TY  - JOUR
A1  - Pathiraja, Sahani Darschika
A1  - Anghileri, Daniela
A1  - Burlando, P.
A1  - Sharma, A.
A1  - Marshall, L.
A1  - Moradkhani, H.
T1  - Insights on the impact of systematic model errors on data assimilation performance in changing catchments
JF  - Advances in water resources
N2  - The global prevalence of rapid and extensive land use change necessitates hydrologic modelling methodologies capable of handling non-stationarity. This is particularly true in the context of Hydrologic Forecasting using Data Assimilation. Data Assimilation has been shown to dramatically improve forecast skill in hydrologic and meteorological applications, although such improvements are conditional on using bias-free observations and model simulations. A hydrologic model calibrated to a particular set of land cover conditions has the potential to produce biased simulations when the catchment is disturbed. This paper sheds new light on the impacts of bias or systematic errors in hydrologic data assimilation, in the context of forecasting in catchments with changing land surface conditions and a model calibrated to pre-change conditions. We posit that in such cases, the impact of systematic model errors on assimilation or forecast quality is dependent on the inherent prediction uncertainty that persists even in pre-change conditions. Through experiments on a range of catchments, we develop a conceptual relationship between total prediction uncertainty and the impacts of land cover changes on the hydrologic regime to demonstrate how forecast quality is affected when using state estimation Data Assimilation with no modifications to account for land cover changes. This work shows that systematic model errors as a result of changing or changed catchment conditions do not always necessitate adjustments to the modelling or assimilation methodology, for instance through re-calibration of the hydrologic model, time varying model parameters or revised offline/online bias estimation.
Y1  - 2017
U6  - https://doi.org/10.1016/j.advwatres.2017.12.006
SN  - 0309-1708
SN  - 1872-9657
VL  - 113
SP  - 202
EP  - 222
PB  - Elsevier
CY  - Oxford
ER  -