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The GEMS/WATER Programme
The Global Environment Monitoring System (GEMS) grew out of the 1972 Stockholm Conference on the Environment. At that world conference, governments requested the establishment of a global monitoring programme that could determine the status and trend of key environmental issues. The GEMS/WATER Programme was initiated in 1976 by UNEP and the World Health Organization, with the assistance of UNESCO and WMO. The Programme had the twin objectives of improving water quality monitoring and assessment capabilities in participating countries, and determining the status and trends of regional and global water quality.In Phase 1 of GEMS/WATER, 1976-1990, the global network was established with the Global Data Centre located at the Canada Centre for Inland Waters, Canada. This publication summarizes data collected during Phase 1 of the Programme and marks the completion of the first phase of GEMS/WATER.
In Phase 2, the GEMS/WATER Programme has realigned its data network in order to focus on new global priorities such as land-based sources of pollution, toxic chemicals and the need for improved communication and decision skills for water quality management. The GEMS/WATER Programme works with other United Nations agencies and with donor countries to build new capacity in selected national agencies by offering programmes of analytical quality assurance, information systems and software, and more effective ways to carry out monitoring and assessment.
The GEMS/WATER Programme has published numerous books and reports on water quality issues at a global scale (ref. 24), water quality monitoring (ref. 25), and an Operational Guide for agencies participating in the programme (ref. 26).
About this Publication
As with any global summary, data quantity and quality are variable, especially as the GEMS/WATER Programme relies on national water quality agencies to submit data to the GEMS/WATER Global Data Centre. Data submitted to the Global Data Centre are reviewed both manually and by automated data quality standards. Although data on major ions, nutrients, and microbiological information are relatively complete, the reader will note that there is very little information on toxic chemicals. This reflects the cost and difficulty of collecting and analyzing contaminants, especially in developing countries. To fill out the global picture, information is also drawn from other scientific sources.The data are presented by watershed (drainage basin). The 82 watersheds represent major world rivers, or smaller rivers that have regional significance. Water quality data are strongly site dependant, and results must therefore be carefully assessed, especially when a watershed is characterized from a limited number of sampling points in time or space.
This publication attempts also to provide a basis for scientific understanding of observed water quality conditions. The text represents, therefore, a compromise between scientific rigor and extreme simplification. The publication is organized around major themes that have significance for managing the quality of the earth's surface waters. However, for a publication of restricted length, it is not possible to provide a complete regional and global summary of all water quality conditions. We have therefore chosen to provide selective overviews which take into account all the GEMS/WATER parameters, but use illustrations drawn from various parts of the world. Complete data for all 82 watersheds are provided in Tables.
Throughout the analysis and production of this book, the information processing system RAISON was intensively used. This system, developed by Environment Canada and used widely within the GEMS/WATER Programme, is a versatile and user-friendly computer software for integrating, analyzing and displaying environmental and socio-economic information in a geographical context.
About Statistical Diagrams
Statistical plots for various parameters in this book are given as box plots. These represent the 10th, 25th, 50th, 75th, and 90th percentiles of the parameter distribution. They are generally presented for each of the continents and compared to the global distribution. The data used in these comparisons are derived from the GEMS database. These figures should be used with caution since the existing database is fairly sparse in regions such as Africa and parts of South America.Acknowledgement
The 60 countries, large and small, that contribute data to the GEMS/WATER programme can take much of the credit for this volume. The provision of data by Russia filled a large geographical gap that had existed in the GEMS/WATER programme and we thank Dr. V. Tsirkanov for his participation. WHO regional offices have been important focal points for country participation. The authors wish to acknowledge specifically Kelly Hodgson and Janice Jones for their major contribution in the development of this publication. We also acknowledge the personal involvement of Dr. V. Vandeweerd (UNEP) and Dr. R. Helmer (WHO) in the enterprise. The Canadian Government, through Environment Canada, and Foreign Affairs and International Trade Canada, provided significant financial support for this project through their support of the GEMS programme.
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