Turkey being in the form of a peninsula consisting of a
plateau rising an average height of 1000-1500 m. and surrounded
by sea on three sides a very considerable amount of water
flows down from the centre of this plateau into the seas
surrounding it. The most important of these rivers are the
Sakarya, the Kizilirmak, the Yesilirmak the Harsit Çayi
and Çoruh in the north, all of which flow into the
Black Sea: the Bakirçay the Gediz, the Greater and
Lesser Menderes and the Dalaman in the west, all flowing
into the Aegean: in the south the Düdençay,
the Aksu, the Göksu, the Seyhan and Ceyhan, which all
flow into the Mediterranean and finally the Tigris and the
Euphrates in the south-east, both of which flow into the
Gulf of Basra.
The amount of water in these rivers varies very markedly
between the summer and winter months. The water in most
of the waterfalls is so reduced in the summer that some
of them practically dry up altogether while in others one
only finds a meagre trickle of water. When we add to natural
causes the water required of agricultural irrigation and
the effect of the great dams and hydroelectric plants that
supply the country's energy needs it is not surprising to
find that in summer most waterfalls are completely dry.
It is therefore advisable to visit the Turkish waterfalls
in the rainy seasons when there is an abundance or even
superfluity of water.
The Dumanli underground river mingles with the Manavgat
river. This is subject of a separate article.
The Tortum waterfall and Tortum Lake are dealt with elsewhere
as are the Konya and Yerköprü waterfalls.
Düden river. Düdenbasi and the Düden waterfalls
are the subject of the section "A Natural Wonder in
The Bendimahi (Muradiye) Waterfall (Van)
Bendimahi waterfall is one of the least known of our natural
beauty spots. It lies 8 km from Muradiye about 90 km north-east
of Lake Van. The Muradiye (Bendimahi) river rises from the
volcanic formations and basalt lavas of Eastern Anatolia
and apart from the main waterfall near the village of Degerbilir
(fomerly knows as Gevrika) gives rise to a cascade of smaller
waterfalls extending as far as the Devil's Bridge 4 km away.
The Devil's Bridge is itself a very old and interesting
monument constructed in the basalt rock at a very narrow
section of the river 4 km from Muradiye and we strongly
advise anyone visiting this region to make a point of seeing
In 1985 a suspension bridge was built in front of the main
waterfall thus providing visitors with a magnificent view
of the waterfall and an ideal spot from which to take photographs.
Kursunlu Waterfall (Antalya)
The Kursunlu is a waterfall which is reduced to a mere
trickle in the summer months. It is located 19 km from Antalya
at the end of a 7 km road branching off to the north of
the Antalya-Serik-Alanya highway at a point 12 km from Antalya.
The waterfall is on one of the tributaries of the Aksu
river and its situation in the midst of a pine forest is
of quite exceptional beauty. The countryside around the
water forms a lovely picnic and pleasure spot only twenty
minutes from the centre of the city of Antalya.
The Manavgat waterfall is one of the best known waterfalls
in Turkey. It is located on the Oymapinar dam road 3 km
from the town of Manavgat 75 km west of Antalya. The water
falls from a platform 2 m in height and since the construction
of the Oymapinar dam, there has been a regular flow.
Tarsus Waterfall (Tarsus)
This Waterfall is located on the outskirts of the city
of Tarsus. Since the construction of the Berdan regulator
the water of the Tarsus river has been distributed in canals
for irrigation, with the result that the waterfall can now
be seen only in seasons of very heavy rainfall. The photograph
reproduced here was taken twenty years ago.
The Göksu waterfall is located on the Göksu,
a tributary of the Kizilirmak, near the large village of
Sizir in the vicinity of Gemerek. A hydroelectric plant
was erected on the Göksu river twenty-five years ago
by the General Directorate of the Iller Bank in order to
supply the city of Kayseri with electricity, but was later
attached to the national grid.
The Karstic springs arising from the skirts of the Ali
Dag mountain in the village of Sizir have been diverted
by the construction of a dam into a canal leading to the
hydroelectric plant, with the result that, like most of
our waterfalls, the Göksu fall is worth visiting only
in very rainy seasons.
Gürlevik Waterfalls (Erzincan)
These are situated 29 km south-east of Erzincan. In the
years 1950-53, the State Hydraulic Works (D.S.I.) built
a hydroelectric power plant at its lower section of 3040
KW. When third group was added in 1965, the water capacity
of the Gürlevik power station rose to 3*866 1/sec.
