BENGALURU: Changing rainfall patterns across the Western Ghats have contributed to increased rainfall in Karnataka’s interior regions, benefiting agriculture and horticulture, even as the coastal areas and western slopes of the Ghats have witnessed a decline in rainfall, according to a study by the University of Agricultural Sciences (UAS), Bengaluru.
The study, presented by Agrometeorology Scientist Dr MB Rajegowda, examined changes in the state’s climate and rainfall distribution and their impact on agriculture. It found that Karnataka’s average temperature increased by up to 1.5 degrees Celsius between 1900 and 2020. The state’s average annual rainfall also rose from 1,140mm during 1901–1950 to 1,208mm during 1950–2008.
However, rainfall changes varied across regions. Annual rainfall along the coastal region declined from 4,500mm to 4,000 mm, while the western Ghats recorded a decrease from 4,010mm to 3,680mm. In contrast, North Interior Karnataka saw rainfall increase from 640mm to 740mm, while South Interior Karnataka recorded an increase from 685mm to 836mm.
Explaining the changes, the study attributed the shifting rainfall distribution partly to the orographic effect. Monsoon clouds originating over the Indian Ocean enter the western coast through the Arabian Sea. Around 75% of these clouds precipitate along the coast and Western Ghats, while the remaining 25% cross the mountain range towards interior Karnataka.
According to the study, rising land and atmospheric temperatures influence cloud density and movement, pushing clouds towards the eastern side of the Ghats, where they contribute to rainfall in the interior regions.
The study also highlighted the impact of industrialisation, urbanisation, agricultural expansion, road construction, small hydropower projects and tourism on forest density in the Western Ghats. It noted that the Gadgil and Kasturirangan committees constituted by the Centre had examined biodiversity, environmental conditions and development activities in the region.
However, detailed assessments of climate change and its implications for agriculture across Karnataka were beyond their scope.
The changing rainfall patterns have coincided with an expansion in cultivation. Agricultural land increased from around 50–60 lakh hectares in the 1950s to 100–105 lakh hectares by 2020. Agricultural production rose from 40–50 million tonnes to 130–135 million tonnes. Horticultural cultivation expanded to 22–24 lakh hectares, with production reaching 180–185 million tonnes.
The study projects that Karnataka’s average annual rainfall could increase to 1,235mm during 2020–2035. While rainfall in the coastal and Western Ghat regions is expected to decline further, interior Karnataka is projected to receive more rainfall.
It emphasised the need for long-term planning to make better use of the changing availability of rainwater, particularly in the interior regions, to support agricultural and horticultural production.
