As seen in two halves of image below are the normal course (top) and flooded course(bottom) of the Indus river as seen from satellite images.
A ClimateWire investigation into the origins of the flood disaster uncovered evidence that points to a calamity caused by man, the cumulative effect of erratic weather forecast by climate change models, massive deforestation, and lax attention to infrastructure maintenance and engineering standards.
The story of the 2010 flooding in Pakistan is a warning to other vulnerable nations that experts believe will bear the brunt of the gradual shifts in climate and weather patterns expected over the coming decades. Read from following article..
Floodwaters contain disease causing bacteria, dirt, oil, human and animal wastes, and farm and industrial chemicals.
Contaminated drinking and washing water and poor sanitation
Flooding impairs clean water sources with pollutants and devastates sanitary toilets. Direct and indirect contact with the contaminants – whether through direct food intakes, vector insects such as flies, unclean hands, or dirty plates and utensils – result in waterborne illnesses and lifethreatening infection diseases.
Mosquitoes and animals
Prolonged rainfall and floods provide new breeding grounds – wet areas and stagnant pools – for mosquitoes and can lead to an increase in the number of mosquito-borne diseases such as malaria and dengue and West Nile fevers
Molds and mildews
Excessive exposure to molds and mildews can cause flood victims – especially those with allergies and asthma – to contract upper respiratory diseases and to trigger cold-like symptoms, e.g. sore throat, watery eyes, wheezing and dizziness
Carbon monoxide poisoning
Post-flood carbon monoxide (CO) poisoning is reported to be a growing problem in many developed countries. CO can be found in combustion fumes, e.g. fumes generated by small gasoline engines, stoves, generators, lanterns, and gas ranges, or by burning charcoals and woods.
Other hazards when reentering and cleaning flooded homes and buildings
Besides the flood related health problems described above, flooded homes and buildings can pose other significant health hazards and risks after floodwaters recede. First of all, electrical power systems including fallen power lines can become hazardous during cleanup activities.
Mental stress and fatigue
A flood can cause both emotional and physical stress. However, various reports attribute a major health hazard of floods to mental stress or psychological distress due to exposure to extreme disaster events.
excerpt from Health risks and hazards caused by floods by Naoki Minamiguchi
above from Palm Beach County, Florida webpage
Read from this WWF report of 2007 about the World's top 10 rivers at risk - and what are the risks? The primary objective of this report is to illustrate the most menacing threats to the world’s great river basins, in order to encourage dialogue, provoke debate, and urge governments and other stakeholders to take action before it is too late.
Usually floods develop over several days. However, very heavy rainfall over a short period of time can lead to a flash flood with little or no warning.
Flooding is an overflowing of water onto land that is normally dry. It can happen during heavy rains, when ocean waves come onshore, when snow melts too fast, or when dams or levees break. Flooding may happen with only a few inches of water, or it may cover a house to the rooftop.
A river flood occurs when water levels rise in a river due to excessive rain from tropical systems making landfall, persistent thunderstorms over the same area for extended periods of time, combined rainfall and snowmelt, or an ice jam.
Some of the controls that can be implemented to prevent flooding