Modeling stream temperature in the Anthropocene: An earth system modeling approach

Abstract

A new large-scale stream temperature model has been developed within the Community Earth System Model (CESM) framework. The model is coupled with the Model for Scale Adaptive River Transport (MOSART) that represents river routing and a water management model (WM) that represents the effects of reservoir operations and water withdrawals on flow regulation. The coupled models allow the impacts of reservoir operations and withdrawals on stream temperature to be explicitly represented in a physically based and consistent way. The models have been applied to the Contiguous United States driven by observed meteorological forcing. Including water management in the models improves the agreement between the simulated and observed streamflow at a large number of stream gauge stations. It is then shown that the model is capable of reproducing stream temperature spatiotemporal variation satisfactorily by comparing against the observed data from over 320 USGS stations. Both climate and water management are found to have important influence on the spatiotemporal patterns of stream temperature. Furthermore, it is quantitatively estimated that reservoir operation could cool down stream temperature in the summer low-flow season (August-October) by as much as 128C due to enhanced low-flow conditions, which have important implications to aquatic ecosystems. Sensitivity of the simulated stream temperature to input data and reservoir operation rules used in the WM model motivates future directions to address some limitations in the current modeling framework.

River Regulation Alleviates the Impacts of Climate Change on U.S. Thermoelectricity Production

“…This study adopts a physically based stream temperature model that is coupled with the Community Land Model (CLM) version 4.0 and a WM model (Li, Ruby Leung, Tesfa, et al, ), as shown in Figure . Individual components of Figure are explained below.…”

“…This alters the flow regime and seasonal variability of stream temperature (Yang et al, 2005) through the storage of water during high-flow periods and enhancement of low flows during the summer dry season (WWF, 2006;Ziv et al, 2012). On the contrary, water extraction that withdraws water directly from unregulated local streams reduces local discharge and tends to warm the stream especially in summer (Li, Ruby Leung, Tesfa, et al, 2015).…”

A Multilayer Reservoir Thermal Stratification Module for Earth System Models

“…Significant effort and progress have been made in large-scale representation and modeling of water management impact of reservoirs on streamflow (Hanasaki et al, 2008;Voisin et al, 2017Voisin et al, , 2013 and temperature (Li et al, 2015;Miara et al, 2017;Niemeyer et al, 2018;van Beek et al, 2012;van Vliet et al, 2012van Vliet et al, , 2013. In modeling stream temperature in the continental United States, Li et al (2015) suggested the inclusion of reservoir stratification models in river transport models to better represent stream temperature downstream of reservoirs. When it comes to understanding the stratification effect on stream temperature, most studies have focused on a single reservoir (for example, Bonnet et al, 2000).…”

A Thermally Stratified Reservoir Module for Large‐Scale Distributed Stream Temperature Models With Application in the Tennessee River Basin

“…Downstream of these reservoirs, the river shows a narrow seasonal range in observed temperature (approximately 4.0 to 10.0 °C), suggesting releases from the cooler hypolimnion of a stratified reservoir. Similarly, Li et al () simulated distributed river temperatures across the continental United States and had the poorest model performance below Hoover Dam which impounds Lake Mead, a stratified reservoir with a long residence time. As a result, Li et al () recommended incorporating thermal stratification into distributed river temperature models.…”