The Water cycle exam questions

Explain why water budgets vary between different Drainage basins (6)

Explain why water budgets vary between different Drainage basins (6)

-water budgets describe the amount of water within a drainage basin when taking into account that added by precipitation and that lost through evapotranspiration, as well as of run off and changes in storage. One of the reasons this can vary between drainage basins is the physical factors that may effect the basin. For example areas that have high levels of vegetation cover will have high levels of interception and evapotranspiration leading to much lower levels of surface runoff whereas areas that are more sparsly vegetated will experience greater rates of surface runoff due to soils often being dryer and eroded, meaning are unable to absorb rainfall when it does occur.-human factors then also heavily influence differences within drainage basins, such as to do with over abstraction of water resources that lead to reduced ground water flow and then reduce the amount of water available in times of drought/lack of precipitation. This can also be seen when looking at land use change and urbanisation, where due to increased impermeable surfaces infiltration is reduced as well as overall evapotranspiration, as well as increasing rapid surface runoff. Also man made resvoirs create new area of water surface storage, adding to rates of evapotranspiration?:-This can then be linked to the climate of an area as can then effect how much water is available within an area, as although areas may have similar levels of rainfall, where evaporation is higher than precipitation the actual amount of effective rainfall left can be much lower, resulting in some areas then having much lower amounts of rainfall and so water left. This can be seen when comparing both Arizona and somewhere such as Essex in the UK, where despite both having similar levels of annual rainfall due to Arizona having a much more arid climate and landscape, rainfall effectiveness is much lower within Arizona.

Explain why river regimes might vary (6)

-One reason as to why river regimes vary is as a result of the geology present. Hard impermeable surfaces such as granite will lead to reduced availability of both infiltration and percolation, leading to an increased occurrence of surface run off and so river regimes that are more flashy and quick response with higher variability and peak flows will occur. However regimes with more porous geology allow greater percolation, resulting in water entering groundwater stores and so being released much slower, resulting in a steadier regime.-Another reason is due to climate and temperature. In hotter and more humid climates, such as the tropics as with the Amazon, regimes are much less variable as there is higher rates of both evapotranspiration and precipitation with this occurring all year round, leading often to higher flows all year round or lower flows if there is a greater rate of evaporation. Climate can also lead to greater precipitation falling as snow, meaning regimes may have higher flows during summer months as a result of meltwater and then lower flows during winter as water is held as snowpack, with this being seen with the Yukon. The overall size of the basin then equally impacts regimes, with rivers that go through different climatic zones such as the Murray darling being more complex compared to a more simple regime that occurs in a more temperate climate with distinct high and low flow + seasons, such as the Rhone.

Explain how physical and human factors contribute to an increased risk of water insecurity. (8)

Intro- water insecurity can be split into two categories, with water stress being where a population has less than 1700m3 of freshwater a day and water scarcity being less than 1000m3. This can be seen be a consequence of both a lack of physical supply as well as a growing demand.-The main human factors that are contributing to water insecurity are mainly based on the rising demand, for water to drink but also for the use of agriculture and industry. This is leading to the overabstraction of many groundwater sources as well as leading to increased rates of water pollution meaning freshwater supplies can't be used. this is particularly true for both agriculture and industry, for example through the use of harmful pesticides in farming leeching into water sources and dyes/toxic chemicals from industrial factories. this is increasing also due to rising population sizes and rising living standards particularly within emerging countries. With agriculture alone counting for 70% of global water use up to 90% in developing world this plays a large role in depleting stores.-There are also physical causes, such as the impact of El nino events which change weather patterns leading areas such as south east asia more at risk of droughts. Also salt water encroachment is increasing the salinity of freshwater sources as a result of rising sea levels. Also increasingly variable rainfall patterns are also leading to areas having reduced levels of precipitation, although this could be said to be more human induced as a result of climate change.

