The greatest soda-water lake in the world and how it is ... rises that may cause economic losses to agriculture and human activities along the lake shores. Such rises become nuisances

The greatest soda-water lake in the world and how it is in¯uencedby climatic change

M. Kad�ogÆ lu, Z. S�en and E. Batur

Istanbul Technical University, Meteorology Department, Hydrometeorology Research Group, Maslak 80626 Istanbul, Turkey

Received: 10 December 1996 / Revised: 30 April 1997 /Accepted: 12 May 1997

Abstract. Global warming resulting from increasinggreenhouse gases in the atmosphere and the localclimate changes that follow a�ect local hydrosphericand biospheric environments. These include lakes thatserve surrounding populations as a fresh water resourceor provide regional navigation. Although there may wellbe steady water-quality alterations in the lakes withtime, many of these are very much climate-changedependent. During cool and wet periods, there may bewater-level rises that may cause economic losses toagriculture and human activities along the lake shores.Such rises become nuisances especially in the case ofshoreline settlements and low-lying agricultural land.Lake Van, in eastern Turkey currently faces suchproblems due to water-level rises. The lake is uniquefor at least two reasons. First, it is a closed basin with nonatural or arti®cial outlet and second, its waters containhigh concentrations of soda which prevent the use of itswater as a drinking or agricultural water source.Consequently, the water level ¯uctuations are entirelydependent on the natural variability of the hydrologicalcycle and any climatic change a�ects the drainage basin.In the past, the lake-level ¯uctuations appear to havebeen rather systematic and unrepresentable by mathe-matical equations. Herein, monthly polygonal climatediagrams are constructed to show the relation betweenlake level and some meteorological variables, as indica-tions of signi®cant and possible climatic changes. Thisprocedure is applied to Lake Van, eastern Turkey, andrelevant interpretations are presented.

Introduction

Lakes are natural water storage reservoirs whose basinshave evolved as a result of past geological activities. Inmany areas, they constitute signi®cant fresh waterreserves, accounting for about 26% of the global freshwater resources. Elsewhere lakes are too saline to be

used for supply. According to Gleick (1993), the totalvolume of fresh water in the world's lakes is about91 ´ 103 km3; that of saline water is 85 ´ 103 km3.

Unfortunately, in some parts of the world, unplannedurban areas have developed along lake shores withoutconsideration of the possible future rates in level rises.Lake Van, in the eastern part of the Anatolian penin-sula, Turkey, exempli®es one such case. A water levelrise of 2 m during the last 10 years and its consequenceshave provided a salutary lesson to administrators, localgovernmental authorities, people and researchers alike.There are two aspects to the problem, namely, itsidenti®cation and its solution. At the identi®cationstage, it is necessary to evaluate possible explanationsfor the water level rise. Among the present explanationsare many theories such as the sedimentation in the lake,geotectonic movements, sun spot and climate changee�ect (Kad�ogÆ lu, 1995). Most of these are ratherspeculative without convincing scienti®c evidence.

This study proposes that the recent-lake level rises aredue to meteorological variability. A digression is madefrom traditional methodology in that possible trends inwater level rises are sought neither in the arithmeticaverages nor in the meteorological historical lake leveltime series analysis, but in the average standard devi-ation from monthly climate polygons.

Location and climatic features

The world's largest soda lake, Lake Van, is situated onthe eastern Anatolian high plateau of Turkey at about43°E and 38.5°N (Fig. 1). At this latitude, winter is verysevere with temperatures frequently under 0 °C duringat least three months of the year. Most of theprecipitation in the lake drainage basin falls during thewinter season, as snow and as a rainy season in latespring. Precipitation is low over the rest of the year.Highest rates of runo� occur in the spring, followingsnow melt and heavy rain, with the greatest amounts inMay of each year. On average, the discharge to the lakein the spring period amounts to almost 80% of the water

Ann. Geophysicae 15, 1489±1497 (1997) Ó EGS ± Springer-Verlag 1997

volume. The period from July to September is thewarmest and driest with average temperatures of 20 °C.The average range of diurnal temperature variations isabout 20 °C. The average extent of the lake is 3600 km2

(Kempe et al., 1978). It is surrounded by a relativelylarge drainage basin of 12 500 km2 with the Bendimahiand Zilan rivers (Fig. 2) being the most important. The

average elevation of the lake is 1650 m above mean sealevel. It is surrounded by hills and mountains, some ofwhich have elevations well above 4000 m. The lake doesnot have any natural outlet and, hence, it gathers surfacewater from all around the lake. With these propertiesthe Lake Van constitutes the world's fourth largestclosed basin lake with a volume about 600 km3. It hasbeen calculated that annually 4.2 km3 of water is lost tothe atmosphere by evaporation. This is balanced by thelong-term averages of annual surface runo� and precip-itation respectively of 1.7 km3 and 2.5 km3.