The Gürlevik waters fall from a travertine platform
in a disorderly fashion.
One of our most valuable assets is situated in the province
of Konya 116 km south-west of Hadim and on the river Göksu.
This area is called "Yerköprü" where
the Göksu river passes through a 500 metres long cave.
Yerköprü is a natural bridge over the river formed
Travertines are the result of limestone or a calcium carbonate
compound melting in a carbon acid solution producing a perforated
entity. This is most frequently seen in Antalya.
The Yerköprü travertine bridge is a natural phenomenon
resulting from a landslide from both the right and left
banks of the Göksu River. The landslide rubble blocked
the front of the right bank gave rise to a calcareous tuft
travertine which together formed a bridge.
What gives Yerköprü its remarkable beauty is
that the Karasu spring both at its entrance and exit plunges
over the travertine plateau into the Göksu bed with
a 20 m drop. Thick vegetation grows over the Yerköprü
at the spot where the waterfall flows and continues to grow
both at the entrance and exit. This growth is today expanding
To reach the Yerköprü cave from the Göksu
river one enters at an altitude of 800 m. A syphon just
near the mouth obstructs the entrance to the cave. (This
means that the syphon mingles with the water at the ceiling
of the cavern thereby closing it. Further on the ceiling
is higher. Cave explorers can cross this section by diving
if the water is deep enough). As will be seen from the sketch
the section which is impassable is quite short. If it is
desired to visit the cavern in a rubber dinghy, it is recommended
that entry be from the exit. However due to its present
untouched state only experienced speleologists should attempt
to visit the cave. A winding staircase will enable tourists
to take a boat trip in the cave on the "lake"
formed here by the Göksu river. In the case of the
Heaven and Hell Caves near Narlikuyu (Dilek). when opened
to tourism a similar staircase was built.
The Yerköprü cave is a 2-hour drive from Konya
and thus it could become a popular picnic and recreation
spot. As it is also situated on flat ground, it is ideal
How to get to Yerköprü:
There are two routes and today they can both be covered
by tourist buses.
Route 1: Turning south after
60 km on the Konya-Karaman highway to Karasinir village
plus a further 11 km=71 km. Between Karasinir-Yerköprü
is a good road. At the 82nd km you pass Karaagzi village
and at 92nd km Habiller, after which one descends into the
Göksu valley. At the Yerköprü-Göksu
hydroelectric plant, 111 km distant, bearing right, Yerköprü
Route 2: After following
the Konya-Hadim highway 121 km, turn at the Aladag sign,
10 km before Hadim in an easterly direction. Ten km before
the road parts a very good gravel road 29 km long takes
you to Yerköprü. Even though this road is a little
longer, it is preferable.
The Göksu river first disappears underground and then
reappears in the Taurus, and again before reaching Yerköprü,
in the area of Bozkir. The last 5 km to this area is reached
on foot about 25 km south of Bozkir via Bozkir-Üçpinar
district in the south-west direction of Dedemli and near
Dolhanlar village to Gökdere a source of the Göksu.
A landslide from the left bank of the waters swelled, caused,
through their pressure, a cavern to be formed on the right
shore as the big fissure in the limestone expanded as a
result of both mechanical and chemical erosion. Thus the
stream which disappears underground at 1500 m, after traveling
underground for 800 m, rises from the depths 1460 m later
in the form of a boiling Vaucluse type spring.
Düden Waterfall Karstic System (Antalya)
Most of the domestic and foreign tourist visiting Antalya
only see Düdenbasi falls without noticing how these
falls come out from the deep section of the water by making
a syphon (by pressure); and without knowing that these are
the part of an exciting hydrogeologic and Karstic system.
At the 28th and 30th km's of the old route from Antalya-Burdur
(which goes through Dösemealti town) there appear two
big Karstic sources.
Kirkgözler and Pinarbasi are the sources which are
very rich waterwise, coincide after a very short flow and
they disappear finally in Biyikli Sinkhole. Some of the
sinkholes are so big that they can swallow a huge river
or a big lake. In this region there are the Sugla (Konya)
big sinkhole the Biyikli sinkhole with its output of 30
m3/sec and which can swallow 30.000 1/sec. This quantity
is the output of Kirkgöz and Pinarbasi springs at inundation.
