【文章內(nèi)容簡介】 reservoirusually 100 years or more。 (3)Design the reservoir outlet at the dam at least as high as the expected silt accumulation level at the point(the outlet may be higher if the plan calls for maintaining a higher minimum reservoir pool for any purpose)。 (4) Provide outlets at more than one level if cost is not excessive。 (5)Consider , in the project plan, the possibility and the suitability of sites for constructing sediment detention basins short distance above the reservoir。 (6) Consider the merits, possible methods, and costs of providing watershed protection and management against accelerated erosion.以下準則適用于方案選擇和項目設計：（1）當有其他選擇時，避免在一條含沙量大的河流上建設水庫；（2）作為總庫容的一部分，提供至少與水庫設計經(jīng)濟壽命（100年或以上）內(nèi)的預計的泥沙淤積量相同的空間；（3）在大壩處設計水庫出口，至少與該處預期的泥沙淤積具有相同的高度（如果方案處于某種目的要求保持較高的最小庫容，那么出口可能會更高）；（4）在不超成本的條件下設置超過一個高程；（5）在項目方案中考慮在水庫上游短距離處建設泥沙滯蓄區(qū)的可能性和適合性；（6）考慮提供控制水土流失加劇的流域保護和管理的有點、可能的方法及成本。2. Selection of Dam Sites and Sizes2. 壩址及大壩規(guī)模的選擇The dam sites are determined by the functions of the project. The exact site within the general location must be determined by careful project consideration and systematic studies. Upon pletion of the feasibilitygrade investigations the sites and the size of project dams have been provisionally selected. It is probable that these selections will prove to be the final ones, but the possibilities remain of making some further adjustments in the final, preconstruction phases of investigations. An adjustment of capacity of a storage reservoir may prove to be necessary。 this, or any new design data may disclose the need of changing the axis location of the dam even though the reservoir site remains the same. Latest criteria on the project functional requirements of a diversion or afterbay dam may require an adjustment of dam height, or in an exceptional case a change of the site.壩址由工程的功能決定。大致位置內(nèi)的確切壩址必須經(jīng)過細致的工程考慮和系統(tǒng)的研究確定。當可行性階段研究完成時，大壩工程的壩址和規(guī)模就暫時被選定了。這些選擇可能會被證明是最終選擇，但是這種可能性也要有最后進一步的調(diào)整，即施工前階段的研究。水庫庫容的調(diào)整可能被證明是必需的；而這，或者任何新的設計數(shù)據(jù)可能顯示有必要改變壩軸線的位置，即使水庫位置保持不變。關于導流或尾水池壩功能要求的最新標準可能要求對拔高進行調(diào)整，特殊情況下可能會改變壩址。In the shaping up of the project plan to this point the following steps will have been taken affecting dam site and size selection: 在編制工程方案時以下步驟的選擇會影響壩址和規(guī)模的選擇：1) The project functions will have been decided. The project may be singlepurpose, or may include two or more functions. This is determined by the plan formulation studies in which valuations are made to test whether the inclusion of more than one project function is economically justified.1）工程功能要確定。該工程可能是單一功能的，或者包括兩個或更多的功能。這是由項目制定的研究所確定的，其中通過估算以檢驗加入多于一個的工程功能的經(jīng)濟合理性。2) The locations of dams and reservoir sites will have been decided. This is done as the result of investigations of the site alternatives, usually in the reconnaissance phases of studies, but subject to possible changes and corrections in later stages. The site selections will have been made by evaluating the physical characteristics of each site, making parative estimates of costs and potential acplishments for each site that would be adaptable to a project plan. Consideration will also have been given to whether one site, or set of sites, would have important and possibly overriding advantages or disadvantages to the nextbest available alternative from environmental impact standpoints.2）大壩位置和水庫地址要確定。這是壩址比選研究的結果，通常在研究的勘察階段，但是受到可能后續(xù)階段可能的變化和更正所影響。壩址選擇將通過評估各個壩址的物理特性而進行，對每個適用于工程方案的壩址進行成本和潛在效果的對比估算。還要從環(huán)境影響的觀點考慮，是否某個壩址或是一系列壩址對次好的可用選項有重要和可能占優(yōu)的優(yōu)點或缺點。3) The gross capacity of any storage reservoir will have been selected. This will have been done by (1) estimating the amount of sediment accumulation that will take place in the reservoir over its economic life period。 (2) estimating the amount of inactive storage capacity needed to maintain a permanent minimum pool for fishery preservation, recreational value, and/or power plant minimum head。 and (3) determining the justifiable amounts of active storage capacity for reservoir operation for the one or more project function. The amounts of active storage capacity will have been selected by the plan formulation procedures whereby costs and acplishments are estimated for a range of reservoir sizes, benefit values assigned to the different kinds and variable amounts of acplishments, and parative economic evaluations made for the range of reservoir sizes. Again, consideration will have been given to whether there would be a serious adverse environmental impact if water was impounded higher than any critical elevation. 3）任意水庫的總庫容要確定。這將通過以下完成：（1）計算水庫經(jīng)濟壽命中的泥沙淤積量；（2）估算需要維持為漁業(yè)保護、旅游價值和/或最小發(fā)電水頭的死庫容容量；以及（3）確定為滿足一個或多個項目功能時水庫運營有效庫容的合理容量。有效庫容量將會通過方案制定過程選擇，其中會估算一些列的水庫規(guī)模的成本和成果，將收益值分配給不同種類和不同數(shù)量的成果，并對水庫規(guī)模大小進行經(jīng)濟評估比選。此外，還要考慮如果水位被蓄積超過任意高度是否會有嚴重的不良環(huán)境影響。The final adoption of dam sites and sizes occurs after a project has been authorized and funded for construction. Some adjustments may be made to either sites or sizes provisionally selected by the feasibility investigation. The adjustments may be warranted by improvements in data collected for making final designs, or by any changes in project scope as required by financial and repayment considerations and limitations.工程被批準并投資建設后，壩址和規(guī)模被最終采納。可行性研究暫時選定的壩址或規(guī)?？赡軙龀鲆恍┱{(diào)整。這些調(diào)整可能通過用于最終設計所收集的數(shù)據(jù)，或通過由財務或還款考慮和限制所要求的工程范圍變化來支撐。3. Investigation of Construction Materials3. 建筑材料的調(diào)查Investigations of construction materials are usually concerned with one of two questions: is there a sufficient quantity of a specified construction material available within a reasonable haul distance, or what construction materials are available in the area. The proper selection of the type of dam to be built at a site must include a careful evaluation of the construction materials determines the type of dam that can economically be considered at a given site.建筑材料的調(diào)查通常關心一兩個問題：合理運距范圍內(nèi)是否有足量的特定種類的建筑材料？或該地區(qū)能夠獲得何種建筑材料？某個壩址處要建造壩型的選擇必須有對決定壩型的建筑材料仔細的評估，這必須從經(jīng)濟方面考慮一個給定的壩址。An efficient investigation can be realized only through proper planning of the office, field, and laboratory work. Generally, the investigation cont