Weather conditions in India are greatly influenced by the El Niño Southern Oscillation (ENSO) that causes widespread floods and droughts almost at intervals. The frequency, intensity, and impacts of such extreme events vary dramatically with geographical location over the Indian subcontinent. Thus, addressing the inter-annual variability in precipitation patterns becomes an important concern over India.

South west summer monsoon, spreading from June to September is a grand period of rainfall in India as monsoonal torrents supply about 80% of India’s annual rainfall. The distribution of rainfall varies temporally as per an annual cycle of seasons. The meteorologists recognise four seasons:

Cold Weather Season:

• Little rainfall in some parts of India.
• Some weak temperate cyclones from the Mediterranean Sea cause rainfall in north-western India, which are called Western Disturbances.

Hot weather season

• A sudden contact between dry and moist air masses gives rise to local storms which are associated with torrential rains.

 Southwest Monsoon season

• Over 80% of the annual rainfall is received in the four rainy months of June to September.
• The monsoon may burst in the first week of June in the coastal areas of Kerala, Karnataka, Goa and Maharashtra while in the interior parts of the country; it may be delayed to the first week of July.       
• Monsoonal rainfall is largely governed by relief or topography and rainfall has a declining trend with increasing distance from the sea.

Retreating Monsoon

• By the end of September, the monsoon becomes weak in response to the southward march of the sun.
• The weather is dry in north India but is associated with rain in the eastern part of the Peninsula.

Floods in India:

Nearly 40 million hectares of India’s land is prone to floods. Usually during La-Nina years, occurrence of floods is as follows:

• Through heavy precipitation: Heavy rainfall over natural bank of rivers, of about 15 cm or more in a single day exceeds the carrying capacity of rivers causes a flood in that region.  Such effect can be seen in the West Coast region of the Western Ghats, Assam and sub-Himalayan West Bengal and Indo-Gangetic plains.
• Floods through cyclonic rainfall: Flood after cyclone is a very common phenomenon in the eastern coast of Tamil Nadu, Andhra Pradesh, Odisha and West Bengal. 
• Cloudbursts: Quite regular in the Himalayan region during monsoons as well.
• Strong NE monsoons: In November and December 2015, the annual North-East monsoon generated heavy rainfall in south India causing floods along the Coromandel Coast in Tamil Nadu, Andhra Pradesh and Pondicherry. Chennai and surrounding area were hardly hit by these floods.
• Western disturbance in winter: Showers the Gangetic plain and causes heavy snowfall in Himalayas. Excessive precipitation due to this disturbance can cause crop damage, landslides, floods and avalanches.

Droughts in India:

More than 44 per cent of India’s areas were under various degrees of drought conditions (abnormally dry to exceptionally dry) as of June 10, 2019 Drought Early Warning System (DEWS).

• Deficit in SW-monsoon rains: Felt to a large extent especially in areas that have large rain variability-leeward side of Western Ghats (Marathwada and Vidarbha) and North-west extremities of the country.
• Untimely delay in monsoons: The sluggish pace of the south west monsoon has compounded the severe dry spell. Most of these are in Andhra Pradesh, Kerala, Madhya Pradesh, Maharashtra, Chhattisgarh, and the north eastern states. Only four sub-divisions in Karnataka, Gujarat, and Lakshadweep have witnessed ‘normal’ rainfall.

Way Forward:  

Dealing with floods and droughts in India, is a complex situation, given the numerous unpredictable factors associated with it.

Flood mitigation strategies:

• Planting of the tree and mangrove belts along river banks and coastlines.
• Planned settlement growth.
• Shared flood warning mechanisms.
• Recharge and rejuvenation of wetlands.
• Identification and assessment of flood-prone areas.

Drought mitigation:

• Adoption of micro-irrigation techniques 
• Stringent application of water harvesting measures not only at the individual level but at community and village level too.
• Seechwal model can be implemented especially in acute water deficit areas. This model is currently being extended along the banks of the Ganga
• Wastewater recycling facilities in urban and industrial centres to allow for non-drinking uses.
• Agricultural practices should focus on more crop, per drop. 
• Agro-climatic basis for crop selection.

As India is poised to turn into a major power in the world, vagaries of the rainfall patterns is one of the most important challenge we have to face. Effective and committed solutions, policies and implementation by all stakeholders are the only way to strengthen our ability to deal with it.