[insu-01060161] Multivariate Prediction of Total Water Storage Changes Over West Africa from Multi-Satellite Data

West African countries have been exposed to changes in rainfall patterns over the last decades including a significant negative trend This causes adverse effects on water resources of the region for instance reduced freshwater availability Assessing and predicting large-scale total water storage TWS variations are necessary for West Africa due to its environmental social and economical impacts Hydrological models however may perform poorly over West Africa due to data scarcity This study describes a new statistical data-driven approach for predicting West African TWS changes from past gravity data obtained from the gravity recovery and climate experiment GRACE and concurrent rainfall data from the tropical rainfall measuring mission TRMM and sea surface temperature SST data over the Atlantic Pacific and Indian Oceans The proposed method therefore capitalizes on the availability of remotely sensed observations for predicting monthly TWS a quantity which is hard to observe in the field but important for measuring regional energy balance as well as for agricultural and water resource management Major teleconnections within these data sets were identified using independent component analysis and linked via low-degree autoregressive models to build a predictive framework After a learning phase of 72 months our approach predicted TWS from rainfall and SST data alone that fitted to the observed GRACE-TWS better than that from a global hydrological model Our results indicated a fit of 79 % and 67 % for the first-year prediction of the two dominant annual and inter-annual modes of TWS variations This fit reduces to 62 % and 57 % for the second year of projection The proposed approach therefore represents strong potential to predict the TWS over West Africa up to 2 years It also has the potential to bridge the present GRACE data gaps of 1 month about each 162 days as well as a--hopefully--limited gap between GRACE and the GRACE follow-on mission over West Africa The method presented could also be used to generate a near-real-time GRACE forecast over the regions that exhibit strong teleconnections



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