Monsoon rains
Most of the precipitation of a monsoon rain occurs in comparatively short periods of time. This is usually a very intense and comparatively short-phase heavy rain with usually a few hours of rain , i.e. in particular - as a rule - no continuous rain . Since its intervals are very short, i.e. there are usually two to three precipitation events per day , and often contain a considerable amount of precipitation, there is a sometimes considerable runoff coefficient . However, the orographic conditions of the site also lead to a very strong regionally resolved mean amount of precipitation, about which no generally valid statements can be made.
Role of monsoon rains
Consequences of weak monsoon rains
Without the monsoon winds and their precipitation, agriculture, for example in India, could in no way be carried out intensively and the population would then not even come close to being supplied. Here the winter monsoon is very dry and shows only minimal, very changeable precipitation, which is why a delay in the rainy summer monsoon can lead to major droughts and consequently to crop failures . These effects are particularly dramatic when there is insufficient provision in the form of food and water reserves.
Due to an enormous increase in the Indian population and a simultaneous decrease in water quality and reserve capacity, the dependence of agriculture on the monsoons had increased significantly in the course of history. This resulted in catastrophic famines in years of weak monsoons. In 1770 a third to half of the population of Bengal fell victim to this water shortage, in 1866 a quarter of Orissa's population and in 1943 Bengal again experienced the greatest famine of the 20th century , with an estimated three million deaths . Emergency aid programs like the one in 1987 and the expansion and intensification of agriculture have prevented further famines in the past few decades.
Consequences of heavy monsoon rains
The heavy rains of the summer monsoon also cause problems. The floods caused by the monsoon rains repeatedly lead to humanitarian emergencies. Most affected are the coastal areas, especially Bangladesh, which, due to its low topographical location, functions as a drainage area for monsoon rains. The Ganges and Brahmaputra have their mouth here. But even smaller, heavily sedimented rivers and especially mud flows are very serious if cultivation techniques or plant species are not adapted and the soil erosion associated with them . In the case of land use that does not counteract these effects, the topsoil can be easily removed, which ultimately leads to soil degradation , makes agricultural use impossible in many places and, in extreme cases , can result in desertification . In 2007, 17 African countries were hit by the strongest floods in 30 years as a result of heavy rainfall, which has so far resulted in at least 250 deaths. From Senegal to Ethiopia , homes and crops have been destroyed. More than 1.5 million Africans have been left homeless
Drinking water and water quality
A reduction in soil fertility at the same time increasing use of environmental poisons and fertilizers (see for example the " Green Revolution " in India) in conjunction with the comprehensive through the precipitation of the summer monsoon soil elutriation even further to can Pollutant - Contamination of drinking water reserves and eutrophication natural waters lead. Since the local population of the countries affected by the monsoon, especially in India, for reasons of poverty , ignorance, tradition , religion or other causes very often get "drinking water" from rivers , the sometimes catastrophic quality of these waters, which mostly already Larger cities and areas of intensive agriculture have happened to be a not to be underestimated public health threat . Only around ten percent of Indian cities have sewage treatment plants.
This is only put into perspective by the fact that these waters are more heavily diluted with fresh water during the summer monsoon, but this is not always sufficient and in the vicinity of larger industrial plants or contaminated soils can also lead to an accumulation of numerous pollutants.