen for sharing seismic data. The authors thank Sébastien Hameau from BRGM for general help.