1 Environmental Dynamics, Department of Science and Environment, Roskilde University2 The Department of Environmental, Social and Spatial Change, Roskilde University3 Quaternary Research Group (QRG), Department of Science and Environment, Roskilde University
The purpose is to elucidate climate change impacts on water related to precipitation, catchment hydrology, water management and land development in fruit export regions at the desert margin in Chile. The case is a region exposed to intense globalization and severe climate change. A timeline (past, present, future) was applied to four valleys for comparative purposes. Data collection included field observations, semi-structured interviews, archives and library investigations. Precipitation decreased during the last century and varied as a function of El Niño Southern Oscillation impacts on precipitation. The change and variability is most serious in the northernmost valleys that receive less than 200 mm/yr. This is strengthened by the northwards decrease in the importance of mountains. Precipitation in the mountains, glaciers and snowfields are the main source of irrigation water – not the lowland precipitation. As a result annual discharge is up to 50 times lower compared to the southernmost valleys. This did not impede the expansion of fruit plantations explained by the expansion of irrigation canals, and the adoption of drip irrigation. More serious are land tenure barriers, the lack of water rights, conflicts between water managers, the absence of risk-aversion strategies in times of drought, the lack of a unified irrigation systems, and the lack of control and regulation of irrigation water explained by the absence of dams. Climate change is expected to result in a 40 % decrease in precipitation in 2100 and regional warming. Peak run-off will be displaced from spring to winter, run-off may be reduced by more than 40 % because of warming and rivers in the driest valleys may become intermittent streams with no water for irrigation except if minor reservoirs are constructed. In conclusion two-century climate change impacts on water barriers and possibilities only explain a part of their complexity in space and time.