2 ObjectiveBy the time you finish this lesson you should be able to identify and describe the geographic effects of monsoon rains on South AsiaBased upon what you learn here, you should be able to predict similar effects in different regions that also experience monsoon rains, such as Southeast Asia and East Asia
3 Why Knowing Effects is Important East AsiaSouth AsiaSoutheast Asia
4 VocabularyMonsoon – seasonal winds that produce a yearly pattern of rainfallFloodplain – the areas near a river that are covered by water when the river floodsErosion – the gradual wearing away of rock, usually by wind and waterSediment – particles of sand, silt and clay that are transported downstream by rivers; these are deposited in the river channel and its floodplain
5 DisclaimerThis lesson is calling these effects “geographic”, but many are also social and economic effects because they affect people and the way that people satisfy their wants and needs so there is a lot of overlap in how we classify themFor example, if a river overflows its banks due to heavy runoff from rain, this is a geographic effect. If those flood waters wash away someone’s farm, then it also has a social and economic effect
6 Start with What You Know Describe the water cycle
7 Precipitation and What Comes After Precipitation is “water that falls from the sky” (rain, snow, sleet, hail, etc. – it’s all 2H2O)What happens to the water after it falls out of the sky?For solid water, it just stays where it is until it becomes liquid (melts)If it stays in place long enough and there is enough of it, it is called a glacierFor liquid water, some is absorbed by the soil, some evaporates back into the air, and some runs off into streams and rivers
8 AbsorptionPrecipitation that is absorbed by the soil is used by plants and a lot will eventually evaporate back into the air. Any excess sinks down through the ground until it reaches a layer of rock that it cannot pass throughWhen it reaches that layer of rock it either sits there or flows along (very slowly – feet or meters per year); this is called an aquifer. Remember that word – you’ll need it next year.If the water reaches the surface again, it is called a springWater from springs runs off just like excess rain
9 Runoff Runoff is precipitation that is not absorbed or evaporated The heavier the rain, the more runoff that is producedThe runoff goes into streams and rivers, causing them to fill upIf there is enough runoff, the streams and rivers overflow their banks – this is called “flooding”Rivers in areas that have monsoon rains also have annual floods
11 Runoff – It’s not Just Water Water that runs off also causes erosion – it picks up particles of sand, silt and clay from the ground that it passes over; it also picks up loose plant matterThe particles and plant matter are carried along by the river or stream and will eventually settle to the bottom of the river or streamWhen the river floods, then the plant matter and particles will also settle out onto the floodplain, fertilizing the soil of the floodplain
12 Soil Fertility Affects Population (People Live Where the Food Is) OK – it affects trains, but only because trains go where the passengers are and passengers are people, too.
13 Effects - EconomicWhen the monsoons arrive on time and bring sufficient rain, farmers are able to produce enough food for the population.When the monsoons arrive too early or too late, the plants do not get the water that they need at the time that they need it, so the harvest is poorIf the monsoons bring too much rain, farms and fields get damaged by flooding.If the monsoons do not bring enough rain, the plants do not get the water they need.
14 Effects - SocialIn the modern world, the social effects of poor monsoons are not as bad as they were in earlier times.Poor monsoons used to mean famine (not enough food for everyone). Today, a poor monsoon means higher prices for food, but few people actually starve.A heavy monsoon, even today, causes destructive flooding, contaminated water, and other problems.
15 Effects - PoliticalIndia is a democratic republic. It calls itself the “world’s largest democracy”.When food and fuel prices rise dramatically due to abnormal monsoons, people expect their government to do something to fix or control the problem. They also expect the government to fix roads, buildings and other infrastructure that get damaged by destructive flooding.But fixing these kinds of problems requires the government to spend money that it may not have, resulting in higher taxes.