Throughout the ages, man has been forced, often as the result of his own activities, to live in lands where fresh water supplies are deficient, highly variable and of inferior quality. Historically, people in these regions have had to accept the consequences of mismanaging their soil and water resources. Only when water supplies completely failed, or were made useless by salinization or massive siltation or when floods or wars swept away everything, were their activities abandoned.
In many of the more humid areas, exploitative and shifting agriculture has depleted the upland forests and mountain areas to the extent that the flow of rivers they supply becomes destructive during flooding and insufficient during dry periods. Dams to control the flow and protect more valuable lands downstream have been the usual simplistic solution, but due to siltation from the depleted uplands, the effectiveness of dams mss be shortlived. The result is a dubious, short-term benefit with no lasting improvement of the total system. In fact, the temporary security offered by the structures may lead to a precarious over-development downstream.
However, it has been amply shown that upstream watersheds can be protected and even the most devastated and marginal lands can be made productive again. But to do this, there suet be an awareness of the total soil and water resource system, both upstream and downstream, and of the inter-related benefits that can be obtained by the proper application of modern technology.
The papers of this series are an attempt to relay some of the examples from technical specialists who have had broad association with the problems of the soil and water conservation aspects of watershed management, especially in mountain catchments and forested areas. particular effort has been made to obtain a cross-section of authors from various countries and to present practical examples of hydrology which are applicable to conservation work.
Special appreciation is offered to the many authors who have given generously of their time and energy to provide contributions to this series of papers. Likewise the many organisations and agencies which we have contacted have been exceptionally cooperative in providing materials, photographs, advice or in allowing their own staff to assist us. S.H. Kunkle of the Forest Resources Division of FAO was the coordinator for this "•AO Conservation Guide" series.
The FAO Forestry Department is especially grateful to the School of Renewable Natural Resources, University of Arizona, for their support in providing a consultant, J.L. Thames, to assist in the editing.
This "FAO Conservation Guide" is one of a series of readings which provide some practical examples and case studies of conservation and land protection from various regions of the world. The emphasis of the series is on protection forests, rangelands, steep terrain and other areas where the returns from lard use are marginal, where degradation is a problem or where resource protection is (or should be) a mayor objective. The main emphasis is on techniques which may be useful for developing countries.
The "FAO Conservation Guide" are:
Number 1: "Watershed Management - Guidelines and Examples". This collection of papers reviews the concepts of watershed management and conservation and illustrates practical methods for: erosion and degradation surveys; erosion prediction: gully correction; some remote sensing techniques for watershed management; :'crest road protection against erosion; environmental impact evaluations; terracing: steep slope restoration; and protection against landslides.
Number 2: "Hydrological Techniques for Upstream Conservation". This group of papers reviews some aspects of forest hydrology and other essentially "upstream" Questions of hydrology related to conservation work. There are examples of: field runoff estimation; torrent control; infiltration estimation; snow surveys for water in the mountains; evaluation of mountain land degradation; recycling of wastewater in forests; stream water quality evaluations: transpiration; and surveys of sedimentation in reservoirs.
Number 3: "Examples in Conservation for Arid and Semi-arid Zones". This collection of papers reviews desertification and presents examples of shelterbelt establishment, dune afforestation, erosion evaluation, terracing for slope afforestation, restoration of rangelands, rainfall harvesting and techniques on managing vegetation.
Number 4: "Special Readings in Conservation Techniques". These papers are an assortment of readings which are more specialised or research oriented. The topics covered are: guidelines for controlled fires for forest conservation; concepts of snow management in high mountains; a case study of mulches for soil restoration; and research techniques for soil temperature estimation.
The Editors
This "Conservation Guide", Number 2, contains 12 papers which are examples and case studies of hydrological methods related to conservation work, particularly in mountain and forested zones. The examples include torrent control, sedimentation surveys, some field techniques for estimating runoff, measurement of snow cover in the mountains, surveys for erosion and water quality measurements, as well as case studies of forest influences and evaporation measurements.
