Water:Statistics and Information

Nepal, occupying 0.10 percent of the global land area contributes almost 0.47 percent of the water discharged by the global rivers. Similarly, Nepal stores almost 0.08 percent of the global fresh groundwater. The proportion of high percentage of available surface water makes Nepal a country rich in water resources; however, uneven distribution of precipitation, high variation in seasonal stream flows and deterioration of water quality as water flows downstream are some of the major challenges faced by the country.

Hydropower is the major source of electricity in Nepal. On the contrary, electricity consumption in Nepal is one of the lowest in the region. Similarly, only about half of the population have access to piped water supply and only about half of the arable lands are irrigated. Because of high dependence of agriculture on precipitation, failure of monsoons can have devastating impacts on the socio-economy of the country. Rapid urbanization and impacts of climatic changes are additional concerns regarding the availability and quality of water.

Besides domestic water supply, irrigation and hydropower development, proper assessment of available water and hydrology is essential for several other components of environment and livelihood, such as hydro-meteorological disaster mitigation, sediment management, watershed management and recreation. With several competing uses of finite resources, judicious planning and management are essential with long-term vision, sustainability contemplation and environmental consideration.

Urgent requirements are, hence, the assessments of reliable water use information, water resources potentials and hydrological data. Lack of data is one of the major challenges faced by scientific communities, policy makers and investigators involved in water-related activities. On the other hand, available data are not properly assessed and managed in a format suitable for information and knowledge development. Several water users and several agencies dealing with water-related issues make it difficult to assess water information in an integrated manner. Bringing out a comprehensive publication by compiling all the pertinent data and information available from different sources in a single volume has become an essential aspect for the overall management of water resources.

Easy access to such data is a primary step necessary for scientific studies and water resources investigations. This publication intends to fill in some gaps in this regard. It is also hoped that the additional global and regional data, included in this publication, will help to assess the water use scenarios in wider scales with broader insights.

The objective of this publication is to help engineers, scientists, managers, students and educators in their water-related plans, programs and education. In addition, factual data are also useful to clear misconceptions among general public about water related issues within and outside the country

Changes in development patterns bring changes in natural flows and water use. The Aral Sea, fourth largest body of inland water in the 1960s dried up to less than one-fifth of its size within fourteen years from 1960. The Sanmexia reservoir, one of the ten largest reservoirs of the world in 1960s lost almost forty percent of its volume within 18 years of its operation. Power generation of the Sanmexia reduced to 250 MW from 1200 MW within three years of its commencement. The Colorado River, draining about 18 km3 to the Gulf of California, has gone almost dry with extensive river diversion schemes upstream. Similarly, statistics is also infl uenced by operational status of a scheme. For example, only 18% of the water supply schemes in Nepal are reported to be functioning properly; others being non-functioning or requiring repairs. Similarly, the Vajont dam, the eighth highest dam of the world is not in operation following 1963 disaster. Changes are further amplified by long-term climatic variability and climatic changes. The data, hence, need frequent updating and verifi cations. As some statistics is based on time series, updating is also necessary with the availability of additional hydrological data.

All the data included in this publication are carefully checked and verified comparing alternate sources. In addition, some experts in the field contributed their valuable time in providing comments and verifying data. We would like to express our sincere thanks to Mr Bhubanesh Kumar Pradhan, Mr Kiran Shankar Yagacharya, Mr Som Nath Poudel and Mr Naveen Mangal Joshi in this regard. Despite such efforts, some errors are bound to exist primarily because of the volume of included data. We welcome feedbacks from readers and users of this publication, which will be useful in updating and making this publication error free in next editions.

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Dr. Keshav Prasad Sharma
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