LAKE RARA
A view from the lakeside hill
Photo: B.D.Swar
A. LOCATION
- Karnali Zone, Mugu District, Nepal.
- 29 24 N, 82 05 E; 3,000 m above sea level.
B. DESCRIPTION
Lake Rara is situated in the western part
of Nepal, at about 300 km northwest of Kathamndu, the capital of Nepal.
It is a warm, oligotrophic lake with a monomictic type of water circulation.
It is surrounded by hills and mountains from which more than 30 brooks
flow into the lake. It has only one outlet, Khater Khola, on its western
shore (khola=stream). Khater Khola forms a deep gorge at about 7 km downstream
from the outlet and finally joins Karnali River, a tributary of the Ganga.
Lake Rara is somewhat oval in shape. It has relatively
large maximum depth for its surface area. It has two basins. The main basin,
occupying the western part of the lake, covers about 80% of the total surface
area. It is characterized by a steep margin and vast flat bottom. The area
below 160 m accounts for about 27 % of the lake area. The eastern sub-basin
has a gently sloping margin and a small bottom. Lake Rara is a part of
'Rara Lake Naitonal Park and Wildlife Conservation Area' (Q).
C. PHYSICAL DIMENSIONS
| Surface area [km2] | 9.8 |
| Volume [km3] | 0.98 |
| Maximum depth [m] | 167 |
| Mean depth [m] | 100 |
| Length of shoreline [km] | 14.3 |
D. PHYSIOGRAPHIC FEATURES
D1 GEOGRAPHICAL (Q)
- Bathymetric map: Fig. ASI-03-01.
- Outflowing rivers and channels (number and name): 1 (Khater Khola).
Fig. ASI-3-1
Bathymetric map(2).
D2 CLIMATIC
- Climatic data at Rara, 1983-1984
| Jan | Feb | Mar | Apr | May | Jun |
Jul | Aug | Sep | Oct | Nov | Dec | Ann. |
|---|
| Mean temp. [℃] | 1.1 |
2.4 | 9.3 | 8.6 | 14.4 |
13.2 | 15.5 | 16.0 | 14.1 |
9.2 | 7.0 | 3.9 | 9.6 |
| Precipitation [mm] | 41 |
94 | 34 | 63 | 23 |
201 | 189 | 337 | 346 |
216 | 0 | 12 | 1,556 |
- Water temperature [℃] (2)
Station2, May 20, 1983
| Depth[m] | Jan | Feb |
Mar | Apr | May |
Jun | Jul | Aug |
Sep | Oct | Nov |
Dec |
|---|
| Surface(0) | - |
- | - |
- | 12.1 |
- | - |
- | - |
- | - |
- |
| 8 | - | - |
- | - | 11.9 |
- | - | - |
- | - | - |
- |
| 16 | - | - |
- | - | 11.3 |
- | - | - |
- | - | - |
- |
| 32 | - |
- | - | - |
9.2 | - | - |
- | - | - |
- | - |
| 60 | - | - |
- | - | 8.3 |
- | - | - |
- | - | - |
- |
| 120 | - | - |
- | - | 8.3 |
- | - | - |
- | - | - |
- |
| 160 | - | - |
- | - | 8.3 |
- | - | - |
- | - | - |
- |
- Freezing period: None.
- Mixing type: Monomictic.
E. LAKE WATER QUALITY
E1 TRANSPARENCY [m]
Station 1-7, May 16, l983
| Stn.2 | Stn.3 | Stn.4 |
Stn.5 | Stn.6 | Stn.7 |
|---|
| 16.6 | 16.6 | 16.2 |
15.9 | 13.0 | 15.0 |
E2 pH (2)
Station 2, May 20, 1983
| Depth[m] |
Jan | Feb | Mar | Apr |
May | Jun | Jul | Aug |
Sep | Oct | Nov | Dec |
|---|
| Surface(0) | - |
- | - | - |
8.48 | - | - |
- | - | - |
- | - |
| 8 | - | - | - |
- | 8.52 | - | - |
- | - | - | - |
- |
| 16 | - | - | - |
- | 8.56 | - | - |
- | - | - | - |
- |
| 32 | - | - | - |
- | 8.60 | - | - |
- | - | - | - |
- |
| 60 | - | - | - |
- | 8.40 | - | - |
- | - | - | - |
- |
| 120 | - | - | - |
- | 8.36 | - | - |
- | - | - | - |
- |
| 160 | - | - | - |
- | 8.30 | - | - |
- | - | - | - |
- |
E4 DO [mg l-1]
Station 2, May 20, 1983
| Depth[m] |
Jan | Feb | Mar | Apr |
May | Jun | Jul | Aug |
Sep | Oct | Nov | Dec |
|---|
| 0 | - | - |
- | - | 7.50 |
- | - | - | - |
- | - | - |
| 8 | - | - | - | - |
7.59 | - | - | - | - |
- | - | - |
| 16 | - | - | - |
- | 7.93 | - | - |
- | - | - | - | - |
| 32 | - | - | - |
- | 8.06 | - | - |
- | - | - | - | - |
| 60 | - | - | - |
- | 6.91 | - | - |
- | - | - | - | - |
| 120 | - | - | - |
- | 6.58 | - | - |
- | - | - | - | - |
| 160 | - | - | - |
- | 6.52 | - | - |
- | - | - | - | - |
| 167 | - | - | - |
- | 4.84 | - | - |
- | - | - | - | - |
E6 CHLOROPHYLL CONCENTRATION [μg l-1]
Station2, May 20, 1983
| Depth[m] |
Jan | Feb | Mar | Apr |
May | Jun | Jul | Aug |
Sep | Oct | Nov | Dec |
