Assessing daily GRACE Data Assimilation during flood events of the Brahmaputra River Basin: OL and DA outputs

General description.

This dataset contains the result of 36 daily and monthly GRACE Terrestrial Water Storage (TWS) Data Assimilation (DA) experiments performed in the Brahmaputra basin, with the purpose of assessing the potential of daily GRACE DA into water balance models for detecting fast evolving water storage anomalies. In these experiments, monthly and daily GRACE(-FO) TWS data derived from the GRACE level 2 (L2) ITSG-2018 product [1,2] were assimilated into the World Wide Water Resources Assessment model [3,4]. The sequential Data Assimilation (DA) was performed through a classical EnKF as well as an EnKS [5] that allows to smoothly disaggregate monthly TWS increments into the daily model timesteps. Different covariance localization degrees were also considered, ranging from no-localization to a 70 km half-radius localization. The experiments were performed for the years 2004, 2007 and 2008, for which the Brahmaputra River Basin was affected by major flooding events. The considered daily and monthly DA approaches were assessed in terms of their impact on the TWS signal as well as their performance on the vertical and horizontal TWS disaggregation. More details about the processing and the main resulting findings can be found in [6].

Content

Main data

This dataset contains the results of the aforementioned experiments. Two type of files can be found:

Subbasin-averaged TWS and individual compartment (e.g., shallow water, ground water, surface water, snow) estimates (denoted TWS_COMP_SUBB).

2D TWS distribution maps (denoted TWS_2D).

These results are available for :

the three DA approaches (daily DA, monthly DA EnKF, and monthly DA EnKS),

four localization degrees (non-localized, 300 km, 150 km, and 70 km),

and the three years under study (2004, 2007 and 2008).

That is, 3x4x3=36 experiment results are available in total. In addition, estimates of the Open Loop run (OL, i.e., model run with no DA) are also provided for the period 2002 to 2016.

Additional content

The geospatial data necessary to interpret the results have also been provided. These include:

Shapefiles containing the boundary of the sub-basins used in the DA process.

Coordinates of each of the grid cells for which the 2D TWS data is provided.

To ease the interpretation and visualization of the results, some Matlab scripts that represent sub-basin averaged time series and 2D TWS distributions have been included.

The structure of the directory and file naming is described on the README.txt file.

Citation

Please, when using this dataset, remember to cite:

L. Retegui-Schiettekatte, M. Schumacher, H. Madsen, and E. Forootan, “Assessing daily GRACE Data Assimilation during flood events of the Brahmaputra River Basin,” Science of The Total Environment, vol. 975, p. 179181, May 2025, doi: 10.1016/j.scitotenv.2025.179181.

References

[1] T. Mayer-Gürr et al., “ITSG-Grace2018 - Monthly, Daily and Static Gravity Field Solutions from GRACE.” GFZ Data Services, 2018. doi: 10.5880/ICGEM.2018.003.

[2] A. Kvas et al., “ITSG-Grace2018: Overview and Evaluation of a New GRACE-Only Gravity Field Time Series,” Journal of Geophysical Research: Solid Earth, vol. 124, no. 8, pp. 9332–9344, 2019, doi: 10.1029/2019JB017415.

[3] A. van Dijk, “The Australian Water Resources Assessment System. Technical Report 3. Landscape Model (version 0.5) Technical Description. CSIRO: Water for a Healthy Country National Research Flagship.,” Jan. 2010.

[4] A. I. J. M. van Dijk, J. L. Peña-Arancibia, E. F. Wood, J. Sheffield, and H. E. Beck, “Global analysis of seasonal streamflow predictability using an ensemble prediction system and observations from 6192 small catchments worldwide,” Water Resources Research, vol. 49, no. 5, pp. 2729–2746, 2013, doi: 10.1002/wrcr.20251.

[5] B. F. Zaitchik, M. Rodell, and R. H. Reichle, “Assimilation of GRACE Terrestrial Water Storage Data into a Land Surface Model: Results for the Mississippi River Basin,” Journal of Hydrometeorology, vol. 9, no. 3, pp. 535–548, Jun. 2008, doi: 10.1175/2007JHM951.1.

[6] L. Retegui-Schiettekatte, M. Schumacher, H. Madsen, and E. Forootan, “Assessing daily GRACE Data Assimilation during flood events of the Brahmaputra River Basin,” Science of The Total Environment, vol. 975, p. 179181, May 2025, doi: 10.1016/j.scitotenv.2025.179181.