水电工程的经济效果,可从投资偿还年限的长短、内部回收率的高低和益本比的大小来衡量,三种经济指标都以工程投产时的总投资和纯收益的现值为根据。因此水电站设计者必须在同一安全、便利的条件下,尽量减少造价和增加发电量。国外投资财团利用内部回收率或益本比的指标作为向企业贷款的决定条件,如联合国所 The economic effect of hydropower projects can be measured by the length of investment repayment period, the level of internal recovery rate, and the size of the benefit-to-benefits ratio. All three economic indicators are based on the current value of the total investment and net income when the project is put into production. Therefore, the hydropower station designers must minimize the cost and increase the power generation under the same safe and convenient conditions. The foreign investment consortium uses the internal recovery rate or the benefit-to-benefits ratio as the deciding conditions for the loan to the enterprise, such as the United Nations.