The Kelani River (Sinhala: Kelani Ganga) is a 145 km (90 mi) long river in Sri Lanka. Ranking as the fourth longest river in the country, it stretches from the Sri Pada Mountain Range to Colombo. It covers approximately 80% of the water supply to Colombo. In addition to that, the river is used for transport, fisheries, sewage disposal, sand mining and for production of hydroelectricity. Due to these, many people depend on the river for their daily routine in life. Depending on the operation of three reservoirs, the river flow varies from 20 m3 (706 cu ft) to 25 m3 (883 cu ft) in the dry seasons, and 800 m3 (28,252 cu ft) to 1,500 m3 (52,972 cu ft) during the monsoon season. The annual sand extraction from the river is approximately 600,000 m2 (6,458,346 sq ft) to 800,000 m2barge, people dive to the river bed, from where the sand is lifted to the barge in a bucket, and when the barge is full, it is taken to the river bank unloaded by a separate team. The sand mining causes the river bed to sink by approximately 10 cm (4 in) per year. At present, two main concerns in connection with the river are: (8,611,128 sq ft) per year. From a
- Flooding during the monsoon.
- Saline intrusion in the dry season.
The problems are related; the saline intrusion is enhanced by the deepening of the river caused by the sand mining. Regulation in order to prevent the saline intrusion can reduce the water quality in other ways, and can increase the flood risk. Sand mining is economically important for both nationally and to the many involved people.
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