The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform

Heinz G Stefan - One of the best experts on this subject based on the ideXlab platform.

  • Modified Equilibrium Temperature models for cold‐water streams
    Water Resources Research, 2011
    Co-Authors: William R. Herb, Heinz G Stefan
    Abstract:

    [1] Water Temperature determines the spatial distribution of fish species, including cold-water fish such as trout, and is driven by the balance of the heat flux across the water surface and the heat flux across the sediment surface. In this study, a modified Equilibrium Temperature model was developed for cold-water streams that includes the effect of groundwater inflow. The modified Equilibrium Temperature model gives estimates of daily average stream Temperature based on climate conditions, riparian shading, stream width, and groundwater input rate and Temperature. For a small tributary stream with relatively uniform riparian shading, the modified Equilibrium Temperature was found to be a good predictor of daily average stream Temperature, with a root-mean-square errors (RMSE) of 1.2°C. The modified Equilibrium Temperature model also gave good estimates (1.4°C RMSE) of daily average stream Temperature for a larger stream when riparian shading was averaged over sufficiently long distances. A sensitivity analysis using the modified Equilibrium Temperature model confirmed that water Temperature in cold-water streams varies strongly with riparian shading, stream width, and both groundwater inflow rate and Temperature. These groundwater parameters therefore need to be taken into account when climate change impacts on stream Temperature are projected. The stream Temperature model developed in this study is a useful tool to characterize Temperature conditions in cold-water streams with different levels of riparian shading and groundwater inputs and to assess the impact of future land use and climate change on Temperature in these streams.

  • stream Temperature Equilibrium Temperature relationship
    Water Resources Research, 2003
    Co-Authors: Travis Bogan, Omid Mohseni, Heinz G Stefan
    Abstract:

    [1] Equilibrium Temperature is the water Temperature at which the sum of all heat fluxes through the water surface is zero. It can be calculated from weather data. Mean weekly stream Temperature was found to be linearly related to mean weekly Equilibrium Temperature above 0°C. The slopes and intercepts of the linear relationship were used to identify effects of shading, sheltering, cold water inputs (groundwater, meltwater, and deep reservoir releases) and warm water inputs (wastewater, cooling water, and lake surface water). The linearity hypothesis was confirmed for data from 596 U.S. Geological Survey stream gaging stations in the eastern and central United States. For approximately 15% (89 of 596, NSC ≥ 0.90) of stream gaging stations, weekly Equilibrium Temperature was a good estimator of weekly stream Temperature with zero wind sheltering and sun shading. With sheltering and shading the number rose to 26% (156 of 596). For these streams the heat exchange through the water surface has the most controlling effect on stream Temperatures. For the remaining 74% of streams the relationship between weekly stream Temperature and weekly Equilibrium Temperature was also linear, but its slope was significantly less than 1.0 (even after calibration for shading and sheltering), indicating that processes other than surface heat exchange have an influence. Cold water inflows were dominant for 8% (46 of 596) of stream gaging sites. Less than 5% of all stream gaging stations showed evidence of unnatural heat inputs. Fitting an Equilibrium Temperature linearly to recorded stream Temperatures, e.g., at a weekly timescale, can be of use to project stream Temperatures under different weather-climate scenarios or to identify both natural and anthropogenic heat and hydrologic inputs to streams.

  • Stream Temperature‐Equilibrium Temperature relationship
    Water Resources Research, 2003
    Co-Authors: Travis Bogan, Omid Mohseni, Heinz G Stefan
    Abstract:

    [1] Equilibrium Temperature is the water Temperature at which the sum of all heat fluxes through the water surface is zero. It can be calculated from weather data. Mean weekly stream Temperature was found to be linearly related to mean weekly Equilibrium Temperature above 0°C. The slopes and intercepts of the linear relationship were used to identify effects of shading, sheltering, cold water inputs (groundwater, meltwater, and deep reservoir releases) and warm water inputs (wastewater, cooling water, and lake surface water). The linearity hypothesis was confirmed for data from 596 U.S. Geological Survey stream gaging stations in the eastern and central United States. For approximately 15% (89 of 596, NSC ≥ 0.90) of stream gaging stations, weekly Equilibrium Temperature was a good estimator of weekly stream Temperature with zero wind sheltering and sun shading. With sheltering and shading the number rose to 26% (156 of 596). For these streams the heat exchange through the water surface has the most controlling effect on stream Temperatures. For the remaining 74% of streams the relationship between weekly stream Temperature and weekly Equilibrium Temperature was also linear, but its slope was significantly less than 1.0 (even after calibration for shading and sheltering), indicating that processes other than surface heat exchange have an influence. Cold water inflows were dominant for 8% (46 of 596) of stream gaging sites. Less than 5% of all stream gaging stations showed evidence of unnatural heat inputs. Fitting an Equilibrium Temperature linearly to recorded stream Temperatures, e.g., at a weekly timescale, can be of use to project stream Temperatures under different weather-climate scenarios or to identify both natural and anthropogenic heat and hydrologic inputs to streams.

Travis Bogan - One of the best experts on this subject based on the ideXlab platform.

  • stream Temperature Equilibrium Temperature relationship
    Water Resources Research, 2003
    Co-Authors: Travis Bogan, Omid Mohseni, Heinz G Stefan
    Abstract:

    [1] Equilibrium Temperature is the water Temperature at which the sum of all heat fluxes through the water surface is zero. It can be calculated from weather data. Mean weekly stream Temperature was found to be linearly related to mean weekly Equilibrium Temperature above 0°C. The slopes and intercepts of the linear relationship were used to identify effects of shading, sheltering, cold water inputs (groundwater, meltwater, and deep reservoir releases) and warm water inputs (wastewater, cooling water, and lake surface water). The linearity hypothesis was confirmed for data from 596 U.S. Geological Survey stream gaging stations in the eastern and central United States. For approximately 15% (89 of 596, NSC ≥ 0.90) of stream gaging stations, weekly Equilibrium Temperature was a good estimator of weekly stream Temperature with zero wind sheltering and sun shading. With sheltering and shading the number rose to 26% (156 of 596). For these streams the heat exchange through the water surface has the most controlling effect on stream Temperatures. For the remaining 74% of streams the relationship between weekly stream Temperature and weekly Equilibrium Temperature was also linear, but its slope was significantly less than 1.0 (even after calibration for shading and sheltering), indicating that processes other than surface heat exchange have an influence. Cold water inflows were dominant for 8% (46 of 596) of stream gaging sites. Less than 5% of all stream gaging stations showed evidence of unnatural heat inputs. Fitting an Equilibrium Temperature linearly to recorded stream Temperatures, e.g., at a weekly timescale, can be of use to project stream Temperatures under different weather-climate scenarios or to identify both natural and anthropogenic heat and hydrologic inputs to streams.

  • Stream Temperature‐Equilibrium Temperature relationship
    Water Resources Research, 2003
    Co-Authors: Travis Bogan, Omid Mohseni, Heinz G Stefan
    Abstract:

    [1] Equilibrium Temperature is the water Temperature at which the sum of all heat fluxes through the water surface is zero. It can be calculated from weather data. Mean weekly stream Temperature was found to be linearly related to mean weekly Equilibrium Temperature above 0°C. The slopes and intercepts of the linear relationship were used to identify effects of shading, sheltering, cold water inputs (groundwater, meltwater, and deep reservoir releases) and warm water inputs (wastewater, cooling water, and lake surface water). The linearity hypothesis was confirmed for data from 596 U.S. Geological Survey stream gaging stations in the eastern and central United States. For approximately 15% (89 of 596, NSC ≥ 0.90) of stream gaging stations, weekly Equilibrium Temperature was a good estimator of weekly stream Temperature with zero wind sheltering and sun shading. With sheltering and shading the number rose to 26% (156 of 596). For these streams the heat exchange through the water surface has the most controlling effect on stream Temperatures. For the remaining 74% of streams the relationship between weekly stream Temperature and weekly Equilibrium Temperature was also linear, but its slope was significantly less than 1.0 (even after calibration for shading and sheltering), indicating that processes other than surface heat exchange have an influence. Cold water inflows were dominant for 8% (46 of 596) of stream gaging sites. Less than 5% of all stream gaging stations showed evidence of unnatural heat inputs. Fitting an Equilibrium Temperature linearly to recorded stream Temperatures, e.g., at a weekly timescale, can be of use to project stream Temperatures under different weather-climate scenarios or to identify both natural and anthropogenic heat and hydrologic inputs to streams.

