Kalatuwawa reservoir was built for the purpose of providing water for Colombo city and its sub-urban areas. A sub tributary of Kelani River was obstructed in 1955 to build this water body by Colombo Municipal Council. It could be reached through Hanwella-Labugama Road.
Charateristics of Kalatuwawa Reservoir:
Catchment - 13.5 Sq. Km.
Length of Dam - 283.46 m.
Height of Dam - 21.9 m.
Capacity - 17.8 millions cu. m
Parakrama Samudra, the Sea of King Parakrama as the name literally means, is a shallow reservoir with a surface area of 22.6 km2. It consists of three separate reservoirs connected only by narrow channels at low water. The northernmost reservoir is the oldest and referred to as Topa wewa (Sinhalese wewa=lake or reservoir). The middle section is Eramudu wewa and the southernmost portion at the highest elevation is Dumbutula wewa. Topa wewa was built around A.D. 386. The other sections were added and the reservoir expanded during the reign of King Parakrama Bahu the Great (A.D. 1153-1183).
Lake Parakrama forms one of the larger reservoirs of an ancient, intricate and sophisticated water storage system for the irrigation of rice fields in Sri Lanka. During the twelfth century A. D. it was situated in the capital of Sri Lanka and in a densely populated area, judging from the extensive ruins of a magnificent civilization. Later the area was abandoned, the city reverted to jungle, and the lake was drained due to damage to the dam. The reservoir was restored to its present status about thirty years ago, and the surrounding area has attracted increasing numbers of immigrants, mainly rice cultivators and more recently fishermen.
Lake Parakrama has a catchment of about 75 km2. This consists mainly of a forest reserve which is limited by high ground in the west. The reservoir is supplied by water from rainfall in its catchment carried by small streams and also by a channel running north from a small river. Water from the river traverses a distance of about 8 km before reaching the lake. Considerable amounts of silt are deposited in the channel and do not reach the reservoir. The stored water is supplied mainly for the irrigation of rice fields. There has been encroachment on the forest reserve by fishermen in the last twenty years.
Human use of water for domestic purposes has grown with settlement of a large number of immigrants in the vicinity of the lake. The lake receives a considerable load of faecal pollution from the human population in the vicinity. During the low water season when large areas of the lake bed are exposed, cattle graze on the lush growth of grass and leave considerable quantities of faeces behind, enriching the lake (1).
| Surface area [km2] | 23 |
| Volume [km3] | 0.1273 |
| Maximum depth [m] | 12.7 |
| Mean depth [m] | 5.0 |
| Water level | Regulated |
| Normal range of annual water level fluctuation [m] | ca. 4.4 |
| Catchment area [km2] | ca. 75 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Ann. | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean temp. [deg C] | 24.9 | 26.2 | 28.1 | 28.7 | 28.6 | 28.8 | 28.7 | 28.7 | 28.4 | 27.4 | 26.6 | 25.0 | 27.5 |
| Precipitation [mm] | 218 | 141 | 99 | 140 | 63 | 16 | 57 | 64 | 86 | 211 | 326 | 430 | 1,849 |
| Station 3, 3 August 1980 | ||||||
| Depth [m] | Daytime | |||||
|---|---|---|---|---|---|---|
| 0600 | 0850 | 1230 | 1520 | 1830 | 2340 | |
| 0.0 | 30.0 | 31.0 | 33.8 | 34.2 | 31.6 | 30.6 |
| 0.5 | 30.2 | 30.5 | 32.3 | 34.0 | 31.8 | 30.7 |
| 1.0 | 30.2 | 30.3 | 32.0 | 32.1 | 31.6 | 30.7 |
| 1.5 | 30.2 | 30.2 | 31.2 | 31.8 | 31.3 | 30.7 |
| 2.0 | 30.2 | 30.2 | 30.8 | 31.2 | 31.0 | 30.6 |
| 2.5 | 30.1 | 29.6 | 30.6 | 30.4 | 31.1 | 30.6 |
| 3.0 | 29.3 | 29.4 | 30.3 | 29.2 | 31.1 | 30.6 |
| 3.5 | 29.1 | 29.3 | 30.0 | 29.2 | 30.6 | 30.6 |
| 3.8 | 29.0 | 29.3 | 30.0 | 29.2 | 29.9 | 30.6 |
The annual totals of the water balance components [mm] (1950-1977)
| Inflow | 9,933 |
| Outflow | 10,067 |
| Precipitation | 1,849 |
| Evaporation | 1,786 |
| Change in storage | -133 |
Phytoplankton count, fresh-weight biomass and chlorophyll a concentration for selected samples from 1979 and 1980 (7)
| Phytoplankton count [cells l-1 x106] | Fresh wt. biomass [mg l-1] | Chlorophyll a [micro l-1] | |
|---|---|---|---|
| 1979 | 25.15-71.79 | 6.4-29.50 | 26.2-105.0 |
| 1980 | 8.42-129.99 | 1.99-20.53 | 5.3-20.8 |
| Station 3, 1 September 1979 | ||
| Time of day | Numbers mill. m-2 | Numbers mill. m-3 |
|---|---|---|
| 0600 | 8.381 | 5.278 |
| 0800 | 8.832 | 5.514 |
