The protection, improvement and rehabilitation of mountain and/or upland watersheds are of critical importance in the achievement of overall development goals. Recognizing this, many developing countries are turning increasing attention and resources to the field of watershed management. Initial efforts have often been "fire-fighting" in nature, i.e. an immediate but isolated response to a perceived problem. However, in many if not most developing countries, the nature and magnitude of the problem of watershed degradation, and the scarce availability of resources mandate a comprehensive long-term approach. The keys to successful implementation of any such effort are accurate and appropriate survey and planning.
As a starting point, it is appropriate to set some basic definitions. A watershed is a topographically delineated area that is drained by a stream system, i.e. the total land area that is drained to some point on a stream or river. A watershed is a hydrological unit that has been described and used as a physical-biological unit and also, on many occasions, as a socio-economic-political unit for planning and management of natural resources. Catchment is often used as a synonym for watershed. There is no definite size for a watershed; it may be as large as several thousand square kilometres or as small as only a few square kilometres.
A watershed is differentiated from a river basin in that a river basin, with its trunk stream flowing to the sea, may encompass hundreds of watersheds and many other types of land formations.
Watershed degradation: Watershed degradation is the loss of value over time, including the productive potential of land and water, accompanied by marked changes in the hydrological behaviour of a river system resulting in inferior quality, quantity and timing of waterflow. Watershed degradation results from the interaction of physiographic features, climate and poor land use (indiscriminate deforestation, inappropriate cultivation, disturbance of soils and slopes by mining, the movement of animals, road construction, and badly controlled diversion, storage, transportation and use of water). Watershed degradation, in turn, leads to accelerated ecological degeneration, reduced economic opportunities and increased social problems.
Watershed management: Watershed management is the process of formulating and carrying out a course of action involving the manipulation of resources in a watershed to provide goods and services without adversely affecting the soil and water base. Usually, watershed management must consider the social, economic and institutional factors operating within and outside the watershed area.
All watersheds contain many kinds of natural resources - soil, water, forest, rangeland, wildlife, minerals, etc. In developing and managing a watershed, the use of some natural resources will be complementary while others will be competitive. For instance, logging may affect water resources and recreation. Changing intensive land use to less intensive ones may benefit soil and water resources. The key is to use these resources as efficiently and perpetually as possible, with minimum disturbance to the watershed as a whole. Although in many cases, watershed managers may not be the decision-makers on resource uses, their task is to plan and carry out practices which will encourage those uses which are complementary and suggest preventive and protective measures for those uses which could impair the watershed.
Since watershed management involves decision-making about use of resources for many purposes, a multi-disciplinary approach is essential. Work should include government institutions from various disciplines, and also involve people from different parts of society. On the other hand, involvement of too many elements in planning and decision-making can lead to inefficiency and unsatisfactory end results. Participation should be limited to representatives from key government institutions and the local communities which will be directly affected. For example, if the main objective is to protect an irrigation reservoir, the irrigation agency should be involved and not the power company. However, its inclusion might well be necessary if the reservoir was to be used as a source of hydro-electric power.
Watershed management is an ongoing undertaking. New elements, both man-made (road building, mining, logging, and cultivation) and natural occurrences (landslides, wildfire, floods) may become a factor at any time. It is important to remember that when new challenges arise, the original management plan must be revised. It is the watershed manager's or planner's responsibility to make the government authorities aware that watershed management is a continuous and flexible process.
Watershed survey and planning: Watershed survey and planning is the preparatory work which, if properly conceptualized and carried out, permits the successful implementation of actual watershed management.
Watershed survey and planning should be undertaken at four levels with a problem-oriented approach (See Fig. 1).
At the national level, a quick reconnaissance type of survey, assisted by aerial photographs or other remote sensing techniques, is often sufficient for identifying major watershed problems and areas. This type of survey can identify broad land use categories, main causes of disturbance and, combined with existing data, can provide enough information for a simple classification of the nation's watersheds.
