Policy and practice in the management of tropical watersheds
Misuse of land on tropical watersheds in developing countries in increasing rapidly in association with accelerating population growth and the accompanying poverty. Destruction of natural vegetation without replacement by productive agriculture or forestry imposes severe penalties of soil erosion and sediment transport. Sedimentation destroys reservoir storage capacity and inhibits investment in power generation and irrigation. Tropical meteorological events create seasonal water surpluses that produce floods in the lowlands. Flood abatement requires construction of storage structures in addition to good land use: only storage dams can both regulate flows and harvest the energy from them. Watershed management for stable conditions of vegetation, soils, and water is a critical requirement for investment in such flood protection. Every corrective step to arrest watershed degradation improves the welfare of the inhabitants, both rural and urban: -Restoration of a productive and protective tree cover on steep slopes can provide the fuelwood to forestall the impending crisis in the supply of domestic energy in developing countries. -Planting of fodder and control of livestock can improve animal productivity and increase the supply of manure available for crops. Technologies of soil conservation are well known but are durable only if the standard of farming is also improved. Productivity of crops and the stability of soils improve together. In this book, the upper watershed technologies are described in plain language and successful examples are quoted. Where it has been possible to assess cost and benefits examples are quoted. In the lowland reaches of tropical and subtropical river basins, the critical deficiencies are in the provision and maintenance of drainage. Salinity is the penalty for waterlogging: it denies to the third world the use of much of the great arid alluvial plaing the could be irrigated by the Upper Ganges, Indus, Euphrates, Tigris, and Nile. Distribution of water from irrigation canals between farms and within farms has been neglected as an aspect of management so that severe water losses and waterlogging occur widely. Successful solutions are described. National, international, bilateral, and non-government agencies are making important contributions to the correction of watershed misuse, but are not coordinated either by country of by watershed. The national governments of tropical developing countries are not yet giving priority to rural area development in spite of growing food shortages. The primary cause of the watershed resource destruction in the tropical world has been rapid growth of population, which has overwhelmed government machinery for rural development and the management of natural resources. There is much confusion of emotion wiht moral judgment of this issue. No assumptions need be made, or should be made about the ultimate size of the population of any country. It is, however, an inescapable concern of common humanity that the arrival of extra millions of children should be delayed until arrangements can be made to feed them. In the meantime, irrevocable losses of soil, of water resources, and of reservoir sites reduce the agricultural and forestry production needed for the maintenance of growing populations. The race against time is being lost in Africa and is being narrowly held in Asia and South America
| Main Author: | |
|---|---|
| Format: | biblioteca |
| Published: |
Boulder, CO (EUA) Westview Press
1989
|
| Subjects: | MANEJO DE CUENCAS, CICLO HIDROLOGICO, EROSION, RECURSOS FORESTALES, POLITICAS, ASPECTOS INSTITUCIONALES, |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|