O00 oooOoN&Ooó - HYDROLOGY SYMPOSIUM

7-i t-t-

wwww ???o9 mm

Y

,. r-FIow r3r3

d t-t-

wwww

??Y"?

e 01 W

Y????

wmt-mm

. 4FI d

.Y

t-r-t-t-

99:.

ooem me

fX1

r-l

I

?

Powt-t-m rl

T

wwom Ad

mwt-m mmmm NNNN w wwwwe-t-t-t-t-t- t- Co m o d c.1 M -3 m ' c-t-t- NNN 01 N N c.i N N hl N N N

The water

D I S C U S S I O N

MR.

DROUHIN. With regard to the chemical composition of water in relation to its utilization in agriculture, there appear to be two different schools of thought.

According to E. Robaux' report, there is a large margin of adaptability and the chemical composition of the water is only one aspect of the question.

I

share his view, rather than that of Mr. Caglar, who holds that, in classifying water as utilizable or not, its chemical composition should be the sole criterion. I immediately think of the example of a flourishing orange grove near Oran in Algeria, which is ir&

gated with water containing more than 3 gm. of NaC1 per litre.

adaptation of cultivation methods. According to experiments carried out on permeable soils, even excessively salt water can be used without ill-effects,

while

impermeable soils cannot be irrigated

with

salt water.

It

is dangerous for salts to accumulate in the soil.

I

agree with Mr. Drouhin that the problem is a very complex one.

MR.

T~ERONT.

I would ask the lecturer to give us the detailed composition of a type of water which he classifies as salt water NO. 4, and one belonging to the category of salt water No. 5-

The

composition is of a basic factor, but

PROFESSOR CAGLAR. 1.

The detailed composition of a type

Sample procured The chemical composition of the water account should also be taken of : the nature of the salts dissolv-

ed in the water; the nature of the soil; the choice of varieties of plants and the adaptation of cultivation methods.

With regard to the nature of the salts, certain ions can be harmful in two very different ways, some because they actÚally

poison Plants, and others because they have a bad effect upon

CI:

12; SO,: 63.9; NO,: nil;

H c - , , :

3,191;

Nazco,:

2,385.

the soil in which the plants are growing (for example, alkaline

ions willsuffocate and kill vegetation growing in certain Total hardness (Geiman measurement) 20.14; temporary clayey soils). hardness 20.14; permanent hardness 0.00. Alkalinity The problem is thus a complex one, cm. of

HCI

n/10 used for 100 CU. cm. of always necessary to make a chemical ana

any means the only process which must

order to classify in a given region, Indeed, the prohW ration of experts in various branches lem calls for the

of science (chemistry, soil science, botany, agriculture).

PROFESSOR CAGLAR. I

had stated in my report that water containing more than 1 gm. of different kinds of salt per litre was not suitable for agriculture and could only be used under certain circumstances for irrigating cultivated fields.

As

Mr. Drouhin has said, its utilization for this purpose depends upon the nature of the salts dissolved in it, the nature of the soil, the of plants and ,the

of water belonging to the cat%orY salt water NO. 4 (sodium waters) is as

Locality: Erzincan (in eastern Turkey).

in April 1946.

is (values given in mg./l.):

r): 52.38; reaction (pH): 8.8.

2. The composition of a type of water belonging to the No. 5 ^' category (water containing many and various salts):

Locality: Konya (central Anatalia):

CI:

9,450 mg.;

SO,:

3,650.6 mg.;

HCO,:

527 mg.; reactio (pH): 7.2. ,

3. A further example:

Locality: Hatay (in the southe

C1:

7,950 mg.;

SO,:

1,097

mg.; HCO,:

457.5 mg.; total hardness: 35.25; temporary hardness: 21.00; permanent hardness: 14.25; alkalinity: 3.6 and reaction (pH): 7.3.

par*. of the corntry).

