Page - 558 - in Book of Full Papers - Symposium Hydro Engineering

environmental metrics to assess the environmental performance of new hydropower. The peer-reviewed process starts with defining what sustainability means for hydropower, then setting performance measures for different environmental effects, such as fish migration, energy efficiency and greenhouse gas emissions [7]. As a case study, a team from the University of the Philippines Diliman (UPD) has designed a system for the Gaia dam in Philippines that can control or prevent flooding from torrential rains on farms, along rivers and in coastal areas by minimizing and re-routing the flow of water through storm runoff pathways. Its main structural frame consists of gabion cages: wire mesh baskets filled with sturdy columns of recycled concrete cylinders or rocks, which provide stability against the hydrostatic forces pushing through the dam [8]. Like a miniature hydroelectric power plant, the Gaia dam could divert water into the powerhouse where turbines are installed, yet do so less expensively than the concrete dams that are usually used for this purpose. In addition, the dam is designed to release proprietary proteins and enzymes when water passes through its specialized core. Its proteins are designed to help crops absorb soil nutrients and minerals, while its enzymes would gradually dissolve the exoskeletons of insects and other pests that attack the crops, thereby acting as natural fertilizers and pesticides. Thus the Gaia dam has the potential to help in the production of organic crops. The dams themselves often flood large expanses of forest (creating methane emissions). Also, dams require networks of roads for dam and power grid construction. These roads frequently open a Pandora's Box of environmental problems, including illegal deforestation, mining, poaching, and land speculation. For instance, the 12 dams planned for the Tapajos River in the Brazilian Amazon are projected to increase deforestation by nearly one million hectares, by 2030 [9]. The modern dam explosion and its indirect impacts via road construction into remote frontiers are arguably its worst consequences of all. 2.1. FIXING EXISTING PROBLEMS Many dams in Iran and worldwide have been constructed in the past when environmental and social impacts were not that much of concern. Recently, endless efforts are being made to retrofit the hydropower projects in the operation phase [11]. Restoring fish passage is a major focus. Many large dams were built without fish ladders and remain an absolute barrier to fish migration. Climate change makes this an even greater concern, because migratory species like salmon and steelhead need access to cold-water spawning habitat above dams as temperatures warm. Adding fish ladders however, exceeds the original construction cost of some large dams. Compromises include trap-and-haul programs, in which fish are collected and transported by tanker truck around dams, and motorized lifts in various configurations. 558