Extreme events and associated risk over Godavari Basin: implications on vulnerabilities

Ramkumar Bendapudi

It is expected that some extremes will become more frequent, more widespread and more intense during the 21st century (IPCC, 2014). As a result, the demand for information services on weather and climate extremes is growing. The sustainability of economic development and living conditions depends on our ability to manage the risks associated with extreme events in the river basins. The historical trend of rising extreme event has been reflected in many studies. In recent times, more and more emphasis is given to river basin approach for integrated water resources management. Therefore, it is important to understand the rainfall characteristics at a basin level that would help in developing a more comprehensive adaptation plans at local level.
The objectives of study are to examine the spatial and temporal distribution of extreme rainfall across the Godavari river basin (cover 7 states) in India and assessing the future risk of wet and dry extreme events in the next 20 and 100 years in order to contribute to adaptation strategies to secure the livelihoods and disaster prevention.
Method:
The indices studied include number of consecutive wet and dry days, intensity of heavy rainfall events during southwest monsoon season. Six climate indices are used for the period 1984-2015 in order to identify the climate extremes (Wet and Dry). All the indices are taken from the expert team on climate change detection and indices (ETCCDI). The long term change has been studies by performing the trend test. Linear regression is one of the simplest methods to calculate the trend of data in time series. Risk analysis is done using extreme value theorywhichsolely uses the maximum likelihood estimation (MLE) methodto fit the extreme value functional models.
Consecutive dry days are seen to be highest in the Ahmednagar district (western part of basin) with more than 18 days in the semi-arid region of basin.In last 30 years the highest one day precipitation is found in the coastal regions (>220mm/day).In terms of long term trend, September month has shown significant trend (at 0.05) for all extreme events (wet). This is line with results of Deshpande et al (2016) which showed that intense rainfall has increased over the Godavari basin. This could impact crop production by at maturity stage. When a 20-year return level is considered then the central and western part of basin shows highest rainfall amount (141-167mm) whereas consecutive dry days are found to be 12-14 days (lesser than current days( 15-18).
Agriculture is particularly vulnerable to extreme events and the farming sector would have to bear the maximum impact of increased wet and dry extremes. Farmers in the semi-arid and coastal regions are highly vulnerable and have low adaptive capacities despite various initiatives by the national and the state governments. It is vital to establish robust assessment systems of climate change projections as well as impact assessment at the regional and local level, which would aid in developing appropriate adaptation plans.
 

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