Declines in water quality and increased exposure to infectious disease, particularly those that cause diarrhea, are recognized as persistent global health threats, especially in water-scarce areas of the world. In these dry regions, river floodplains are critical for human communities, but these same areas are also extremely vulnerable to human impacts. This project will use a multidisciplinary research approach to examine these linkages in order to improve the management and forecasting of diarrheal disease in general and particularly in vulnerable dryland systems. The project will serve as a foundation for a multidisciplinary education program that will strengthen cross-cultural understanding and leadership in coupled natural and human systems research. This study brings direct benefits to society through the development of knowledge and tools that will identify periods of increased risk of diarrheal disease and degraded water quality allowing vulnerable communities in dryland regions sufficient lead time to identify public health preparedness. A technical description of the project: This project focuses on three significant problems: (1) basic knowledge of the coupled dynamics of fluvial processes and water quality in drylands and the influence of anthropogenic and natural influences on pathogen pollution and health; (2) sociocultural and economic variables that influence waterborne disease dynamics and system feedbacks; and (3) appropriate tools to monitor indicators of system change and intra-annual forecasting ability. The project will examine the coupled natural human dynamics in dryland river floodplains in southern Africa by using advanced sensing, molecular, microbiological, and modeling tools that span multiple disciplines. The study area spans part of Namibia and Botswana in a region where human diarrheal disease outbreaks are coupled to fluvial processes and microbial water quality dynamics. Empirical studies of this dryland river system will be integrated with dynamical modeling of the environmental and human- system components of diarrheal disease. Project outcomes will: i) provide robust empirical data; ii) advance dryland fluvial, soil microbial, and socioeconomic theory and public health policy; and iii) produce generic tools for managing and forecasting the coupled dynamics of microbial water quality and health in other drylands globally.