ABSTRACT
Large population migrations are arising as well as national turmoils and territorial divisions. River valleys are populated and once adopted technical solutions of the river hydropotential exploitation are underestimated. Therefore, it is feasible and only advisable to build several small hydroelectric power plants, observing the environmental and legal aspects. The problem is to prove this mathematically. Their reservoirs shall mostly remain in the river bed, while the hydroelectric power plants shall be most often (if head are approximately the same) cascades in series provided with uniform equipment.
