WATER RESOURCES OF TAIGA-ALAS LANDSCAPES IN CENTRALYAKUTIA AND PROBLEMS OF WATER SUPPLY FORTHE POPULATION
Desyatkin R.V.
Institute for Biological Problems of Cryolithozone, SB RAS, Lenin ave., 41, 677890, Yakutsk, Russia
el: +7 (4112) 33 64 71, fax: +7 (4112) 33 58 12, e-mail: rvdes@ibpc.ysn.ru

Alas lakes are the only source for water supply for more than 20% of Yakutia’s total population. The waters of alas
lakes are saturated by many mineral and organic compounds. During summer warm season in shallow alas lakes therapid development of animal plankton, animal benthos and algoflora takes place. Based on the results of biological andchemical analysis the water in lakes is evaluated as enough pollutioned. As affected by natural climat rhythms the lakesof alas suffer cyclical flustuations. During short period of time these lakes may have not only abrupt water level
fluctuations, but can completely dry up and appear again. Recently as an addition to natural factors the anthropogenic
factors play role. For water supply of population living on alas region by qualitative potable water the system of large
water lines was constructed from Lena river with the total lenght about 250 km and with planned production capacity of
20 million cubic meters per year.
Keywords: alas, lakes, composition, cycle, problems of water supply

Introduction

The river network on the Central Yakutia plains isdeveloped weakly, as proposed by G.E.Chistyakov(1964) its density equals 0,2 km/km2 and is the lowest
not only in Yakutia but through the entire zone ofboreal forests. Owing to weak degree of drainage of thearea lakes are broadly distributed there. The mostnumerous genetic group of lakes is constituted by lakesof thermokarst depressions – alases. There are over 16000 alases and two-three times more lakes scattered on
this area, because an alas may have several lakes. Thewater mirror area of alas lakes varies within a broad
range from some square meters to 20-25 square
kilometers. The water volume difference in lakes isalso great from some dozens to millions of cubic
meters. Alas lakes are the only sources of water supply
for the 1/5 of the whole population of Yakutia.

Alas lakes features

Alas lakes developed on the thermokarst basinbottoms are local bases of erosion and centers ofbiogeochemical accumulation for enclosed local areas.
Owing to this cause their waters are saturated by many
mineral and organic compounds. By the concentrationlevel of matters soluble in water these lakes arereferred to fresh or salty natural waters. Mineralizationof lake waters fluctuates within 0,5 to 3,2 g/l of salts
and higher. By their chemical composition lake waters
belong to the hydrocarbonate class, sodium group withpredominance of HCO3 ions. The ratio of ion
bicarbonate to the amount of Ca2+ and Mg2+ varies
depending on the year season and lake age andapproximates to 4-8. Sulfate-chloride ratio in salty
lakes is < 1, that is characteristic of soda-sulfate waters,
and in fresh water lakes it is > 1 indicating a sodachloride type. Among cations ions of alkali elements
are the most. The correlation of the sodium andpotassium ion amount to the one of calcium andmagnesium in waters of the examined alas lakes
changes from 1,7 to 4 and greater. By pH value lakewaters are referred to an alkaline series. The organic
matter content in alas lakes is always high varying
from 305,9 to 517,7 mg/l. Peculiarities of lake waterhydrochemistry are caused by chemistry of motherrock mainly represented by carbonate loess-like loams.
The biogenic elements content is very importantfor biological productivity of a water pond. Theirconcentration decline in water results in total decreaseofbiologicalproductiveness.
Phytoplankton
development together with higher water vegetationentails
biogenicelement
consumption
andmineralization of dead organisms and organic matter
causes their accumulation in water thickness. The
processes of organic matter decomposition are faster inless mineralized waters and low content of ammonia
nitrogen in water of salty lakes evidences it indicating
oxygen deficiency in these ponds. The contents ofnitrite nitrogen in all pond waters is high enough and,most likely, shows general phytoplankton enhanced
activity. The nitrite amount becomes greater since midsummer when there is the highest water warming-up inlakes and abundant “flowering” of ponds owing tophytoplankton activity. The amount of nitrate nitrogenis also sufficiently high and gives several times
increase in salty lake waters. Nitrogen accumulation byautumn goes at the expense of organic matter
mineralization and plankton dying.
The greatest phosphate concentration is marked inwaters of young thermokarst basins. This feature ofwater composition of in alas lakes may be bound withthe fact that they appear in taiga flooding the woodaround, mineralization of which in anaerobic
conditions enriches water by phosphates. There issoluble iron and silicon in all pond waters, their content
decreases in summer season and this is bound withmass algae production in alas lakes. In waters of alllakes there is much organic matter (300 to 500 mg/l
and more) and by this index these shallow ponds wellwarmed-up in summer may be regarded as eutrophiclakes. During a warm period of the year there is a highlevel of chemical oxygen intake (COI = 400-700 mg/l).
Oxygen intake and organic matter content increases
even greater after mid-summer and show a rapid
development of organisms in lakes during this time of
the year.
In water of the studied lakes 21 zooplankton
species are recorded. Their amount by mid-summer

