Water and Energy Budget in the Southern Mountainous Region of Eastern Siberia*Jumpei Kubota1 , Kazuyoshi Suzuki2, Yusuke Yamazaki3, Tetsuo Ohata2 and Varely Vuglinsky4(1: RIHN, 2: IORGC, JAMSTEC, 3: Kyoto University, 4: SHI)
* Research Institute for Humanity and Nature, 335, Takashima-cho, Kamigyou-ku,
Kyoto 602-0878, Japan. e-mail: jkubota@chiku.ac.jp
Abstract
To understand water and energy cycle in Siberia, an intensive field campaign was carried out at a small watershed on thewatershed-divide of the Lena and Amur rivers. The amounts of precipitation, discharge, evapotranspiration and interception
loss, in the warm period from April 19 to October 13, 2001 (178 days) were 434.5mm, 204.7mm, 127.5mm, and 55.2mm,respectively. The contribution of the evaporation from forest floor was significant, around 80% of the total. The Bowen
ration after the snowmelt, in the middle of April, was around 2.0. Just after the opening leaves at the beginning of June, itdecreased due to transpiration, and then began to increase at the end of August with falling leaves.
Keyword: Siberia, water and energy budget, seasonal change

1. Introduction
Siberia, which is located in the northern part of theEurasia continent, has the widest permafrost area on earth.
Discharges by big rivers in Siberia play an important roleas fresh water supply to the Arctic Sea, affecting not only
the hydrological and thermal conditions of the Arctic Sea,
but also the polar region climate. At the same time, thesouthern mountainous region is important as the main
source of the Lena River (Ma et. al., 2000). To understandwater and energy cycle in Siberia, an intensive field
campaign was carried out at a small watershed on thewatershed-divide of the Lena and Amur rivers in thesouthern mountainous region. Both the catchment scalehydrological observation including time and spatial
distribution of thawing depth and soil moisture and theobservation of water and heat exchanges between land
surface and atmosphere on several surface conditions
within the watershed, including snow processes, werecarried out from August 2000 to June 2002.

2. Methods
2.1 Site description
The Mogot experimental watershed (55°36’ and124°53’) is located in the southern mountainous region ineastern Siberia (Figure 1). The watershed is a headwater of
the Nelka River, which is a tributary of the Amur River. It
belongs to discontinuous permafrost region. The basin area
is 30.8 km2. The elevation ranges from 550 m to 1130 ma.s.l. The average annual precipitation and discharge from1976 to 1985 were 572 mm and 303 mm, respectively. The
average annual air temperature was –7.7 °C from 1976 to1985. It belongs to a continuous permafrost region withdepth varying from 100 m to 250 m. Mountainous
permafrost taiga podzolized soil formed with a podzol
layer on the upper part of slopes. Turf taiga long-term
permafrost loamy soils covered approximately 64% of themiddle and lower slops. On slope sectors covered withFig. 1: Map of the study area
thick moss, on plains and high flood plains there were
wide spread peat bog permafrost taiga soils underlinedwith a close permafrost ground layer. There wereintermontane depression soils of sub brown, alluvial
laminated, weakly sod or sod-gley which met only in thelower part of the valley. Alluvial bog soils were spread inlowland swampy river and creek flood plains. Larch (Larixgmelinii) is dominant on the lower part of slopes and birch

An 18m-high observation tower was installed. An
ultrasonic anemometer (KAIJO, DA-600) and a water
vapour analyser with clothed path (Li-COR, LI-6262) wereoperated with a sampling rate of 10Hz at 18.6 m. The
outputs of these instruments were recorded by a personal
computer directly. Latent and sensible heat flux werecalculated every 30 minites.

