owusugeorge946-afk/lower-volta-flood-mapping

Reproducibility code for Sentinel-1 SAR flood mapping, flood frequency, backscatter change, hydro-climatic analysis, exposure assessment, and Sentinel-1/Sentinel-2 inter-sensor comparison in the Lower Volta Basin, Ghana. # Lower Volta Basin Flood Mapping (2023) — corrected reproducibility package Reproducibility code for **Cloud-Independent Flood Mapping and Surface Water Dynamics Using Sentinel-1 SAR in the Lower Volta Basin, Ghana**. ## Reproducibility corrections incorporated - Sentinel-1 is explicitly restricted to `resolution_meters = 10`, in addition to IW and VV/VH filtering. - ERA5-Land hydro-climatic analysis uses **total runoff** (`runoff_sum`), converted from metres to millimetres. - Hydro-climatic correlations are frozen to the four manuscript dates: **4, 11, 16 and 23 October 2023**. - GHSL 2020 uses the explicit image `JRC/GHSL/P2023A/GHS_BUILT_S/2020`. - Sentinel-2 cloud/no-data pixels retain their mask and are excluded from inter-sensor sampling; they are not converted to non-flood. - Agreement statistics require the actual exported 600-point CSV. No archived confusion counts are substituted. - Method benchmarking and the 3×3 VV/VH sensitivity grid are recomputed in Earth Engine by `gee/05_method_benchmark_and_threshold_sensitivity.js`; the Python script only tabulates/plots the exported results. - Acquisition metadata exports include exact Sentinel-1 image IDs and a `manuscript_hydro_date` flag so the nine flood-period scenes and four hydro-climatic observations can be archived. ## Frozen principal configuration - Study area: `projects/nana-469713/assets/lower_volta` - Dry season: 2023-01-01 to 2023-02-28 - Wet season: 2023-06-01 to 2023-07-31 - Pre-flood: 2023-08-01 to 2023-09-14 - Flood period: 2023-10-01 to 2023-10-31 - Sentinel-1: GRD, IW, VV+VH, 10 m - Principal water rule: VV =25% OR JRC GSW occurrence >=50% - Recurrent inundation: >25% of valid flood observations - Sentinel-2 comparison: 2023-10-15 to 2023-10-31; scene cloud 0.20 - Sentinel-2 sensitivity: 0.10, 0.20, 0.30 - Sentinel-1 sensitivity: VV {-18,-17,-16} dB × VH {-24,-23,-22} dB ## Run order 1. `gee/01_preprocessing_and_flood_products.js` 2. `gee/02_frequency_backscatter_terrain.js` 3. `gee/03 …