water
Asia + Pacific impacts from water issues
1/3 of pop lack access to safe drinking water Water pollution, level of bacterial waste = 10x greater than recommended Agriculture uses 90% of freshwater withdrawals in S Asia Salinity + arsenic (industrial pollution) affects 60% of groundwater supplies across Indo-Gangetic Basin (750 million) Aquifer depletion led to drop from 10,000m3 per capita in 50s to less than 3700m3 in 2010. 42% of China's sewage + 45% industrial waste dumped into Yangtze river each year China = 6% of world's fresh water
Water supply + human well-being
15% of population rely on unimproved water, 2.5 billion no access to improved sanitation facilities. Lack of sanitation = source of many water-related disease. Diseases related to lack of clean water/sanitation = high levels morbidity, affecting ability to work/look after family so unable to escape poverty
Case study, Australia
2 main causes of droughts, serious deficiency (rainfall totals within 10% of values record for at least 3 months). Severe deficiency (rainfall totals within the lowest 5% of values in record for at least 3 months) 30% of country affected by droughts in 1 year Low, highly variable rainfall total happens as climate dominated by sub-tropic high-pressure belt of southern hemisphere Droughts vary considerably, some intense/short lived. Some very localized some cover vast areas Droughts closely linked to el nino ie, East Coast drought 2002-3 Since 70s, shift in rainfall patterns with eastern area where most people live, becoming drier compared to NW areas Big dry associated with long-term climate change = trend of warmer, drier climate for SE Aus. Assessed as 1 in 1000 year event. Affected more than 1/2 of farmlands especially Murray-Darling Basin which provides 50% of nations agricultural outputs. Devastating effects on food, wool, wheat + meat exports. Farmers relied on water for irrigating farms Cities designed to withstand multiple episodes of low run-off, their reservoirs fell to 40% of their capacity, Adelaide vulnerable due to drawing 40% of drinking water from basin. River has became over-extracted so much no water has flowed at its mouth Future demands likely to exceed supply new schemes required ie, desalination plants, recycling of grey water + sewage
Colorado river
2,230 km2, 637,000 km2. 97% of basins = USA 3% Mexico. Source =rocky mountains and mouth @ Guld of California in Mexico. Past agreement 1922, fair shares of the rivers water to surrounding 7 states + Mexico, made when population was lower & rainfall 10% higher Mexico = 10% total flow, states in lower basin = 50% & upper basin 10%. Californian = 20% more than allocation but agreed separately in 1963. Native American owed 5% but can claim more as reservation extend across river. Background = supplies 8 states, 11 major dams + reservoirs, irrigates 1.4 million hectares of farmland + drinking water 50 million. Controls flooding + produces HEP, demand + climate change depleted storage to 48%. Since 90s, annual colorado flow decreased by 15%. Been in persistent drought since 2000 Stakeholders = farmers, Mexican people, Indigenous groups, US Federal gov, city dwellers, environmentalists Benefits = flood control, power to pummp water, electricity, domestic water supply, irrigation, industrialisation, sediment control, recreation opportunities, wildlife protection Costs = water loss through evaporation + seepage, salinisation due to irrigation, ground waste overdraft, water waste, environmental damage Arizona created Water Banking Authority 1996 in aims of using water share efficiently + storing surpluses in aquifers. Nevada tried negotiating for larger water allocation (Las Vegas) Grand Canyon Protection Act 1992c (environmental protection laws complicated managment
Use by industry/energy
20% of all fresh water withdrawal is for energy production + industry. Developed countries = half of all water used. Concern = global shift in industrial production in emerging countries. Half of water used either for HEP/cooling of thermal + nuclear power stations. New Zealand affected due to heavy reliance on HEP = changing patterns of rainfall Growth of bio fuels = crops grown to produce bioethanol/diesel are very thirsty. 10,000 litres water needed to produce 1 litre for bioethanol & 20,000 litres for 1 litres of biodiesel 75% of UK's water consumption linked to energy generation
Water scarcity 2
20% of worlds pop live in areas where water's physically scarce. Low rainfall + high temos = suffer physical water scarcity Changes in pattern/frequency of rain will affect recharging of water stores + increasing temps will increase evaporation/transpiration rates Problem of water insecurity links to: availability (having water supply/water distribution network), access (freedom to use/income to buy), usage (entitlement/understanding of water use + health issues)
water supply
Agriculture use = rain-fed agriculture fields + grazing lands dependent on rainwater. Farmers focus on storing water (rainwater harvesting) to conserve supplies. Surface/ground/blue water added to enhance crop production. 5th of world's land is under full irrigation. Industrial scaled irrigation began in 60s with fertilisers + pest control. 30% of this irrigation provided using dams, systems of irrigation canals radiate. Irrigated land = waterlogged = salination of soils. Irrigation's pumped electrically from aquifiers = groundwater depletion Dietary revolution = pressure on water systems. Maxim for irrigated system = more crop per drop using modern automated spray tech + more advanced drip irrigation By 2050 food production will need 140% more water, agriculture will need to produce 60% more food globally + double in developing countries.
Berlin rules
Approved by International Law Association in 2004. outline international law relating to freshwater resources within a nation/international boundaries. Participatory water management, public have right to be involved with decision making Coordinated use, surface water + groundwater to be managed to maximise availability + reliability of water supplies Integrated management, all drainage basin considered ie, vegetation, watercourses, settlements + all stakeholders Sustainability Minimisation of environmental harm Cooperation over shared resources Equitable utilisation of shared water resources Avoidance of transboundary harm, control of actions upstream Equitable participation, all countries/players to have equal status
Suistanable water management scheme, Singapore =
Area of 710km2 + pop of 5.4million Receives of 2,400mm but limited land for collection + storage the high rainwater evaporation due to tropical climate + lack of groundwater resources. Considered to have water scarcity, national water agency has invested in research + tech to create diversified water supply. Compromising local water catchment water, imported water, recycled water + desalinated water Local catchment water collected rainwater through network of drains, canals, rivers, storm-water collection ponds + reservoirs before treated to supply drinking water agreement until 2061 to import water from Malyasia NEWater = high-grade recycled water produced from used water that's treated & purified more using advanced membrane technologies + ultraviolet disinfection = clean + safe. Country's NEWater plants can mete up to 30% of current water needs. 2060 aims to meet 55% of water demands with NEWater
spheres
Atmosphere = area from above 30 metres above ground to space. Biosphere = area where all living things live. From 30 metres above ground to 1 metre below ground. Lithosphere = crust Hydrosphere = water Cryosphere = frozen
ITCZ
Belt of low atmospheric pressure around equator. Moves north or south of equator seasonally At ITCZ air rises due to intense heating by sun's energy + high evaporation especially from oceans. Causes alternating wet season when it arrives and dry season when it moves away Subtropical high-pressure zones associated with descending part of convection cell = hadley, block high humidity, rain-bearing masses so pattern is modified Africa = lower humidity levels as less water evaporates and if high pressure blocks arrival of wet season = drought can occur
Nile case study
Blue + white nile provides egypt with vital water, 85% comes from other countries. Burundi, D.R Congo, Eritrea, Ethiopia, Kenya, Rwanda, Sudan, Tanzania, Uganda 6700km long, two main sources = white + blue nile. Confluence = Khartoum where it flows into egypt. 84 billion cubic metres (flow) White nile provides 30% of flows at Aswan, blue nile catchment is small the monsoon rainfall means it is the greatest contributor to lower nile flows. Differences are clear as its dependable on inter-annual + decadal fluctuations brought by el nino/la nina. Droughts/flood cycles = issue for Ethiopia + Sudan. Much of river located in hot arid areas (high evaporation losses). Sudd area suffers with 50% of white nile loosing its flow so there are shortage of summer water. Jonglei canal scheme created due to Egypt suffering shortages so decided to sponsor it, started in 1979 but yet to be completed due to deteriorating relationships, revived as part of latest nile initiative
Southern Oscillation Index
Change in air pressure in normal ears = ENSO. Its strength, direction + speed called Southern Oscillation Index Record air pressure at easter island and subtract it from that @ Darwin to calculate it Sharp drop indicates el nino is imminent
Physical factors influencing drainage basin
Climate = Soils = determines amount of infiltration + throughflow + type of vegetation Geology =impact subsurface processes ie, percolation + groundwater flow Relief =altitude Vegetation = presence/absence = major impact
Physical features that influence drainage basin cycle
Climate = role in influencing type + amount of precipitation overall + amount of evaporation (major inputs + outputs). Also impacts vegetation type Soils = determines amount of infiltration + throughflow (lateral unsaturated flow of water in the soil zone) and indirectly type of vegetation Geology = impact on subsurface processes ie, percolation + groundwater flow ( + aquifers, body of rock/sediment that holds groundwater) Relief = altitude impact on precipitation, slopes can affect amount of run-off Vegetation = presence/absence of vegetation = major impact on amount of interception, infiltration + occurrence of overland flow + transpiration rates.
