在社会义经济条件下,利用河川的能量,需要广泛而深入地预先研究其水力资源。要使水力资源的研究能大大地超过水电站的建筑,必须拟定一个国家的动力经济发展计划。为了在某一地区选择国民经济每一发展阶段中效益最大的水电建设工程,必须把在这个地区可能实现的所有各个工程的动力、经济和另外一些指标加以比较。这种比较,只有在带有一定程度近似性的抵定好了各个个别水电站或其梯级电站的设计的基础上才有可能。 Under the social economic conditions, the use of the energy of the river requires extensive and in-depth study of its hydraulic resources in advance. To make the research of hydraulic resources can greatly exceed the construction of hydropower stations, a national plan of dynamic economic development must be drawn up. In order to select the most profitable hydropower construction project in every area of ​​national economy in a certain area, the power, economy and other indicators of all the various projects that may be realized in this area must be compared. Such comparisons are possible only on the basis of a certain degree of approximation of the design of individual individual stations or their cascades.