[A-HW22] Advancements in quantification of natural and anthropogenic influences on terrestrial water cycle

[AHW22-P01] Validation of reservoir operation for H08 model using multi-satellite remote sensing.

*Kedar Otta¹, Naota Hanasaki¹ (1.National Institute for Environmental Studies)

Keywords:reservoir storage, multi-satellite, remote sensing, validation, equifinality, H08

Reservoir operation has been incorporated into a number of global hydrological models, but systematic validation has yet seldom been carried out because of the complexity of the system and scarcity of accessible data. Further, the equifinality of reservoir storage (i.e., various inflow and outflow components determine the reservoir storage) exacerbates the challenge for validation. Previous studies have compared global water models based on ground-based observations for a handful of reservoirs (Masaki et al., 2017). However, a comprehensive evaluation of reservoir operation in hydrological models using satellite data has not been done yet. We validated the reservoir storage changes for the H08 model against the remotely sensed multi-satellite data for altimetry and water surface area, inspired by the methodology in recent studies (Busker et al., 2019; Gao et al., 2012). The method assumes a linear relationship between water surface area and elevation towards the upper limit of reservoir capacity, where most of the variability in storage generally occurs. The changes in water surface and elevation are used to obtain the storage changes and compared them with simulated data. In-situ data is also used wherever available. Thirty-two spatially dispersed potential reservoirs on assorted global rivers were selected that cover about 20% of the total recorded reservoir storage capacity. The H08 reservoir operation scheme demonstrated good performance in capturing the storage changes in general. However, the scheme failed to capture the peaks of storage due to the filling up of the reservoir to its upper limit, i.e., the reservoir storage capacity whenever water is available in the H08 scheme. Further, the equifinality issues in several reservoirs were also captured from the inflow and outflow at nearby gauging stations. We have provided suggestions based on our findings to improve reservoir modelling of the community and help in better resolving the equifinality problem.

References
Busker, T. et al. (2019) ‘A global lake and reservoir volume analysis using a surface water dataset and satellite altimetry’, Hydrology and Earth System Sciences, 23(2), pp. 669–690. doi:10.5194/hess-23-669-2019.
Gao, H., Birkett, C. and Lettenmaier, D.P. (2012) ‘Global monitoring of large reservoir storage from satellite remote sensing’, Water Resources Research, 48(9), pp. 1–12. doi:10.1029/2012WR012063.
Masaki, Y. et al. (2017) ‘Intercomparison of global river discharge simulations focusing on dam operation—multiple models analysis in two case-study river basins, Missouri–Mississippi and Green–Colorado’, Environmental Research Letters, 12(5), p. 055002. doi:10.1088/1748-9326/aa57a8.