Half of the world’s population lives in or adjacent to mountain watershed environments and is affected by the way these are farmed. Rising human and livestock populations in developing countries, and the mounting pressure on scarce upland and forest resources, have led to major environmental degradation in the present century. They are the cause of much of the catastrophic flooding, loss of human life, drying up of perennial rivers, increased sedimentation of dams, and disruption of downstream agriculture frequently reported in the international press.
Studies have shown, for instance, that the denudation of water catchment areas has caused the flooding in the Indus River system in Pakistan to be far higher in the last 25 years than during the previous 60 years, and has led to serious silting of the dams and canals of Pakistan’s irrigation system. The cost of repairing flood damage below the Himalayan catchments in India has been, on average, US$250 million a year in recent years, in addition to the loss of production and livelihood suffered by millions. While part of this damage is the result of natural geological erosion, much of it is attributable to excessive population pressure and misuse of land. Severe soil erosion has occurred in the Ethiopian Highlands, and in Java and the Philippines, where five million hectares of denuded, formerly forested watersheds are a source of increasing downstream flooding and disruption of agriculture.
The litany of examples could go on. They illustrate one fact: that as populations increase in developing countries, more and more people are forced onto land that becomes less and less productive. These marginal areas inevitably include the mountainous regions with their thin soils and fragile ecological systems that are particularly susceptible to abuse. Ironically, it is generally the poor who are pushed into these areas, attempting to survive on increasingly unproductive and eroded land without being able—or even knowing how—to prevent the degradation of their source of survival.
The only long-term answer to this problem is to reduce the number of people living off these marginal watersheds. And this could happen, eventually, if economic development could raise the productivity of land and provide more job opportunities in the lowlands. Once population pressure is lifted from the poorer mountainous areas, they can be maintained through sustainable agriculture, forestry, and small-scale industry—as hilly watersheds are being maintained successfully in Austria, Japan, and Switzerland. But the prospect of this happening in time to save the critically overused watersheds in most developing countries is dim. The degradation could be checked if the authorities were willing to force people to move out of endangered areas or were ready (and able) to spend the money needed to tackle the large-scale rehabilitation that is needed. The former is a politically difficult option. As for the latter, expenditure on watershed rehabilitation is usually shelved in favor of shorter-term development priorities.
Given a clearer perception of the negative consequences of ecological damage in watersheds and a political commitment to tackle the issue, there is, nevertheless, a lot that could be done now, at least to prevent the situation from becoming worse. Enough is known about appropriate farming systems, about soil conservation, irrigation, flood control techniques, and reforestation to justify immediate action to contain the current degradation. This article draws on the World Bank’s experience to discuss a multifaceted approach to the rehabilitation and maintenance of watersheds. The key to containment is to improve the practices and productivity of upland farmers; these improvements must be accompanied by physical measures to minimize erosion and flooding and to rehabilitate the land.