climate change impacts on floods
Climate change = Differential changes in the way the hydrological system (open system) operates within world's drainage basin. Climate change (global warming/oscillations ie, ENSO) = intensification, acceleration or enhancement of hydrological cycle. Impacts vary globally ie, differential amount of temp increase, changes/distributions to rainfall = differential changes. Different impacts on drainage basins in different climate zones Modelling climate change trends difficult = Climate dynamics, way atmosphere, ocean, terrestrial, cryosphere + biosphere interact with each other Teleconnections, difficult to distinguish between impacts of oscillations like ENSO/climate warming Global records, very incomplete many parts of world there's insufficient detailed evidence to establish reliable trends for CC impacts/make predictions on the future
Water management israel
Climate, natural geography + politics = manage its limited water supply efficiently . National water carrier developed to transfer water from sea of Galilee in the north to highly populated centre + dry south. Uses smart irrigation, drip. Systems allow water to drip slowly to plants roots by valves + pipes (reduce waste/evaporation) Recycling sewage water for agriculture use, 65% of crops produced this way Reducing agricultural consumption + importing water in food as virtual water Adopting stringent conservation techniques Charging real value prices for water to reflect supply costs Acquires new supply by importing 50 million tonnes of water per year by ship from turkey Piping seawater from red sea + Mediterranean to new desalination plants
Ethiopian water conflict =
Controversial dam building programme (designed to fuel economic growth) = international + internal conflict. Gilgel Gibe III Dam + HEP is on Omo river. Cost $1.8 billion, started in 2008 & produced energy in Oct 2015. Dam will be devasting to downstream indigenous population as it'll prevent seasonal floods. 200,000 people rely on below dam for subsistence agriculture + seasonal floods to replenish dry soils. Many ethnic groups live in chronic hunger = threatens their survival, ears water shortage could equal conflict between tribes Supporters of dam = artificial floods released from reservoir + irrigation projects will allow for cotton + sugar cane plantations - improving livelihoods. But will only benefit ethiopian state-owned companies. + claims of human rights violations from army against those who oppose UNESCO 2011, wanted to stop construction to review impact on Lake Turkana (Kenya-Ethiopia border). Dam could reduce level of lake by up to 10m = affecting 300,000 people + wildlife. Increase in salinity of water = drinking supply + fishing industry + lake ecosystem
El Nino
Cool water by coast of Peru's replaced by warmer water, at same time area of warmer water further west near Aus + Indonesia is replaced by cooler than normal subsurface water in tropical pacific. Occur every 3-7 years for 18 months. Can trigger dry conditions globally, usually 2nd year, especially in SE asia, India, eastern Aus + SE USA, central america + NE Brazil. In india = weak monsoon rains, exacerbating drought by monsoon failure. Trade winds in western pacific weaken + die (disrupted trade wind pattern cam slacken or reverse = knock on effect on currents) May be reverse direction of flow Piled up water in west moves back east = 30c, sea level rise in Peru Region of rising air moves east with associated convectional uplift. Upper air disturbances distort the path of jet streams = lead to teleconnections globally. Eastern pacific ocean become 6-8 warmer. El nino effect overrides cold north bound Humboldt current breaking food chain. Lack of phytoplankton = reduction fish no Conditions calmer across whole pacific
Murray-Darling Basin
Covers 1 million Km2 of SE australia, contains 2 rivers, provides 75% of Australia's water and 40% of farm produce, Under threat from increasing demands, been 5 fold increase in water extraction since 20s. Difficulties due to its size so it compromises many different natural environments ie, rainforests in Queensland to hot semi-arid desert is south Australia The country's size + ENSO variating cycles, annual, seasonal + local variations occur at different parts of Basin, some can be surpluses & some in deficit Key players = Agriculture = taking most water & increasing demand. Irrigation boosts profits & crops that yield best return ie, vegetables been replaced by beef/sheep. Urban residents Industrial users ie, mining in Queensland Aquaculture, freshwater fishing Leisure Environmental groups ie, Environment Victoria International heritage + conservation agencies Aboriginal groups
Rain shadow
Dry area on leeward side of mountain, it receives little rainfall due to mountains sheltering it from rain-producing weather. As moist air is forced to rise on windward side, rainfall occurs as result of adiabatic cooling (when volume or air increases but there's no addition of heat) and condensation to dew point The air without much water left in it, then drawn over the mountains where it descends and is adiabatically warmed by compression Leads to very dry shadow area ie, Owens valley in Sierra Nevada
El nino + la nina
El Nino = when upwelling off the coast of Peru weakens leading to a shift of the warm water that would normally sit in the western tropical Pacific near to Australia to shift eastwards, along the equator La Nina = when the warm mass of water in the Pacific is pushed even further west than normal Teleconnection - climate anomalies which relate to each other at large distances
La nina
Exaggerated version of normal year with strong walker loop Extremely strong trade winds Trade winds push warm water westwards giving sea level up to 1m higher in Indonesia + Philippines Low pressure develops with strong convectional uplift as warm water heats atmosphere = heavy rain in se Asia Increase in equatorial undercurrent + strong upwelling of cold water off Peru = strong high pressure + extreme drought. Can be major problem in semi-arid areas ie, Northern Chile + Peru
Characteristics of hydrological cycle
Example of closed system, there is fixed amount of water in earth, atmosphere system (1385km3). Doesn't have any external inputs or outputs, total volume of water is constant + finite. Driven by solar energy + gravitational potential energy Water can exist in different states within closed system (ie, vapour, liquid + solid). Proportion of each can vary for physical/human reasons
Existing schemes + proposing schemes
Existing schemes = Snowy Mountains scheme, SE Australia = water transferred from lake of Cucumbene westwards by snowy tunnel to headwater of Murray river to irrigate + provide water to drought stricken area South-North transfer, China = began 2003, will take 50 years to complete and costs $100 billion, transfer 44.8 billion cubic metres per year from water secure south to drought stricken north via 1300km canals linking Yangtze river to Yellow + Hai Proposed schemes = Israel, transfer from any agreeing neighbours. Very water deficit plans to transfer water red sea to dead sea India, develop national water networl to gain better distibution of supplues to watter deficit areas America, NAWAPA, plns to transfer water from Alaska + North west Canada to Califrnia + Mexico
