AbstractsGeography &GIS

Agricultural systems are vulnerable to climate variability and the resulting water supply shocks. Vulnerability assessments for agriculture have largely focused on rainfed systems or on individual irrigation systems, with less attention to how nested networks of irrigation systems in large river basins respond to water shortages. Irrigation releases and return flow from upstream irrigation systems become the inflow of downstream systems; if upstream systems reduce releases in years of drought, exposure to water supply shocks may increase with increasing distance downstream. This paper presents an analytical framework for assessing the vulnerability of a network of irrigation systems to water supply shocks in a large river basin, with particular attention to how the position of an irrigation system within that network structures its vulnerability. The concepts of sensitivity and exposure ??? components of vulnerability analysis ??? can be used to describe the spatial structure of the drought response of irrigated agriculture in river basins. This framework is tested in the Krishna River basin in southern India. A time-series of satellite imagery is used to map change in irrigated area between a year of normal precipitation (June 2001- May 2002) and a drought year (June 2002 - May 2003). Precipitation in each reservoir's watershed was quantified using satellite-based rainfall data. It is hypothesized that during drought, the change in irrigated area in reservoir command areas is spatially structured by downstream distance, percentage decrease in precipitation in a reservoir's watershed, and the percent of the watershed that is irrigated upstream of a reservoir. Change in precipitation is a significant predictor of irrigated area change in upstream systems (p = 0.05), while upstream irrigated area is a significant predictor of change in irrigated area basin-wide (p = 0.07). Mid-basin systems show large decreases in irrigated area, and delta systems had unexpected low sensitivity due to the availability of groundwater. This research provides useful knowledge for water management in the Krishna River Basin and contributes an applied case study for vulnerability science. Advisors/Committee Members: Biggs, Trent, Farley, Kathleen, Lauer, Matthew.