Assess the likely impacts of changing precipitation on the hydrological processes in the drainage basins shown. (12)

The Amazon is seeing a high rate of precipitation fall which will change its water budget balance. The Amazon rainforest intercepts majority of the water through the dense forest leaves, water would go down through stem flow. With reduced precipitation there will be less water going through the stem and then to the soil. Also as there are a lot of trees the minimal water amount which does reach the soil will be taken up by roots of plants leaving even less water to travel down to the ground water. Overall there will be a less groundwater storage and so the hydrological processes will become smaller (not as much water). Mississippi has a moderate change in its precipitation levels as some places receive less precipitation however it is the replenished by some places receiving higher precipitation. This means that the hydrological processes will mostly stay the same. The areas which get more precipitation will have more ground water or surface runoff depending on the soil type and its porosity. Lastly there is a very high rate of precipitation in Yukon. This would mean there are higher chances of surface run off and also more stemflow, throughflow. Rivers will see a rise as more water goes from soil into the river (throughflow). The ground water supplies will also see a significant rise as there will be a constant rate of infiltration until the soil is saturated.

Make conclusion - precipitation in the Yukon would likely to fall as snowfall and so this would initially add to the cryosphere stores and might only be released to the river during summer snow melt.

Evaluate the view that some approaches to managing water insecurity are more sustainable than others. (20)

- define water insecurity and sustainable management

- A successful management of water insecurity was Singapore. Singapore experiences a high rate of evaporation. They have implemented many strategies to retain water, which are through local and government efforts. Locally, Singaporeans are able to store water from rainfall which is a small but sustainable initiative. The government has also started desalination, which is a more expensive process, however it provides a better, high quality water. This may only be sustainable for the richer population. However Singapore has also made sure to import its water from Malaysia, this may be unsustainable. It is unsustainable as there is a dependence on Malaysia, which means that if their water supply is cut then there will be a colossal problem for the citizens, they import about 40% of their water from Malaysia which is high.

- Sustainable water management occurs when water is gained from internal means. But there is also another element of successfully managing water insecurity. Secondly water management should not be too expensive otherwise it may become unsustainable. This is true for Lesotho where there has been many dams made to help increase water supply somewhere else where it is more industrialised. Such a top down effect means that the economy gained, as water insecurity elsewhere was reduced but it was unsustainable. Those Lesotho earned 80m in royalties and has enough hydroelectric power to sell, many of its locals are seeing rising costs for water. This means that Lesotho is now facing water insecurity as the money needed to buy water to continue the project is increasing and that is unsustainable as the economy is not strong enough. Lesotho failed to manage their water insecurity

- A cheaper and more local idea to manage water insecurity is more sustainable. This is shown through Lima using fog nets. By placing fog nets in areas where humidity and fogs are dense. The water particles are trapped in the nets and then drop into buckets. Local initiatives are better as they would know how to improve water insecurity, as they can judge the living standards and act accordingly. In comparison to Lesotho, Lima's fog nets are more sustainable because they are economically cheaper and they are appropriate for its economy. They may also prove that top down projects fail to work. These are not the sole provider of water and focuses on improving water security for the very poorest of Lima who are not connected to the water supply system run by Sedapal. Similarly in Australia where water insecurity is also a problem the approach to manage water has also failed as it's instead increased tensions between cotton farmers and fishermen. It can also be seen as a failure of a top down approach. The Murray-Darling river basin is used by fishermen and cotton producers who use a large amount of water for cotton production. Though the government put restrictions on the amount that can be taken up, it was not successful. Cotton producers on the other hand have taken up more water, but also find it more profitable to sell water because of the water insecurity. This is unsustainable as water that is taken upstream will be significantly reduced when it goes downstream and fishermen will also lose out economically. Therefore top down approaches may also be unsustainable for managing water insecurity. However some approaches are inevitable and cannot be changed meaning it will be unsustainable as the party has no power. This is true in the case of Palestine as they have water insecurity as Israel has a water pump from Golan Heights. Due to political and religious tensions they have had to face water insecurity. Therefore it is hard to even have an approach to manage water insecurity. However with Palestine creating a city called Rawabi, the major problem again is water. As they are located on the West Bank, they only have water through rivers or Israel. Therefore they need Israel to allow them to have water. This is unsustainable as Israel has all the power however it is inevitable as the population has nowhere else to go. Local initiatives to reduce water insecurity are sustainable and government actions have a higher rate of failure. However, Singapore shows that government action does not always fail and local actions can work together. Therefore if the local and government get together there will be better management of resources. Yet in some cases the government may have no power, like Palestine, and so whatever approach they do it is better than none though it is unsustainable.