Downward and upward long-wave radiation abovethe canopy was measured using radiometers (Eiko, MS201F) at 16.8 m. Also, Downward and upward short-wave
radiation was measured using radiometers (Kipp andZonen, CF-&F) at 16.8 m. The net all-wave radiation
above the canopy was calculated as the sum of these four
components. When these data were lacking, we used dataobtained by a net radiometer (REBS, Q7) at 16.8 m.
Surface temperature of the canopy was measured byinfrared thermometer (Everette, 4000). Air temperatureand humidity were measured using humicap sensors(VAISALA, HMP-35D and 45D) at 18.0 m and 13.8 m.
Wind speed was measured with three-cup anemometers(Makino, AC-750) at 18.0 and 13.8 m). Wind direction
was measured (Makino, WS-104) at 18.6 m. Groundtemperature was measured with Pt sensors at six depths(0.05, 0.15, 0.25, 0.35, 0.45, 0.55 m). Soil moisture wasmonitored by TDR sensors at three depths (0.1, 0.3, 0.5 m).
Most of these variables were recorded by data loggers
every 10 minutes (Hakusan, Datamark 3300).
In order to consider the effect of plant phenology,
sap flow velocity and growth rate of tree trunks weremeasured every 30 minutes in warm season.
The
understory evapotransipiration was estimated by weighing
lysimeters with 0.2 m in diameter and 0.05 deep,
containing undisturbed soil samples.
Precipitation was measured using a tipping bucket
rain gauge with 0.5-mm resolution and storage type rain
gauge twice a day. Throughfall was measured using 4
plastic gutters with 2 m long and 0.2 m wide, and stem
flow was measured with six trees. River discharge wasobserved at the mouth of the Nelka River, by a floatingwater level gage. Discharge was calculated by the stage
discharge curve obtained by current observations using
both automatic water level and direct flow measurement

Figure 2 shows the seasonal changes in the dailyenergy balance components. The data for rainy days wereexcluded. As it has been reported that the sum of turbulent
fluxes was underestimated compared with available energy
flux in many cases (e.g. Kelliher et. al., 1997, Ohata et. al.,2001), turbulent fluxes accounted only 60% of theavailable energy flux. Figure 3 shows the seasonal changeof the Bowen ratio. Compared with the result of the larch
forest at the central plain taiga forest in Eastern Siberia, thelatent heat flux from the end of April to the middle of May
before opening leaves was rather large. After opening
leaves, the Bowen ratio decreased due to transpiration oflarch. From the end of August, the Bowen ratio began toincrease because of falling leaves.

H eddyLE eddy
LE imbRnG200150-2

We carried out an intensive observation in theMogot experimental watershed from mid-August 2000 tothe end of May 2002. Observation included both
meteorological and hydrological elements.

3.1 Seasonal variation in the energy balance(Wm )2.2 The measurements

3. Results and discussion

10050
0-50
4/1

4/26 5/21 6/15 7/10

Snow covered
Openinng leaves
Falling

8/4

8/29 9/23 10/18

No leaves
FoliatingFig. 2: Seasonal changes in the daily energy
components
Bo10Bo imb

8Bowen ratio(Betula platyphylla) and red pine (Pinus sylvestris) are
dominant in other areas. Forest stand density and mean treeheight at a main flux observation plot were 4128 trees/haand 4.3 m, which trees were more than 5 cm in diameter atbreast height, respectively The LAI was from 0.32 to 0.36
and Plant Area Index (PAI) was 0.45.

6420
4/1

4/26 5/21 6/15 7/10

Snow covered
Openinng leaves
Falling

8/4

8/29 9/23 10/18

No leaves
FoliatingFig. 3: Seasonal Changes in the Bowen ratio

3.2 Short-time water-budget method (SWB)
we used the short time-period water-budget method
proposed by Suzuki (1985). According to this method, theevapotranspiration is defined as the difference betweenrainfall and discharge in a certain period, assuming that thechange in water storage is nearly zero when values ofdischarge at the beginning and the end of analysis periods
are equivalent. The amount of evapotranspiration E (mm)during the analysis period is described with the amount ofprecipitation P (mm) and discharge Q (mm) via equations(3), (4) and (5), assuming watershed storage is constantduring the period (t2-t1)

P = ∫ p (t )dt(3)

Q = ∫ q (t )dt(4)

E = P−Q

(5)

t2

t1

t2

t1

where p (t) (mm day-1) is precipitation, q (t) (mm day-1) isdischarge, and t (day) is time.
The three following criteria were applied to choose aset for the beginning and the end of the analysis period.
These criteria were determined by trial and error toformulate a sample.

Figure 4 shows the comparison of estimatedevapotranspirations. SWB indicates the seasonal change inevapotranspiration by the short-time water-budget method,using daily precipitation and discharge from 1975 to 1984.
ET and ET+I mean 10-days moving average of latent heat
flux at the tower site, and interception loss. Seasonal trendsof evapotranspiration by flux measurement and SWB aresimilar. Total amounts of these two methods are alsosimilar.

