Karnataka, a state in southern India, experiences varied rainfall patterns due to its diverse geography, ranging from coastal plains to rugged highlands. The distribution of rainfall across Karnataka is influenced by the monsoonal system, geographical features, and climatic conditions.
Introduction to Karnatakas Rainfall Patterns
Karnataka receives its rainfall primarily from the southwest monsoon, with contributions from the northeast monsoon in some regions. The spatial and temporal variation in rainfall is significant, leading to distinct climatic zones across the state.
Factors Influencing Rainfall Distribution
Southwest Monsoon (June to September):
Dominates the states rainfall, accounting for over 75% of the total annual precipitation.
Coastal Karnataka receives heavy rainfall due to the orographic effect of the Western Ghats.
Northeast Monsoon (October to December):
Contributes to post-monsoon rainfall, primarily affecting the southeastern parts of Karnataka.
Orography:
The Western Ghats act as a barrier, causing heavy precipitation on the windward side and creating a rain shadow region on the leeward side.
Cyclonic Activity:
Occasionally, cyclones in the Bay of Bengal and Arabian Sea contribute to unseasonal rain.
Regional Rainfall Distribution in Karnataka
Coastal Karnataka (High Rainfall Zone):
Districts: Dakshina Kannada, Udupi, Uttara Kannada.
Average Rainfall: 3,0004,000 mm annually.
Characteristics:
Experiences heavy rainfall during the southwest monsoon.
High humidity and dense forest cover.
Malnad Region (Moderate to High Rainfall Zone):
Districts: Shivamogga, Chikkamagaluru, Kodagu, Hassan.
Average Rainfall: 1,5003,000 mm annually.
Characteristics:
High rainfall due to proximity to the Western Ghats.
Supports coffee plantations and lush vegetation.
Northern Interior Karnataka (Low Rainfall Zone):
Districts: Bijapur, Bagalkot, Bidar, Gulbarga, Raichur.
Average Rainfall: 500750 mm annually.
Characteristics:
Lies in the rain shadow region of the Western Ghats.
Frequent droughts and semi-arid conditions.
Southern Interior Karnataka (Moderate Rainfall Zone):
Districts: Bengaluru, Mysuru, Tumakuru, Kolar.
Average Rainfall: 7501,200 mm annually.
Characteristics:
Receives rain from both southwest and northeast monsoons.
Agriculture-dependent region with mixed cropping patterns.
Seasonal Rainfall Patterns
Pre-Monsoon Season (March to May):
Contribution: 10-15% of annual rainfall.
Occurrence of thunderstorms and pre-monsoon showers.
Monsoon Season (June to September):
Contribution: 70-80% of annual rainfall.
Uneven distribution, with coastal areas receiving the maximum.
Post-Monsoon Season (October to December):
Contribution: 10-15% of annual rainfall.
Affects the southeastern parts, beneficial for rabi crops.
Winter Season (January to February):
Contribution: Negligible rainfall.
Occasional drizzle in some regions.
Rainfall Variability and Anomalies
Spatial Variability:
Coastal regions: Excess rainfall.
Northern interior regions: Deficient rainfall.
Temporal Variability:
Rainfall is concentrated during the monsoon months, leading to water scarcity in dry periods.
Droughts:
Common in the northern and interior regions due to erratic monsoons.
Floods:
Coastal and Malnad regions are prone to flash floods during heavy monsoons.
Rainfall and Agriculture
Kharif Season:
Depends on monsoon rains.
Crops: Paddy, millets, and pulses.
Rabi Season:
Relies on residual soil moisture and post-monsoon rains.
Crops: Wheat, gram, and oilseeds.
Irrigation Dependency:
Regions with low rainfall depend on reservoirs and borewells.
Rainfall Measurement and Monitoring
Meteorological Departments:
Karnataka State Natural Disaster Monitoring Centre (KSNDMC) actively monitors rainfall.
Rain Gauges:
Installed across districts to record daily rainfall.
Remote Sensing:
Used to analyze rainfall patterns and predict anomalies.
Impacts of Rainfall Distribution
Positive Impacts:
Coastal and Malnad regions support biodiversity and dense forests.
Sufficient rainfall aids hydroelectric projects.
Negative Impacts:
Drought in northern Karnataka affects agriculture and livelihoods.
Excess rainfall causes landslides in the Western Ghats.
Government Initiatives
Drought Mitigation Programs:
Rainwater harvesting and watershed management.
Irrigation Projects:
Krishnaraja Sagar Dam, Tungabhadra Dam.
Climate Adaptation Strategies:
Promotion of drought-resistant crops.
Improved irrigation techniques.
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