|---|
| 0 | - | - |
- | - | 0.061 |
- | - | - |
- | - | - |
- |
| 8 | - | - | - |
- | 0.125 | - | - |
- | - | - | - | - |
| 16 | - | - | - |
- | 0.160 | - | - |
- | - | - | - | - |
| 32 | - | - | - |
- | 0.381 | - | - |
- | - | - | - | - |
| 60 | - | - | - |
- | 0.465 | - | - |
- | - | - | - | - |
| 160 | - | - | - |
- | 0.036 | - | - |
- | - | - | - | - |
E7 NITROGEN CONCENTRATION (2)
- Total-N [mg l-1], Station 2, May 20, 1983
| Depth[m] |
Jan | Feb | Mar | Apr |
May | Jun | Jul | Aug |
Sep | Oct | Nov | Dec |
|---|
| 8 | - | - | - |
- | 0.030 | - | - |
- | - | - | - | - |
| 16 | - | - | - |
- | 0.027 | - | - |
- | - | - | - | - |
| 32 | - | - | - |
- | 0.027 | - | - |
- | - | - | - | - |
| 60 | - | - | - |
- | 0.024 | - | - |
- | - | - | - | - |
| 120 | - | - | - |
- | 0.018 | - | - |
- | - | - | - | - |
| 160 | - | - | - |
- | 0.021 | - | - |
- | - | - | - | - |
E8 PHOSPHORUS CONCENTRATION
- PO4-P [mg l-1], Station 2, May 1983
| Depth[m] | Stn.1 | Stn.2 | Stn.3 |
Stn.4 | Stn.5 | Stn.6 | Stn.7 |
|---|
| 0 | 0.010 | 0.007 |
0.007 | 0.003 | 0.003 |
0.003 | 0.010 |
F. BIOLOGICAL FEATURES
F1 FLORA
- Phytoplankton: Ceratium hirundinella, Dinobryon cf. borgei.
F2 FAUNA
- Zooplankton: Rotifera (Conochiloides coenobasis, Keratella quadrata,
K. cochlearis, Lecane spp., Filinia opoliensis) ; Cladocera
(Daphnia longispina, Holopedium spp.) ; Copepoda (Stenodiaptomus
stewartiensis, Cyclops hutchinsoni).
- Fish: Schizothorax raraensis, S. macrophthalmus, S. nepalensis, Schizothoraichthys
esocinus (4,5).
- Supplementary notes on the biota: Fig. ASI-01-03.
Fig. ASI-3-2 Annual change in the individual
number of total zooplankton (-), Dinobryon cylindricum cf. borgei
(- △ -), Ceratium hirundinella
(- - - - ◯ - - - -), Conochiloides coenobasis (- ● -), Filinia
opoliensis (- - - ● - - -) and Copepods including naupll (- ◯ -)
(2).
F3 PRIMARY PRODUCTION RATE [mg O2 l-1 hr-1]
-
Station 2, May 24, 1983
| Community respiration | 0.018-0.058 |
| Gross production | 0.020-0.045 |
G. SOCIO-ECONOMIC CONDITIONS (Q)
G1 LAND USE IN THE CATCHMENT AREA
- Main types of woody vegetation : Abies spectalilis foreset, Pinus
excelsa forest, Quercus semicoapifolia forest, Picea Smithiana
forest, Betula utilis forest.
- Main types of herbaceous vegetation : Alpine grasssland, moist herbosa.
- Types of other important vegetation : Water plant vegetation.
G3 POPULATION IN THE CATCHMENT AREA
No residents (Q).
H. LAKE UTILIZATION (Q)
H1 LAKE UTILIZATION
Sightseeing and tourism (number of visitors in 1984 : ca. 5,000) (Q).
I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS (Q)
I1 ENHANCED SILTATION
- Extent of damage: Not serious.
- Supplementary notes: The sedimentation rate averaged 0.42-0.80g dry weight
m-2 day-1 in May and 0.75-1.00g dry weight m-2 day-1 in September 1983,
and tended to decrease with depth.
I2 TOXIC CONTAMINATION
I3 EUTROPHICATION
- Nuisance caused by eutrophication: Not any nuisance.
I4 ACIDIFICATION
Extend of damage: None.
J. WASTEWATER TREATMENTS (Q)
J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA : (a) Pristine lake
environments (Q).
N. SOURCES OF DATA
-
(Q) Questionnaire filled by Mr.Deep B. Swar, Fisheries Development Center,
Pokhara, based on the data from the following sources.
- Ferro, W. (1978/1979) Some limnological and biological data from Rara,
a deep Himalayan lake in Nepal. J. Nepal Res. Center, 2/3 : 241-261.
- Okino, T. & Satoh, Y. (1986) Morphology, physics, chemistry and biology
of Lake Rara in west Nepal. Hydrobiologia, 140 : 125-261.
- Swar, D. B. (1979) Report on a single species of Cladocera from Rara Lake,
Nepal. J.Inst. Sc., 2 : 185-190.
- Terashima, A. (1984) Three new species of cyprinid genus Schizothorax from
Lake Rara, northwestern Nepal. Jap. J. Ichthyol., 31 (2): 122-135.
- Shrestha, J. (1978) Fish from Rara. J. Inst. Sc., 1: 157-158.
- Tabata, H. (personal communication).
