Nature's Plan (1953)

[Music] And the water that dropped as rain from the clouds to make the land alive. [Music] out water. For no living thing can exist without water. Absolutely nothing. Not even a weed. [Music] For the land cracks open and dries out, and the earth gapes wide and dies. Yet from the beginning, long before man came, there was a natural undisturbed system of water distribution. A system we call today a water cycle. Let's understand what a water cycle is. It is the continuous process by which water from the ocean is drawn into the air by evaporation. formed into clouds, condensed to water, released as rain and snow upon the earth to find its way back to the ocean to start another cycle exactly like the previous one. It is a process that goes on and on unceasingly. Now let's see how it works. Liquid water is forever flowing downward from the air to the earth as rain and snow and flowing from the earth down to the sea. The sea in turn gives water back to the air in the form of vapor. And so there is a neverending cycle of flow from the oceans to the air, from the air to the earth, and from the earth back again to the sea. The force that moves this water lies in the heat delivered by the sun to the earth and in the ability of water to store this heat. When water contains very little heat, it is the solid we call ice. When ice absorbs sufficient heat, it melts into liquid water. If liquid water is warmed, it will turn to vapor and rise into the air. Warm air can hold a large amount of water vapor. But if the air is chilled, some of the vapor will turn back to water. Here on the coast of California, we can see how the cold ocean has chilled the air above it, condensing some of the vapor into tiny particles of water which appear as fog. This fog moves steadily toward the land, carried by the great transcontinental air current that moves across the continent from west to east. As the warm earth gives its heat to the fog particles, they again turn into invisible water vapor and disappear into thin air like this. But the air continues to carry the stream of invisible moisture forward across the country. Day and night, winter and summer, this huge river of water vapor moves onward up out of the ocean and over the United States. At all times, there is in this moving river enough moisture to give a considerable amount of rain. But it can become useful to sustain life only as parts of it are delivered from the air to the earth. Mountains are among nature's most important agents in bringing the moisture to the land. For they force the moving currents upward high above the earth where it is very cold. This shadow on the mountain reflects a cloud about to make a storm. For the moisture is condensing into a cloud as the rising air is beginning to be chilled. The vapor is turning to particles of water too small to fall as rain. But this condensing process releases heat whose energy causes the air to expand and rise like a huge balloon into the very much colder atmosphere high above. Here it is chilled once more. And now the rapidly condensing moisture builds up into this giant thunderhead which climbs until some of its water particles turn to tiny ice crystals. This development frequently prepares the way for rain. For now, the particles of moisture remaining in the cloud may adhere to the growing ice crystals until they become big enough to fall as snow or melt and turn to rain. Much of the water of the western states is produced in this way by the mountains. On the plains east of the Rocky Mountains, the rainfall is caused by another kind of storm. We can see how this small block of ice chills the air beneath it and makes it contract. In the same way, the air over Canada is chilled by the cooling of the land as winter approaches. This cold, heavy air flows southward into the United States. Here, it may meet currents of warm, lighter air that carry moisture northward from the Gulf of Mexico. As these currents meet, the cold, heavy air acts exactly as the mountain barrier did, causing the lighter, warm air to flow upward and thus produce a storm. But this is only the beginning of the story. Now we come to the critical part. For after the storm has delivered the water to the earth, we must understand how nature accomplishes the job of distribution of storing and moving this water before it is evaporated or returned to the sea, making it possible for the water to be used by the land and by the living things who live on and off the land. Watersheds are nature's agents in dealing with this problem. Exactly what is a watershed? This is a whed. So is this. And this many miles away. In other words, a whed is simply a natural basin where water can be trapped and stored and distributed by a stream or in the case of a large whed by a river system. Let us see how this water is trapped and distributed in one of these natural reservoirs. You will see that above the parent rock lies a thin blanket of soil produced through the ages by the forces of nature. This soil is the heart of the natural reservoir that holds the moving water. Above it lies another darker layer that plays an equally important part. This duck earth can ted leaves and rotting roots of trees and smaller plants and is tied into a firm organized structure by the living roots. This is nature's sponge that absorbs and holds the water, passing it down slowly to the reservoir beneath. Above it grows a cover of forest plants that protect the soil from the striking force of hail and raindrops. and overall grows the protecting forest that builds and guards this thin sponge of capacious earth and absorbent rotting vegetation which can hold 5 gallons of water in each cubic foot of its substance over a vast extent of forest land. It can store more water than all the reservoirs that man can build and do it without cost to man. After the rain has fallen on the mountain and the water starts on its long journey down the valley, every bush and tree does its share to intercept the flow and scatter it over the hillside. The smaller plants too help to tame the water, spreading its flow over the surface of the ground until it sinks through passageways dug by roots and worms and insects into the soil below. Here it filters through the earth, growing at last into a vast underground river that moves slowly downward toward the sea. Ponds and marshes do their share, and the beaver help, too, adding their dams to nature's storage system, letting the store of water sink into the soil to join the hidden flow. Where the soil is shallow, this hidden stream may spring to life again in the open, feeding brooks that grow as other springs join them beneath their surface. So the streams on the surface join with those flowing slowly underground, but each is dependent on the other to form inseparable parts of one great hole. And all owe their existence to nature's storage system in the soil that holds the water in place. In the high mountains, the snow forms one of nature's most important reserves of water. Here the moisture that falls in winter may be contained in the summer when this and turns them back to water melting snow thus prolonging the ability of the mountain to maintain a steady flow of water. The branches may intercept great quantities of snow and rain which never reach the ground. Here we see the moisture evaporating from the wet branches of the spruce forest after a heavy rain. But the trees use much water in their growth and sometimes the water yield may be increased by thinning the forests. So the snow may settle among them low melting drifts like this. And so with the help of nature, every hillside stores its share of water in a 100,000 tiny reservoirs, banks of snow, beds of moss, plant and grass stem, fern and root, and rotting wood, and beds of porous soil. Each part does its own microscopic share to hold back its own drop of water, letting it out in due time to join the drops from a 100 million other sources flowing into springs and brooks and rivers. Building timber and the grass is building forage that can be harvested by animals and turned into meat and wool and leather. the opportunity for recreation and enjoyment. [Music] This then has been the story of watershed and water cycle of the natural storage and distribution of water before the coming of mankind. [Music]