Meteorological causes of flooding
Flash floods = very quickly without warning, caused by heavy, intense rain associated w/ thunderstorms/tropical. Contrast, prolonged rain caused by mid-latitude depressions passing over same place can equal slower build up of river flooding. Nov 2013, Sardinia had flash floods killing 18 & 1.14 billion in damage. Mid-latitude depressions = majority cause in UK. Each depression brings 2 bands of rain, shower + rain w/ warm front and heavier rain w/ cold front. Ground can absorb some water but it becomes saturated so through-flow + ground-flow are unable to transfer water quick enough. So rate of infiltration decreases and water moves quickly through system as overland flow & straight into channel. Once capacity is exceeded water spills onto surrounding floodplain. Meteorological situation may arise & polar jet stream meanders steadily in mid latitude Monsoon = seasonal change in direction of prevailing winds of a world region, includes wet + dry seasons throughout subtropical areas (close to oceans). In India + SE Asia summer monsoon associated w/ heavy rainfall. Occurs from april - sep when warm, moist air from SW Indian Ocean blows towards Sri Lanka, India, Bangladesh + Myanmar = humid climate + torrential rain. Happens as ITCZ moves northwards & warm moist air follows behind it. Jul 2015 = 2015 Myanmar monsoon = 103 deaths Snowmelt = melting of winter snowfall caused by sudden warming of temps in spring. Common in mountainous areas resulting in increased surface runoff + flash flood. 2009, red river, N Dakota reached record flood levels
Polar Hydrology
Freeze/thaw seasonal differences Winter snow insulates ground & 85% of solar radiation is reflected Permafrost creates impermeable surfaces Lakes + rivers frozen Limited vegetation cover reduces heat absorbation Spring thaw causes rapid runoff Summer thaw produces surface runoff, increasing evaporation tenfold Freeze-thaw cycle causes seasonal release of biogenic gases (caused by plant decomposition) into atmosphere plus, carbon + nutrients into rivers/seas Characterized by orographic or frontal precipitation + low humidity Annual precipitation = less than 200mm Cryosphere = seasonal thaw brings increased surface saturation + thinning permafrost. If thaw is continuous water flows away and is lost = cryosphere loss
Mid-latitude blocking anticyclones
Frontal precipitation created in low-pressure systems that form along polar front (where warm tropical air rises over cold polar ai. Depressions move west-east due to Coriolis (rotation of earth) and track is directed by polar front het stream (fast moving meandering belt of air in upper troposphere) . Loops of jet stream can stabalise/break up allowing high pressure areas (anticylcones) from subtropic to move north Brings stable weather, heat waves whilst rain depressions forced around them = droughts Very stable due to sinking air + calm conditions = they can persist & block weather systems from the west up to 2 weeks.
Human causes of water insecurity
GDP increasing = increased demand for freshwater as income growth/rising living standard grow (middle class). Led to unsustainable increases if water use. Rising demand for meat, larger homes, motor vehicles, labour intensive devices. Agriculture = human activity with highest use of water. 70% globally + 90% in developing countries. Excessive water withdrawals for agriculture = problems from California - India. Over-abstraction, 2.5 billion depend on groundwater for daily needs. Farmers rely on groundwater for livelihoods/food security. Groundwater = provides 50% of global population's water. 20% of aquifers are over-exploited Pollution + contamination, affect water quality. Caused by intensive agriculture, industrial production, untreated sewage, urban runoff+ mining. Estimated 90% of all waste water in developing discharged directly into rivers. Commercial agriculture = increased nitrate + phosphate fertilizer = eutrophication of freshwater leading to environmental + health risks 2015, 1.35 million m3 contaminated water released by US environmental protection agency into Animas river in CO, water was from mining & contained arsenic 300x normal levels & lead @ 3,500x normal levels. People + livestock = @ risk and local state emergency was declared Energy = freshwater withdrawals accounts for 15% of worlds total energy due to all energy requiring input of water in their production process. For example, thermal power and hydropower account for 80 & 15% of global electricity production Topography + distance from sea = significant. High relief promotes high precipitation + rapid run-off but also more opportunities for surface water storage in natural lakes & artificial reservoirs and combined with impermeable geology = greater storage. Snowfall + glaciers can be locally vital as in Bolivian Andes climate warming has = melting so the cryosphere storage has decreased which threatens water supplies for La Paz-El Alto Rivers = major river systems store large quantities of water & transfer it. Amazon's average annual discharge = 175,000 cubic metres per seconds from catchment area. Recent droughts impacted brazil's water supply, flows were low and tributaries dry impacted high sea temps
Helsinki Rules
General agreement that international treaties must include concepts like equitable use + shares and must be applied to whole drainage basins. Criteria for water sharing based on- Natural factors, rainfall amounts, discharge along water sources, share of drainage basin, impact of CC Social + economic needs, population, welfare size + development plans Dependency, availability of alternative sources Prior use, past historic rights/potential future use Efficiency, avoiding waste + mismanagement But this = not backed by compulsory regulations
future of floods
Generally agreed that the hydrological cycle will intensify and that extremes will become more common. moisture- holding capacity of the atmosphere has been increasing by approx. 7% per degree Celcius of climate warming, creating the potential for heavier precipitation. Hydrological disaster losses have grown much more rapidly than precipitation or economic growth suggests that climate change factors may be involves - although socio-economic factors eg land use changes and greater use of vulnerable areas plays a huge part.
Floods + future
Generally agreed that the hydrological cycle will intensify and that extremes will become more common. The moisture- holding capacity of the atmosphere has been increasing by approx. 7% per degree Celcius of climate warming, creating the potential for heavier precipitation. Hydrological disaster losses have grown much more rapidly than precipitation or economic growth suggests that climate change factors may be involves - although socio-economic factors eg land use changes and greater use of vulnerable areas plays a huge part.