- although top down scheme has increased the costs for some and son increased water insecurity, it has also increased water security for others.

(2018) Explain why land use changes can increase flood risk. (6)

-the main way it can be seen that land use change increase flood risk is through the increase in urbanisation leading to increase in impermeable surfaces such as concrete and tarmac covering further permeable surfaces such as soil and grass. This increases flood risk due to reducing the availability for water to infiltrate into the the ground surface meaning there is increased surface run off which increases river discharge at a quicker rate, shortening lag times and leading to higher peak flows. Where water can infiltrate/percolate into ground water stores this means flow is much slower and steadier, reducing this quick peak flow that increases flood risk. This can be seen in the case of the 2015 where the impact of the town surfaces further exacerbated the flooding due to river discharge levels increasing so rapidly-a further land use change that increases flood risk is that of deforestation, often for agricultural use of the land cleared. An example of this can be seen in Madagascar.... this increases flood risk is because the lack of vegetative cover means that when rain water hits the soil it hits it directly, compacted the soil and causing the soil to erode further reducing infiltration and meaning that soil capacity reaches saturation point much quicker, increasing surface run off and so flood risk. This is also as a result of reduced interception that would usually occur within vegetation, meaning again that more rain water is reaching the ground and soil. Also this soil erosion can often result from farming and the ploughing of land for agricultural use, as well as the impact of livestock grazing that further compacts the soil. Also soil erosion means that this soil and sediment can then be carried by the surface flow into rivers which can choke river mouths, blocking the ability for floodwater to reach the oceans and so more will flood the land behind.

(2018) Explain why the price of water varies globally. (8)

-There are a number of reasons as to why it can be seen that water prices vary globally, with this often being dependent on physical factors such as access to water but also a countries level of development and policies in place. One reason can be seen in countries that may lack the infrastructure needed to provide enough water for often dense urban populations. Due to this infrastructure being expensive and the fact that often low developed countries that may receive loans from the IMF who may restrict government spending on these services, it is often seen as a better option to hand water services to private companies. However due to these TNCs, such as suez, wanting profit consumers therefore have to pay higher prices than they would if water services were owned by the public sector and governments. An example of this can be seen in Bolivia where Agua took over a bolivian city water supply, immediately increasing the cost by 20%.

-Another reason is physical avalibility and ease of accessing water. For example a country such as Israel that has very limited access to water has to charge 'real prices' for its water in order for it to supply its population with water, as due to its arid climate and fact it has to import much of it from countries such as Turkey, prices have to be much higher. However a country such as the UK where abstraction of domestic groundwater is much easier, prices can be much lower

(2019) Assess the role of physical factors in influencing the pattern of future water stress. (12)

- define water stress

- extreme stress is in the Middle East and North Africa

- physical reasons include;

- latitude (high stress areas are in the seasonal tropics)

- Transboundary sources (some areas of stress in middle east have to share aquifers and rivers)

- Climate change

- Geology ( whether a country has aquifers that water is stored in)

- However also influenced by human impacts eg;

- Pollution of water resources like in China

- un sustainable use of water resources

- population pressure leading to a mismatch of supply and demand

- wasteful practises

- conclude which one is worse

Explain how the global hydrological cycle operates as a closed system. (6)

-The reason that the global hydrological cycle operates as a closed system is due to the fact that the amount of water within the cycle never changes as there are no inputs from outside the cycle and no water is ever lost. It is rather that the form of this water changes, as a result of two main processes, the solar energy and gravitational potential energy. The solar energy increases global temperatures increasing rates of evaporation and transpiration. This then increases moisture levels, leading to greater levels of cloud cover and precipitation in some areas where warmer temperatures occur. For example among the tropics where there high levels of evapotranspiration due to the dense vegetation, which then increases the precipitation there, however there is not any actual water being added, it is just this combination of the fluxes of evaporation and transpiration.Gravitational potential energy then keeps this same amount of water moving throughout the cycle through these inputs, outputs, stores and flows, under the force of gravity.-Water stores then also play a role within the closed cycle, such as the cryoshpere where as warming temperatures increase melt water this is then being added into the oceans contributing to the circulation of water and heat globally. This is known as the thermohaline circulation, with water from the polar regions being cooler and denser therefore as this sinks, it draws warmer water from ocean surface accross from tropics. This continuous flow therefore ensures water is transferred throughout the global cycle without being lost.-ICTZ also then plays role located within the tropics where solar radiation is most intense. Strong convectional currents lift air so it cools and condenses into clouds causing heavy rainstorms, creating much of the worlds rainfall. Troposphere rivers of atmospheric moisture then transfer this water from these areas of high evaporation onto the land as precipitation, further helping maintain the global water budget as a closed system with no water being lost or gained.

