Monsoon Rains: Is Sindh Prepared To Face The Fury Of The Nature?
Pakistan Meteorological Department (PMD) has forecast heavy rainfall, thunderstorms, urban flooding and heavy downpour in different areas of Sindh, warning that a monsoon system may enter Sindh.
The system is likely to unleash its fury mainly in Sindh, encompassing Karachi, Hyderabad, Thatta, Badin, Sanghar, Mirpurkhas, Tharparkar, Umerkot, Jamshoro and Dadu. These areas may witness thunderstorms during the spells. Heavy downpour may generate urban flooding in Karachi as a result.
The 2019 Karachi floods refer to the urban flooding caused by monsoon rains between 29-31 July that killed at least 17 people.
Floods are common and costly natural disasters. These are usually local, short-lived events that happen suddenly, sometimes with little or no warning. They are caused by intense storms that produce more runoff than an area can store or a stream can carry within its normal channel.
Rivers can also flood when dams fail, or ice or landslides temporarily block a channel, or when snow melts rapidly. In a broader sense, normally dry lands can be flooded by high lake levels, high tides, or waves driven ashore by strong winds.
Floods can occur at any time, but weather patterns have a strong influence on when and where they happen. Cyclones or storms that bring moisture inland from the ocean can cause floods.
Thunderstorms are smaller but intense storms can cause floods in smaller streams. Frontal storms form at the front of large, moist air mass moving across the country and can cause floods. Hurricanes are intense tropical storms that can also cause floods.
Flood plains are lands bordering rivers and streams that are normally dry, but are covered with water during floods. Floods can damage buildings or other structures placed in their plains. Confluence of river basins, the canal irrigation network and interrupted drainage system are some of the major reasons of flooding in Pakistan.
Floods can be divided in five major categories:
Flooding along rivers is natural and inevitable. Some floods occur seasonally when monsoon rains, coupled with melting snows, fill river basins with too much water too quickly. Torrential rains from decaying hurricanes or tropical systems can also produce river flooding.
An arroyo is a water-carved gully or a normally dry creek found in arid or desert regions. When storms appear in these areas, the rain water cuts into the dry, dusty soil, creating a small, fast-moving river. Flash flooding in an arroyo can occur in less than a minute, with enough power to wash away sections of pavement. Because of its rapid nature, flash floods are difficult to forecast and give people little time to escape or to take food and other essentials with them.
Floods Due to Breaches
Floods due to the breaches of river embankments and canal breaches are a frequent occurrence in all districts of Pakistan.
As undeveloped land is paved for construction, it loses its ability to absorb rainfall. Rainwater cannot be absorbed into the ground and becomes runoff, filling parking lots, making roads into rivers, and flooding basements and businesses. An urban area can be flooded by an amount of rainfall that would have no impact in a rural area. But in crowded towns and cities, rainwater flows into storm sewers and drainage, thus flooding them.
Hurricanes and tropical storms can produce heavy rains, or drive ocean water onto land. Beaches and coastal houses can be swept away by water. Coastal flooding can also be produced by sea waves called tsunamis, giant tidal waves that are created by volcanoes or earthquakes in the ocean.
The topography of Sindh is almost flat and located at the bottom of Indus basin. The surplus water of Indus River and its tributaries, including monsoon, has to pass through Sindh.
Hill torrents which emanate from Balochistan are also adding up to the pressure on both accounts till its outfall in the Arabian sea. The River Indus in Sindh is dangerous, because it flows at ridge. In case of breach, the out flowing water can not be drained back into the river at any point. The Indus River is also popular for changing its course.
The rains of 2003 monsoon in Sindh affected around 411,000 acres of crop area, while 18,500 kilometres of road infrastructure suffered huge losses. Roughly, losses are estimated at around 45 billion rupees. This estimate includes crop damage, damage to health, education and road infrastructure, houses and destruction of irrigation and drainage facilities.
During the rains, one-fifth of Pakistan’s total land area was submerged, affecting about 20 million people and killing over 2,000. The cost of the damage in Khyber Pakhtunkhwa, Punjab, Sindh, Balochistan and Gilgit- Baltistan was estimated at over $43 billion. The crisis begun in July 2010 during seasonal monsoon rains.
Given the frequent incidences of floods in Sindh during the monsoon season, the government has to take adequate measures for flood control and management down to the district level. The resource and technical inadequacy in response is normally cared for by the Pakistan Army which is expected to play a significant role by providing search and rescue services and emergency relief in the affected areas during the calamity.
The author is a Development Specialist based in Karachi