Global withdrawals of water have doubled over the past 40 years as irrigated agricultural land expanded from 138 million ha to 277 million hectares during the period from 1961 to 2003. Irrigated land is responsible for more than 85 percent of global consumptive water use, producing approximately 45 percent of the global food supply on only 20 percent of global cropland. The combination of the increasing use of irrigation in agricultural production and the importance of snowmelt in many agricultural areas has led to a situation where more than one-sixth of the world's population relies on glaciers and seasonal snow packs as their primary source of streamflow. Climate change processes are projected to impact the amount of snowfall and the seasonality of discharge around the globe. Temperature effects of climate change alone will be sufficient to alter both snowpack accumulation and snowmelt dynamics of many agricultural systems. While additional climate change impacts on growing season rainfall, streamflow, and drought could serve to either exacerbate or mitigate shifts in snowmelt climatology on water available for crops, the dependence on snowmelt and irrigation in many agricultural systems may reduce their ability to respond to future changes. Of additional concern is the fact that many temperate and tropical agricultural areas dependent on glacial meltwater are now facing the threat of complete glacier loss, making climate changes in these regions potentially more disruptive than in areas where only seasonal snowmelt is used as a water resource. In the face of water shortages, governance institutions established to allocate water may be disrupted and forced to change. Critical tensions exist between the potential impacts of climate change and existing and future patterns of water use in regions highly dependent on glacier-fed streamflow for agricultural irrigation. This interdisciplinary research project will examine how human populations will be impacted by these changes and the capacity of users in glacier-irrigated agricultural systems to adapt. The investigators will examine semi-arid agricultural systems that are dependent on snowmelt located across strongly contrasting institutional and hydrological settings in eastern Kenya and the western United States. They will integrate information gathered from focus groups, water-user interviews, field hydrological measurements, role-playing games, and scenario-based models of potential climate change impacts to assess community vulnerability to climate variability and understand how communities might respond to changes in water availability in the future. They will address interactions among human actors, the physical and social capital they construct and maintain, and the dynamics of water availability and allocation across spatial scales.
This project will have significant implications for the governance of water resources and how communities and households cope with water scarcity. The empirical analysis of past and present water governance will support the development of scenario-based models of potential climate change impacts to assess community vulnerability to climate variability and to understand how communities might respond to changes in water availability in the future. Findings from this project will be of value to policy makers who are seeking more nuanced policy responses than simple "one size fits all" solutions. Many policy analysts recommend one-type of governance, such as government or private ownership, as being "ideal" to cope with threats to ecological systems. This research will develop new knowledge about the ways in which institutional diversity can contribute to the effective management of water resources. This project is supported by the NSF Dynamics of Coupled Natural and Human Systems (CNH) Program.