In general, within-year water ¯uctuations have apronounced increment starting from January and end-ing in June with a decline in the water level. However,over recent years, such ¯uctuations have been observedto have been increasing interannually as is obvious fromthe record in Fig. 3, covering the period 1944±1994. Inthis ®gure, the vertical axis indicates the readings on asta� gauge located at the Tatvan discharge measurementstation. As is also obvious, the lake level increases ratherrapidly from 1987 onwards. Although the long-rangeaverage of the lake level is at 1648 m above the mean sealevel, it has reached 1650 m with a 2 m rise. Conse-

Fig. 1. Location map

Fig. 2. Lake Van drain-age basin

1490 M. Kad�ogÆ lu et al.: The greatest soda-water lake in the world and how it is in¯uenced by climatic change

quently, much usable land along the lake shore has beenin undulated, except where it was protected by defensivelevees. However, even these levees have now beenoverspilled. Flood water circumvents the levees fromthe unprotected lowlands. Under normal climatic con-ditions, the lake water level ¯uctuations have yearlyamplitudes of between 40±60 cm at the most. In fact, thelake level average amplitude was calculated by Degensand Kurtman (1978) for 29 years of record between1944±1974 annually as about 49.7 � 18 cm with astandard deviation of 18.5 cm. However, the record inFig. 3 has average and standard deviation values of136.8 cm and 70.8 cm, respectively. These indicateaverage percentage increases of 275 and 383 in themean lake level and in the ¯uctuations amplitude,respectively. They show clearly that for some reason theaverages of the mean and standard deviations haveincreased greatly. Such increases are attributed toclimatic variations in the catchment area. This hasbecome more humid, implying more precipitation andless evaporation. A similar interpretation suggests thatthere have been cooler seasons with wet periods ofincreased precipitation. During normal annual ¯uctua-tions, the lake loses and gains about 1.5% of its totalwater volume.

Lake Van had also experienced level increases in late1880s, when Sieger (1888) reviewed various explanationfor the level ¯uctuations. According to his study, thelevel ¯uctuations were in the order of few meters.Because there were no climatic data he could not relatethis ¯uctuation to any external phenomena.

Sun-spot activity was considered by Kempe et al.,(1978) as a possible cause of level change. During thisperiod, the lake behaved in a normal manner in thatthere were no signi®cantly abnormal years which coulda�ect the hydrological or climatological balances. Theytried to relate the level ¯uctuations to the annualnumber of sun-spots. During normal years, there wasa close agreement between these two variables, as shownin Fig. 4. Both curves have a frequency of about 11years. This suggests that the solar activity in¯uences the

overall water balance of Lake Van during normal years.It has also been observed that an increased activity isfollowed by an increase in the water level of the lakewith a delay of about one year. Such an increase in thesun-spot activity probably leads to unstable weatherconditions, and consequently greater cloud cover wouldhave brought more precipitation and lower evaporationrates, because the climate was more humid.

However, it is noticeable from Fig. 4 that towardsthe end of the period they deviate from each other,indicating that the lake level change was no longerdependent on the number of sun-spots but some othere�ects which are considered in this study as the climatechange related events.

Geological setup

According to Blumenthal et al., (1964) extensive volca-nic eruptions took place in the eastern parts of Turkeyduring the Late Pleistocene. This volcanic area extendsabout 230 km along a northeast-southwest trending line,ending in the southwestern point with the Nemrutvolcanic mountain. Another volcanic mountain, SuÈ p-han, is located to the north of the lake. Its last eruptiontook place in 1441 according to the record in thesediments of the lake. Present-day activity is con®ned to

Fig. 3. Van Lake level ¯uctuationrecord from 1944 to 1994

Fig. 4. Lake level relationship to number of sun-spots during 1944±1974 period

M. Kad�ogÆ lu et al.: The greatest soda-water lake in the world and how it is in¯uenced by climatic change 1491

hot springs. The lake level rose rapidly after thenortheast-southwest trending ¯uvial system was dam-med and the water impoundment began.

