J. C. Rodda: On The Problems Of Assessing The World's Water Resources
Table III. Seventeenth century water budgets from the Perrault and Mariotte studies in the
Seine basin (from Tixeront ([ II])).
Perrault - Aignay-Ie-Duc
lMariotte - Paris
From the
Present Real
From the
Present Real
Author
Values
Author
Values
Catchment Area (kro 2 )
118.8
93
53500
44320
P = rain per year (mm)
518
900
459
750
R = runoff per year:
9.5
31.5
millions of m 3
3574
8600
mm / year
80
340
67
194
Deficit: P - R (mm)
438
560
392
556
19
Lingering doubts over the ability of the atmosphere to transport sufficient
moisture were finally scotched by Dalton ([12]). He combined Iysimeter-made
measurements of evaporation with discharge estimates based on measurements
carried out on the Thames and with a large number of records of rainfall, to
determine the water balance for England and Wales.
During the 19th century there was an increase in the ability to measure the
different hydrological variables and a gradual expansion of countrywide
instrument networks. The skills of collecting and analysing hydrometeorological
data were developed together with the organization of the earliest national
hydrological and meteorological services. A few of these analyses were for purely
scientific purposes, but an increasing number were aimed at the design and
operation of various structures and schemes to cope with the increasing demand
for water, to provide drainage and to alleviate floods. Water balance studies were
important to a number of these purposes and to questions which began to be asked
about the impact of human activities on the water balance, such as about
deforestation. These studies involved the range of scales ([13]) pertinent to water
as a resource; at one extreme, studies of the global water balance, at the other,
studies of experimental plots and small basins.
3 MAKING A WATER BALANCE
Probably the earliest example of a water balance study on the smallest scale started
in the 1890s in the basins of the Sperbelgraben and Rappengraben in
Switzerland ([14]). This investigation into the hydrological differences between
forest and pasture was the first in a long series of paired basin studies ([ 15], [16]),
such as Waggon Wheel Gap (USA), Coweeta (USA), Valdai (Russia), Hupselse
Beek (Netherlands), and Plynlimon (UK), aimed primarily at determining the
hydrological impact of land use differences and changes.
Table III. Seventeenth century water budgets from the Perrault and Mariotte studies in the
Seine basin (from Tixeront ([ II])).
Perrault - Aignay-Ie-Duc
lMariotte - Paris
From the
Present Real
From the
Present Real
Author
Values
Author
Values
Catchment Area (kro 2 )
118.8
93
53500
44320
P = rain per year (mm)
518
900
459
750
R = runoff per year:
9.5
31.5
millions of m 3
3574
8600
mm / year
80
340
67
194
Deficit: P - R (mm)
438
560
392
556
19
Lingering doubts over the ability of the atmosphere to transport sufficient
moisture were finally scotched by Dalton ([12]). He combined Iysimeter-made
measurements of evaporation with discharge estimates based on measurements
carried out on the Thames and with a large number of records of rainfall, to
determine the water balance for England and Wales.
During the 19th century there was an increase in the ability to measure the
different hydrological variables and a gradual expansion of countrywide
instrument networks. The skills of collecting and analysing hydrometeorological
data were developed together with the organization of the earliest national
hydrological and meteorological services. A few of these analyses were for purely
scientific purposes, but an increasing number were aimed at the design and
operation of various structures and schemes to cope with the increasing demand
for water, to provide drainage and to alleviate floods. Water balance studies were
important to a number of these purposes and to questions which began to be asked
about the impact of human activities on the water balance, such as about
deforestation. These studies involved the range of scales ([13]) pertinent to water
as a resource; at one extreme, studies of the global water balance, at the other,
studies of experimental plots and small basins.
3 MAKING A WATER BALANCE
Probably the earliest example of a water balance study on the smallest scale started
in the 1890s in the basins of the Sperbelgraben and Rappengraben in
Switzerland ([14]). This investigation into the hydrological differences between
forest and pasture was the first in a long series of paired basin studies ([ 15], [16]),
such as Waggon Wheel Gap (USA), Coweeta (USA), Valdai (Russia), Hupselse
Beek (Netherlands), and Plynlimon (UK), aimed primarily at determining the
hydrological impact of land use differences and changes.