The water cycle revision - paper 1 Flashcards
(6 cards)
5.2c) Humans disrupt the drainage basin by accelerating processes like deforestation and land-use change and changing storage of reservoirs
Deforestation - This is the removal of trees for their timber - this can affect the drainage basin because interception and infiltration rates are decreases as tree roots and leaves do not intercept the water. This leads to an increase in surface run off which can affect the drainage basin because their is more overland flow which can affect the capacity and storage of rivers.
Changing land-use - Urban surfaces of concrete and tarmac are impermeable which therefore reduce infiltration of water, increasing surface run off. This means that drainage systems become stressed more easily as water exceeds their capacity and water is moved to rivers at a faster rate. This affects the drainage basin because the storage of the river does not change but the amount of water in the river increases, which increases the likelihood of flooding.
Agriculture and livestock farming increases compaction of soil and removes large vegetation meaning that water is less well intercepted and surface run off is increased.
Reservoirs - the construction of dams and reservoirs reduce water flow downstream which increases evaporation rates upstream as there is a larger body of water - an increase in evaporation rates as temperatures get warmer due to global warming could lead to restrictions on water usage as drought is more likely because of the lack of water.
5.3c) The shape of storm hydrographs depends on physical features of basins as well as human features
Flashy hydrograph - flooding is likely
Flat hydrograph - flooding is not likely
FLASHY HYDROGRAPH - Basin size is much smaller with steep steep slopes that promote surface run off so the water reaches the rivers much more quicky.
Impermeable rocks like granite restrict infiltration and percolation which increases surface run off
Heavy or prolonged rainfall and rapid snowmelt means that the ground is already saturated and the excess water exceeds the capacity of the soil increasing surface run off.
Deciduous plants means that interception levels are low in the winter this is because they loose their leaves in the winter so they cannot retain any water.
Human activity - urbanisation increases the amount of impermeable surfaces so percolation levels are low.
Livestock farming increases compaction of soil and agriculture reduces large vegetation that can intercept water.
FLAT hydrograph - Large basins that have low gentle slopes that allow for infiltration and percolation of water. Permeable rocks allow for percolation of water so there is less overland flow.
Dry conditions means that soils are unsaturated so infiltration is high and surface run off is low, reducing the risk of flooding.
High levels of vegetation which is promoted by sustainable human activities like afforestation - South Korea planted 11 billion trees in 2008.
5.4a) The causes of drought can be meteorological, hydrological and ENSO cycles
Meteorological drought - this is a rainfall deficiency - This can be caused by global warming or changes in weather patterns - this can cause restrictions on water usage and vegetation may die which affects ecosystems. This can be seen in USA with their dustbowl of the 1930’s. This was a 10 year drought that meant that the ground dried up and soil was vulnerable to erosion.
Hydrological drought - this is when there is a lack of water in rivers - this is caused by high evaporation rates and low precipitation rates. This causes reduced storage in rivers and poorer water quality which can cause threats to wetlands and ecosystems . Rural northern Brazil have no permanent rivers which means there population is dependent on seasonal rainfall, which is stored in resevoirs - the amount of water stored in resevoirs can be affected by global warming as it increases evaporation rates.
ENSO CYCLES - An ENSO cycle is the movement of warm water in the pacific ocean; it occurs due to changes in trade winds, atmospheric circulation and oceanic currents.
EL NINO - This is a reversal of the normal process so there are now weak east to west trade winds. EL NINO occurs when sea temperatures are 0.5 degrees above average and this leads to warmer weather in the easter pacific; Water off the coast of Australia and Indonesia is cooler and precipitation is reduced leading to droughts in Australia. This affects the hydrological cycle because there is less precipitation is Australia which leads to droughts.
5.7b) Causes of water insecurity from human actions - over abstraction of water from groundwater aquifers and water contamination from agriculture
Human actions - over abstraction from groundwater aquifers - CASE STUDY IS MEXICO CITY - Over abstraction is when too much water is taken from groundwater resources so that they cannot recharge which leads to water scarcity. Over abstraction of water can be seen in Mexico city - Mexico city is densely populated, population is 22 million which means that aquifers have been depleted. This has led to the city shrinking by up to 0.2 meters a year.
Water contamination from agriculture - Fertilisers can run off crops and into rivers which can cause algae blooms, this process is known as Eutrophication. This process can lead to fish dying which increases the risk of disease for humans who consume the water. This can be seen in Australia in the Murray darling basin - There has been an increase in cropland nearer to the area which has increased the use of fertilisers and the rate of Eutrophication - 1 million fish have been killed in the basin in the last 50 years, due to the expansion of farming.
Changes in ocean health
Salt water encroachment - this is when saltwater moves inland, making the previous freshwater unusable. This has occurred in florida where saltwater has encroached further inland which has meant that they have to abstract their freshwater from further inland; This impacts peoples well being because shortages may be placed on water in those developing countries that cannot afford the advanced technology like desalination plants that allow people to change the salt water into freshwater. Water restrictions can impact people’s wellbeing because they may not have enough water for industry or agriculture which would affect their economic wellbeing and a lack of water affects their social wellbeing as they cannot maintain high sanitation levels.
Threats to ocean health includes ocean acidification - ocean acidification is the decline in the pH of the ocean. Ocean acidification means that carbonic acid dissolves the calcium carbonate that makes up the base of the reef; The dissolving of calcium carbonate reduces buidling of the coral reef so that coral polyps have no where to live. This significantly impacts humans in coastal areas like the maldives because the coral reef is stunted in growth so their economy is stunted and tourism is decreased because fishing industries are lost due to disruption in food chains.
Transboundary water conflicts are impossible to solve
A transboundary water source is one that occupies territory shared by more than one state;
Transboundary water conflicts can be solved because of water treaties and frameworks like Helsinki rules
Transboundary water conflicts cannot be solved because there are high levels of geo-political tensions - The Nile river
Transboundary water conflicts can be solved through IDBM - Colorado basin
Water conflicts cannot be solved unless the government takes direct action. In china the authoritarain government takes control over the population so they do not get chance to make disputes about development projects - this project aims to transfer significant quantities of water from the humid south to the arid north. This project was needed because water resources could not meet the demands of the population or agriculture due to varying weather conditions. This has led to the development of the project which has reduced water insecurity and boosted food security as more water is available for irrigation . This project can however lead to conflicts because hundreds of people were displaced due to the construction of dams and reservoirs and the project caused a significant amount of money to tax payers. There government is Authoritarian though which means there is little consideration for the population, this has meant that they have little say in development projects and the consequences of these projects have little implication for the population but high social costs.
