A flash flood is a rapid flooding of geomorphic low-lying areas - washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or melt water from ice or snow flowing over ice sheets or snowfields. Flash floods can also occur after the collapse of a natural ice or debris dam, or a human structure such as a man-made dam, as occurred before the Johnstown Flood of 1889. Flash floods are distinguished from a regular flood by a timescale less than six hours. The temporary availability of water is often utilized by plants with rapid germination and short growth cycle, and by specially adapted animal life.

Causes
Flash flooding occurs when a barrier holding back water fails or when …show more content…

Areas in Mumbai badly affected by the flooding

The rains also impacted the state of Goa and some parts of western Maharashtra on July 25. Adding to the chaos was the lack of public information. Radio stations and many television stations did not receive any weather warnings or alerts by the civic agencies. The Met department blamed it on the lack of sophisticated weather radars which would have given a 3 hour prior warning which came due to high tides.

Threat to public health
The rain water caused the sewage system to overflow and all water lines were contaminated. The Government ordered all housing societies to add chlorine to their water tanks while they decontaminate the water supply.

Thousands of animal carcasses floated in the flood waters, raising concerns about the possibility of disease.

Reports in the media warned of the threat of waterborne diseases, and hospitals and health centers geared up to distribute free medicines to check any outbreak.

Topography
India's western coast receives high rainfall due to the presence of the Western Ghats which lie at about 50 km (30 miles) from the coast. The hill range runs parallel to the Indian coast at an average altitude of 1,200 metres (3,900 ft). Rain bearing clouds generally deposit much of their moisture through orographic rainfall along India's western coast which lies on the windward side of the hills...

Areas in Mumbai badly affected by the