The main purpose of this overall classification is to identify the following important items:
- nature of watersheds, i.e. municipal watersheds, forest and wildland watersheds, agricultural watersheds, etc.;
- main problems and critical areas, i.e. problems caused by man, nature or both, seriousness of the problems, extent of critical areas, etc.;
- watershed sites, i.e. upland or highland watersheds, lowland watersheds, watersheds with downstream interest, watersheds without downstream interest, etc.
This classification can be an important input in determining national policy and in setting priorities.
Regional or district level survey and planning is either carried out specifically for a cluster of watersheds or in conjunction with regional development plans. The work covers a more restricted area than the national study but is not necessarily as detailed as the plans for individual watersheds. These studies are important in the formulation of long-term development plans for the region or district.
Most detailed survey and planning is carried out on the watershed level, both because a watershed is a functional unit which links upstream and downstream areas in an integral system, and because it is a convenient unit for planning and economic analysis. This manual aims at this level. In a large watershed, detailed survey and planning can also be concentrated on sub-watersheds with particularly serious problem areas or critical areas.
Individual farm planning, group farm planning and planning for community development are also necessary. These can either be done during the planning period or at the beginning of the implementing stage, depending upon actual needs. The main objective is to improve farm management and community development within the watershed area. Emphasis is usually put on conservation as well as on development.
Local survey and planning provides basic data and also involves local farmers and communities in the planning process. If there are local bodies such as local government, farmers' associations, private interest groups, etc., their representatives should be involved in the planning process. Direct survey of farmers or watershed inhabitants by properly designed questionnaires on important watershed issues is also a way to get local people involved.
To make use of limited manpower, resources and time, watershed survey and planning should be carried out in as practical a manner as possible. Surveys should be oriented towards identifying main objectives and major problems, and plans and recommendations should be centred on solving or alleviating these problems, although the overall potential of the watershed should not be neglected.
Major watershed problems vary from country to country, but the following list identifies some of those most common to developing countries. Most of these are interrelated and cannot easily be separated for diagnosis. However, for the sake of presentation they may be grouped as follows:
Rural poverty in the uplands, causing migration to crowded urban centres and/or destroying watershed resources.
Improper land use (slopeland farming, shifting cultivation without proper fallow, overgrazing, etc.) resulting in degradation of land and other watershed resources.
Deforestation, thereby increasing hazards of seasonal flooding and/or drought downstream.
Poorly planned and executed development activities (roads, housing, mining, recreation, etc.), impairing streams and polluting the natural environment.
Natural disasters (heavy storms, landslides, wildfire, etc.) damaging watershed conditions.
Natural and accelerated soil erosion, causing heavy deposits of sediment in storage reservoirs, irrigation channels and other public installations.
Practical watershed planning should not overlook resource availabilities and constraints. An over-ambitious or unrealistic plan is less likely to be approved or implemented successfully.
Some of the main constraints facing watershed projects in developing countries include:
- lack of funds;
- insufficient manpower, especially at the professional level;
- poor coordination among government organizations;
- low mobility and insufficiently equipped field staff;
- lack of data and research for continuous improvement;
- other socio-economic, institutional or policy constraints.
These constraints should be taken into consideration seriously and strategies to overcome them should be developed at the early planning stage. Watershed managers or planners should find out what resources are or will be available to realistically manage the watersheds.
The capacity of present technology to cope with the major problems of the watershed is a subject to be well considered at the planning stage. If expertise is insufficient, technology exchanges with other countries should be contemplated. This may include sending fellows abroad, or inviting foreign consultants.
Technology transfer from government staff to local farmers is also important and should be considered at the planning stage. Proper extension, education and training activities for farmers in the watershed area will help ensure ongoing success. (See 10.3 for details).
If there are not enough professionals or technicians to handle the work of survey, planning, design and implementation, an early identification of the problem is always preferable, because both institutional strengthening and personnel training take time. Experience in many developing countries has shown that watershed management or soil conservation projects can only grow as fast as trained and experienced persons are available.
In many developing countries, there are enough agronomists, foresters and agricultural extensionists, but watershed specialists, forest engineers, hydrologists, specialists in torrent control, landslides and resource economics are often sorely lacking. Therefore, the question of how to recruit and train the needed technical personnel for upgrading the capabilities of various agencies must be taken into serious consideration.