Analytical Study of Monsoon Rainfall South Mahanadi Delta and Chilika Lagoon, Odisha

摘要

The rainfall has become anomalous today along Odisha coast, India. The southern distributaries, Daya and Bhargovi in Mahanadi delta join the sea via Chilika lagoon. The lagoon stands variations in geomorphology, ecology and biodiversity for changes in precipitation and threshold flushing flow. The abnormal rainfall has caused high floods during 2001, 2003, 2006, 2008, 2011 and 2014. Year 2000 was the minimum discharge year of the millennium. Chilika Lagoon, largest in Asia receives 61% of inland flow from Mahanadi system. The tourist, flora and aqua catch decreased remarkably 1995-2000 for lagoon?s reduced salinity, siltation and biodiversity. As engineering intervention, a new inlet dredged, few barrages and cuts constructed upstream in the river system. The anomaly in monsoon precipitation has trimmed down the threshold flushing flow to maintain salinity. Hence frequency analysis and prediction of rainfall at a desired recurrence interval became univocal. As post studies of hydrology to the engineering interferences, the frequency analysis of rainfall has been done after verifying the outliers, goodness of fit with handful recorded data. A suitable probability distribution pattern has been selected and PDF function used to predict monsoon rainfall against various recurrence periods. Out of L-moment, PWM methods available, Log Pearson type III method is found the best and realistic for rainfall analysis. Attempt has been made in this paper to predict annual monsoon rainfall of the delta and lagoon for 10000 years at different return periods.