Vincent Bustillo - One of the best experts on this subject based on the ideXlab platform.

  • a multimodel comparison for assessing water Temperatures under changing climate conditions via the Equilibrium Temperature concept case study of the middle loire river france
    Hydrological Processes, 2014
    Co-Authors: Vincent Bustillo, Florentina Moatar, Agnes Ducharne, Dominique Thiery, Alain Poirel
    Abstract:

    This paper investigates three categories of models that are derived from the Equilibrium Temperature concept to estimate water Temperatures in the Loire River in France and the sensitivity to changes in hydrology and climate. We test the models' individual performances for simulating water Temperatures and assess the variability of the thermal responses under the extreme changing climate scenarios that are projected for 2081–2100. We attempt to identify the most reliable models for studying the impact of climate change on river Temperature (Tw). Six models are based on a linear relationship between air Temperatures (Ta) and Equilibrium Temperatures (Te), six depend on a logistic relationship, and six rely on the closure of heat budgets. For each category, three approaches that account for the river's thermal exchange coefficient are tested. In addition to air Temperatures, an index of day length is incorporated to compute Equilibrium Temperatures. Each model is analysed in terms of its ability to simulate the seasonal patterns of river Temperatures and heat peaks. We found that including the day length as a covariate in regression-based approaches improves the performance in comparison with classical approaches that use only Ta. Moreover, the regression-based models that rely on the logistic relationship between Te and Ta exhibit root mean square errors comparable (0.90 °C) with those obtained with a classical five-term heat budget model (0.82 °C), despite a small number of required forcing variables. In contrast, the regressive models that are based on a linear relationship Te = f(Ta) fail to simulate the heat peaks and are not advisable for climate change studies. The regression-based approaches that are based on a logistic relationship and the heat balance approaches generate notably similar responses to the projected climate changes scenarios. This similarity suggests that sophisticated thermal models are not preferable to cruder ones, which are less time-consuming and require fewer input data. Copyright © 2012 John Wiley & Sons, Ltd.

Omid Mohseni - One of the best experts on this subject based on the ideXlab platform.

  • stream Temperature Equilibrium Temperature relationship
    Water Resources Research, 2003
    Co-Authors: Travis Bogan, Omid Mohseni, Heinz G Stefan
    Abstract:

    [1] Equilibrium Temperature is the water Temperature at which the sum of all heat fluxes through the water surface is zero. It can be calculated from weather data. Mean weekly stream Temperature was found to be linearly related to mean weekly Equilibrium Temperature above 0°C. The slopes and intercepts of the linear relationship were used to identify effects of shading, sheltering, cold water inputs (groundwater, meltwater, and deep reservoir releases) and warm water inputs (wastewater, cooling water, and lake surface water). The linearity hypothesis was confirmed for data from 596 U.S. Geological Survey stream gaging stations in the eastern and central United States. For approximately 15% (89 of 596, NSC ≥ 0.90) of stream gaging stations, weekly Equilibrium Temperature was a good estimator of weekly stream Temperature with zero wind sheltering and sun shading. With sheltering and shading the number rose to 26% (156 of 596). For these streams the heat exchange through the water surface has the most controlling effect on stream Temperatures. For the remaining 74% of streams the relationship between weekly stream Temperature and weekly Equilibrium Temperature was also linear, but its slope was significantly less than 1.0 (even after calibration for shading and sheltering), indicating that processes other than surface heat exchange have an influence. Cold water inflows were dominant for 8% (46 of 596) of stream gaging sites. Less than 5% of all stream gaging stations showed evidence of unnatural heat inputs. Fitting an Equilibrium Temperature linearly to recorded stream Temperatures, e.g., at a weekly timescale, can be of use to project stream Temperatures under different weather-climate scenarios or to identify both natural and anthropogenic heat and hydrologic inputs to streams.