Lake Van has been formed by the damming of the¯uvial system by debris that came from the Nemrutvolcanic eruptions. The water has been impoundedbehind this natural dam and formed the present-daylake. Initially, the lake level increased very rapidly andprogressively. A water balance was reached between thetotal in¯ow in forms of direct rainfall on the lake surfaceand delayed surface runo� from the surrounding drain-age basin, due to evaporation losses. After balance wasachieved, water level ¯uctuation depended on the annualclimatic ¯uctuations. In such a closed system, dramaticwater level changes take place only if the imbalancesoccur as a result of changing climatic conditions. Duringpast geological times slow, steady or episodic lake leveldrops must have accompanied the subsidence of theTatvan Basin (Wong and Finckh, 1978). After a balancehad been struck, lake level ¯uctuations would haveoccurred in response to two major factors. One of thesewas rather rapid, due to climatic changes and the shapechange of the basin, and the second one was a rathergradual subsidence, due to the steep boundary faultsand the deep-lying basement over which the sedimenta-tion accumulates.

The impounded water in Lake Van is very alkalinewith pH values well over 9 and it contains considerablymore potassium, lithium and sodium than sea water. Itis the greatest soda lake in the world with the sum ofbicarbonate and carbonate ion contents slightly greaterthan chloride content. Carbonate contents are 100 timesricher than oceanic sea water (Kempe et al., 1978).

Monthly climate polygons

In general, these are de®ned as the scatter diagram for12-monthly averages of two hydrometeorological vari-ables on a Cartesian coordinate system. The 12 pointsare connected sequentially by straight lines which thenform a polygon. The general appearance of such apolygon, its successive sides and corners summarizemonthly climate change information about within-yearbehavior over long periods. Monthly lake levels areconsidered in relation to other meaningful meteorolog-ical variables through these climate polygons.

In order to show the patterns of lake level ¯uctua-tions, their monthly averages are plotted against themajor hydrometeorological variables as shown inFigs. 5±10. Each one of these ®gures shows a closedpolygon indicating the within-year average balance.Their interpretation gives clues about the lake level¯uctuations' dependence on these variables. The follow-ing interpretations come from lake level-relative humid-ity polygonal diagrams in Fig. 5.

a. In general, lake level increases with decreasing relativehumidity starting from January until June. Duringthis period the e�ect of humidity is rather insigni®-cant initially from January to March but the steepest

lake level increases occur during April±May especial-ly in Fig. 5a. On the other hand, there is lake leveldecrease during June±December monthly period.

b. Comparison of 1944±1968 and 1969±1994 annualperiods shows clearly that although the within-yearpattern remains the same but interannually lake levelincreased on the average by 1±1.2 m. This is tanta-mount to saying that there is a steady increase in thelake level. The two polygons do not overlap andtherefore, there is implication of climate change in theregion.

c. The maximum lake level occurs in June and theminimum levels are during November±Decemberperiod.

d. From December onwards although there is nosigni®cant change virtually in the relative humiditythe lake level increases rather rapidly. The reason oflevel increase during this period should be soughtoutside the relative humidity.

e. Starting from March onwards the relative humiditydecreases but the lake level increases steadily almostlinearly, (see Fig. 5b).

f. After June although the decrease in the relativehumidity continues until the end of August the lakelevel starts to decline.

Fig. 5a, b. Lake level-relative humidity polygons a 1944±1968 period,b 1969±1994 period


g. Increase in the relative humidity starts at a slow rateafter August coupled with steep decrease in the lakewater level. However, from September to Novemberthere is steady decrease both in lake level and therelative humidity.

Figure 6 shows monthly lake level changes with meanmonthly areal precipitation. At ®rst glance this diagramhas two adjacent polygons compared to the level-humidity polygon in Fig. 5. The general features of thispolygonal diagram are as follows:

a. From January until the end of April increase in arealprecipitation causes lake level increases in rather highrates. This is a direct consequence of rainfall transfor-mation into runo� that contributes to the lake storage.

b. After April until August the precipitation decreasescontinuously but during this period the water levelcontinues to rise until June because of delayedcontribution from the runo� and then with thediminishing runo� contributions the level starts todrop until the end of August.

c. The wet period starts in September and continues tillthe end of October then snowfall takes place causingan overall decrease in the areal precipitation becausethe snowmelt does not occur until later.

