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Watershed management

Famine can be caused by too much water or too little. Water is needed for irrigated agriculture in and areas. Ever-growing urban concentrations and modern industries need fantastic quantities of water.

Every year water-induced erosion ruins stupendous amounts of topsoil. Every year floods destroy vast property values and take a heavy toll of human life. Rivers are polluted with the effluent of thousands of cities, or are silting up and blocking navigation.

In human affairs, therefore, water plays a vital part. If properly cared for, it is the bringer of life. If neglected, it can be the cause of disaster.

Controlling water in amount, regular flow and purity, is a vast field in which governments can perform prodigious feats. If in most parts of the world they have not done much, it is due partly to incomplete realization by both experts and laymen of the basic necessity, partly to inability to appropriate the necessary funds.

The water necessary to man derives from watersheds or catchment areas, and hence logically arises the concept of watershed management, an extension of sound land-use planning. The deliberate planning of land use, whatever the objectives in mind, is a necessity in modern times. It is essential to the development of the great river basins or vast natural regions.

But when it comes to the practical implementation of such planning, it if; important to be able to deal with areas which are sufficiently homogeneous in their physical, economic and social characteristics to provide a suitable basis for a management program. The watershed, be it large or small, provides such a unit.

The management methods employed over it will in part be the sum of the individual skills exercised by farmer, forester and agricultural engineer in their everyday tasks of soil conservation and of regularizing streamflow. Each, however, will have a natural tendency to think that his method is the best and provides the solution to all problems. But the two basic resources, land and water, must be used in the most efficient manner compatible with sustained production. Therefore, a careful coordination of techniques and a close collaboration of technicians is necessary, not to mention a sensible division of labor. The watershed provides just the framework for such co-ordination, collaboration and division of labor.

To encourage this trend FAO organized a regional training center on watershed management in India in 1957 and then, a two months' seminar and study tour in the United States of America in the summer of 1959. Hundreds of examples of watershed management problems were observed and discussed during the tour, and there was general recognition of the following points:

1. increasing acceptance of the feasibility of managing watersheds, and of the technical possibilities for improving the quantity and quality of water, and for controlling floods through combined programs of land treatment and engineering structures;

2. growing awareness of the physical unity of a watershed and of the area served by its water: water development is no longer considered as an isolated technical operation but, on the contrary, erosion control, reforestation, channel improvement, reservoir construction, and even ground water development are being considered as parts of an over-all water and watershed management activity;

3. relative lack of technical knowledge relating to watersheds: in spite of very large research programs, there is as yet no clear and conclusive evidence on many strategic issues, and for this reason there is a decided need for a further expansion of research;

4. unhappy status of economic evaluation of watershed development proposals: there is still a substantial debate as to the methodology which should be used in guiding decisions on watershed development expenditures;

5. human problems involved in watershed management, and the efforts needed to enlist the support and active participation of land users.

The lessons from this tour were studied by the last FAO Conference and, as a result, it was decided that the Organization should give more prominence to problems of watershed management in some of its publications. The contents of this number of Unasylva have been planned with this mind, and some later issues will also contain special feature articles on the same theme.

FIGURE 1. - Forestry combined with grazing on a New Mexico watershed maintained in excellent condition. Prior to 1900 this area wag grazed almost exclusively by sheep, then by sheep and cattle until 1925, then gradually the sheep were excluded. Now the area is grazed by cattle for only four months, June to September, and a range rider is employed to get good distribution of grazing. The aspen stand is managed to aid control of water run-off.

FIGURE 2. - Driving a soil tube to obtain a soil moisture sample from beneath the surface within the aspen stand. Moisture content will be found by weighing and drying the sample. - Courtesy, United States Forest Service


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