Desalination
Global boom in desalination, sustainable process as conserves supplies for future generations Recent tech (reverse osmosis process) = more cost effective, less energy intensive ++ easier to implement on large scale TNCs = GE, USA building plants globally. 6 nations with desalination capacity = SA, UAE, USA, Spain, Kuwait + Japan Advancement of carbon nanotube membranes that require less pressure = greater energy efficiency + costs decreasing further so it could become more available More viable than hard engineering but concerns of environmental impacts. Left-over water has 2x salt concentration of sea water. Dumping it near shore = consequences on ecosystems
Physical causes of water insecurity
Global variations in distribution/availability of freshwater resources due to climate variability between arid/humid climates + wet/dry seasons. Increasing variability in precipitation patterns = direct/indirect effects of hydrological cycle with changes in runoff + aquifer recharge +in water quality Warmer climate increases rates of evaporation + transpiration = less effective precipitation (amount added + stored in soil after losses) Higher water temps of warmer climate + localised industrial charges of warm water waste can increase pollution. As warmer water encourages growth of bacteria harmful to human health, quality of water affected by sedimentation, nutrient enrichment, dissolved organic carbon, pathogens, pesticides etc. = negative impacts on eco systems, human health + water system reliability + operating costs Seward movement of freshwater reduces saltwater encroachment in coastal zones = soil moisture + groundwater stays fresh. But seal level rise + localised abstraction is increasing risk of saltwater intrusion into many coastal areas. Increased groundwater pumping from freshwater wells lowers water table & permits saltwater to move into soils/aquifiers. Thermal expansion = enables saltwater inland Geology = controls distribution of aquifiers that provide groundwater storage. Permeable chalk + porous sandstones store vast quantities (valuable as not subject to evaporation loss). Water supply from springs accessed by wells giving even supply throughout year despite uneven distribution/variability of rainfall
Water prices varying
Governments/local authorities usually provided water as service but charged at a cost price. Colonial gov's often installed limited infrastructures to cover the small cities @ But urban growth means the infrastructure's been outgrown. IMF limits gov spending on services, so countries responsibility for water relies on the control of private sector Giving responsibility to private sector for modernising infrastructure but has resulted in rising costs for consumers (provides benefits/profits for company). = conflict Case study, water privatization Bolivia = 1999, Agua del Tunari took over Cochabamba's water system. Company increased price so they cost 20% of average income. Resulted in 4 days protest & the government cancelled the contract High income countries price still varies: Canada still lies w/ public sector charged 80% less than Germany. Ireland only started to charge for water in 2012. Denmark has most expensive water in hopes of decreasing consumption.
Sustainable management of water resources
Groundwater management = aquifer storage + recovery, groundwater quality + quantity modelling Waterway management =river rehabilitation, sustainable water allocation, waterway health, environmental flows, waterway structures Integrated urban water management = water treatment technology, water sensitive urban design, water harvesting + reuse Monitoring technology = sensor technologies, real-time wireless monitoring + control systems Successful schemes = Gujarat India. Bottom-up approach designed to overcome water poverty, technology schemes provide year round supply = triple cropping + quadrupling of production per hectare. = raised incomes 5 fold Colorado =river drains 7% of USA. Countless treaties + agreements needed to allocate fair shares of its water to 7 surroundings states + mexico
Growing problems
Growing problems Climate change will make areas more arid/rainfall more unreliable Glacial waters sources will reduce due to climate change Unsustainable use of supplies will decrease quality/quantity Demand rises due to economic/population growth Data = 12% of worlds pop consumes 85% of its water 1.8 billion people lack clean drinking water, 2.4 billion lack adequate sanitation + 0.7 billion water shortages By 2025 pop + economic growth expected to create 20% increase in demand for water supplies
Human causes of flooding
Impermeable surfaces, roofs, pavements etc. london land taken up by car parks is 25km Speeding up of drainage of water in built up areas via artificial conduits ie, drains/sewers Impeding channel flow by building alongside river ie, bridge supports + structural engineering ie, levees. Straightening channels (realignment) to increase the flow = flooding downstream. Resectioning by dredging involves widening + deepening the channel to increase efficiency by increasing capacity + water moving at quicker rate (environmental cost) Changing land use associated eith agricultural development. Deforestation, overgrazing, ploughing + drowning wetlands (occurs @ upstream) = knock on effect downstream with increased run-off + increased levels of sediment (washed into rivers + block river channels) Urbanisation concentrated on lower-lying lands within drainage basins (especially floodplains) = natural + human factors coincide enhancing frequency + magnitude of flood risk
Climate change affecting hydrological cycle
Increasing anthropogenic greenhouse gas emissions = increasing heat trapped in atmosphere (enhanced global warming) = increasing air temperatures + sea surface temps Increasing convection/evaporation = increased condensation + cloud cover = increased precipitation in low pressure regions in tropics + mid latitudes = increased flood risk Decreased snow, permafrost + ice cover. Initial increase in meltwater increase river floods in next decade but decrease after, Increasing high-pressure systems in certain seasons/high-pressure regions ie, subtropics = decreased humidity + precipitation in these locations = increasing incidence + severity of drought
General processes taking place
Intense solar radiation @ equator warms the air which rises and starts convection. Air cools as it rises and water vapour condenses to form clouds/rain Subtropical high pressure zone created where air that had risen at equator has cooled and sinks to form belt of high air pressure & hot, dry conditions Air returns to ground levels at equator creating trade winds Trade winds meet @ Intertropical convergence zone where warmed air rises. Position of ITCZ moves with seasons. Northern hemisphere summer = ITCZ north of equator but dec-feb the southern hemispheres tilted towards sun and therefore ITCZ is south of equator. Movement = alternating wet + dry seasons in tropics Warm air moving from subtropics to mid-latitudes meets cold polar air at polar front where the warm, less dense air rises = condensation + rainfall Warmer air rises into polar front jet stream and transferred at high altitude towards poles where it cools + sinks. Creates movement of air at ground level back towards equator.