Furthermore, as a representation of local precipita-tion, the average monthly values in Tatvan station areindicated in Fig. 7 with the lake level ¯uctuation for twoconsecutive periods of 1944±1968 and 1969±1994. Ingeneral, these two polygons have the same monthlypattern but interannually they occur at two di�erentlevels. There is almost 125 cm di�erence in level betweenthe two polygons. The polygon in the later period, i.e.,Fig. 7b has a wider vertical width which implies thatduring this period the water level changes were com-paratively more rapid.

Evaporation polygons in Fig. 8 indicate oppositegeneral trends to the humidity and precipitationpolygons in that during the January±June period,increase in evaporation causes lake level increases. Thereason for such an increase is due to relatively smallrates of evaporation which cannot cancel out the runo�and direct precipitation contributions to the lake.However, the July±December limbs of some polygonsshow a decrease in the evaporation rate coupled withlake level decrease. Initially the level decrease is rathersharp but with time, it decreases at slower rates.Again the thickness of polygon in Fig. 8b impliessigni®cantly more water level ¯uctuation during therecent period.

Lake level ¯uctuation-sun spot number polygons inFig. 9 indicate clearly that during the 1944±1968 periodthere is a signi®cant relationship between the twovariables on a monthly basis. However, in a more recentperiod (1968±1994) the general appearance of thepolygon is almost vertical on the average around 90sunspot number which means that the changes in thelake levels are independent of the sunspot numbers. Thisis tantamount to saying that in the second period thelake level changes are more dependent on the localclimatic change and hence hydrologic cycle rather thanthe e�ects from space.

Finally, runo� polygons in Fig. 10 at two di�erentlocations, on the SuÈ frezar and Bendimahi streams, have

Fig. 6. Lake level-areal precipitation polygon

Fig. 7a, b. Lake level-Tatvan precipitation polygon a 1944±1968period, b 1969±1994 period


more or less similar trends in that a sharp increase inruno� from February onwards until the end of Aprilcauses an increase in the lake level but after Aprilincreases in lake level occur with decreasing runo�. Inboth runo� polygons sharp decreases start to occurfrom June onwards with no signi®cant change in theruno� volume.

Table 1 summarizes the trends in the climate poly-gons on a bimonthly basis. In the interpretation ofarrows in the Table 1 it must be remembered that the

lake water level ¯uctuations are on the vertical axis andthe hydrometeorological variables are on the horizontalaxis. For instance, in order to deduce the e�ect of eachhydrometeorological variable on the lake level in June±August column 8 must be considered against each of thevariables in turn. Average decreases coincide withdecreases in the relative humidity, areal precipitationand evaporation, runo� has no e�ect and sunspotnumber increases cause a decrease. Each polygon maybe interpreted in detail.

Fig. 8a, b. Lake level-evaporation polygons a 1944±1968 period,b 1969±1994 period Fig. 9a, b. Lake level-sun spot number polygons a 1944±1968 period,

b 1969±1994 period

Table 1. Lake level ¯uctuations relationship to various hydrometeorological variables


Average standard deviations of water level ¯uctuations

The basic information about long-term ¯uctuation oflake level water are the past records at a set of givenlocations. These indicate many irregular and ratherrandom ups and downs in the observed extreme values.The irregularity and random pattern can be modeled asaverages but the episodes of the water level increase ordecrease as well as the extreme values in the future areall expected to exceed the recorded values in the past.

Hence, in modeling the water highs and lows, not justthe extreme values are needed but also the episodes mustbe carefully examined and modeled. It is outside thisstudy's scope to model these features. However, qual-itative accounts will be presented here.

Here, the series of precipitation records and theirrelationships to the lake water level records will beinvestigated statistically leading to scienti®c evidenceabout the signi®cance of the climate change in the waterlevel ¯uctuations within the study area. Lake Vanprovides a unique opportunity to study the climatechange e�ect because its water is not regulated byhuman intervention and there are no normal outlets.Hence, the water balance in the lake is governed entirelyby natural phenomena like climate change and localhydrological e�ects. Such a fortunate situation arisesbecause of the unsuitable quality of water for irrigationor water supply purposes. Besides, deep lakes such asVan and its inland sea margins provide researchers suchas hydrometeorologists, hydrologists and geologistswith a unique opportunity to study the climatic ¯uctu-ations in the very recent or geological past.

