1. Summary: This dataset contains water surface slopes (WSS) every kilometer along 11 Polish rivers derived from cross-calibrated multi-mission satellite altimetry (Schwatke et al. 2023a (in review). ). The approach to derive WSS is based on a weighted least-squares approach, which is described in detail in Schwatke et al. 2023b (in review). 2. Data Formats: This dataset is provided in netCDF and shapefile formats. Each netCDF file contains the data of a single river and parameters such as river chainage, WSS, WSS error, location, and nearest centerline information from the SWORD database (v1.1, Altenau et al., 2021). The shapefile consists of five files (.cpg, .dbf, .prj, .shp, .shx) containing the data of the 11 Polish rivers. The attributes are identical to the netCDF, but the river name has been added. 3. Attribute Description: The attributes of netCDFs and shapefiles are described in the following list: river_chainage: The river chainage describes the distance from the river mouth to the location of each bin along the river (units: km) wss: Water surface slopes (WSS) at each bin along the river. WSS are set to NaN/NULL for unprocessed lakes/reservoirs or short river segments (units: mm/km). wss_error: Errors of WSS at each bin along the river. WSS errors are set to NaN/NULL for unprocessed lakes/reservoirs or short river segments (units: mm/km). longitude: Longitude of the 1 km bins along the river (units: degree). latitude: Latitude of the 1 km bins along the river (units: degree). centerline_id: Nearest centerline id extracted from the SWORD database (v1.1, Altenau et al., 2021). node_id: Node id from the SWORD database (v1.1, Altenau et al., 2021) for the corresponding centerline id. reach_id: Reach id from the SWORD database (v1.1, Altenau et al., 2021) for the corresponding centerline id. river_name: The name of the river is only available in the Shapefile. 4. References: Schwatke C., Dettmering D., Passaro M., Hart-Davis M., Scherer D., Müller F. L., Bosch W., Seitz F.: OpenADB: DGFI-TUM`s Open Altimeter Database. Geoscience Data Journal, 2023a (in Review) Schwatke C., Halicki M., Scherer D.: Generation of high-resolution water surface slopes from multi-mission satellite altimetry. Water Resources Research, 2023b (in Review) Altenau E.H., Pavelsky T.M., Durand M.T., Yang X., Frasson R.P.d.M., Bendezu L.: SWOT River Database (SWORD) (Version v1) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.4917236, 2021