hard engineering water managment
Israel's desalination plant = 5 plants opened in 2013 taking water from Mediterranean, aim = provide 70% of its domestic water by 2020 Each plant needs own power station = adding to CO2 but most energy is solar Produces mass amounts of salt/brine contain anti-scaling agents = harmful ecosystems Produces 600 tones of potable water per hour Three gorges dam = Control flooding on Yangtze + improve water supply by regulating river flow, generate HEP + river navigable. Lets surplus water to build up and diveryed to northern China via south-north water project. Generates energy = key for increasing pop 632km2 land flooded to form reservoir 1.3 million relocated (1500 villages/town) Reservoir water quality = low, as waste from industry, sewage + farms enter from upstream Decomposing vegetation = methane which released when water passes through HEP turbines
Europe/Central Asia
Lack of access to clean drinking water in Eastern Europe + Central Asia Increasing water consumption, cities over-exploiting groundwater reserves Declining water quality in countries w/ groundwater pollution (nitrates, pesticides) ie, Aral Sea
Causes of Desertification
Land degradation in arid, semi-arid + dry sub-humid regions resulting from various factors ie, climatic variations + human activities Physical = Short term = less rainfall (total amounts/reliability) increased drought (frequency + intensity) = rivers, waterholes + wells dry up = vegetation dries and decrease in protective vegetation cover & exposed soil to wind/rain (erosion) Long term = global warming; higher temps, increased evaporation & reduced condensation = less reliability & amount = vegetation dries and decrease in protective vegetation cover & exposed soil to wind/rain (erosion) Human = Increase in animals = (above carrying capacity of fragile grasslands) = some areas livestock no increased by 40% in water pluvial) years before mid 60s. = overgrazing, soil depleted of nutrients and land stripped of protective grass cover so vegetation can't reestablish itself = increase in evaporation from soil (possible salination) Sahel population growth = higher birth rates + lowering death rates. Farmers forced to change traditional methods of land use as more needed for food (grass ploughed up) + cash crops. = overcultivation, reduced soil fertility, left exposed to wind + rain so vegetation removed Immigrants (refugees, civil wars/droughts) = increased demand for wood ie, cooking + heating + building = deforestation for fuelwood, vegetation's removed = increased risk of soil erosion
impacts, cumbria
Long term impacts = Social costs = 3000 homes flooded in 2005, 5200 in 2015, residents lived in temp accommodation, local services forced to close, residents suffered anxiety, stress + psychological trauma Economic costs = businesses, transport + infrastructures damaged, costs of flooding 2005 = 2005 100 million, 270 million 2009 and 400-500 in 2015,insurance claims exceeded 6 billion, farmers lost hedgerows + expensive dry stone walls + sheep washed away, houses prices fell, deterred tourists Environmental costs = river banks eroded (added to future flood risk), rivers choked with debris with sewage + effluents/pollutants, soils eroded, habitats destroyed + ecosystems, saturated ground = decomposition of dead plants/animals = noxious gases ie, hydrogen sulphide. Poisons contaminated food chain + threatened wildlife, saturated ground led to landslides
types of droughts
Meteorological drought = occurs when precipitation is lower than normal over long period Agricultural drought = occurs when there is insufficient soil moisture to meet the needs of the crops Hydrological Drought = occurs when there are deficiencies in surface and subsurface water supplies Socio-Economic/Famine Drought = occurs when the demand for water for social and economic purposes exceeds the availability, may lead to famine + a widespread humanitarian crisis
Drought characteristics
Meterological (rainfall deficit) = low precipitation, high temps, strong winds, increased solar radiation + reduced snow cover. Impacts = loss of soil moisture + supply of irrigation water declines Hydrological (streamflow deficit) = reduced infiltration, low soil moisture, little percolation + groundwater recharge. Impacts = reduced storage in lakes/reservoirs, less water for urban supply + power generation= restrictions, poorer water quality + threats to wetlands/wildlife habitats Agricultural drought (soil moisture deficit) = low evapotranspiration, plant water stress, reduced biomass + fall in groundwater levels. Impacts = poor yield from rain-fed crops, irrigation systems start to fail, pasture + livestock productivity decline, rural industries affected, some gov aid required Famine drought (food deficit) = loss of natural vegetation, increased risk of wild fires, wind-blown soil erosion + desertification. Impacts = widespread failure of agricultural system, food shortages on seasonal scale, rural economy collapses, rural-urban migration, increased malnutrition + related mortality, humanitarian crisis, international aid needed
Evaporation (Drainage basin system outputs)
Moisture lost directly into atmosphere from water surfaces + soil. Results from effect sun's heating + air movement so rates increase in warm, windy, dry conditions,. Climatic factors influencing evaporation rates include temp, hours of sunshine, humidity + wind speed. Other factors = size of water body, depth of water, water quality, type of vegetation cover + colour of surface (albedo)
Brazil 2014-15 drought
Most air moves in westerly direction from south atlantic across amazon basin. When moist air encounters high andes mountains to west of continent its forced to turn southwards = maintaining flow of moisture around the basin 2014 series of high pressure systems diverted rain bearing winds further north away from Amazon and prevented them from diverting southwards from the Andes Heavy rains the occurred in Bolivia + Paraguay whilst Brazil had dry air Impacts = Water rationing for 4 million people, water supplies cut off 3 days a week Halting of HEP production = power cuts Depletion of Brazil's 17 largest reservoirs to dangerously low levels (some to just 1% capacity) Increased groundwater abstraction = aquifiers dangerously low Reduced crop of Arabica coffee beans (pushed global coffee prices up to 50%)
colorado pt2
New agreements = 2007 new agreement reached, 7 states divides up storage. Water available determines supply = California reduced amount by 20% 2012, Minute 139 signed between USA + Mexico. Gives Mexico right to store some water in Lake Mead. In return, water providers in Colorado river basin can purchase water conserved by improving Mexico's canals + storage infrastructures Policies being considered = Domestic conservation, repairing leaks/metering supplies. Re-using wastewater Concrete storm-drains cold redirect + save storm water into urban parks for irrigation Farms = 80% of Californias water, reducing irrigation by 10% would double amount of availability for urban areas Smart planning, new housing only permitted where water supplies are adequate Initiatives = International decade for action 05-15 'water for life' March 22nd world water day Global action Earth summit Agenda21, blueprint for planet management @ global scale 1990-2006, 1.1 billion in developing world got access to toilers, latrines + improved sanitation
How thermohaline circulation works
Ocean water in polar region is colder, more saline + denser than tropics so it sinks Cold sinking water sinks draws n warmer water from the ocean surface above, which in turn draws water across the surface from the tropics Movement of water from the tropics draws cold water up from the ocean bottom, to be warmed again
global water stores
Oceans = volume, 1335,040 km3, 96.9%. . 0% of fresh water. Residence time 3,600 years Icecaps = 15,300km3, 1.9% total water, 68.7% fresh water, 15,000 years depending on size Groundwater = 15,300km3, 1.1% total, 30.1% fresh water. Deep ground water residence time = 10,000 years and 100-200 years for shallow groundwater Rivers + lakes = 178km3, 0.01% total, 1.2% fresh water. 2 weeks to 10 years for residence time Soil moisture = 122km3, 0.01% total, 0.05% freshwater, residence time = 2-50 weeks Atmospheric moisture = 13km3, 0.001 % total water, 0.04
Case study; Amazon
Over 20% of forest destroyed from cattle-ranching, large-scale commercial agriculture (biofuels + soya beans), town development + illegal/legal logging 60% of world's rainforest In forest environments 75% of intercepted water returned by EVT to atmosphere reducing to about 25% when forest's cleared. More water runs off into amazon drainage system = increases severe flooding/mudslides. Also leads to aquifer depletion as less water infiltrates to recharge them. Overland flow increases soil erosion + degradation as nutrients washed away
Human impacts affect water quantity
Over abstraction for domestic, agriculture + industrial usage 2025, total projected water withdrawals predicted to reach 5000 cubic km per year (agriculture use 2/3) Population growth, urbanisation, increased living standard will rise water demand Removal of fresh water from aquifers on coastal locations can disturb natural balance of saline/fresh water. Lead to water incursion + salinisation of wells, boreholes + wetlands Agriculture use to absorb over 70% of extraction globally but industrial usage increasing in developing countries. Proportion can be up to 60% (paper/metal industries) Energy industry = needs more & more due to new energy developments like biofuels/fracking.