The major in¯uences on water level ¯uctuations insuch a closed basin lake are contributed by the followingfactors.

a. The geomorphological features of the drainage basin,size and shape of the lake itself.

b. Hydrologic elements such as the surface and riverruno� toward the lake.

c. Climatic elements over the region including especiallythe precipitation records and to some extent evapo-ration and temperature.

The interaction of these di�erent factors make up thewater level ¯uctuation scenario of the Lake Van. In fact,these factors do not only control the water level changesbut additionally the water quality changes, dissolvedand sediment load of rivers and their biological popu-lations, though all of these are outside the scope of thisstudy. A detailed account about these is provided byDegens and Kurtman (1978).

Monthly water level ¯uctuations from 1944 to 1994are shown in Fig. 3. This time series of lake levels is®ltered through Fourier analysis and hence the generaltrend is also shown on the same ®gure. A closeinspection indicates that there are abnormal water risesduring years 1968±1969 and, again when the present-daytrend starts, from 1986 onwards. It is possible to makesimple mathematical models for these ¯uctuations bydetrending the whole ¯uctuation into deterministic andstochastic parts. So far, in all researches the averages ofdi�erent types either as stated through Fourier analysis(Batur, 1996) or various order of moving averageprocedures are used in the literature. However, adigression is adopted here in that the average standarddeviation variations with time are analyzed by applyingmoving averages of various orders. The main reason forthe adaptation of the average standard deviation vari-ation is due to the fact that arithmetic averages do notprovide meaningful information about the long-term¯uctuations but the departures from long-term averages

Fig. 10a, b. Lake level-local runo� polygons a SuÈ frezor, b Bendimahi


contribute directly to the water level ¯uctuations.Besides the amplitude of the ¯uctuations is related tothe standard deviation directly. Standard-deviation, byde®nition, shows the average deviations about the meanwater level. Figures 11±13 indicate 3-, 6- and 12-monthlymoving averages of the lake level ¯uctuation standarddeviations. Moving averages of 3-, 6- and 12-monthlyorders are chosen to show the seasonal, half-yearly andannual standard deviation variation patterns. Inter-pretation of these ®gures leads to the following signi®-cant results.

a. The standard-deviation ¯uctuations are rather hap-hazard which implies inconsistency in their time

variations. Such a non-deterministic variation meansthat the weather events in the area are ratherunstable.

b. Standard deviations greater than the overall periodstandard deviations are more abundant than thebelow-average standard deviations. Extreme stan-dard deviations are clustered in certain periods.For instance, in Fig. 12, six time zonations aredistinctively apparent. First, third and ®fth zonesare the normal periods during which ups anddowns have almost the same magnitude, but inthe other three zones, abnormal standard devia-tions extend over the whole record standarddeviation. As the moving-average order increasesthese normal and abnormal zones become more clearand obvious.

c. In Fig. 13, there is initially a very slightly decreasingtrend in the ®rst zone which is followed by thedisturbance during the second zone because thestandard-deviation ¯uctuation is comparatively verypronounced. In the last zone, there is a steadilyincreasing trend in addition to there being the higheststandard deviation records within this zone.

Simple suggestions for solution

Lake Van is more than 1000 m above the mean sea leveland it is located in the southern low-lying platformsfrom which the Tigris River ¯ows southward. Such agreat elevation brings to mind the possibility ofhydroelectrical energy production by releasing the lakewater down through an arti®cially constructed channel.

Such a solution will lead to deterioration in the river¯ow and it might be not suitable for irrigation purposes.In order to alleviate this situation OÈ lcË gen (1995)

Fig. 11. Six monthly moving averages of the standard deviation

Fig. 12. Three monthly moving averages of the standard deviation

Fig. 13. Twelve monthly moving averages of the standard deviation


suggested that the surface runo� from the major riversthat ¯ow into Lake Van including the rivers Zilan,DelicË ay and Bendimahi in the northeast, Karasu, Moraliand Engil rivers in the east, Murdasu and PepicË ek in thenorth runo�s should be carried by light underwaterpipes to a southern low-lying point on the lake shore.From there onwards by a diversion tunnel will provide ahead of more than 1000 m for hydroelectric powergeneration. There are four-fold bene®ts from such asolution. First the generation of hydroelectric power forsale, second, the maintenance of water quality in theTigris river, third, avoidance of Lake Van level ¯uctu-ations by controlling it through the underwater pipe-linenet, and fourth, augmentation of the Tigris river runo�.

