Precipitation Patterns, Supply Planning and Demand Curves: The Complexities of Assessing Water Supply Risks

Drinking water utilities must consider many variables and potential risks in planning for an adequate water supply to meet customer demand. While knowing the amount of precipitation that falls within a utility's reservoir system during a specific time period is a critical component of supply planning, understanding current demand and anticipating future supply needs involves studying many additional variables. In addition to understanding changing precipitation patterns (such as storm duration and frequency) and extreme events (whether a 100-year storm or a prolonged drought), water utilities also must consider variables such as water use, conservation, and demand curves. These variables are affected by a changing climate and also by other factors such as population growth, urban development and water-efficient appliances, to name a few.

This presentation will compare and contrast the approaches that are being taken by drinking water utilities in the Pacific Northwest (Seattle area) and the Texas area to plan for current and future supplies in light of changing precipitation patterns. The author will explain how these agencies are using weather and climate information as well as utility-driven supply and demand forecasts and planning scenarios to identify risk levels and tipping points related to water supply planning and utility operating thresholds. Examples of how these utilities are planning to become climate resilient both individually and where possible, regionally with other agencies, will also be provided.