drought's measured
Palmer Drought Severity Index (PDSI) = applies to long term drought + uses current amd preceding data as drought's dependent on previous conditions. Focuses on monitoring duration + intensity of large-scale, long-term, drought-inducing atmospheric circulation. Crop Moisture Index (CMI) = short term drought on weekly scale and useful for farmers to monitor water availability during growing season Palmer Hydrological Drought Index = hydrological system responds slowly to drought, both in reacting to drought & recovering from it so different models need to be developed for rivers, lakes etc
Human factors that influence the drainage basin system
Precipitation = cloud seeding, introduction of silver iodidc pellets/ammonium nitrate acts as condensation nuclei which attracts water droplets. Evaporation + evapotranspiration = changes in global land use ie, deforestation is a key influence. Also increased evaporation potential resulting from huge artificial reservoirs behind mega dams. Channelisation of rivers in urban areas into conduits cuts down surface storage and therefore evaporation Interception = deforestation + afforestation (planting of trees in an area that hasn't been forested in recent times). Deforesting = reduction in evapotranspiration + increase in surface run-off. Increases flooding potential leading to decline of surface storage + decrease in lag time between peak rainfall and peak discharge. Effectively speeding up the cycle Over abstraction = leads to rivers drying up in times of low rainfall.
Inputs
Precipitation = conditions needed: air cooled to saturation point with a relative humidity of 100%, condensation nuclei ie, dust particles to facilitate growth of droplets in clouds, temp below dew point (temp which dew forms, measure of atmospheric moisture) Influencing factors impacting drainage basin hydrological cycle = Amount of precipitation, impacts drainage discharge. Higher the amount - less variability in its pattern Type of precipitation, ie snow can act as temporary store/large fluxes of water can be released after period of rapid melting due to a thaw Seasonality, climates like monsoon, Mediterranean/continental climates. The strong seasonal patterns of rain/snowfall = major impact Intensity of precipitation, as impacts flows on/below surface. Difficult for rain to infiltrate if very intense & soil capacity is exceeded Variability = secular variability = long term, ie, result of climate change trends. Periodic = annual, seasonal, monthly or diurnal Stochastic variability = random factors ie, localisation of a thunderstorm within basin
Key terms
Precipitation = movement of water in any form from atmosphere to ground Evaporation = change in state of water from liquid to a gas Residence time = average time water molecule will spend in reservoir/store Fossil water = ancient, deep groundwater from former pluvial periods Transpiration = diffusion of water from vegetation into atmosphere, involving a change from gas to liquid Groundwater flow = slow transfer of percolated water underground through pervious porous rocks Watershed = imaginary line around edges of basin seperating one basin from another
Potential impacts to different hydrological variables
Precipitation input = type more important the average rainfall in determining hydrologic impacts. Widespread increases in intense rainfall occurred but overall amounts stayed steady/decreased. Areas with increases are tropics/high latitudes with decreases of 10-30 north + south of equator. Length, frequency + intensity of heat wave has increased widely in southern europe + africa. = increase in droughts. More rain falls due to warming, consistent with warmer atmosphere + greater water holding Evaporation + evapotranspiration = large areas of asia/ north america evaporation increasing, although increased cloud cover from increased water vapour may work against this. Transpiration linked to any vegetation changes , linked to any changes in soil moisture + precipitation + increasing transpiration = vegetation more productive Soil moisture = amount of soil moisture related to many factors, climate change = only one Run-off + stream flow = evidence to suggest that more climate extremes = increase in hydrologic extremes. More low flows + high flows. Accelerated cycle w/ more intense rain increases run-off rates + reduce infiltration. Marked decreases in continental interiors of Mediterranean Groundwater flow = limited evidence, no definitive link between groundwater amounts + climate change as human abstraction = dominant influence on supplies Reservoir, lake + wetland storage = regional variations in lakes liked to regional climate variations. Changes in wetland storage occurring but can't be conclusively linked to climate change. Wetlands affected when decreasing water volumes + higher temps Permafrost = changes in physical climate @ high latitudes, mainly increasing air/ocean temp leading to permafrost degradation in northern areas. Deepening of active layer has impact on ground water supplies + releases methane from thaw lakes. Leads to positive feedback accelerating change. Snow = studies suggests length of snow cover season decreased, especially northern hemisphere (last 50-100 years), spring melt has occurred earlier possibly accelerating, coincides with river regimes Ice = glaciers retreated globally since end of little ice age with downwasting accelerating in most areas since 70s. Result of rapid temp increase + change in precipitation type. Tropical high-altitude glaciers ie, Andes have shown most changes = low flow from dwindling cryosphere supply Oceans = work on measuring sea surface temp has lagged behind land-based research but in areas of ocean warming increased evaporation will occur but limited evidence that more cyclones generated.