Conclusions

An historical account of Lake Van waterlevel ¯uctua-tions in the western province of Turkey is presented.This lake is the greatest soda water lake in the world andhas a closed basin with no outlets. Within the lastdecade a steady water-level increase in the lake hascaused some socioeconomical and irrigational problemsalong the lake shore-line. The lake-level ¯uctuations arerelated to three di�erent e�ects of which the climatechange over the whole lake drainage basin is the mostcritical. The other two e�ects, namely, sun-spot number-related lake-level ¯uctuations and sediment depositionat the bottom of the lake or the tectonic activitiesleading to subsidence in the lake level give rise tocomparatively insigni®cant level changes. In particular,the geological alternative causes very slow and perhapsunappreciable level ¯uctuations, if any. However, sun-spot number changes with an average period of about 10to 11 years do give rise to level ¯uctuations of similarperiod. Abnormal, unexpected and disturbing lake-levelchanges occur due to climate change and globalwarming as a result of unstable weather activities. Inthis study, the climatic polygons that show the scatterdiagrams of monthly average lake levels with variousmeteorological variables are obtained and the necessarygeneral interpretations are presented.

All the classical lake-level change approaches arecon®ned to past-level records and especially on their®ltered forms, in order to avoid random ¯uctuations.Consequently, the interpretations are drawn on theaverage-level ¯uctuations. An entirely di�erent view istaken if the standard deviation rather than the meanvalues play a de®nitive role in the explanation ofabnormal level rises or falls. The past record is dividedinto subzones of time durations based on the ®lteredstandard deviation ¯uctuations by using seasonal, half-annual and annual moving averages.

Acknowledgements. Topical Editor D. J. Webb thanks C. Rey-nolds for his help in evaluating this paper.

References

Batur, E., Van GoÈ luÈ nuÈ n Su BuÈ tcË esi ve Havza, Iklimi. UnpublishedMSc Thesis, _Istanbul Technical University, Meteorology De-partment, 124 pp (in Turkish), 1996.

Blumental, M. M., V. D., Kaaden, and V. I., Vlodaveta, Catalogueof the active volcanoes of the world including solfatara ®elds.Part XVII Turkey and Caucasus. Int. Assoc. Volcanol, 23 pp,1964.

Degens, E. T., and Kurtman, F., The geology of Lake Van. TheMineral Research and Exploration Institute of Turkey, Rep.169, 158 pp, 1978.

Gleick, P. H., Water in Crisis. A Guide to the World's Fresh WaterResources, Oxford University Press, 473 pp, 1993.

Kad�ogÆ lu, M., Van GoÈ luÈ ndeki Su Seviye YuÈ kselmesinin Meteorol-ojik FaktoÈ rler ile olan _Ilgisi, Lake Van Water Level RiseSymposium, T.C. Van ValiligÆ i, 21±39 pp (in Turkish), 1995.

Kempe, S., Khoo, F., and GuÈ rleyik, Y., Hydrography of Lake Vanand Its Drainage Area. pp. 30±45 in the Geology of Lake Van,edited by Degen and Kurtman, The Mineral Research andExploration Institute of Turkey, Rep. 169, 1978.

OÈ lcË gen, A. S� ., Van GoÈ luÈ Ta+kyÂ n De+arj TuÈ neli HidroelektrikSantralleri Projesi, Unpublished Report, 8 p (In Turkish), 1995.

Sieger, R.,Die Schwankungen der hocharmenisehen Seen Seit 1880im Vergleich mit einigen Verwandten Erscheinungen.Mitt. K.K.Geogr. Ges., 95±1155, 1888.

Wong, H. K., and Finckh, P., Shallow structures in Lake Van,pp. 20±27, in the Geology of Lake Van, Ed. Degen andKurtman, The Mineral Research and Exploration Institute ofTurkey, Rep. 169, 1978.


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The greatest soda-water lake in the world and how it is ... rises that may cause economic losses to agriculture and human activities along the lake shores. Such rises become nuisances