South Korea's natural rivers provide the route that gather the water that flows down from the mountain in its entirety and that enable it to reach the ocean. Natural rivers have the ability to purify themselves by enabling water to flow down slowly and windingly with appropriate width and depth. When artificial force is added on here, both the mountain and water die at the same time. When the mountain, which is the source of water, is damaged, then the rivers are naturally damaged as well. If we are to prevent shortage of water, then we need to protect mountains even before building dams. Cutting the mountainside to build roads and paving the roads by cutting off high places to gap the lower places will reduce the time water stays in the mountain. Since rivers need to flow down large amount of water downward at once, flood become inevitable. As incoming of earth and sand increases, river bed becomes higher and the scope of ceiling river, where river bed becomes higher than surrounding plains, expands increasingly by repeatedly building bridges by straightening out the river embankment and building it higher. At the end, it becomes as if mountain was cut down to fill up the river, and the river where flood has gone away, becomes dry stream.

 Natural phenomenon does not occur independently. All phenomena on the earth are closely interrelated and they form strict relationship of cause and effect. The wisdom of human beings is to understand and apply the Greater Law of Nature, and to use it appropriately. The basis of flood control afforestation is the simultaneous preservation of the mountain and water. Human beings, whose livelihood is rooted in the Greater Nature, should actively prepare themselves against the danger of nature, but they should also exert caution in pursuing after convenience.