Explain why a drainage basin can be regarded as an open system. (6)

-Drainage basins are local areas that are drained by a river and its tributaries and are considered as being an open system as inputs are not governed by outputs, with water being able to be gained as well as lost from each individual basin. For example water can be lost via evaporation and evapotranspiration into the atmosphere, through surface runoff into the sea, and through percolation into groundwater stores. The input of precipitation then moves through the system via flows such as interception, infiltration and throughflow, with some of this then being stored within vegetation or soil moisture and some leaving the system as outflow such as river discharge and evaporation. These processes occur in a sequential system, with this varying between different basins and at different times.-This includes human factors such as urbanisation and deforestation which can reduce the amount of infiltration and interception, reducing water storage and increasing rapid surface runoff leading to more water to be lost from the system. Also basin wide factors such as the geology and relief, with a basin that has impermeable geology having more runoff and so reduced depressed groundwater storage whereas more permeable geology and soils allow greater percolation, and so greater groundwater storage.

Using examples assess ways in which deficits within the hydrological system can have significant impacts. (12)

- define deficits

- pantanal impacts

- impacts of environment can kill trees/ fires / destroy habitats

- impacts on people lack of water / migration

Using examples assess the extent to which human activities can exacerbate flood risk. (12)

refer to essay already written

Using examples assess the impacts that climate change may have on the hydrological cycle. (12)

Intro- climate change is increase in atmospheric temperatures, leading to more moisture holding capacity by the atmosphere and overall increasing global land temperatures, all of which can be seen to be having a large impact on the hydrological cycle.-Climate change can be seen to be increasing global temperatures as well impacting upon short term weather patterns such as ENSO cycles. El nino events involve weather reversals, leading to different areas to experience sever droughts and floods due to increases in rainfall in areas such as peru and droughts in areas such as australia. Many scientists predict that with increasing global temperatures, events such as El nino are likely to increase in frequency, therefore so will events such as floods and droughts. This combined with increasing average temperatures therefore can be seen to be having a large impact, both globally and locally. An example of where such deficits have already begun to have a significant impact can be seen upon vital ecosystems such as rainforests that play an important role in the water cycle, both locally within areas where this occurs but also globally too. An example of this can be seen in the Amazon rainforest, where as a result in decreasing levels of precipitation, droughts are becoming much more common. This is then leading to the rainforest being able to perform functions such as absorb carbon from the atmosphere which is then in turn just exacerbating the effects on the water cycle. More carbon is increasing temperatures, drying out vegetation and then reducing the vegetarians ability to transpire and evaporate, reducing the amount of moisture in the air further reducing precipitation levels. This is what many scientists are calling a positive feedback loops, with warming temperatures just leading to further impacts on the vegetation causing a domino effect on its function within the hydrological cycle, adding to the frequency of deficits within countries such as Brazil, as well as then impact globally on precipitation patterns as a result of such reduced evapotranspiration and reduction of the amazon operating as a carbon sink, something that plays a key role in helping to maintain the carbon balance and so reduce increasing temperatures.-another impact on a more local scale of increasing temperatures can be seen as a result of reductions in precipitation in areas such as California, a state that relies heavily upon rainfall patterns but that has begun to experience what scientists are now calling 'Mega droughts', expected to last up to 30 yrs. This increase in temperatures is impacting upon all elements of the hydrological cycle within the region, each then having a significant knock on effect upon each. Evaporation rates have increased combined with a decrease in precipitation, leading to snowpack upon the sierra nevada mountain range to rapidly decrease in size, something that is extremely impactful for the population which rely on the melt water usually produced within both cities and farms. This has then lead to average streamflow to decrease as well as soil moisture levels, with this then reducing the resilience of forested areas much like within the amazon, with this then further exacerbating precipitation levels as well as leading to these areas to just turn to grasslands. Already evidence shows that wildfires have now increased by 3x as a result, and with these droughts set to continue these are only like to get worse, showing just how impact climate change is likely to have upon regions such as California.However, it must be acknowledged that predictions around such climatic patterns as the ENSO cycles are still not certain. They are very unpredictable, not only if they will occur but also when and just how long lasting they actually will be, as well as which areas will be directly effected. However as can be seen with California, such variable rainfall patterns + warming temperatures are already having a significant impact, therefore indicating evidence these may well continue or if not get worse.-It must though be said that climate change may well lead to some positive impacts, perhaps not globally but particularly upon certain localised regions. An example of this can be seen in the Sahel region, a place known for being extremely dry and arid that has recently experienced greater levels of precipitation than normal. With greater levels of rain this has helped the region in a process called 'regreening', meaning there is possibility for greater vegetation growth, something that may help the region not only in providing further levels of precipitation but also more farmland. Although this evidence is still overall weak with the increased precipitation not occurring consequentially long enough to identify a certain trend, this example does show how climate change cannot be a definite negative on all areas of the hydrological cycle, but this may be more locally especially compared to the global evidence of changing detrimental weather patterns already being seen. The fact that evidence only shows about 6 years of this increased precipitation, when compared to the severe impacts upon both the amazon and places such as california this therefore could be said to be insignificant in comparison, with the negative impacts overriding this small positive.Conclusion- therefore in conclusion it can be seen that in the majority of cases as a result of increasing global temperatures as well as increasingly variable rainfall patterns, the impacts upon the hydrological will be significant, with this occuring locally but even more significantly on a global scale, particularly in regard to changing weather patterns.

