Hydroelectric potentiality of Mexico

The hydroelectric resources of mexico are conditioned by two essential factors, namely, available water and waterfalls. The mean annual surface water runoff of the country´s principal rivers is 183,000 million cubic meters brought about by irregular rainfall which occurs for the most part during the summer months. More than 75 per cent of the annual rainfall occurs during these months and this causes the runoff of the rivers to be erratic, making it impossible to take advantage of it to develop power constantly. Reservoirs invariably are reqired to regulate the flow but only 75 per cent to 80 per cent of the total of such stored up water can be utilized as a result of losses occurring through evaporation, spills, and so forth.