The water which disappears at Biyikli Sihkhole goes 14
km underground and comes out again at Varsak pit; after
a very short fall it disappears again from the other end.
To understand the mechanism correctly you must follow the
map and schema. The water which disappears at Varsak goes
underground for 2 km and comes out again at Düdenbasi
by pressure made by a syphon. The water which falls from
Düdenbasi is the water coming from Kepez Hydroelectrical
Complex. By all these actions (water coming in and out)
Kepez Hydroelectrical Complex has been built.
By means of regulator built in front of the Biyikli Sinkhole,
the waters of Kirkgözler and Pinarbasi are directed
into a canal and then by a long canal to the Kepez Hydroelectric
Plant to the collector from where by a pressure pipe it
is carried to the balancing funnel and then dropped over
the plant's turbines.
The water from the plant's discharge unit is brought to
Düdenbasi again by a long canal where it forms artificial
cascades. From there the amount of water is that of a large
river and this water by means of seven irrigation trenches
is used to irrigate the land north-east of the city of Antalya.
After Düdenbasi the waters of Düdençay
separate into a number of streams and finally east of Antalya
at a height of 40 m plunge from a platform into the Mediterranean
in the form of cascades.
At the spot where the cascades fall into the Mediterranean
is an attractive park. In spring when water is plentiful
this is a sight not to be missed. They can be seen from
the sea by talking a boat trip from Antalya yacht harbour,
which is a very pleasant trip.
Karapinar Crater Lakes (Konya)
Close to the township of Karapinar, 95 km east of Konya,
lies one of the world's natural wonders the Mekedag Salt
Crater Lakes and which can easily be reached by a tourist
coach, as it takes you within 2 km. along the Konya-Eregli
highway in a southerly direction. The Meke salt crater lake,
beautiful enough to be included in the world's geomorphology
literature is an example of a Caldera. "Caldera"
is a world of Spanish origin but is it now used worldwide
to describe a volcano with two mouths one inside the craters
of volcanoes and which rise up. In the case of the Meke
salt lake a second eruption took place inside the first
giving rise to a second mouth within the crater lake itself.
Seen from the air it resembles Mexican hat, with a lake
forming a ring around a peak in the centre.
The Turkish Monopolies administration used to extract salt
from the Mekedag salt crater lake and the ruins of the ancient
salt mine can still be seen. The water level of the lake
is 981 m. the height of the second small crater inside the
large crater is 1120 m. The crater's circumference is approximately
4 km. Facing the high plateau village of Karapinar (Kürtül
plateau) which is a left turn after traveling 6 km. along
the Eregli main road, is an earth road going south and which
leads to the shore of the crater. As trucks use this road
to load building material from the shore of the crater it
is in good condition.
Acigöl Crater Lake
This lies 3 km north-west of the Mekedag crater lake, turning
left on the Konya-Karapinar-Eregli highway. This lake, which
can be seen from the highway is at the same level as Mekedag
lake. It is in a hollow 70 m from the road. As will be understood
from its name the water in this lake is bitter and not potable.
It is circular and covers an area of approximately 1 km².
When descending to the shore of the lake one encounter volcanic
tufa and sand layers and is said to be deep.
By moonlight the waters of the lake sparkle and shine like
the sea's phosphorescence.
Kovada Lake National Park (Isparta)
Kovada Lake is the result of the overflowing of lake Egridir.
Between both lakes and all around the Kovada lake can be
seen Karstic patterns, with these and as a result of chemical
changes within the limestone, sink holes which swallow up
the water appear. In the ground between Egridir and Kovada
lakes the waters of the lower Egridir lake used to flood,
while the sinkholes east and especially west of the alluvial
plain stretching north-west absorbed the water. Finally
DSI deepened the bed of the lake's outlet and the formerly
frequent flooding ceased.