Assess the risks associated with water insecurity. (12)

Intro- Water insecurity is defined as where a country does not have the sufficient water to meet demand, with this being a combination of both water scarcity + water stress. Water scarcity is where there is less than 1000m3 water available per person a year,with this being either economically meaning a lack of resources to harness the water available, or physically meaning there just isn't the water available at all. Water stress is when there is less than 1700m3 per person, with this often then leading to more temporary water shortages for a region. This can be seen to significantly impact a region in a number of ways, and with increasing energy demand and rising populations this insecurity is only set to increase.-One of the major risks associated with water insecurity is just how vital water is to peoples livelihoods, in terms of for food and drink but also often for countries economic development in terms of industry and manufacturing, with this then having a knock on effect on development. Due to many regions being so focused upon economic development this is therefore resulting in many people often those that are poorer to have a lack of access to clean and reliable water sources, resulting in clear negative impacts upon health and overall life expectancy. An example of where this can be seen is in many regions within Asia, such as an emerging economy such as China. Due to chinas rapid economic development largely being as a result of manufacturing, this has resulted in serious water pollution, with 70% of all its rivers and lakes now polluted and so china now only has 6% of the global freshwater supply. The fact that china has one of the worlds largest populations as well as living stanfdards (and so energy demand) increasing, this clearly poses a large problem for those who are unable to access this. This is then also efecting regions on a global scale, with a water gap to emerge between developing/developed nations and those within lower developed that are suffering much of the shortfall. 800 million people still cannot access safe water, with regions particularly in africa such as nigeria having thousands of children dying a year as a result. This therefore shows just how significant water insecurity can be, both locally and on a global scale.-A further large impact from water insecurity is the impact this is having on transboundary water sources, impacting not only on the regions competing for water but then also leading to conflict. An example of where this can be seen to be occuring is along the tigre-euphrates river, used by syria, turkey + iraq. Due to their location these regions suffer from water shortages as it is, however Turkey has recently begun its GAP project, building over 20 HEP dams to provide HEP as well as irrigation and agriculture. This has therefore led to significant impacts upon both syria + iraq, with it estimated to lead to a 40% reduction of flow into syria and a further 80% into iraq, therefore not only impacting on water availability byt also these regions electric output + irrigation. Estimates state that by 2040 the river may not even reach the sea, diminishin so much in flow therefore showing again just how impactful water insecurity may have, with both already threatening conflict. Although it must be identified that this region is already in large amounts of conflict as it is, it clearly cannot be ignored that if not cause the conflict the issue with water resources are clearly going to exacerbate them.-It must though be identified that in regard to transboundary water sources they could be said to be much less significant as a risk when compared to the global water shortages, with evidence showing that they can be managed and resolved. For example the Murray darling basin in australia, provides 75% Australias water and as a result of so many players being involved as well as natural climatic changes such as El nino cycles reducing precipitaion, is now suffering from water shortages + much reduced flow, therefore impacting heavily upon those that use it. However 2012 new basin plan was implemented to help ensure that the amount of water extracted does not have a negative impact on the environment and overall groundwater source. This therefore aims to improve overall water security, showing that risks do not always have to occur. (could mention COLORADO basin instead?) It must then also be said that risks do not have to occur, only actually accessing half of worlds freshwater, it is more the fact is large mismatch between water usage, therefore some areas are more at risk despite this could be able to be overcome. Also transboundary compared with the risk of the actual physical scarcity as well as economic within more developing regions could be argued to be much more significant, especially as economic development + global energy demand is only set to rise.

