DOI: 10.5281/zenodo.18731978
title: Water Surfrace dynamics of El Chafi Marchland Iraq

description: This version integrates the specific file names, the technical details of the sensors, the processing methodology, and the socio-political conclusions from your previous analysis. It is designed to be a comprehensive and professional README for your Zenodo repository.



Dataset: Multidecadal Surface Water Dynamics and Spatial Extent for Ahwar el Shafi, Iraq (2003–2024)

Overview

This dataset provides a comprehensive hydrological record of the Ahwar el Shafi marshes in Southern Iraq. It was developed to serve as a high-fidelity demonstrator of regional water resource variability, bridging the gap between high-resolution spatial observations and long-term historical trends.

The repository provides the empirical evidence used to analyze the "pulse" of the Iraqi marshes, reflecting a complex interplay between hydro-climatic forcing and human management.

1. Spatial Dataset: Sentinel-2 High-Resolution Maps

Files: WaterRatio_2016.tif, WaterRatio_2017.tif, WaterRatio_2018.tif, WaterRatio_2019.tif, WaterRatio_2020.tif, WaterRatio_2021.tif, WaterRatio_2022.tif, WaterRatio_2023.tif, WaterRatio_2024.tif.

These GeoTIFF files represent the surface water extent at a 10-meter spatial resolution.





Source: Copernicus Sentinel-2A and 2B Level-2A (L2A) Bottom-of-Atmosphere (BOA) reflectance products.




Temporal Consistency: Each map represents a snapshot from the month of July. This period was selected to capture the marshes at their most vulnerable state during the peak of the dry season, providing a consistent baseline for monitoring summer water retention.




Methodology: Surface water was delineated using the Normalized Difference Water Index (NDWI):



NDWI = (B3 - B8) / (B3+ B8)

where B3 is the reflectance from Green and B8 reflectance from Near InfraRed





Technical Specifications: A standardized threshold (NDWI > 0.0) was applied. All files are georeferenced to WGS 84 / UTM zone 38N (EPSG:32638).



2. Temporal Dataset: Multidecadal Time Series

File: modis_timeseries.xlsx

This dataset provides the foundational data for the long-term hydrological narrative from 2003 to 2024.





Source: NASA MODIS Terra (MOD09A1) 8-day composite BOA reflectance maps (500m resolution).




Sensor Fusion & Harmonization: To account for the spatial and spectral differences between the 500m MODIS and 10m Sentinel-2 sensors, a linear correction was applied based on the overlapping operational period (2016–2024):



y = 0.983x + 0.062


(Where y is the corrected area and x is the raw MODIS estimation).




Content: The file includes raw and corrected flooded area calculations (km2), allowing for a robust assessment of shifts in the hydrological regime over 21 years.



3. Key Findings & Scientific Significance

The data contained in these files reveals critical insights into the water security of Southern Iraq:





Extreme Variability: The spatial maps (e.g., WaterRatio_2018.tif vs WaterRatio_2019.tif) vividly depict the radical shifts between severe drought and record-breaking flood pulses.




Resilience and Vulnerability: The modis_timeseries.xlsx data highlights that while the marshes show a capacity for rapid recovery (as seen in 2003 and 2019), the baseline water availability remains under constant threat.




Drivers of Change: Our analysis concludes that water availability in El Chafi is not merely a function of local climatology. The results demonstrate a strong dependency on:





Climatological conditions constraining inbound water from upstream headwaters.




Transboundary water management and riparian governance.




National water management priorities.




The impact of regional political instability.