ISLAMABAD: Tarbela Dam has reached maximum capacity, which experts believe is a disturbing sign for the regional environment because this was mainly due to adverse effects of climate change.

The water level at Tarbela rose to 1,550 feet, and the key inflow to the dam was from the melting of snow and glaciers. Greater inflow was recorded in the recent weeks, after the absence of clouds over the western Himalayas gave way to more sunshine.

Dr Ghulam Rasool, director general at the Pakistan Meteorological Department, said: “This is not a good sign for long term water availability and the region’s ecosystem, as these situations mean glaciers are melting faster than their replenishment rate.”

The influence of the monsoon rains, meanwhile, can be seen at Mangla Dam, which is 7ft below its maximum capacity of 1,234.95ft. However, more water is being released from Mangla than is entering the lake.

Met Office predicts 30pc lower rainfall in August compared to average rainfall this time of year

The water inflow at Mangla Dam measures 18,000 cubic feet per second (cusecs). However, outflow is 23,100 cusecs due to the demand from the farming sector, as the last watering is needed for standing paddy crops.

Halfway through the monsoon, accumulated rainfall in August has been significantly lower than precipitation received in July. Monsoon in Pakistan stretches from July to September, and the Met Office has predicted that rainfall in August will be around 30pc lower than the average rainfall at this time of year.

“The situation shows anomalies of climate change because there was higher than average rainfall in July, while there is below normal rainfall in August. On the contrary it used to rain almost daily in this month,” Dr Rasool said, adding, “Due to this factor and less cloud cover, the feeling of a hot and humid climate is higher this year.”

Local water reservoirs like the Rawal and Simly lakes have yet to be filled to capacity due to the reduced rainfall, and their floodgates have not been opened so far during the season.

Except for the Indus River, which is at low flood level at Guddu and Kotri, all the other major rivers are in the state of normal flow, which also signifies reduced water storages in various local reservoirs across the country.

However, despite the low rainfall, the Met Office has not discounted the possibility of a devastating flood in any part of the country, especially in September.

“September is the month of retreating monsoon and the winds along with moisture are intense at times, but the floods are caused if there is clash of these winds with western currents,” Dr Rasool added.

Monsoon winds, also known as easterlies, originating from the Bay of Bengal arrive in the country after crossing central India, while westerly winds come from Central and Eastern Europe towards the region.

While eastern winds are fast moving, warm and filled with moisture, the western currents are cool and usually dry. In the event that both winds reach the north, west or central part of the country at the same time, they could trigger massive rainfall in a short span of time.

This phenomenon was witnessed in 2010 from Mianwali to Nowshera, when 600 millimetres of rain fell in 24 hours.

In 2001, Rawalpindi and Islamabad also saw 620mm of rainfall in 10 hours and massive flooding due to the same pattern.

The current forecast is of low monsoon currents moving towards Pakistan from central India, likely to bring isolated rain in the Malakand, Hazara, Rawalpindi, Gujranwala and Lahore divisions, Gilgit-Baltistan and Kashmir during the weekend, while the rest of the country remains hot and humid.

Published in Dawn, August 19th, 2017