  • Stream Temperature‐Equilibrium Temperature relationship
    Water Resources Research, 2003
    Co-Authors: Travis Bogan, Omid Mohseni, Heinz G Stefan
    Abstract:

    [1] Equilibrium Temperature is the water Temperature at which the sum of all heat fluxes through the water surface is zero. It can be calculated from weather data. Mean weekly stream Temperature was found to be linearly related to mean weekly Equilibrium Temperature above 0°C. The slopes and intercepts of the linear relationship were used to identify effects of shading, sheltering, cold water inputs (groundwater, meltwater, and deep reservoir releases) and warm water inputs (wastewater, cooling water, and lake surface water). The linearity hypothesis was confirmed for data from 596 U.S. Geological Survey stream gaging stations in the eastern and central United States. For approximately 15% (89 of 596, NSC ≥ 0.90) of stream gaging stations, weekly Equilibrium Temperature was a good estimator of weekly stream Temperature with zero wind sheltering and sun shading. With sheltering and shading the number rose to 26% (156 of 596). For these streams the heat exchange through the water surface has the most controlling effect on stream Temperatures. For the remaining 74% of streams the relationship between weekly stream Temperature and weekly Equilibrium Temperature was also linear, but its slope was significantly less than 1.0 (even after calibration for shading and sheltering), indicating that processes other than surface heat exchange have an influence. Cold water inflows were dominant for 8% (46 of 596) of stream gaging sites. Less than 5% of all stream gaging stations showed evidence of unnatural heat inputs. Fitting an Equilibrium Temperature linearly to recorded stream Temperatures, e.g., at a weekly timescale, can be of use to project stream Temperatures under different weather-climate scenarios or to identify both natural and anthropogenic heat and hydrologic inputs to streams.

Xinzhong Du - One of the best experts on this subject based on the ideXlab platform.

  • Incorporation of the simplified Equilibrium Temperature approach in a hydrodynamic and water quality model – CE-QUAL-W2
    Water Science & Technology: Water Supply, 2018
    Co-Authors: Xinzhong Du
    Abstract:

    Water Temperature is an important indicator for biodiversity and ecosystem sustainability. In this study, a simplified Equilibrium Temperature model was incorporated into the CE-QUAL-W2 (W2) model. This model is easy to implement, needing fewer meteorological variables and no parameter calibration. The model performance was evaluated using observed data from four stations on the Lower Minnesota River. Results show that the simplified Equilibrium Temperature model performed as well as the original Equilibrium Temperature model and the term-by-term process model for water Temperature predictions with the values of the coefficient of determination ( R 2 ), Nash–Sutcliffe Efficiency (NSE), and Percent Error (PE) in the accepted range ( R 2 = 0.974, NSE = 0.972, PE = 1.377%). The impact of the water Temperature on Carbonaceous Biochemical Oxygen Demand (CBOD) concentrations under three different water Temperature models was evaluated, and results show that the monthly averaged CBOD concentrations of the simplified Equilibrium Temperature model were almost the same as that of the term-by-term approach. For all the four calibration stations, the simplified Equilibrium Temperature approach performs better than the other two models for dissolved oxygen simulation ( R 2 = 0.791, NSE = 0.65, PE = 7.596%), which indicates that the simplified Equilibrium Temperature model can be a potential tool to simulate water Temperature for water quality modelling.