3.3 The role of understory evapotranspiration
In order to clarify the role of understory
evapotranspiration to the whole fluxes above the canopy,
we measured understory evapo-transpiration by lysimeters,
and estimated transpiration by larch trees. Figure 5 shows
the comparison among understory evapotranspiration
measured by lysimeters, transpiration of larch trees
estimated by sap flow velocity and latent heat flux by eddy
correlation technique above the canopy. Figure 5 indicatesthat the sum of understory evapotranspiration andtranspiration was almost same as total latent heat flux. Also,understory evapotranspiration accounted for about 80% oftotal fluxes.
2.5

E pan

E sap

E eddy8/319/71) There was no antecedent precipitation on acorresponding day and the 2 days before the beginning(t1) and the end (t2) of the analysis periods as to prevent
water storage from including direct runoff.
2) Differences in discharge between the beginning, q(t1) and the end, q (t2) of the analysis period should bewithin 2%.
3) Periods within 8 days and over 60 days are omitted toprevent fluctuations when periods are too short or too
long to see seasonal changes.

Evapotranspiration (mm/day

3.0
2.5(mm/day)

2
1.5
1
0.5
0
8/29

9/2

2000

9/7

8/21

8/24

8/28

2001

Fig. 5: Comparison among understory evapotranspiration
measuredbylysimeters,
transpiration of larch trees estimated by sap flow
velocity and latent heat flux by eddy correlation
technique above the canopy

2.0SWBETET+I

1.5
1.0
0.5
0.056789MonthFig. 4: Comparison of seasonal change
in evapotranspiration

103.4 Water budget
Table 1 shows the water budget of the Mogot experimental
plot during the warm seasons. Evapotranspiration was
estimated as the sum of latent heat flux by eddy correlation
technique above the canopy and the interception loss
estimated by the measurement of throughfall and stemflow.
Interception loss accounted for 12.7% of the total ofprecipitation. As to the water budget during winter period,
we have not finished analysis at the moment.

Siberia. The authors thank all of the members of theGAME-Siberia project for their cooperation and discussion.

4. Summary
Water and energy budget of an small water shed in
the mountainous region of eastern Siberia was investigated.
The summary of the obtained result of this study were asfollows;
The amounts of precipitation, discharge, evapotranspiration by flux measurement and interception loss, inthe warm period from April 19 to October 13, 2001 (178days) were 434.5mm, 204.7mm, 127.5mm, and 55.2mm,respectively. According to measurements of transpirationby the sap flow method and the evaporation from forest
floor by the pan method, the contribution of theevaporation from forest floor was significant, around 80%of the total. The Bowen ration after the snowmelt, in themiddle of April, was around 2.0. Just after the opening
leaves at the beginning of June, it decreased due totranspiration, then began to increase at the end of Augustwith falling leaves.

Acknowledgements

References
Kelliher, F. M., D. Y Hollinger,., E. D. Schulze, N. N.
Vygodskaya, J. N. Byers, J. E. Hunt, , T. M. McSeveny, I.
Milukova, A. Sogatchev, A. Varlargin, W. Ziegler, A.
Arneth, and J. N. Bauer: Evaporation from an eastern
Siberian larch forest. Agriculture and Forest Meteorology,
85, 135-147, 1997.
Ma, X., Y. Fukushima, T. Hiyama, T. Hashimoto, and T.
Ohata: A macro-scale hydrological analysis of the Lena
River basin. Hydrological Processes, 14, 639-651, 2000.
Ohta, T., T. Hiyama, T. Tanaka, T. Kuwada, T. C.
Maximov, T. Ohata, and Y. Fukushima : Seasonalvariation in the energy and water exchanges above andbelow a larch forest in eastern Siberia, Hydrological
Processes, 15, 1459-1476, 2001.
Suzuki M. 1985. Evapotranspiration estimates of forested
watersheds in Japan using the short-time period waterbudged method. Journal o f Japanese Forestry Society 67,
115-125. (in Japanese with English abstract)

Japan Marine Science and Technology Center (JAMSTEC)
conducted this project. This project was also carried out aspart of GAME (GEWEX Asia Monsoon Experiment)Table 1 Water budget of the Mogot experimental plot from April 19 to October 13, 2001
Year2000
Period
8/22-10/25
Number of days
65
Precipitation(mm)81.00Discharge(mm)60.94
Evapotranspiration(mm)18.69Interception loss(mm)12.64
ｄS(mm)-11.27ratio

2001
4/19-10/23
178
434.5075.2%
204.7023.1%
127.5415.6%
55.18
113.9%
47.08

ratio

47.1%
29.4%
12.7%
89.2%