which annually varies from 45 (for the years of 1804and 1818) up to 190 spots (for 1957). The sun mostbrightly shines at a maximum solar spots, in such
periods the Earth temperature becomes higher. There
are 11-year cycles, from which 90-year and longer
rhythms are composed, they render determining
influence on ecosystems functioning on the Earth,causing fluctuations of the climate. The analysis ofmeteorological data for the whole observation period
on city station “Yakutsk”, carried out by Gavrilova
M.K. (1987), has allowed to reveal the rhythm ofoscillatory movements on years, basing on the 11-yearcycle. The greatest rhythm in temperature andprecipitation makes approximately 55 years, i.e.
includes five 11-year cycles. There are "max" airtemperatures occurred in January in the years of 18461855, 1903-1912, 1955-1964. and "min” in 1836-1845,
1891-1990, 1946-1955. As for “max” precipitation ofJanuary they were recorded in 1903-1912, 1954-1963,and "min" in 1890-1899, 1944-1953. Fluctuations ofmeteorological parameters cause dynamics of alas
humidity and water abundance supply of lakes.
Observations for the water supply on a small
model alas during 1987-2003 show that the area andvolume of lake’s water had significant fluctuations.
The meteorological conditions for the given interval oftime had also essential fluctuations: amount ofsummer precipitation was from 68 up to 234 mm (fig.
1), height of a snow cover was from 31 to 51 cm andwater stock in snow - from 30 to 99 mm.
350
300

Precipitations in mm

250
200
150
100
50
2003

2001

1999

1997

1995

1993

1991

Yearly precipitations,mm
Precipitations in summer,mmFig.1. Precipitations quantity of year andsummer, mm

Hydrological conditions of lakes

40000

73500030000

6525000
20000
15000
10000
5000
0

432
1

1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001

0

Volume, cubic meters

Area, hectares

Fig.2. Water volume and alas lake area dynamics
during period 1987-2003

Area, hectares

For the period of observation the area of the alas lakechanged from 0,03 to 5,78 hectares, and volume ofwater declined from 90 to 36414 cubic meters (fig. 2).
So we can observe essential dynamics because the lakearea showed a 192 time change, and water volume
decreased more than 400 times.
Volume, cubic meters

Under influence of natural rhythms of the climate
the alas lakes fluctuate cyclically. During the shortperiod of time these lakes can have sharp fluctuationsof water level and completely dry and appear again.
Many researchers note cyclical character of alas lakes
concerning water abundance supply (Nemchinov,1958; Bosikov, 1991; Makarov, 1983, Desyatkin, 1998,
Desyatkin, 2001). Generalizing the archival
documents, D.S. Makarov found the droughty periodthat lasted till 1861, which was replaced by a damp
period within 1862-1905, then a new droughty period
came (1905 –1950), and since 1951 there was a damp
season again. The existence of the found century
rhythm proves to be true thanks to archival data andmodern equipment observation of the Russianhydrometeorological service system.
The activity of the main power source of the Earth– the Sun is of cyclic recurrence. It is shown by thechange of spot number on a visible surface of the sun,

1989

01987

reaches 34000-64000 ind./m3 on the open littorals but
is not less than 19000-20000 ind./m3 in different partsof lakes when decreasing. Zooplankton can produce
from 595 to 4500 mg of biomass per every cubic meterof lake water space. In some alas lakes of the LenaAmga interfluve zooplankton amount comprises 1,5
mln ind/m3, and their biomass makes 9-10 g/m3
(Larionova, 1983). Biomass of zoo benthos is evengreater. The bulk of zoo benthos of alas lakes iscomposed of organisms referring to 17 systematicgroups. The dominant group is chironomids larva.
There are from 75 to 340 individuals belonging todifferent forms of zoo benthos per every square meterof water surface. Biomass produced by zoo benthos
varies from 0,8 to 13,2 g/m2. As found by
A.M.Larionova (1983) the number of zoo benthos in
the interfluve lakes may be 12,3-65,0 g/m2.
Quantitative figures of zooplankton and zoo benthos inlakes of Central Yakutia during summer is a lot higher
because of favorable living conditions unlike the lakesof the entire taiga and tundra zone.
Algoflora of alas lakes comprises 204 algae
species of 8 divisions. Genera Oscillatoria, Cosmarium
and Navicula are rich in species diversity among lake
algoflora. The number of algae species, their amountand biomass in lakes depends on intraseasonal
dynamics. There is one peak in numbers and biomass
which occurs since late July until mid-summer. This is
the time for abundant development of blue-green algae
causing water “flowering”. This event goes
simultaneously with the highest water warming-up inlakes, and its volume and depth decline on the accountof strong evaporation. Basing on figures showing thenumbers (538 mln cells/l), biomass (over 28 mg/l),
Tuhnmark coefficient equal 2,9 Pshennikova E.V.
(1994) attributes alas lakes to euthropic and highly
euthropic ponds. 44 algae species or 22,3% of the total
species number found in lakes are saprobe indicators inlake algoflorathat most often belong to α-βmesosaprobes and polysaprobes. By biological andchemical analysis water of these lakes is consideredsufficiently polluted.

