Kashif Shaad , Nicholas J Souter , Derek Vollmer , Helen M Regan, Maíra Ometto Bezerra 

Natural ecosystems are fundamental to local water cycles and the water-related ecosystem services that humans enjoy, such as water provision and protection from natural hazards. However, integrating ecosystem services into water resources management requires that they be acknowledged, quantified, and communicated to decision makers. We present an indicator framework that incorporates the supply of, and demand for, freshwater-related ecosystem services, which provides an initial diagnostic for natural resource managers as well as a mechanism for evaluating tradeoffs through future scenarios. Building on a risk assessment framework, we present a three-tiered indicator for measuring where demand exceeds supply of services, addressing the scope (spatial extent), frequency, and amplitude for which objectives (service delivery) are not met. The Ecosystem Service Indicator is presented on a scale of 0-100 which encompasses none to total service delivery. We demonstrate the framework and its applicability to a variety of services and data sources from case studies in China and the Lower Mekong region. We also evaluate the sensitivity of the indicator score derived from these methods, to communicate uncertainty. The proposed indicator framework is conceptually simple, robust, and flexible enough to accommodate the inevitable evolution and expansion of tools, models and data sources used to measure and evaluate the value of water-related ecosystem services.