Water infrastructure projects are a significant portion of the World Bank’s lending portfolio and a major need for developing countries throughout the world. Many water resources projects have long periods of economic return, with significant uncertainties in the behavior of the natural system as well as that of human factors (technology, population dynamics, economic development, and the like). The uncertainties associated with climate change, however, have led to a reconsideration of whether the water development community is adequately taking into account the uncertainties that characterize the future. The goal of this book is to outline a pragmatic process for risk assessment of Bank water resources projects that can serve as a decision support framework - a decision tree to assist project planning under uncertainty. The decision tree described in this book is based on the growing consensus that robustness-based approaches are needed to address uncertainty and its potential impacts on infrastructure planning. These approaches emphasize assessment of individual projects and their ability to perform well over a wide range of future uncertainty, including climate and other uncertainties. The decision tree is designed to address the fundamental issues to provide a path forward for project planners who face decisions potentially affected by climate change uncertainty. The decision tree was also designed so that human and financial resources can be used economically. The goal of this work was to develop a tool that will be applicable to all water resources projects, but that will also allocate climate risk assessment effort in a way that is consistent with each project’s potential sensitivity to that climate risk. Report is organized as follows: chapter one gives introduction. Chapter two provides background on the risks relevant to water systems planning, describes the different approaches to scenario definition in water systems planning, and introduces the decision scaling methodology upon which the general structure of the decision tree framework is based. Chapter three describes the decision tree tool and explains each of the steps and processes that make up the tool. Chapter four focuses on a case study of a small hydropower project as an illustration of the decision tree procedure. Chapter five describes some of the tools available for decision making under uncertainty and methods available for climate risk management. Concluding thoughts on implementation are presented in chapter six. See Less -