Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Tham khảo tài liệu 'electricity infrastructures in the global marketplace part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Harnessing Untapped Hydropower 119 nutrient levels thermal modification and heavy metal levels. Relatively few reservoirs have acute problems and mitigation measures can be adopted if necessary. Again the effects are highly dependent on size shape depth and operation rules. Narrow reservoirs with high inflows relative to outflows will tend to have minimal effects on water quality. In contrast large reservoirs with greater storage capacity and large surface area subject to seasonal solar gain allow development of seasonal stratification resulting in significant changes in water quality at various depths. At depth - particularly if biomass is present where light does not penetrate sufficiently for photosynthesis oxygen levels can become depleted. Solutions to these complications include the removal of biomass by careful clearing before impounding the use of multi level intakes and discharge through oxygenating facilities such as Howell Bunger Valves. Unfortunately an opposite problem may occur from that of lack of oxygen that is an excess of nitrogen. Deep spillway plunge pools can allow air-entrained water to plunge to a depth at which the pressure is sufficient to supersaturate the water with nitrogen. Simplistically fish in the area can suffer similar afflictions to that sometimes-affecting deep-sea diver which is the bends known as gas bubble disease in fish . The solution to this difficulty is to use turbines to discharge and to try to use energy dissipation devices that avoid excessive plunging. Despite the various attributes of reservoirs that must be addressed many reservoirs provide an excellent environment for fish that develop in the new expanded aquatic ecosystems. In several situations game management agencies have stocked fish in and below the reservoir with high economic or recreational value. 2.12.7 Social Aspects As with other forms of economic activity hydro projects can have both positive and negative social aspects. Social costs are mainly .