As a result the water from lake Egridir passing into a
deepening canal flows regularly. When Kovada I hydroelectric
power station was installed, the water was taken from Kovada
lake. A canal from Egridir lake brought out. Subsequently
the system was changed and now with a small regulator on
the canal carrying the water from Egridir lake, some water
is left in the lake. This needs to be regularly checked
and measures taken to prevent a big drop in the water level,
whereas in mid-September 1984 the water level of Kovada
lake had dropped by 4-5 metres and the hundreds of plane
trees surrounding the the lake had dried up. The sink holes
situated on the shores of Kovada lake and particularly south
of the lake in the district of Denizalti naturally kept
the lakes at a stable level. During flooding most of the
sinkholes are reactivated and prevent the Kovada lake from
rising, in any case this is why the Kovada lake could not
be used as a reservoir and because of this, without putting
any strain on the hydrologic functioning, too much water
should not be drawn from the water leaving the lake. The
best way of checking it would be as formerly, to draw it
into a closed lake and to make do with the amount of water
coming out from it as thanks to the balance of nature lake
Kovada was named a national park. Otherwise with the water
level dropping by 4-5 metres the vegetation will be affected
and take shore will be denuded. The surplus water running
into the lake should be directed to the sinkholes. The sinkholes
in the Denizalti district are now 100-150 m below ground
level. The waters of the lake's southern sinkholes flow
underground for a distance of 5-6 km south into the Gökpinar
karstic spring which bursts its banks. As soon as possible
the Gökpinar springs with an output of 3 m3/sec should
be supplemented partly by the Kovada lakeside sinkholes
and partly from the small underground streams flowing from
another direction from inside the limestone massif. Erection
of the Kovada I hydroelectric power station announced in
1951, was opened to operation in 1960 and was constructed
by the General Directorate of the Iller Bank.*
* This includes all local authorities, municipal and rural
bodies, and other decentralized public administrations.
DSI built the Kovada II hydroelectric power station and
put it into operation in 1971 and obtained the water from
nearby the exit point of Kovada I. This installation with
a power capacity of 53 MW, produces more than 7 times the
power of Kovada I. The Kocaçay stream from the Kovada
Lake after passing through Kovada I and II power stations
goes on to become the main tributary of the Aksu near Antalya,
which runs into the Mediterranean .
"Kovada Lake has all the qualities of an open air
recreational area, and as it is far from highways and city
centres has been able to preserve its natural environment.
It is imperative that these characteristics be preserved
and kept under control and organized to provide the public
with a cool place to relax in during the summer. Kovada
Lake and its surroundings is one of the places in Turkey
blessed by the almigthy with unparalleled natural beauty.
As a living national source, Kovada Lake should be maintained
for future generations."
Ucan Waterfalls: Like heaven on earth
by: Hasan Ustun, Antalya- Turkish Daily News
"It is written in the Koran that in heaven water will
flow beneath your feet. The Ucan 1 Waterfall is like seeing
heaven while living on earth." That is the highlight
of the description Dilek is going to give her mother, who
was ill and had to remain at home, of her visit to the Ucan
1 and Ucan 2 Waterfalls in the vicinity of Antalya's Gebiz
When we arrived outside the club building of TODOSK (the
Taurus Mountain Sports Club), it looked as though a small
bus station had been established. "Friends, today we
have more than 200 people on seven buses. It's a big crowd.
In order not to cause confusion, please don't forget me,"
our guide Faik told us and repeated the warning in English
to 20 foreign guests on his bus. The convoy of seven small
buses set off at 8.00 a.m. with a first stop at Gebiz, 47
km from Antalya. Here needs were met for food, drink and
so forth which had been overlooked in the hurry of leaving
From Gebiz, there are two roads, an upper and a lower one,
leading to the Ucan Waterfalls. The road which runs below
the waterfalls from Akcapinar village eight kilometers from
Gebze is very well-known. The road we took, though, was
unknown and difficult, hard to find without a guide. A short
time after taking this road, we were forced to ford a wide
stream which flows from the waterfalls. The buses took us
straight across in a style which made jeeps unnecessary.
A Norwegian tourist sitting next to me, seeing the red earth
road, the green forests on either side and the white of
the snow on the peaks of the Taurus Mountains, said it was
very like northern Norway. As we were thinking we were climbing
to the summit of the Taurus instead of the waterfalls, Kozan
village appeared before us and all the buses stopped at
its entrance. As we got off, the children and old men of
the village surrounded us. For whatever reason, there were
no women around. The villagers were trying to understand
why more than 200 people should descend on their hamlet
of just 20 houses at 9 o'clock on a Sunday morning. From
here we were to continue on foot. After everybody, including
dogs, had drunk, washed their faces and refreshed themselves
with the icy water flowing from the village fountain, we
set off under the guidance of the villagers. Amongst our
local guides was the village imam, Mustafa. Because, despite
all his efforts, Kozan's economic situation was progressively
worsening, the young imam Mustafa lived far from the village
in Antalya and this was his greatest concern. In the hope
that the increasing traffic of visitors to the fountains
would provide a solution, he provided us with information
in such a way as to render a professional guide unnecessary.