Explain the meteorological causes of river flooding. (8)

- meteorological droughts refer to the degree of dryness compared to 'normal' precipitation.

- increased evaporation and transpiration

- high temps, high wind, low relative humidity etc.

- precipitation deficiency (amount, intensity and timing)

- reduced infiltration, runoff deep percolation and ground water recharge

Explain why there is an increasing global demand for water. (8)

- increase in middle class

- growing population

- increase in water consuming products

- increase in agriculture to meet food demand

- 12% of the world's population consume 85% of its water

Explain the advantages and disadvantages of a sustainable water management scheme. (6)

- define sustainable water management

- water management in Israel

- advantages; helps meet demand, less wasteful with drip irrigation, recycling sewage water for 65% of agricultural use, desalination

- disadvantages; expensive and energy consuming

Evaluate the contribution of large-scale schemes to increasing water security. (20)

Water security means having access to sufficient, safe (clean) and affordable water. Typically the world's poorest countries are the most water insecure. One way of tackling water insecurity is through large scale water projects e.g. the Three Gorges dam in China or the Aswan dam in Egypt. However there is much controversy over whether these projects are truly sustainable and therefore beneficial in the long run.

The Three Gorges dam project in China blocks the Yangtze River; it cost £17 billion to build and was completed and fully functional on the 4th of July 2012. The dam drains an area of 1.8 million km2 and will supply Shanghai (population of 13 million) and Chongqing (population of 3 million) with sufficient supplies of water. It not only has provided a lot of people with water it is also the worlds largest HEP scheme (generating 18,000 mega watts) and it also protects 10 million people and 25,000 hectares of farmland from flooding. This suggests that these large scale projects increases water security.

Although it meets some of the criteria that makes water security, you could argue that it hasn't resulted in 'clean' and affordable supplies, also the huge environmental, economic, cultural and social impacts it has caused may prove It to be an unsustainable scheme. Up to 1.2 million people, 1,600 enterprises, 140 towns and 4,500 villages have had to be relocated; many of these people still haven't received compensation - over $30 million of funds set aside for this has been taken by corrupt local officials. The environmental impacts have been devastating; the dam has trapped huge amounts of human and industrial waste (Chongqing pumps in over 1 billion tonnes of untreated waste each year) which has impacted the biodiversity in the area. The dam has interfered with aquatic life e.g. the Siberian Crane and the white flag dolphin which are threatened with extinction. Fish stocks have also declined as the number of phytoplankton they feed on has fallen. Archaeological treasures have also been drowned e.g. the famous Zhang Fei Temple. The port at the head of the lake may become silted up as a result of increased deposition which could cause the development of a delta at the head of the lake - this could affect the longevity of the scheme.

Another scheme which has attempted to improve water security in Egypt is the Aswan High Dam. Most of Egypt only receives less than 125mm of rain a year and the Nile is the only river in Egypt therefore the management of the Nile to create water security is absolutely vital. Work started on this dam in 1960 and by 1968 the reservoir, Lake Nasser, was full. It has created a reliable source of water for virtually all Egyptians (60 million). This secure water supply has also had a positive impact on agriculture in the area as it has extended the amount of irrigated land along much of the desert margin of the valley and delta. It has increased crop yields and provided locals with more cash crops to be exported.

