Incorporating Climate Change Into Water Resources Planning in England and Wales1

Arnell, Nigel W., 2011. Incorporating Climate Change Into Water Resources Planning in England and Wales. Journal of the American Water Resources Association (JAWRA) 47(3):541‐549. DOI: 10.1111/j.1752‐1688.2011.00548.x Abstract: Public water supplies in England and Wales are provided by around 25 private‐sector companies, regulated by an economic regulator (Ofwat) and environmental regulator (Environment Agency). As part of the regulatory process, companies are required periodically to review their investment needs to maintain safe and secure supplies, and this involves an assessment of the future balance between water supply and demand. The water industry and regulators have developed an agreed set of procedures for this assessment. Climate change has been incorporated into these procedures since the late 1990s, although has been included increasingly seriously over time and it has been an effective legal requirement to consider climate change since the 2003 Water Act. In the most recent assessment in 2009, companies were required explicitly to plan for a defined amount of climate change, taking into account climate change uncertainty. A “medium” climate change scenario was defined, together with “wet” and “dry” extremes, based on scenarios developed from a number of climate models. The water industry and its regulators are now gearing up to exploit the new UKCP09 probabilistic climate change projections – but these pose significant practical and conceptual challenges. This paper outlines how the procedures for incorporating climate change information into water resources planning have evolved, and explores the issues currently facing the industry in adapting to climate change.     

Does More Storage Give California More Water?

Increasing reservoir storage is commonly proposed to mitigate increasing water demand and provide drought reserves, especially in semiarid regions such as California. This paper examines the value of expanding surface reservoir capacity in California using hydroeconomic modeling for historical conditions, a future warm‐dry climate, and California's recently adopted policy to end groundwater overdraft. Results show expanding surface storage capacity rarely provides sizable economic value in most of California. On average, expanding facilities north of California's Delta provides some benefit in 92% of 82 years modeled under historical conditions and in 61% of years modeled in a warm‐dry climate. South of California's Delta, expanding storage capacity provides no benefits in 14% of years modeled under historical conditions and 99% of years modeled with a warm‐dry climate. Results vary across facilities between and within regions. The limited benefit of surface storage capacity expansion to statewide water supply should be considered in planning California's water infrastructure.     

SOCIOECONOMIC IMPACTS OF CLIMATE CHANGE ON U.S. WATER SUPPLIES1

ABSTRACT: A greenhouse warming would have major effects on water supplies and demands. A framework for examining the socioeconomic impacts associated with changes in the long-term availability of water is developed and applied to the hydrologic implications of the Canadian and British Hadley2 general circulation models (GCMs) for the 18 water resource regions in the conterminous United States. The climate projections of these two GCMs have very different implications for future water supplies and costs. The Canadian model suggests most of the nation would be much drier in the year 2030. Under the least-cost management scenario the drier climate could add nearly $105 billion to the estimated costs of balancing supplies and demands relative to the costs without climate change. Measures to protect instream flows and irrigation could result in significantly higher costs. In contrast, projections based on the Hadley model suggest water supplies would increase throughout much of the nation, reducing the costs of balancing water supplies with demands relative to the no-climate-change case.     

Nonstationary Water Planning: An Overview of Several Promising Planning Methods1

Waage, Marc D. and Laurna Kaatz, 2011. Nonstationary Water Planning: An Overview of Several Promising Planning Methods. Journal of the American Water Resources Association (JAWRA) 47(3):535‐540. DOI: 10.1111/j.1752‐1688.2011.00547.x Abstract: Climate change is challenging the way water utilities plan for the future. Observed warming and climate model projections now call into question the stability of future water quantity and quality. As water utilities cope with preparing for the large range of possible changes in climate and the resulting impacts on their water systems, many are searching for planning techniques to help them consider multiple possible conditions to better prepare for a different, more uncertain, future. Many utilities need these techniques because they cannot afford to delay significant decisions while waiting for scientific improvements to narrow the range of potential climate change impacts. Several promising methods are being tested in water utility planning and presented here for other water utilities to consider. The methods include traditional scenario planning, classic decision making, robust decision making, real options, and portfolio planning. Unfortunately, for utilities vulnerable to climate change impacts, there is no one‐size‐fits‐all planning solution. Every planning process must be tailored to the needs and capabilities of the individual utility.     

SUMMER FLOODING AT CHICAGO AND POSSIBLE RELATIONSHIPS TO URBAN-INCREASED HEAVY RAINFALL1

ABSTRACT: : Studies of two measures of flooding in the Chicago metropolitan area reveal a wide range of floods with the magnitude related to recurrence interval expressions of rain intensity. Minor type floods (in basements and underpasses) usually result from localized heavy rains (≤ 3-hour duration) with return intervals of 1 to 2 years, and more major floods result from rains with return intervals of 2 to 5 years (or more). Urban-factors help lead to increases in warm season rain events in Chicago with 1- to 4-year return intervals. These apparently help lead to 10 to 100 percent more flooding events in Chicago than expected. The range of increase varies depending on locale and type of flood, but the increases in storms should be accounted for in drainage designs.     

THE FLOOD OF '96 AND ITS SOCIOECONOMIC IMPACTS IN THE SUSQUEHANNA RWER BASIN1

ABSTRACT: The meteorology flood hydroclimatolog and socioeconomic impacts of the Flood of January 1996 in the Susquehanna River Basin are explored. The analysis explains how an unusual storm system brought high humidities, high temperatures, strong winds, and heavy rain to the basin. The rapid melt of the deep snowpack, combined with the heavy rainfall, produced the sudden release of large volumes of water. Because the ground surface was frozen or saturated, this water moved primarily as overland flow. Thus, the flood waters were not restricted to areas immediately adjacent to stream channels and, consequently, some of the largest impacts were on people, property, and infrastructure in areas not normally prone to flooding. Socioeconomic patterns of flooding over time and space are investigated to put this flood into context and to highlight its impacts. The analysis concludes that if such overland flooding is a more common feature of climate change, then the current vulnerability to this form of flooding and its economic implications must be considered carefully.