After an hour's walk amongst wildflowers, especially Manisa
tulips and daisies, we arrived at Ucan 2. The beauty of
the waterfall and its surroundings made everybody forget
their tiredness. As we began our picnic meal in front of
the extremely pleasing panorama of the waterfall, photo-hunters
like me gave way to the excitement of trying to get the
best shot. One photographer friend guaranteed the job by
using three different cameras with black-and-white, color
print and color slide film. Somebody who was so overcome
by the beauty of the scene that she neglected to look in
front of her escaped lightly from an accident when the inside
of the tree trunk she struck with her foot and which then
fell on top of her proved to be hollow. Despite all the
guide's warnings accidents such as thisstill occurred. The
small pools formed at the bottom of the waterfall made some
of the group lose their senses. I was extremely jealous
of those who, filled with the joy of spring, plunged into
the water in their underwear. However, as somebody who had
previously survived pneumonia, I consoled myself by taking
pictures of them. Two hours later the group gathered again
and we set out for the Ucan 1 Waterfall, three to four kilometers
below. This provides an even more magnificent view than
Ucan 2, flowing over a wider area and from a greater height.
Two hundred people took turns to shoot their souvenir pictures.
Because the vehicles which had brought us were waiting
in Kozan village, we had to climb back up the way we had
descended. But never mind. Seeing heaven before death was
bound to have some difficulty attached. On the way back
I asked a Danish yachting couple which was more beautiful,
the seashore or the land. "The countryside is more
beautiful with all kinds of waterfalls, rivers and lakes,"
they replied. Tommy Madsen and his wife, who have been staying
on their yacht "Helena" at the Setur Marina since
October 1996, have, under the leadership of their friend
Gisela Bacher, visited historical sites and beauty spots
around Antalya every weekend. Some of these visits have
been made with TODOSK. Gisela pointed out that sightseeing
with TODOSK is different, explaining, "They give to
others journeys of discovery they themselves have made previously.
In particular, TODOSK takes people to little-known places
where few tourists go." In fact, never mind the tourists,
very few Antalya citizens realize that these little pieces
of heaven on earth exist so close to their city.
Tortum Lake and Waterfall (Erzurum)
One of the most remarkable natural treasures of Turkey
and of Eastern Turkey in particular, is the Tortum Lake
and Waterfall, 100km north of Erzurum. The lake 8 km long
and 1 km wide was formed as the result of a great landslide
which blocked the valley though which the Tortum River flowed.
At the same time the water sought a new outlet over a fault
with a drop of 40m. The hollow left in the Kemerlidag slope
on the left of the valley by the fall of rock is still clearly
Some geologists say that this landslide is a very old one.
These experts, among whom are to be counted a number of
foreign geologists believe that the landslide took place
at the end of the Quaternary period. However there is also
another opinion on this subject that the landslide was comparatively
recent and could not have occured more than a few centuries
The Tortum Waterfall was the largest and most beautiful
waterfall in Turkey. Since the completion of the Tortum
Hydroelectric Plant water is drawn from the lake though
canals and tunnels and allowed to rush down into the turbines.
The waterfall is fed only from the surplus water and thus
now functions only for a very short time during the winter
months when the water level of the lake is exceptionally
high. Now during the summer months the bed of this magnificent
waterfall is dry.
After the great waterfall with its drop of 48 m. the river
flowed over a series of cascades until its arrival in the
Tevs Valley. The combination of cascades and waterfall was
particularly beautiful. At the same time four small lakes
were formed on the rubble from the landslide by water seeping
from underground through the material from the rock fall.
The water of these lakes is remarkably clear and blue.
These four small lakes-Incegöl, Karagöl, Efendigilin
Gölü and Nazligilin Gölü-contain large
quantities of trout. The Tortum Lake is surrounded by limestone
marls of the Cretaceous Period. Earth pillars can be seen
on the eastern shores of the lake. The view of the lake
from the steep slopes along the edge is particularly beautiful
as this is a landslide lake is depth begins from zero and
reaches 100 in the deepest part. The lake lies about 100
m above sea level.
