Coupled daily streamflow and water temperature modelling in large river basins

Abstract

Abstract. Realistic estimates of daily streamflow and water temperature are required for effective management of water resources (e.g. for electricity and drinking water production) and freshwater ecosystems. Although hydrological and process-based water temperature modelling approaches have been successfully applied to small catchments and short time periods, much less work has been done at large spatial and temporal scales. We present a physically based modelling framework for daily river discharge and water temperature simulations applicable to large river systems on a global scale. Model performance was tested globally at 1/2 × 1/2 • spatial resolution and a daily time step for the period 1971-2000. We made specific evaluations on large river basins situated in different hydro-climatic zones and characterized by different anthropogenic impacts. Effects of anthropogenic heat discharges on simulated water temperatures were incorporated by using global gridded thermoelectric water use datasets and representing thermal discharges as point sources into the heat advection equation. This resulted in a significant increase in the quality of the water temperature simulations for thermally polluted basins (Rhine, Meuse, Danube and Mississippi). Due to large reservoirs in the Columbia which affect streamflow and thermal regimes, a reservoir routing model was used. This resulted in a significant improvement in the performance of the river discharge and water temperature modelling. Overall, realistic estimates were obtained at daily time step for both river discharge (median normalized BIAS = 0.3; normalized RMSE = 1.2; r = 0.76) and water temperature (median BIAS = −0.3 • C; RMSE = 2.8 • C; r = 0.91) for the entire validation period, with similar performance during warm, dry periods. Simulated water temperatures are sensitive to headwater temperature, depending on resolution and flow velocity. A high sensitivity of water temperature to river discharge (thermal capacity) was found during warm, dry conditions. The modelling approach has potential to be used for risk analyses and studying impacts of climate change and other anthropogenic effects (e.g. thermal pollution, dams and reservoir regulation) on large rivers.

StreamFlow 1.0: an extension to the spatially distributed snow model Alpine3D for hydrological modelling and deterministic stream temperature prediction

“…For example, the variations of temperature resulting from the fluctuations in discharge can be better resolved (e.g. van Vliet et al, 2012;Null et al, 2013). The use of both discharge and temperature measurement data to calibrate the model has also been shown by Comola et al (2015) to improve the quality of the simulation.…”

“…Out of the 13 semi-distributed coupled models listed in Table 1, only 1 was specifically developed for mountainous environments (MacDonald et al, 2014). The other ones were either tailored to large-scale applications (Morrison et al, 2002;Ferrari et al, 2007;van Vliet et al, 2012;van Beek et al, 2012;Null et al, 2013) or aimed at being used over low-altitude catchments (e.g. Sullivan et al, 1990;Chen et al, 1998;Haag and Luce, 2008), except for the model of Sun et al (2015) which has been tested over Alpine watersheds.…”

Adaptation Turning Points in River Restoration? The Rhine Salmon Case

“…Textbox 1 specifies the hydrological-water temperature modeling framework used in this study. The performance of the modeling framework for daily streamflow and water temperature simulations has previously been evaluated by van Vliet et al [44], and shows a realistic representation of the observed water temperature conditions for the Rhine basin. For details about the application of this framework under the climate in the future, we refer to van Vliet et al [45].…”

Eco-environmentally friendly operational regulation: an effective strategy to diminish the TDG supersaturation of reservoirs

“…In the authors' previous studies , it was found that the TDG dissipation process is quantitatively different from the reaeration process of DO. Some biological studies also indicate that the supersaturated TDG is more harmful to the fishes than the supersaturated DO (Rucker, 1976). For these reasons, TDG is chosen as the key variable to study the eco-environmental regulations for mitigating the conflict between dam spilling and fish protection in the paper.…”

“…An optimized regulation policy for Bala Reservoir is proposed based on the numerical results. Politano (2009), Urban et al (2008, and Fu et al (2010) have developed unsteady two-phase threedimensional models to calculate the TDG downstream evolution of spillways. The accuracy is satisfied in their simulations.…”