Daily flow simulation in Thailand Part II

Daily flow simulation in Thailand Part II: Unraveling effects of reservoir operation

Wannasin, C. (Wageningen University & Research)
Brauer, C. C. (Wageningen University & Research)
Uijlenhoet, R. (TU Delft Water Resources; Wageningen University & Research)
van Verseveld, W. J. (Deltares)
Weerts, A. H. (Wageningen University & Research; Deltares)

2021

Study region: Upper region of the Greater Chao Phraya River (GCPR) basin in Thailand. Study focus: The upper GCPR basin is highly regulated by multipurpose reservoirs, which obviously have altered the natural streamflow. Understanding quantitative effects of such alteration is crucial for effective water resource management. Therefore, this study aims to assess how reservoir operation affects the water balance, daily flow regime and extreme flows in this basin. For this purpose, we reconstructed streamflow in the naturalized (no reservoir) and baseline operation scenarios using the (∼1 km resolution) distributed model. To overcome data scarcity, we ran the model with global data and parameterization. A target storage-and-release-based reservoir operation module was applied in the baseline operation scenario. The model results were analyzed in comparison to observations in a wet year, a dry year, and the period 1989–2014. New hydrological insights for the region: The reservoir operation resulted in more evaporation. It inverted the natural flow seasonality and smoothed the daily flow regime with decreasing high flows, increasing mean flows and low flows, greater baseflow contribution, and lower flashiness. It prevented or mitigated many historical extreme flow incidents. The annual flood peaks and minimum flows were markedly mitigated in terms of both magnitudes and frequencies, but their timing became more variable and difficult to predict. Altogether, the results highlighted the importance of effective decision making for real-time operation, which remain challenging in practice.

Chao Phraya basin
Distributed hydrological model
Naturalized flow
Reservoir effects
Scenario analysis
Wflow_sbm

http://resolver.tudelft.nl/uuid:6f3a9c83-f68d-4424-a527-3ff74a0839a0

https://doi.org/10.1016/j.ejrh.2021.100792

2214-5818

Journal of Hydrology: Regional Studies, 34, 1-17

Institutional Repository

journal article

© 2021 C. Wannasin, C. C. Brauer, R. Uijlenhoet, W. J. van Verseveld, A. H. Weerts