Assessing reservoir operations risk under climate change

Abstract

[1] Risk-based planning offers a robust way to identify strategies that permit adaptive water resources management under climate change. This paper presents a flexible methodology for conducting climate change risk assessments involving reservoir operations. Decision makers can apply this methodology to their systems by selecting future periods and risk metrics relevant to their planning questions and by collectively evaluating system impacts relative to an ensemble of climate projection scenarios (weighted or not). This paper shows multiple applications of this methodology in a case study involving California's Central Valley Project and State Water Project systems. Multiple applications were conducted to show how choices made in conducting the risk assessment, choices known as analytical design decisions, can affect assessed risk. Specifically, risk was reanalyzed for every choice combination of two design decisions: (1) whether to assume climate change will influence flood-control constraints on water supply operations (and how), and (2) whether to weight climate change scenarios (and how). Results show that assessed risk would motivate different planning pathways depending on decision-maker attitudes toward risk (e.g., risk neutral versus risk averse). Results also show that assessed risk at a given risk attitude is sensitive to the analytical design choices listed above, with the choice of whether to adjust flood-control rules under climate change having considerably more influence than the choice on whether to weight climate scenarios.

Global change in streamflow extremes under climate change over the 21st century

“…Another study of runoff projections from a larger ensemble of GCMs also confirms such trends in runoff for the 21st century (Tang and Lettenmaier, 2012). Changes in runoff, and consequently in streamflow, under current and future climate change have strong implications for available freshwater resources (Arnell, 2004;Brekke et al, 2009;Oki and Kanae, 2006;Stocker et al, 2013;Vörös-marty et al, 2000). Climate change is projected to decrease mean runoff in land areas around the Mediterranean and some parts of Europe, southern Africa, and Central and South America, and consequently increase water stress in those regions (Arnell, 2004).…”

Outlet work optimization in flood control reservoirs

“…In normal operating situations, therefore, a larger volume of stored water can be counted on and made available to any other uses for which the reservoir is designed (drinking water, irrigation, electricity production), thus providing an indubitable economic advantage. A further advantage of this type of outlet device lies in the possibility to modify management of the fl ow rate discharged to deal with a different fl ood event evaluation or with problems linked to climate change and safeguarding the environment [16][17][18][19].…”

A Snowpack Forecasting Model for the Eastern Sierra Nevada Based on Cointegration With the North Pacific High Sea-Level Pressure Anomaly

“…The statistical tool presented in this work, relating NPH anomaly to precipitation or snowpack indices, can be applied to other California watersheds, where it may allow reservoir operators additional insight, on a year-to-year basis, on whether some of the flood storage could be utilized for water supply storage. This additional insight could be of great value in coming decades, where operators must make the most from a potentially more variable precipitation season, as well as declining snowpack due to higher temperatures and a partial shift from snowfall to rainfall, and greater peaks in runoff in wet years (Fissekis, 2008;Brekke et al, 2009;Hanak and Lund, 2012).…”