  • Incorporation of the Equilibrium Temperature approach in a Soil and Water Assessment Tool hydroclimatological stream Temperature model
    Hydrology and Earth System Sciences, 2017
    Co-Authors: Xinzhong Du, Narayan Kumar Shrestha, Darren L. Ficklin, Junye Wang
    Abstract:

    Stream Temperature is an important indicator for biodiversity and sustainability in aquatic ecosystems. The stream Temperature model currently in the Soil and Water Assessment Tool (SWAT) only considers the impact of air Temperature on stream Temperature, while the hydroclimatological stream Temperature model developed within the SWAT model considers hydrology and the impact of air Temperature in simulating the water–air heat transfer process. In this study, we modified the hydroclimatological model by including the Equilibrium Temperature approach to model heat transfer processes at the water–air interface, which reflects the influences of air Temperature, solar radiation, wind speed and streamflow conditions on the heat transfer process. The thermal capacity of the streamflow is modeled by the variation of the stream water depth. An advantage of this Equilibrium Temperature model is the simple parameterization, with only two parameters added to model the heat transfer processes. The Equilibrium Temperature model proposed in this study is applied and tested in the Athabasca River basin (ARB) in Alberta, Canada. The model is calibrated and validated at five stations throughout different parts of the ARB, where close to monthly samplings of stream Temperatures are available. The results indicate that the Equilibrium Temperature model proposed in this study provided better and more consistent performances for the different regions of the ARB with the values of the Nash–Sutcliffe Efficiency coefficient (NSE) greater than those of the original SWAT model and the hydroclimatological model. To test the model performance for different hydrological and environmental conditions, the Equilibrium Temperature model was also applied to the North Fork Tolt River Watershed in Washington, United States. The results indicate a reasonable simulation of stream Temperature using the model proposed in this study, with minimum relative error values compared to the other two models. However, the NSE values were lower than those of the hydroclimatological model, indicating that more model verification needs to be done. The Equilibrium Temperature model uses existing SWAT meteorological data as input, can be calibrated using fewer parameters and less effort and has an overall better performance in stream Temperature simulation. Thus, it can be used as an effective tool for predicting the changes in stream Temperature regimes under varying hydrological and meteorological conditions. In addition, the impact of the stream Temperature simulations on chemical reaction rates and concentrations was tested. The results indicate that the improved performance of the stream Temperature simulation could significantly affect chemical reaction rates and the simulated concentrations, and the Equilibrium Temperature model could be a potential tool to model stream Temperature in water quality simulations.

  • Incorporation of the Equilibrium Temperature approach in a Soil and Water Assessment Tool hydroclimatological stream Temperature model
    2017
    Co-Authors: Xinzhong Du, Narayan Kumar Shrestha, Darren L. Ficklin, Junye Wang
    Abstract:

    <p><strong>Abstract.</strong> Stream Temperature is an important indicator for biodiversity and sustainability in aquatic ecosystems. The stream Temperature model currently in the Soil and Water Assessment Tool (SWAT) only considers the impact of air Temperature on stream Temperature, while the hydroclimatological stream Temperature model developed within SWAT model considers hydrology and the impact of air Temperature in simulating the water-air heat transfer process. In this study we propose using the Equilibrium Temperature approach to model complex heat transfer processes at the water-air interface, which reflects the influences of air Temperature, solar radiation, wind speed and stream water depth on the heat transfer process. The thermal capacity of the streamflow is modelled by the variation of the stream water depth. An advantage of this Equilibrium Temperature model is the simple parameterization, with only two added parameters to model the heat transfer processes. The Equilibrium Temperature model is applied and tested in the Athabasca River Basin (ARB) in Alberta, Canada. The model is calibrated and validated at five stations throughout different parts of the ARB for which high-frequency observed stream Temperature data are available. The results indicate that the Equilibrium Temperature model provided better and more consistent performances for the different regions of the ARB with the values of Nash-Sutcliffe Efficiency (> 0.67) greater than those of the original SWAT model and the hydroclimatological model. Overall, the Equilibrium Temperature model uses existing SWAT meteorological data as input, can be calibrated using fewer parameters and less effort, and has an overall better performance for the simulation of daily stream Temperatures. Thus, it can be used as an effective tool for predicting the change in stream Temperature regimes under varying hydrological and meteorological conditions. In addition, the impact of the stream Temperature simulations on chemical reaction rates and concentrations was tested. The results indicate that the improved performance of the stream Temperature simulation could significantly affect chemical reaction rates and the simulated concentrations and the Equilibrium Temperature model could be a potential tool to model stream Temperature for water quality simulations.</p>