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Bihar - Climate

The state generally has three seasons, hot from March to May, the rainy season from June to September and the cold season from November to February. The climate of Bihar comes under tropical to sub tropical region. The Himalayan Mountains in the north have a significant bearing on the distribution of monsoon rainfall in Bihar.

The state has a tropical monsoon climate with three distinct seasons-winters, summer and rainy. The state can be divided into two climate zones; the Sub-Himalayan and the Ganga plain. The winter season exists from December to February, January being the coldest month when temperature falls below 10C. The winter season is characterized by fog, cold wave and western disturbances. Winter rainfall is received by western disturbances in the state.

The summer season covers the period from April to June, May is the hottest month in the greater part of the area and the maximum temperature some time reaches above 45C and causes the heat waves of the state. The monsoon season normally starts in the third week of June and lasts up to end of September and downpour accumulated seasonal rainfall of 120-150 cm throughout the state. The rainfall is also triggered by monsoon depression which formed in Bay of Bengal, entered in Bihar and produced wide spread rainfall. During monsoon season, the state experienced flood and drought in almost every year and affect the water resources and agriculture of Bihar.

An important feature of the retreating monsoon season in Bihar is the invasion of tropical cyclones originating in the Bay of Bengal at about 12N latitude. Bihar is also influenced by the typhoons originating in the South China Sea. Normal rainfall for Bihar state is 1255 mm. Minimum temperature goes as low as 12C in the month of January.

Bihar is richly endowed with water resources, both the ground water resources and the surface water resources. It has considerable water supply from the rivers, which flow outside the territory of the state. Ganges is the main river, which is joined by tributaries with their sources in the Himalayas. The important rivers that join the Ganges from the north are, from west to east, Ghaghra, the Gandak, the Burhi Gandak, the Kosi, the Mahananda and its tributaries. The Karmanasa, the Sone, the Punpun, the Phalgu, the Sakri and the Kiul are the principal streams that join the Ganges from the south. There are several rivers in Bihar, which contribute a lot to the people of Bihar. These rivers make the water available for irrigation purpose and also help in generating the hydrothermal energy for the state. Apart from this, they provide a medium for water transport, provide fishes for fishery industry and enrich the natural resources of state in many other ways. All the above rivers have their impact on the Bihar plain. State also has non-exhaustible source of ground water, which is in use for drinking purposes, irrigation and industries. Rivers are major source of irrigation in Bihar.

Climate change is only likely to exacerbate Indias already high physical exposure to climate-related disasters (65 percent of India is drought prone, 12 percent flood prone, and 8 percent susceptible to cyclones). As a consequence, climate change is highly likely to impact livelihoods by disrupting social, cultural, economic, ecological systems, physical infrastructure, and human assets, accentuating health risks, and as such, posing severe risks to the development of the country.

Available evidence shows that there is high probability of increase in the frequency and intensity of climate related natural hazards due to climate change and hence increase in potential threat due to climate change related natural disasters in India, and Bihar is no exception to this. It is highly vulnerable to hydro-meteorological natural disasters, with North Bihar in general being highly flood-prone, and South Bihar being highly drought prone. In the (relative) absence of state level climate models and/or vulnerability studies, as well low community awareness, Bihar is potentially more sensitive and vulnerable to the climate change and its impacts.

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Page last modified: 24-10-2021 15:29:41 ZULU