choice of varieties

II

T H E STATICS A N D D Y N A M I C S

OF U N D E R G R O U N D W A T E R

S O M E R E C E N T STUDIES IN G R O U N D - W A T E R P R O B L E M S

F. DIXEY,

c.M.G., o.B.E.,

Director of Colonial Geological Surveys, London

INTRODUCTION

With

increasing populations and a steadily rising standard of

living

in m a n y countries, water is increas-

ingly

recognized as a basic necessity of life, and

in

the more arid regions it is a

limiting

factor

in

the progress of modern civilization. The development of industrial and social economies has created demands exceeding all previous expectations, and m a n y important supplies formerly considered inexhaustible are n o w k n o w n to be limited. In

the

UnitTd States, for example, increase

in

the use of water

in

cities, farms, and industry is a n

impelling

force

in

the acceleration of investigation and appraisal of water resources; in the cities

the

water requirements per day n o w amount to

130-150

gallons per head of population, and m a y even exceed

1,000

gallons per head

in

summer

in

some communities.1

In

South Africa,

the

developments of agriculture, forestry, and industry are

limited by

poor water

sup-

plies,

and

the desired development in other parts of the continent is checked

by

insufficient water. Through:

out Africa, this problem is of the utmost importance.

In

m a n y parts of Australia, permanent occupation and

full

production can

be

achieved and maintained only

by

full development and conservation of all available water resources.

Owing to the widespread and vital importance of this question, policies and organizations for the investigation, exploitation, conservation and replenishment of ground-water resources have been developed or considerably expanded in recent years

in

m a n y countries, such as the United States [51],3 Great Britain [6], South Africa

[as],

and the British Colonies

[i?, 18,

191.

The outstanding water-supply work of the United States Geological Survey

in

fundamental principles and

in

technical advances, as well as

in

the publication of results, is well-known throughout the world and is of immense value to all workers in this important

field.

The

problems of the more

humid

and the more arid territories at h s t sight appear to be of

widely

different character, but hydrologists are coming to recognize that they differ not so m u c h

in

principle as

in

degree.

In the United States, for example, supplemental irriga- tion and artificial recharge are employed in the

.humid

east, while problems of flood control are encountered in

the

arid valleys of the west. Great centres of population

like

Los Angeles, San Francisco, and N e w York, whether situated

in

arid or humid areas, have often to import their water supplies from great distances.

Moreover,

in

the more arid territories, where development is still somewhat primitive, problems of surface waters have often

been

regarded as different

in

nature and as requiring separate treatment from those of ground waters. Yet

the

logy

are investigated, the more closely are all aspects of water resources found to be related.

For these reasons the study of the hydrologic cycle

in

all its phases is receiving increasing attention

in

endeavours to appraise the total water resources of a region and to develop the m a x i m u m supplies for all purposes. Moreover, just as the river basin has become widely accepted as the local unit for regional planning and development, as under the Tennessee Valley Author- ity and

in

the Missouri River basin, so the total water resources of a unit area, as defined

by

geological or geographical conditions,

in

m a n y cases are becoming of paramount importance as constituting the focus on which the integrated development and utilization of other resources tend to cpnverge. This knowledge of total water resources is arrived at partly from a close study of transpiration, evaporation, infiltration and run-off,

and

partly from the records of observation wells and of pumping tests, which have given m u c h information not only on the movement of,the water-

* United States Geological Survey, 1950.

z The figures in brackets refer to the bibliography at the en'd of this report.

The statics and dynamics of underground water

table and the direction and rate of flow of

the

ground water, but also on the physical constants of the aquifers

on

which depend

their

capacity, safe yield and recharge

potential. of ground water.

A

later stage is the application of methods of artificial recharge

so

as to conserve surface waters that would otherwise run to waste, and to increase the resources

Arid

regions are, as a rule, better adapted for quantitative studies than

humid

regions, and m a n y of the available methods of estimating ground-water supplies have been developed in arid regions.

A

wider range of methods is none the less available

in

developed than in underdeveloped areas.

A

number of methods, however, do not depend at au on development, and m u c h successful quantitative work has

been

done, areas that were virtually undeveloped

l.40,

411.

Dans le document HYDROLOGY SYMPOSIUM (Page 37-41)