Data assimilation using the ensemble Kalman filter in a distributed hydrological model on the Tocantins River, Brasil

Abstract

In this work, the data assimilation method namely ensemble Kalman filter (EnKF) is applied to the Tocantins River basin. This method assimilates streamflow results by using a distributed hydrological model. The performance of the EnKF is also compared with an empirical assimilation method for hourly time intervals, in which two applications based on information transfer from gauged to ungauged sites and real time streamflow forecasting are assessed. In the first application, both assimilation methods are able to transfer streamflow to ungauged sites, obtaining better results when more than one station located upstream or downstream of the basin are gauged. In the second application, integration of a real time forecast model with EnKF is able to absorb errors at the beginning of the forecast. Therefore, a greater efficiency in the Nash-Sutcliffe index for the first 144 hours in advance in relation to its counterpart without assimilation is obtained. Finally, a comparison between both data assimilation methods shows a greater advantage for the EnKF in long lead times.

Quantifying the climate change‐driven impacts on the hydrology of a data‐scarce watershed located in the Brazilian Tropical Savanna

“…The method used to estimate each component of the natural flow is presented in ANA (2011). Naturalized streamflows have been used in several hydrological modelling studies in Brazil, such as those by Nóbrega et al (2011), Jiménez et al (2019), Amorim et al (2020), Cassalho et al (2020), and Mello et al (2021).…”