Although this project isn't at the same gigantic scale of the three gorges, its negative impacts are very similar, suggesting it hasn't increased water security. The water quality has declined because of pollution by fertilizers. There has had to be a lot of resettlement - formerly the area was inhabited by 120,000 people who were forced to leave and seek a new home and lifestyle. It has also reduced the amount of silt that is being deposited which creates a loss of soil nutrients. It has also increased erosion - river banks are collapsing because of increased scour, resulting in the loss of agricultural land.

Water stress is a massive problem in California and it depends on 3 major water supply lines in order to supply its growing industry and population. These schemes (SWP and the CVP) provide drinking water for around 22 million Californians. Water is transported 500km across the desert via a system of aqueducts from Lake Havasu to Phoenix and Tucson in Arizona. The water has to be raised 400m by using several pumping systems along the route, using hydro-electric power generated by the Colorado River. However, by the time the water reaches Tucson it has become very salty therefore it has to be treated before it can be used.

These methods of controlling the Colorado are unsustainable, creating social, economic and environmental implications. Wetlands have been drained, natural habitats altered, and fish stocks depleted, to secure water supplies. Pollution is also a massive problem as well as the over extraction of groundwater and increasing salinity.

In my opinion, the massive negative implications involved with large scale water management projects outweigh the benefits and in some cases e.g. the three gorges dam, it hasn't actually improved water security. I believe that a greater quantity of small scale projects is the way forward in improving water security.

Water conservation involves reducing and re-using our water rather than simply trying to increase supplies. In a world where the supply is finite, this is an important strategy, which can be carried out as small projects at local levels. In agriculture, it can involve more efficient irrigation where as in industry water can be treated or recycled for further use. Domestically, water savings and water harvesting are beginning to move from a DIY basis to a more commercial footing. In some areas in California they are saving storm water to make supply more efficient; concrete channel storm drains which prevent flooding by directing the storm water into the sea, could instead be directed to urban parks. In California there would be 30% savings if leaks were repaired, supplies were metered and all the appliances were more efficient. There would also be 50% savings by planting California-friendly, drought resistant plants and using smart sprinkler systems.

More small scale water projects have been carried out by Water Aid - an international charity with a mission to overcome poverty by enabling the world's poorest people to gain access to safe water, sanitation and hygiene education. For example, Water Aid has set out to improve water security in Ethiopia, using techniques that are appropriate to local conditions, affordable and easy to maintain.

In conclusion, I believe that large scale water projects do not create a large contribution to increasing water security and therefore smaller projects that are carried out at a local level are more effective.

Evaluate the extent to which transboundary water resources always lead to conflict between different players (20) intro, 4 points, conclusion

Intro- transboundary water sources are those sharing political boundary + often cross international boundaries, many players involved e.g governments + communities-can lead to tensions particularly where a number of countries/governments share it e.g. tiger Euphrates where war has been threatened due to threats to water supplies, although this could be argued not just to look at the water as other political challenges exist showing this may be a more determining factor-In a lot of cases though conflicts don't arise due to agreements being made, such as the Helsinki rules and the UN water courses convention that offer help + give certain frameworks, as well as agreements within countries such as the Colorado river basin + its 2 main agreements-tensions can though arise when different players within a basin have different interests + don't all agree, e.g. Mekong river basin, a sign that certain agreements/rules don't always work-however within countries despite basins having large populations tensions + different players being involved conflict doesn't have to arise, e.g. Murray darling basin Australia where plans + policies have been agreed to help combat water problems and so players can see how their problems will be resolvedConclusion- don't always lead to conflict, however tensions do often arise where other factors such as political tensions are at play or large populations where it is hard for all groups to agree

Explain how the physical features of a Drainage Basin affect the shape of storm hydrographs (6)

A drainage basin that is small and has a high drainage density allows water to reach river channels rapidly as the water has a shorter distance to travel and it can be dissipated into channels faster if there is a large number of surface streams per km². Therefore, this results in a flashy hydrograph with a high peak discharge and a low lag time.

A shorter precipitation duration and low precipitation intensity mean that water can infiltrate the soil and prevent it from being too saturated. As a result, it will not flow as surface run-off into the river channels. This means that the water reaches a river channel much slower and allows the water to be stored as groundwater. Therefore, a flat hydrograph with a low peak discharge and long lag time is formed.