Very Heavy Rains In Chhattisgarh, Jharkhand In Next 48 Hours May Make Mahanadi Swell

The current well-marked low pressure area, which is lying over coastal Bangladesh and adjoining West Bengal, will not bring widespread rainfall across Odisha. The system will be inducing heavy to very heavy rainfall in the north-interior parts of the State from July 29.

Though the model forecasts made by IMD, ECMWF, NCEP-GFS reveal that north-interior Odisha is going to receive excess rainfall between July 27 - August 2, the prediction of extremely heavy rainfall in neighbouring Jharkhand and Chhattisgarh holds a potential flood risk for the State.

What seems worrisome for Odisha is, another low pressure will be forming over the northeast Bay of Bengal on August 5, which will be bringing moderate to heavy rains for the State's north-interior districts.

The Alert

As per the NCEP-GFS model forecast, during the week of August 3 - 9, when the entire coastal, and southern districts in the State are going to record 45 - 55 per cent excess accumulated rainfall vis-a-vis the normal, the rest of the districts (especially north interior) in the State will be witnessing an excess accumulated rainfall in the range of 55-75 per cent.   

Current Weather

As per the model forecasts by IMD, ECMWF and US-GFS, the current well-marked low pressure will pound the states of West Bengal, Jharkhand and Chhattisgarh. The forecast predicts heavy rain during the morning hours (5 am) on July 29 in Odisha districts bordering Jharkhand and West Bengal.  

Odisha Impact: The current low pressure will induce heavy rains over Odisha from June 29 (morning hours) and will continue till noon. Moderate to heavy rain will hit the districts of Bhadrak, Jajpur, Mayurbhanj, Keonjhar, Dhenkanal, Angul and Sundargarh again in the morning hours on July 30. The rest of the districts may record very light rainfall with the predicted accumulated rainfall in 6 hours ranging in between 0.5-2 mm.

Is There Any Flood Threat?

The model forecasts show as the well-marked low pressure on its way towards north-west India will be pounding the states of West Bengal, Jharkhand and Chhattisgarh. The forecast of very heavy to extremely heavy rainfall between July 29-31 in Jharkhand and Chhattisgarh poses the possibility of a higher inflow of water into the downstream basins of Mahanadi, Brahmani, Baitarani, Budhabalanga and Subarnarekha.

The Current Status:  At present majority of the base stations in the river basin regions here have not recorded any rainfall till the morning hours today. Moreover, the measured water levels at the majority of the base stations have been 2-3 metres below the warning levels. Though none of the base stations in the State has received any rainfall till this morning, few base stations on the river Brahmani-Baitarani and Mahanadi basins have a water level very close to the danger level.

Given the forecast of very heavy to extremely heavy rainfall in the upstream states of Chhattisgarh and Jharkhand, along with heavy rainfall downstream here, there is a possibility of rivers going spate in the State.

The CWC Forecast

Hirakud Reservoir: As per the Central Water Commission (CWC) Forecast, Sundargarh will be recording 5-6mm rainfall per hour on July 31. With heavy rainfall upstream, the forecast says that discharge from Hirakud reservoir by August 2 would touch 10,000 cubic metres per second. And the inflow is set to touch 800 million cubic metres (MCM) per 24 hours. The inflow to Hirakud in next 24 hours will be 349.29 MCM.

Rengali: As per the CWC forecast, the Panposh site on the river Brahmani is predicted to record extremely heavy rainfall of  9-10 mm per hour on July 31. The forecast shows by July 30, when the discharge from the reservoir will be 1000 cubic meters per second, the average inflow will reach nearly 600 MCM per 24 hours on August 1

Baitarani: Even as the Anandpur site on the river is predicted to record rainfall in the range of 5 mm per hour on July 31, there seems no flood threat till August 2.

Govindpur: As per the forecast, the site on river Budhabalanga will receive 1.2mm rainfall per hour on July 30. But there is no flood threat till Aug 2.