J. C. Rodda: On The Problems Of Assessing The World's Water Resources
17
They can also hinder developed countries in pursuit of this goal. But, of course,
water encapsulates the dilemma of development or environment. Every scheme to
provide a better water supply, to reduce the risk of flooding or to meet other
human needs, modifies the hydrological cycle. They alter the transport of
materials about the earth through the geochemical cycles. They also impact on
the various living organisms that depend on the aquatic environment. They may
also be changing the global patterns of transport of energy.
With these worries, it might be assumed that reliable information on freshwater
resources and on the use of water would be readily available on a national basis,
regionally and globally. But this is not so. For many nations, countrywide
knowledge of the hydrological cycle is at best imprecise, while data on water use
are in an even worse case. There are a number of reasons for this. Precipitation,
evaporation, river flows and the storage of water in the soils, aquifers, lakes,
glaciers and seasonal snow cover are not easy to measure. Neither are their
chemical constituents. The acquisition and analysis of these data are rudimentary
in many areas. The necessary government institutions are lacking and are badly
equipped to meet their responsibilities in many others. In addition, there is to date
no world-wide system for collecting and exchanging these data for forecasting and
other purposes as there is for meteorological data through WMO's World Weather
Watch. And while a few countries have working systems for collecting data on
water use, most do not have them and figures for water use are unreliable. The
consequence is that the statements of world water resources (Table I) and water use
(Table II) are seriously in error.
Of course, at the level of the individual, these errors must be the concern of
everyone who has or aspires to a wholesome and reliable water supply. At the
global level, they concern the Commission for Sustainable Development and those
bodies who will try to provide an assessment of global water resources to the
Commission and the UN General Assembly for their sessions in 1997.
In the face of a coming water crisis, it seems imperative to improve knowledge of
water resources. And without a proper assessment of water resources defined as
the determination of the sources, extent, dependability of water resources for their
utilization and control ([7]) there can be no integrated river basin planning and
management while the pursuit of sustainable development will remain elusive.
What is required is that governments accept the holistic approach to freshwater
which they supported at the International Conference on Water and the
Environment (Dublin, January 1992) ([6]) and at UNCED. The luxury of an 'it Ia
carte' approach to water resources development and management is no longer
tenable ([8]); the full menu of integrated river basin management must be taken.
2
CAPTURING KNOWLEDGE OF THE HYDROLOGICAL
CYCLE
Several theories are to be found in the early literature to explain how springs rise
and rain forms. But with the birth of scientific hydrology ([9]) in 1674, following
the publication of "De l'origine des fontaines" by Pierre Perrault ([10]), there was
the first scientific evidence that atmospheric transport provides precipitation in
sufficient quantities to cause rivers to flow. Perrault's study of the Coquille at
Aignay Ie Duc, a headwater tributary of the Seine, and the contemporary work of
Mariotte, on the basin of the Seine to Paris ([11]), (Table III) are the earliest
assessments of the water balance of any basin.
17
They can also hinder developed countries in pursuit of this goal. But, of course,
water encapsulates the dilemma of development or environment. Every scheme to
provide a better water supply, to reduce the risk of flooding or to meet other
human needs, modifies the hydrological cycle. They alter the transport of
materials about the earth through the geochemical cycles. They also impact on
the various living organisms that depend on the aquatic environment. They may
also be changing the global patterns of transport of energy.
With these worries, it might be assumed that reliable information on freshwater
resources and on the use of water would be readily available on a national basis,
regionally and globally. But this is not so. For many nations, countrywide
knowledge of the hydrological cycle is at best imprecise, while data on water use
are in an even worse case. There are a number of reasons for this. Precipitation,
evaporation, river flows and the storage of water in the soils, aquifers, lakes,
glaciers and seasonal snow cover are not easy to measure. Neither are their
chemical constituents. The acquisition and analysis of these data are rudimentary
in many areas. The necessary government institutions are lacking and are badly
equipped to meet their responsibilities in many others. In addition, there is to date
no world-wide system for collecting and exchanging these data for forecasting and
other purposes as there is for meteorological data through WMO's World Weather
Watch. And while a few countries have working systems for collecting data on
water use, most do not have them and figures for water use are unreliable. The
consequence is that the statements of world water resources (Table I) and water use
(Table II) are seriously in error.
Of course, at the level of the individual, these errors must be the concern of
everyone who has or aspires to a wholesome and reliable water supply. At the
global level, they concern the Commission for Sustainable Development and those
bodies who will try to provide an assessment of global water resources to the
Commission and the UN General Assembly for their sessions in 1997.
In the face of a coming water crisis, it seems imperative to improve knowledge of
water resources. And without a proper assessment of water resources defined as
the determination of the sources, extent, dependability of water resources for their
utilization and control ([7]) there can be no integrated river basin planning and
management while the pursuit of sustainable development will remain elusive.
What is required is that governments accept the holistic approach to freshwater
which they supported at the International Conference on Water and the
Environment (Dublin, January 1992) ([6]) and at UNCED. The luxury of an 'it Ia
carte' approach to water resources development and management is no longer
tenable ([8]); the full menu of integrated river basin management must be taken.
2
CAPTURING KNOWLEDGE OF THE HYDROLOGICAL
CYCLE
Several theories are to be found in the early literature to explain how springs rise
and rain forms. But with the birth of scientific hydrology ([9]) in 1674, following
the publication of "De l'origine des fontaines" by Pierre Perrault ([10]), there was
the first scientific evidence that atmospheric transport provides precipitation in
sufficient quantities to cause rivers to flow. Perrault's study of the Coquille at
Aignay Ie Duc, a headwater tributary of the Seine, and the contemporary work of
Mariotte, on the basin of the Seine to Paris ([11]), (Table III) are the earliest
assessments of the water balance of any basin.