RIVERS AND LAKES
RIVERS
RIVERS IN SRI LANKA
Ancient Irrigation
All About Rivers
River
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities a stream is defined by its size.
Importance
Many human cities and civilizations are built around the freshwater supplied by rivers and streams. As they are, or were, used as a source of water, for obtaining food, for transport, as borders, as a defensive measure, as a source of hydro power to drive machinery, for bathing, and as a means of disposing of waste.
River Cycle
Rivers are part of the hydro-logical cycle. Water generally collects in a river from precipitation through a drainage basin from surface runoff and other sources such as groundwater recharge, springs, and the release of stored water in natural ice and snow-packs (e.g., from glaciers).
Rivers in Sri Lanka
About Rivers
Rivers of Sri Lanka originate in the central highlands. The rivers are typically unnavigable in their higher reaches, where they flow swiftly and turbulently through highly eroded passages to the plains below. In their lower courses, the rivers slowly meander through flood plains and deltas.
Sri lankan Rivers
The longest river of Sri Lanka, the Mahaweli, traverses a course of about 330 km (about 205 mi). The country’s second longest river is the Aravi Aru, traversing about 220 km (about 135 mi) on a northwestward course, from the central highlands to the Gulf of Mannār.
Importance
Much of Sri Lanka is arid and has only a few permanent rivers. However, the southwestern region’s “wet zone” is characterized by numerous rivers that arise in the high mountains of the central part of the island. These diverse river basins support endemic populations of aquatic plants, bivalves, and fish.
Ancient Irrigation
History Of Irrigation
Together with the rise in population irrigation engineering developed bringing advanced and ambitious irrigation works. According to historical descriptions building, giant-sized reservoirs had been started in the 1st century B.C. According to the historical records the king built 11 large reservoirs and two irrigation canals. Read More..
Present Irrigation
A new Irrigation Ordinance, No.21 of 1867, was also passed, which also reembodied the provisions of the older ordinance of 1856 for the revival and enforcement of the ancient customs regarding the irrigation and cultivation of paddy lands. Further Molesworth proposed the following irrigation works for execution in 1887. Read More ..
Victoria Dam
Victoria Dam is an arch dam located 130 mi (209 km) upstream of the Mahaweli River’s mouth and 4 mi (6 km) from Teldeniya. Its main purposes are irrigation and hydroelectric power production. It is the tallest dam in Sri Lanka, and supports a 210 MW power station, the largest hydroelectric power station in the country. Read More..