Last year's monsoon rains caused the death of over 2,000 people in Pakistan

 

It's not unusual for Pakistan to endure flooding during the monsoon rains. Almost every year, somewhere is inundated and homes are flooded, but the last two years have been exceptional.
This year, Pakistan's Meteorological Office had forecast the monsoon rains to be ten percent below average, but for some parts of the country, the flooding has still been extreme.

The worst hit area this year has been in the southeastern Sindh province. More than 200 people are known to have died and 200,000 have been made homeless.
You might expect that the more rain that falls, then the more flooding there will be, but it's not quite that straightforward. The amount of flooding that an area suffers from depends on a number of things, including the topography of the land, the land type (cement or soil), and how much rain the area normally receives.

August is normally the wettest month for Pakistan, but the monsoon rains don't fall uniformly across the country. The heaviest rains are usually seen in the northeast, with Islamabad recording an average August rainfall of 258mm (10 inches). This contrasts starkly with the rainfall in the south, which is a desert region. Jacobabad, in Sindh Province, only receives a paltry 35mm (1.4 inches) in the whole of August.

This means that in the south, the ground is baked hard by the sun. This reduces the land's ability to absorb water, so it will take less rain to cause flooding.  
In the Sindh province, the city of Badin reported over 145mm (5.7 inches) rain for two days running. This is a serious amount of rain, which would cause flooding in any part of the world. In the dry southern state of Pakistan, it caused devastating floods which marooned several villages and washed away thousands of acres of crops.

There was a slight reprieve in the rains for a few weeks, before they returned towards the end of the month. Since then, the rains have been relentless, with yet more daunting rainfall statistics being seen throughout the province.

The cause of this year’s flooding could well be the La Nina conditions which have established in the Pacific Ocean. La Nina often brings a wetter monsoon season for Pakistan and India, and would explain why this year’s rains have been so heavy in some parts of the region.

In June it was believed that the La Nina conditions were over. The Pacific waters had returned to normal and gradually its impact on the weather around the globe was expected to decrease. However, this didn’t happen, and La Nina surprised scientists by returning to the Pacific. This could well explain why the rains were so much heavier than expected, and the La Nina conditions will continue to have implications on the weather around the globe over the coming months.

There is also another problem for the province of Sindh this year, which was caused by last year's floods. The extent of the flooding in 2010 caused the mighty Indus River to punch holes in its banks and submerged vast plains on either side of it. The damage to dykes and embankments was so bad, that it's reported that the Indus has actually changed its course, meaning that the villages that are now at risk of flooding are villages that have rarely had to face flooding before.

The monsoon rains in Sindh are expected to ease in the next few weeks, as the monsoon starts its annual retreat. However, until the rains finally clear, there can be no guarantee against further flooding in the region.

Source: Al Jazeera