Civil Engineering

Large dams have provided extensive benefits during the past 60 years but have also resulted in ecological and social consequences that were unexpected or were deemed to have a lower societal importance than the design benefits. The management of large dams is still a relatively new scientific issue, compared to the timeframe necessary to detect and understand all the consequences occurring at the watershed scale. This paper summarizes the unforeseen or unanticipated environmental consequences of these projects and potential ramifications to the overall project performance. The value of a central knowledge base and the importance of a system-wide monitoring program to assess pre-and post-implementation conditions and adapt operational rules are presented. Knowledge developed in several basins is reviewed in the context of future strategies for Chile. Chile has a strong economy, looming energy crisis and is faced with balancing the long-term value of a renowned natural landscape with unique ecology and the largest salmon aquaculture industry in the world against the prospect of low cost hydropower to drive other sectors of the economy. This paper outlines the hydroinformatics technologies and scientifically based management approaches that can be applied to this complex issue.

The Baker basin (27 000 km 2) is located in one of the most unique and remote areas of the planet. Its hydrological regime is poised to undergo dramatic changes in the near future due to hydropower development and climate change. The basin contains the second largest lake in South America, and part of a major icefield. This study documents the natural baseline of the Baker River basin, discusses the main hydrological modes and analyses the potential for sustainable management. Annual precipitation varies several-fold from the eastern Patagonian steppes to the North Patagonian Icefield. The westernmost subbasins are strongly governed by glacier-melt with a peak discharge in the austral summer (January-March). The easternmost sub-basins have a much more seasonal response governed by quicker snowmelt in spring (November-December), while they exhibit low flows typical for semi-arid regions during summer and autumn. Topography, vegetation and wetlands may also influence streamflow. The strong spatio-temporal gradients and variability highlight the need for further monitoring, particularly in the headwaters, especially given the severe changes these basins are expected to undergo. The large diversity of hydrological controls and climate change pose significant challenges for hydrological prediction and management.