Interception =
Process where water stored in vegetation. 3 main components: interception loss, throughfall + stem flow. From vegetation interception loss usually greatest at start of storm. Interception capacity of vegetation cover varies with type of tree. Coniferous trees = greater accumulation of water. Contrast between deciduous forests in summer + winter, interception losses in summer are 40% for certain beech forests but under 20% in winter. Deciduous forests intercept 15-25%, coniferous intercepts 25-35%, stable crops 10-15% Wind speeds can decrease interception loss as rain is dislodged but increase evaporation rates. Amount of rain increases relative importance of interception losses will decrease as tree canopies decrease
Smart irrigation in China + Australia, sustainable
Provides crops with suboptimal water supply = mild stress in crop growth stages that are less sensitive to moisture deficiency. Technique found to conserve water without siginificant reduction in yield 6 year study of wheat production on North China Plain showed water savings of 25% + and high yields/net profits. Australia, regulated smart irrigation of fruit trees increased water productivity by 60% with gain in quality + no loss in yield. Controlled irrigation ie, drip-feed makes sure water goes directly into soil next to root of crops = prevents evaporation losses Malaysia supplies 80% of its water Per capita water consumption fell from 165 litres per day in 2000 to 150 in 2015 by metering water supply + educating public Leakages cut to 5%, UK = 20% Water prices = scaled, if usage goes above level prices rise Subsidies protect poorest citizens Whole of country = water harvesting catchment, diversified supplies = local catchment, recycled _ desalinated water
Human impacts affect water quality
Quality, china has issues 300 million people use contaminated water daily + 190 million suffer water related illnesses annually. 1/3 of rivers, 75% major lakes + 25% coastal zones classify as highly polluted. Long term = 2 million chinese may suffer from water related diseases. Cancer cluster villages in Guandong where liver/digestive cancer =responsible for 80% deaths, possibly due to metal toxins from mine washed into Hengshi river 20% all tube wells sunk in Bangladesh & found to be unsafe due to high concentration of arsenic. = major health issues ie, arsenicosis with skin lesions Untreated sewage disposal = water-borne diseases ie, typhoid, cholera + hepatitis. India = 20% sewage is treated before discharged into rivers Chemical fertilisers (part of green revolution) contaminate groundwater = eutrophication in lakes/rivers = hypoxia + formation of dead zones in coastal Industrial waste is dumped Over 60% of world's major rivers are impeded by large dams =impact on sediment movement so impacts on rive ecology
Human changes interfering water cycle
Removal of dense forest canopy protecting topsoil can be bad = deforestation Building new storage reservoirs/abstracting more water from rivers/reserves helps satisfy water demands. = urbanisation Reservoirs interrupt the natural flows of water by delaying flows through a drainage basin & adding to the amounts lost through evaporation. Estimated that 7% more water's evaporated from reservoirs than is actually used by people. In tropics mats of floating plants on the surface make evapotranspiration rates six times higher than open water Salinity levels within reservoir also rise as water evaporates Dams reduce river flow below leading to loss of vegetation ie, Kenya's Tana River
Water poverty index
Resources, quantity of surface/groundwater per person and its quality Access, time + distance involved in obtaining sufficient water Capacity, how well community manages water & its health Use, how economically water is used in homes, agriculture + industry Environment, ecological sustainability Given scored out of twenty to give max possible score of 100
Possible water conflict among nile countries
Riparian led process of joint decision making = Nile Basin initiative (1990s) 2005, 9/10 countries have explored development of NBI partnerships with external agencies ie, World Bank. 2 subsidiary plans - Eastern Nile + Nile Equatorial Lakes 2010 = Ethiopia, Rwanda, Tanzania + Uganda signed new treaty (Kenya promised to join later), stated that all riparian countries should have equal rights to use water. Upstream conditions now urged Egypt + Sudan to sig n and depends on polutics of Nile (both countries are weak). Neo-colonialism of china = effects
Synoptic links
Saltwater encroachment = occurs in coastal areas due to sea level rise (global climate change) but further than this, all coastal processes will change, with stronger storm events +associated storm surges, increased coastal erosion, and flooding of low lying land. Puts pressure on people and whole countries, and superpowers may have to help developing countries to relocate their people Water contamination = particular risk in informal settlements of megacities, with high population densities with inadequate infrastructure for effective sewage treatment. Water supplies may be from occasional standpipes, rather than complete network to every home. Creates poor living conditions + health risks. Poor sanitation encourages spread of waterborne diseases such as cholera and typhoid. = major challenges for countries that consider to be emerging superpowers.
Case study, Sahel
Seasonally, drought sensitive as occupies transitional climate zone. Meaning, under 'normal' conditions, annual rainfall (85%) is concentrated in summer. Varies from 100mm on edge of sahara to 800mm along southern margins Annually, huge variability from year-year, especially Saharan fringe. Unusually warm sea surface temps in tropical seas favour strong convectional uplift over ocean that then weakens West African monsoon + contributes to drought. Decadal anomalies = clear. Human factors acts as positive feedback loop by enhancing impacts. In 1999-2000 Ethiopian drought/famine crisis 10 million people needed food assistance, drought impacts increased by socio-economic conditions due to growing environmental degradation from overgrazing by nomadic tribes, deforestation + high levels of rural povery Population doubled every 20-30 years = outstripped food production in many places. Any agriculture = rainfed so very susceptible to drought with over-cultivation Ethiopia + Eritrea @ war = blocking access to food for many Regreening = restoration technique that involves planting trees + bushes alongside other sustainable land management schemes. Popular in Malawi, Niger + Ethiopia. 100,000s benefit from increasing yields. Also referred to farmer-managed natural regeneration. Benefits, natural, low-cost, use of water-harvesting techniques ie, digging improved planting pits to trap rainfall on fields and increase yields
influences on cumbria flood
Sheep wrecked uplands, over-grazing by sheep = bare slopes replace forests. Trees used to absorbed + released water, meandering channels slowed the flows and bogs held water back. But now there are bare + drier oils, straightened + dredged channels = faster runoff, reduced stream lag times + higher discharge peaks. Rainwater reaches floodplains quicker (urban areas expanding = more impermeable surfaces). Mismanagement = Before 2005, raised riverbanks, pumping stations + diversion channels carried surplus water away. Hard engineering common and reinforced after 2005 floods. Design = based in flood-return period (statistical estimate of how often flood of certain magnitude is likely based on past flood levels ie, 1 in a 50 year) Mitigating flood risk = Environment Agency believe hard-engineering not solution, they're expensive + cant cope with extreme floods Soft engineering like; reafforestation of upland areas (reduce rapid surface runoff), restoration of river channels + floodplains to natural absorbent state, refusal of planning permission to build/expand near rivers
What drives global hydrological cycle
Solar energy + Gravitational potential energy More evaporation occurs as global climate warms = increases moisture levels in atmosphere Lead to an increase in condensation as air cools = greater precipitation. Explains why some places will get an increased cloud cover and precipitation as climate changes. Gravitational potential energy = keeps water moving through the system in a sequence of inputs, outputs, stores + flows. Example = Last ice age, more water was held within the cryosphere in solid form as snows/ice, less held in oceans = sea levels dropped (140m+ lower than today) Recent climate warming - reversing this & major loss of ice in Greenland + Antartica. Smaller scale = humans built lots of water storage reservoirs to increase security of water supplies
Global extremes
Solar energy concentrated in Tropics, much is absorbed by the sea Evaporation from sea produces high rainfall, 74% of world's rainfall occurs at sea. (mainly in tropics) Remaining rainfall is distributed unevenly, both spatially + in time Seasonal monsoons + droughts of Asia/Africa contrast with temperate climates of NW Europe.
