Impact of climate change on Cannonsville Reservoir thermal structure in the New York City water supply

A Anandhi,D C Pierson,E M Owens,E Schneiderman,J S Read,N R Samal,Y Huang

doi:10.2166/wqrjc.2012.020

Abstract

Global Circulation Model values of mean daily air temperature, wind speed and solar radiation for the 2081–2100 period are used to produce change factors that are applied to a 39 year record of local meteorological data to produce future climate scenarios. These climate scenarios are used to drive two separate, but coupled models: the Generalized Watershed Loading Functions-Variable Source Area model in order to simulate reservoir tributary inflows, and a one-dimensional reservoir hydrothermal model used to evaluate changes in reservoir thermal structure in response to changes in meteorological forcing and changes in simulated inflow. Comparisons between simulations based on present-day climate data (baseline conditions) and future simulations (change-factor adjusted baseline conditions) are used to evaluate the development and breakdown of thermal stratification, as well as a number of metrics that describe reservoir thermal structure, stability and mixing. Both epilimnion and hypolimnion water temperatures are projected to increase. Indices of mixing and stability show changes that are consistent with the simulated changes in reservoir thermal structure. Simulations suggest that stratification will begin earlier and the reservoir will exhibit longer and more stable periods of thermal stratification under future climate conditions.

Highlights

Given that change-factor methodology is widely used (Anandhi et al ), is simple to apply and not computationally demanding, it was a good choice for our first attempt to evaluate the impacts of climate change on reservoir thermal structure
Comparisons between simulations based on present-day climate data and future simulations are used to evaluate the development and breakdown of thermal stratification, as well as a number of metrics that describe reservoir thermal structure, stability and mixing
The simulation results of the effects of climate warming on the reservoir’s thermal structure indicate that thermal structure is sensitive to projected future changes in meteorological conditions, with warmer future conditions resulting in earlier and longer periods of summer stratification, under the A1B and A2 emission scenarios that predict greater increases in atmospheric CO2

Summary

Introduction

Samal Department of Civil Engineering, National Institute of Technology Durgapur, M.G. Avenue, Durgapur-713209, West Bengal, India. Read University of Wisconsin-Madison, Civil and Environmental Engineering, Environmental Fluid Mechanics, 1415 Engineering Dr Rm 1261, Madison, WI 53706, USA. Owens Upstate Freshwater Institute, P.O. Box 506, Syracuse, NY 13214, USA and Department of Civil and Environmental. K turbulent diffusion coefficient influence on the water quality and ecology of the correkd diffusion attenuation coefficient of solar sponding aquatic ecosystems Radiation a, b, ; Samal & Mazumdar a, b). Changes in ks surface heat transfer coefficient weather have direct effects on reservoir thermal character-

Methods

Results

Conclusion