The Seven lakes National Park (Bolu)
A well-known author described the Seven Lakes National
Park as "an emerald in the forested area of the western
Black Sea" and the lakes lie north east of the province
of Bolu. While the area can be reached by a 40 km stabilized
road turning out of Bolu, the better way is talking the
Mengen-Devrek-Zonguldak road between Gerede and Yenicaga,
from there to Mengen-Kaynarcahan-Dirgine the former being
reached at 152. nd km along the Ankara-Istanbul highway.
The Seven Lakes area is particularly famous in the autumn
and one should especially visit it during autumn and spring.
The autumn colours of yellow brown and red in various tones
endow it with unparalleled beauty.
In 1965 the Ministry of Forest turned the Seven Lakes into
a National Park. in1969 a trout production station was set
up with a capacity of 1 million fertilized trout eggs annually.
There is also a project to increase the stag population.
The seven lakes are the result of landslide which blocked
the small valleys. To prevent the land from sliding further
a simple expedient of placing wooden props made of oak logs
over the running stream water in step form was utilized.of
the lakes four were permanently and three were sometimes
dried up in the summer months. The waters of the Seven Lakes
came from the Kara stream. Behind the obstruction brought
about by the landslide losing the valley the lake formed
and the stream waters after the resulting depressions had
been filled flowed away over them.
The big lake is on the bottom level which is 780 metres
high, the depth ca.15 metres. Towards the end of of summer
together with the deep lake is a small dried up lake at
the bottom step. The Nazli lake, Sazli lake and two other
small frequently dried up lakes can be found 100 m higher
up at 880 m elevation. Most of the seven lakes resulting
from the landslide are small and the largest is the Büyük
lake which occupies an area of 22.5 hectares followed by
the Nazli lake which covers an area of 16.5 hectares.
While like other national parks the Seven Lakes are still
not endowed with full touristic facilities, it is nevertheless
a very attractive recreation area. It is mostly visited
by people traveling between Istanbul and Ankara, or when
a daily tour is organized from the Bolu hotels and motels
or the Abant hotels. Some Istanbul travel agencies organize
daily tours from Istanbul to visit the lakes.
Subject to certain restrictions (min. 23 cm small and max.
number fished 3), amateur trout fishing is permitted. To
allow amateur fishermen to enjoy this sport at the National
Park. trout is artificially produced in the lakes. However
during the breeding season between November and May fishing
is strictly prohibited.
The Obruk Lakes (Konya)
The Obruk (karstic) Lakes, with their special features
are only to be found in the Konya region in fact these Budurin
lakes exist only in Turkey but for a very long time have
been inaccurately named still today in some books on geography
and geomorphology they are described as windows opening
on to the surface of the earth from underground waters,
whereas these Obruk lakes are opening from under-ground
waterways, which were formed by the very seeping of water
through fissures and crevices in the limestone rock.
The water of the Obruk lakes enters through one end and
exits through the other. Actually as put forward in a number
of geography books there is a movement in the bottom of
the lake an emptying but the deep bowl in the shape of a
basin cannot develop only through chemical erosion. When
the movement of water results in a combination of chemical
erosion rising from below to the surface and erosion downwards
from the surface the last layer of rock which forms a very
slender bridge finally collapses and a round or rather elliptical
Obruk lake makes its appearance. The movement of the obruk
lakes is very slow and cannot be seen with the naked eye.
When the villagers wash wool in the lake, however pieces
are found on the other side of the lake the following morning.
This indicates the movement and direction the lake moves
in which is SE-NW. The Obruk lake region in the province
of Konya lies in a north west direction in the district
of Karapinar. Other lakes in this important region lie south
and south east of Konya. the axis of these lakes is usually
between 100-250 m.
Kizören Obruk Lake
Sixty five km northeast in the province of Konya along
the Aksaray-Nevsehir highway is the subdistrict of Kizören,
and 4 km to the north is an Obruk lake also known as the
Kizören Obruk. Lakes of similar formation in other
places are also known as obruk. The long axis of Kizören
is 180 m. and the short axis 150 m. the depth 145 m. A quantity
of 108 1. per second can be withdrawn from the lake.