# Documentation of Collected Data

**Dataset Name:** `CODER~SO | Oder River Disaster 2022 | Data | SP4: Sentinel-2 chlorophyll-a estimates for the Oder River network`

**Version:** `v1.0`

**Description:** `Time series of chlorophyll-a concentrations derived from Sentinel-2 imagery for the Oder River network between 2016 and 2025. Chlorophyll-a estimates are aggregated to OpenStreetMap-derived hydrographic polygons representing the Oder River main stem, its tributaries (including other rivers, streams, and canals), and associated lateral water bodies. Running-water features were subdivided into approximately 1-km-long segments, while lakes, ponds, reservoirs, and floodplain water bodies were retained as individual units.`

**Creators or Authors:** `Jorrit Scholze (Brockmann Consult GmbH), Kerstin Stelzer (Brockmann Consult GmbH), Paula Torre Zaffaroni (Leibniz-IGB)`

**Dataset Context:** `This dataset was produced within the ODER~SO project to characterize the spatial and temporal dynamics of phytoplankton biomass across the Oder River system using Sentinel-2 observations. The data support analyses of long-term chlorophyll variability, the context for the observed 2022 Prymnesium parvum bloom, and subsequent monitoring efforts.`

**Versioning Information:** `v1.0: initial compilation`

**Limitations and Quality:** `Chlorophyll-a concentrations were estimated from Sentinel-2 imagery using a regionally calibrated retrieval algorithm. Data gaps were filled using a 17th-order polynomial interpolation applied to individual time series. While this approach preserves seasonal dynamics, it may introduce uncertainty near the temporal boundaries of the record and during extended periods without observations. Gap-filled values between November and February should be excluded from analyses. Validation against in situ observations yielded coefficients of determination generally exceeding 0.6, although absolute prediction errors remained substantial (RMSE = 30–50 µg L⁻¹ depending on the reference dataset).`

**Format and Structure:** `The dataset is provided in tabular format. Each record corresponds to a unique date–segment combination and includes chlorophyll-a concentration statistics derived from Sentinel-2 imagery. The river network is subdivided into segments of ~1 km length covering the Oder River, tributary rivers, canals, and streams. Additional records are available for lentic water bodies, including floodplain lakes, reservoirs, and ponds. Spatial units are identified using the format: [water_class]_[feature_id]_[distance_from_main_oder]_[equivalent_oder_km] where water_class indicates the type of water body (main stem, tributary, canal, stream, or lentic water body), distance_from_main_oder represents the longitudinal distance to the main Oder channel, and equivalent_oder_km corresponds to the nearest river kilometer along the Oder. The longitudinal reference point (river kilometer 0) is located in Ostrava, Czech Republic.`

**Access Information:** `The dataset is released under an open data attribution licence. All contents may be reused, adapted, and redistributed *provided that the dataset is cited*. Please check the permanent DOI at https://fred.igb-berlin.de/data/package/1106.`

**Contact Information:** `For further questions, contact: **paula.torre.zaffaroni@igb-berlin.de**`

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