Water fluctuation of another alas that is larger isdemonstrated on the example of the Tungulu alas,with over 10 km long and 6-7 km wide. As archival
materials witness in the 30-s of the 17th century (1630)
this alas looked like an extensive meadow having
about 40 small drying up lakes within scattered throughthe alas. Until the mid-18th century (1730-1750 years)
the Tungulu alas looked like one large lake. The firsthalf of the 19th century was very droughty, during thistime the lake completely dried up again. Since 1862
the damp period began, and by summer of 1885 there
was too much water, that the alas was completely filledwith water again. The end of this damp period falls to1905. The damp period of the 19-th century wasreplaced by a droughty cycle of the 20-th century
lasting till 1951 and was characterized by the data of
the Yakut Hydro-Meteorological Service by 23 drypoor harvest years. For this time there happened asignificant reduction of the lake size, it broke up into
two parts: western - Large Tungulu and eastern - Small
Tungulu. In 1932 the lakes of Tungulu alas weresurveyed by the State Hydrological Institute expedition(Leningrad), and in 1943 and 1953 by the YakutManagement expedition of Hydro Meteorological
Service (System …, 1957). The results of theseresearches are presented in Table 1.
Table 1Size changes of Large and Small Tungulu Lakes

Decrease of lands covered by forests promotes
larger water loss at evoparation. So, the total
evaporation during a warm season of the year by ourobservation (1987-2004) in larch forest averages 163
mm/season while on stubbed taiga sites – 215 mm or in
1,3 times more than in the forest. Grasslands lost water
even greater: xerophylic –225, mesophylic 250 andhygrophylic –320/season that is higher of the total
evaporation in the forest by 138, 153 and 196%,
respectively. Recently negative man-caused effectentailed decrease of river sink and disastrous
dehydration of alas basins with complete lake drying
up. Rural residents faced the problem of acutedeficiency of drinking water and natural grassland
productivity on large alas areas.

Problemofwateraccomplishment

supplyandits

Nowadays Tungulu Lake despite the damp periodthat came after the mid-20th century completely has
dried up owing to anthropogenic influence.

To supply the people living in alas regions bydrinking water, in 1992 a decision was adopted relating
to the construction of the system of large water pipelines stretching from the Lena river to Lake Myuryu
and the upper rivers of the Suola and Tatta. The total
length of water lines should be 250 kilometers withpipe diameter 500 and 1220 mm. By the project
calculation to supply 30 settlement points along thewater pipe line 31 water storage ponds should beerected with the total water volume about 27 million
cubic meters. To gain this goal 20 million m3 of watermust be transferred from the Lena every year. Now thewater pipe system has been completely built, butcannot perform on a large scale because of lack ofreliable source of energy supply and can supply only 7
mln m3 of water every season. Owing to water pipe
operation alas lakes are replenished by river water withgeneral mineralization from 80-100 to 400-500 mg/l
during floodings. Under the natural conditions theselakes got additional water through atmosphericprecipitation (10-30 mg/l of concentrated substances).
Further coming of more mineralized river waters
containing greater iron content may cause with time thechange of hydrochemical composition of artificial pondwaters. We need to study the influence of river water
enriched by iron on hydrochemical and hydrobiologicalstate of lake ecosystems in taiga-alas landscapes.

Anthropogenic influence

References

Date ofsurvey
08. 1932
08. 1943
07. 1953
08. 1932
08. 1943
07. 1953

Max.
depth.,
mLarge Tungulu Lake
32,4
140,54
8,00
27,1
76,5
6,05
20,0
60,04,55
Small Tungulu Lake
12,24
42,60
9,00
3,43
5,92
6,30
3,95
7,80
6,80
S,km2

W,
mln. m3Mid.
depth.,
m
4,34
3,82
3,00
3,43
1,72
1,97

The natural fluctuations of water stock in the alas
lakes are one of the negative factors unfavorablyinfluencing on steady development of the region.
Recently anthropogenic factors were added to thenatural ones. It is established, that for the last 40-50
years dry low productive larch and pine woods weredestroyed by rural people on the area up to 1,0-1,3 mln.
hectares within the Lena and Amga interfluves(Desyatkin, 2003).
Strong anthropogenictransformation of woods combined with grassland
overgrazing and overtrampling, degradation of the alasmeadows caused the occurrence of destroyed centers ofnatural landscapes, and this resulted in water balance
disturbance of large territories towards aridity.

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Makarov, D.S.,
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