| 1000 | 9.179 | 5.737 |
| 1200 | 6.233 | 3.896 |
| 1400 | 3.784 | 2.365 |
| 1600 | 5.792 | 3.622 |
| 1745 | 10.036 | 6.272 |
| List of species found in different habitats of the lake (10) | |||||
| Species | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Ehirava fluviatilis | ++ | ++ | +++ | ++ | |
| Amblypharyngodon melettinus | ++ | +++ | + | +++ | |
| Danio aequipinnatus | ++ | +++ | |||
| Esomus danrica thermoicos | ++ | ||||
| Labeo dussumieri | + | + | + | ||
| Puntius chola | + | + | +++ | + | ++ |
| Puntius dorsalis | +++ | +++ | +++ | ++ | ++ |
| Puntius filamentosus | +++ | ++ | ++ | +++ | +++ |
| Puntius sarana | ++ | ++ | |||
| Rasbora daniconius | ++ | +++ | ++ | + | +++ |
| Ompok bimaculatus | + | + | + | + | |
| Heteropneustes fossilis | + | + | |||
| Mystus keletius | + | ++ | |||
| Mystus vittatus | + | + | ++ | + | + |
| Anquilla bicolor bicolor | + | ||||
| Anquilla nebulosa nebulosa | + | ||||
| Hemiramphidae sp. | ++ | + | ++ | ++ | |
| Ophiocephalus striatus | + | ||||
| Sarotherodon mossambicus | +++ | +++ | +++ | +++ | ++ |
| Etroplus maculatus | + | ||||
| Etroplus suratensis | ++ | + | + | ||
| Glossogobius giuris | ++ | ++ | + | + | ++ |
| Mastacembelus armatus | + | + | + | + | |
+=rare, ++=common, +++=abundant. 1 =PSN, bay with macrophyte cover; 2 =sandy littoral; 3 =PSN, open lake, soft mud bottom; 4 =PSM, open lake with dead, submerged trees; 5 =outflow channel of PSN.
Mostly covered by tropical rain forest.
Source of water (domestic use and irrigation) and fishery.
No evidence of progressive eutrophication.
(e) Severe pollution with no wastewater treatment.
None.
The Mahaweli River Diversion Scheme is planned. This programme aims to improve and expand rice cultivation in the dry zone as well as increase hydro- electric power and control flooding. The scheme will make available an additional 200 km2 of reservoir area and change the hydrological regime of some of the major existing reservoirs, for example, Parakrama Samudra. Within the programme - a long-term project to improve irrigation within the Mahaweli basin - water from the Mahaweli is diverted via the Polgolla tunnel to Amban Ganga which is the largest river of Sri Lanka. Thus the actual catchment area comprises a broad spectrum of geographical regions.
A lake
(from Latin lacus) is a terrain feature (or physical feature), a body of liquid on the surface of a world that is localized to the bottom of basin (another type of landform or terrain feature; that is, it is not global). Another definition is a body of fresh or salt water of considerable size that is surrounded by land. On Earth a body of water is considered a lake when it is inland, not part of the ocean, is larger and deeper than a pond. The only world other than Earth known to harbor lakes is Titan, Saturn's largest moon, which has lakes of ethane, most likely mixed with methane. It is not known if Titan's lakes are fed by rivers; Titan's surface is carved by numerous river beds.
Natural lakes on Earth are generally found in mountainous areas, rift zones, and areas with ongoing or recent glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them.
The pinnacle of irrigation work by King Dathusena was Kalawewa. The benevolent king considered the waters his wealth and treasure. There is rich folklore based on Kalawewa. All those are stories of human interest.
Historical sources indicate that King Mahinda the II (777-797) has expanded Kalawewa.
The modern history of Kalawewa begins with rehabilitation work commissioned by the governor, Sir William Gregory during the British Period. In 1958 the bund structure was rehabilitated to combine Kalawewa to Balaluwewa.
Irrigation uncertainties of Kala Oya valley came to an end once the Mahaweli waters reached Kalawewa in 1976.
Today Kalawewa is a key reservoir in the Mahaweli System. It endows Mahaweli H Zone with hydrological lifeline. Kalawewa also is a beauty spot within the Mahaweli System.
Specifics of Kalawewa
| Catchment | 598 Sq. Km. |
| Length of Dam | 6500 m. |
| Height of Dam | 14.08 m. |
| Capacity | 123.35 millions cu. m. |
Kalatuwawa reservoir was built for the purpose of providing water for Colombo city and its sub-urban areas. A sub tributary of Kelani River was obstructed in 1955 to build this water body by Colombo Municipal Council. It could be reached through Hanwella-Labugama Road.
Charateristics of Kalatuwawa Reservoir:
Catchment - 13.5 Sq. Km.
Length of Dam - 283.46 m.
Height of Dam - 21.9 m.
Capacity - 17.8 millions cu. m