page_title: Kalu Ganga
section_title: Introduction
hierarchical_section_title: Kalu Ganga / Introduction
caption_attribution_description: Deutsch: Der Fluss Kalu in Ratnapura English: River Kalu in Ratnapura (down stream)
context_page_description: Kalu Ganga is a river in Sri Lanka. Measuring 129 km in length, the river originates from Sri Padhaya and reach the sea at Kalutara. The Black River flows through the Ratnapura and the Kalutara District and pass the city Ratnapura. The mountainous forests in the Central Province and the Sinharaja Forest Reserve are the main sources of water for the river.
  Kalu Ganga basin is one of the most important river basins in Sri Lanka which receives very high rainfalls and has higher discharges. Due to its hydrological and topographical characteristics, the lower flood plain suffers from frequent floods and it affects socio-economic profile greatly. During the past several years, many researchers have investigated climatic changes of main river basins of the country, but no studies have been done on climatic changes in Kalu Ganga basin. Therefore, the objective of this study was to investigate precipitation trends in Kalu Ganga basin. Annual and monthly precipitation trends were detected with Mann-Kendall statistical test. Negative trends of annual precipitation were found in all the analyzed rainfall gauging stations.
context_section_description: Kalu  Ganga  basin  is  the  second  largest river basin in Sri Lanka covering 2766 km2 and  much  of  the  catchment  is  located  in the  highest  rainfall  area  of  the  country, which reflects the high annual rainfall. The annual rainfall in the basin is averaged to 4000mm and leads to 4000 million m3 of annual  flow.The  Kalu  Ganga  originates from  the  central  hills  of  wet  zone  at  an altitude of 2250 m and garners rainfall on the western slopes and falls out to the sea at Kalutara after traversing about 129 km. The basin has steep gradients in upper part and  mild  gradients  in  lower part.  Due  to these  hydrological  and  topographical characteristics of the river basin, its lower flood  plain  suffers  from  frequent  floods during  the  Southwest  monsoon  season. Therefore,  the  damages  to  the  socio-economic  profile  are  significantly  high since the lower flood plain of Kalu Ganga is densely  populated  and  it is  a  potential area  for  rice  production.  During the  past several  years,  attention  has  been  paid  to study  on  precipitation  changes  of  main river basins of Sri Lanka. El Niño-southern oscillation influences on stream  flow  in  Kelani  River. In studied  2005  hydrology and environmental flows in the Walawe  River  basin.  However,  we couldn’t  find  any  academic  literature regarding climatic changes in Kalu Ganga basin, which is one of the four main rivers in Sri Lanka. The major possible effects of climate change may include variability in water  resources,  increase  desertification, loss  of  biodiversity  and  changes  in agricultural  productivity. One of the most significant consequences  resulting  from  climate change  may  be  the  alteration  of  regional hydrological  cycles  and  subsequent changes in stream flow regimes. Studies of general  circulation  model  (GCM)  reveals that  increased  global  temperature  could lead to increase the amount and intensity of regional precipitation. Precipitation is a good  indication  of  the  impacts  from climate  change  on  water  resources. Changes in precipitation patterns are very important for water resources managers to deal with the water resources planning and management.  Variations  in  precipitation over  daily,  seasonal,  annual,  and  decadal timescales  influencewater  resource systems.  In  addition  to  the  studies  on short-term  variability  of  precipitation, long-term  detection  of  precipitation  is essential  for  understanding  the  potential impacts on water resources resulting from climate change. Therefore, the objective of this  study  was  to  investigate  long-term precipitation  trends,  which  is  one  of  the crucial  parameters  in  climatic  change,  in Kalu Ganga basin.
caption: Downstream view, in Ratnapura.
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