Trends and Anomalies in Extreme Climate Indices and Influence of El Nino and La Nina over Pranhita Catchment in Godavari Basin, India

摘要

Hydrologic design and planning requires dealing with extremes in precipitation and temperature events caused due to climate change. Long-term trends and variability in 20 extreme climate indices (ECIs) and the influence of El Nino and La Nina over the Pranhita catchment, India are studied for the period of 1951-2013. An overall increase in daily precipitation, more intense rain, and an increase in continuous dry days are observed; however, total rain shows a negative trend. A warming trend is observed with an increase in dry days, warm days, and hot nights, and a decrease in the frequency of cool days and nights. Observed +ve trends for maximum and minimum temperatures are 0.7 and 0.8℃, respectively. El Nino years resulted in -ve anomaly and +ve anomaly was observed during La Nina years for the majority of ECIs. The association between ENSO and yearly temperature indices is found to be weak in comparison with precipitation indices. The study confirmed the multimodal nature of precipitation during El Nino, high precipitation during La Nina, and excess postmonsoon rains during La Nina. A comparison between the Oceanic Nino Index (ONI) and the precipitation anomaly showed that the anomaly changes with a phase change in ENSO with the relation being very prominent during El Nino. The El Nino years have resulted in a precipitation deficit, and the La Nina years have resulted in excess precipitation.