The Water Cycle And Water Insecurity Exam Style Questions And Answers Describe how deforestation is affecting the Amazon basin - The amount of water returning to the atmosphere by evapotranspiration is greatly reduced — from 75% to 25% of intercepted water. More precipitation enters the river by runoff. Overland flow increases the amount of soil erosion. Huge quantities of soil are entering the rivers and causing extensive silting. Mudslides are increasing in frequency and scale. The flood risk is raised by the faster runoff. Aquifers are becoming depleted because less water infiltrates to recharge them Name three other ways in which people disrupt the drainage basin cycle - Urban growth; constructing dams and reservoirs; abstracting water for irrigation Distinguish between a water budget and a river regime - Water budget is the difference between precipitation and evapotranspiration, which varies from place to place and seasonally. River regime is the seasonal variation in the discharge or flow of a river and it too varies, but from drainage basin to drainage basin How does climate affect water budget? - It affects the amount of precipitation received, while temperatures affect rates of evaporation and transpiration Identify three physical factors affecting a river's regime - Amount and intensity of precipitation; geology and soils; vegetation cover How do you explain the seasonal variations in runoff when rainfall is evenly distributed throughout the year? - The lower runoff during the summer and early autumn is due to the higher temperatures and high water losses due to evapotranspiration. Also the dry ground means that much of the rain infiltrates and percolates below ground What is a storm hydrograph? - A storm hydrograph shows the response of a river's discharge following a period of rainfall. A critical aspect of the hydrograph is the lag time between the rainfall peak and the river's peak discharge How does geology affect the shape of a storm hydrograph? - If the geology is hard and impervious, then the speed of runoff will be such as to result in a relatively short lag time. If the geology is soft and porous, then runoff will be less and the water will reach the river more slowly as it takes place below ground. The lag time will be relatively long Why does urbanisation increase the risk of flooding? - The large areas of concrete and tarmac mean that most falling rain becomes surface runoff which moves quickly to the nearest stream or river. Underground drains and sewers also move water quickly to drainage channels. Because of this swift transfer of water, rivers quickly reach the bank-full stage and water begins to overspill their channels as floods What is meant by a store and a flow? - A store is where water is held for varying amounts of 'residence' time. A flow is the movement of water between stores Identify the three largest stores in size order - 1. The oceans 2. Icecaps and glaciers 3. Groundwater Which two water stores are non-renewable, and why? - 1. Fossil water: old, deep groundwater from former wetter periods 2. Losses from the cryosphere: melting of ice as a result of global warming Distinguish between blue and green water - Blue water is stored in rivers, lakes and groundwater in liquid form — a visible part of the hydrological cycle. Green water is water stored in the soil and vegetation — an invisible part of the hydrological cycle