China South-North
South = rich in water resources, water isn't. South-north water diversion started in 2003, going to take 50 years + $100billion. Three canals that run 1300km across eastern, middle + western parts of China Links 4 main rivers Yangtze, yellow, huai + hai. Transfer 44.8 billion cubic metres per year, central gov will provide 60% of costs and rest from local authorities = charging domestic/industrial users Water conservation, improved irrigation, pollution treatment + environmental protection Beijing region = 35% of pop, 40% of arable land but 7% of water. Will submerge 370km2 of land 345,000 forced to relocate Risks draining too much water from southern china Eastern route = industrial + risk further pollution Reduce risk of water shortages in Beijing + boost economic Reduce groundwater abstraction
Key terms =
Systems approach = study hydrological phenomena by looking at balance of input + outputs and how water is moved between stores by flows. Stores = reservoirs where water's held ie, oceans Fluxes = rate of flow between stores Processes = physical mechanisms that drive fluxes of water between stores Cryosphere = areas of the earth where water's frozen into snow/ice Blue water = water stored in rivers, streams, lakes + groundwater in liquid form (visible part of hydrological cycle) Green water = water stored in soil + vegetation (invisible part of hydrological cycle)
climate change impact, california
The bad, California 40 million affected increasing problems due to recent variations in rainfall. 2014, Sierra-Nevada region had 3x normal number of wildfires Cornell Uni forecasting mega droughts lasting 30 years + decade long dry periods. 2015 marked 4th years continuous droughts in the state. 50% of mega droughts in southwest and 90% of decade long drought Rising temp = increased evaporation rates, fall in precipitation. Droughts = surface run-off + soil moisture declined, forested areas reverted to shrub/grassland, groundwater levels in LA fell by 30 metres from 2011-15 Reservoir levels, oct 2016 water storage was 77% of average for time of year but levels varied. Lake Cachuma was down 9% Snowpack levels in 2015 @ record lows due to high temps + lack of winter storms, crucial as meltwater provides 1/3 of the water used by cities + farms
Drainage basin system outputs
Transpiration = Water lost from plants through stomata and transferred to atmosphere. Rates depend on time of year, type + amount of vegetation cover, degree of availablity of moisture in atmosphere & length of growing season Evapotranspiration = Represents most important aspect of water loss t atmosphere, accounts for nearly 100% of annual precipitation in arid/semi-arid areas and 75% in humid. Potential evapotranspiration = Water loss that would occur if there was unlimited supply of water in the soil
Physical factors
UK, flooding causes prolonged + heavy rain associated with passage of low-pressure systems/depressions. Traditional time of year for this sequence = progressive cycle = autumn + winter. But due to unusual positions in jet stream sequence can occur at other times ie, summer floods in 2008) Degree of flooding depends on precise depression sequence sometimes a succession of intense storms occurred in UK from Oct-Dec 2015 = 2015 cumulative effect on drainage Resulted from sinuous jet stream in fairly constant track which = all high-pressure (anticyclone) systems were blocked Around 70% of rainfall of average rainfall within SE Asia occurs during 100 days July - Sep 80% of Bangladeshi people exposed to flood risks. Highest flood risk are along river courses & at edge of the delta Snow + ice = responsible for many flood events, usually in higher latitudes/mountainous areas. Great north flowing Siberian rivers ie, Ob = vast flooding. Quick transition from winter to spring upstream causes rapid snow melting, whilst their lower reaches remain frozen w/ limited infiltration. Flood water often held by temporary ice dams, sometimes rain falss on melting snow when rapid thaw occurs
Compulsory regulations
UNECE Water Convention - promotes joint management + conservation of shared freshwater ecosystems in europe + near by regions UN Water Course Convention - guidelines on protection + use of transboundary rivers WWF -NGO, these agreements have gaps in coverage of issues and lacked enforcement mechanisms/monitoring provision. Only apply to 40% of rivers, Amazon + Zambezi outside any frameworks
Case study, Cumbria
Uplands = orographic rainfall Storm desmond = caused by deep Atlantic low-pressure system, associated fronts stretched across northern Britain = prolonged + heavy through mechanism known as warm conveyor. Dec 2015, 405mm fell at Thirlmere in 38 hours, 5200 homes flooded, major roads + rail service disrupted for several days, landslide closed section of West Coast Mainline, 61,000 homes lost power when electrical substation was flooded. Conveyor of warm + very moist air tracked towards UK from Caribbean where sea temps = unusually high Cumbrian fells = orographic rainfall Moist air mass stayed over for up to 48 hours delivering record amounts of rain Too much rain for already saturated ground to absorb, overland flow carried excess water to rivers which flooded, steep slopes accelerated the process Significant flooding occurred @ river confluence at Cockermouth + Carlisle Impermeable surfaces + sewers/drains blocked by debris meant that surface water flowed rapidly + directly into already over-filled channels Causes of flooding = Carlisle worst hit from river eden. Dece,ber flooding made worse by already saturated ground. Jet streams = driving force which determines direction of depressions + speed of movement. Band of fast-moving air moves north + south but stayed over north west longer than usual = rain laden depressions from Atlantic
Infiltration
Water absorbed into soil. Infiltration capacity is maximum rate which rain can absorbed by soil in given condition. Infiltration capacity decreases with time through period of rainfall until more/less constant low value's reached Rate depends on amount of water in soil as surface/overland flow will take place when soil's saturated Soil texture influences soil porosity Type, amount + seasonal change in vegetations are key. Infiltration more significant in land covered by forests/moorland infiltration rate = 42mm/hour. Permanent pasture infiltration rates = 13-23 mm per hour Nature of soil surface + structure, compacted surface inhibits infiltration Slop angles, very steep slopes encourage overland run-off whilst shallow = infiltration
Rainwater harvesting jars Uganda sustainable
Wateraid = international NGO, raises funds to improve access to safe water, sanitation + hygiene Village, 3,000 people lack access to safe water Local builders trained in construction of rainwater harvesting jars which are made locally available material + have a capacity of 1500 litres. Designed to collect rainwater from roofs + store water for dry periods. Helps community construct on site water supplies close to home. Jars = long life expectancy and can provide water source for years
Synoptic Chart
a map that summarizes atmospheric conditions such as temperature, precipitation, air pressure and cloud cover
Groundwater abstraction
abstracted from aquifiers faster than it's replaced causing reduced groundwater flow + lower water table. In other locations reduced industrial activity or deforestation has increased groundwater storage = increased risk of floods if water table reaches the land surface. Groundwater used to irrigate 40%+ china's farmland and provides about 70% of the drinking water in dry northern/north west regions. Increasing 2.5 billion cubic metres per year and groundwater levels dropped a metre per year 1974-2000 Groundwater rebound occurred in some uk major conurbations ie, Liverpool + Nottingham as result of reduced abstraction for industry.
Anticyclone
an area of high pressure which air slowly circulates in a clockwise (northern hemisphere) or anticlockwise (southern hemisphere) direction. Anticyclones are associated with calm, fine weather.
River regimes
annual variation in discharge/flow of a river at a particular point or gauging station and usually measured in cumecs. Majority of this river flow supplied by groundwater between periods of rain which feeds steadily into river system from base water flow. Masks the fluctuations in stream caused by immediate precipitation Character of the regime can be influenced by factors like: Size of river + location of measurements Amount, pattern + intensity of precipitation Temperatures experienced Geology + overlying soils, their permeability + porosity, water's stored as groundwaters in permeable rocks and gradually released into river as base flow (tends to regulate flow during dry periods) Amount/type of vegetation cover, wetlands can hold water and release it very slowly into the syste, Human activities
Drainage Basin
area of land drained by a river and its tributaries and frequently referred to as river catchment. Subsystem within global hydrological cycle Open system as it has external inputs + outputs that cause the amount of water in the basin to vary over time. These changes can occur at different temporal scales, from short-term hourly through to daily, seasonal + annual Boundary of drainage basin is defined by watershed, which is usually a ridge of high land which divides + separates waters flowing to different rivers.
Wetlands
area of marsh, fen, peatland or water, natural/artificial, permanent or temporary with water that's static or flowing, fresh, brackish or salt. Covers 10% of earth's land surface Acts temporary water stores, mitigating river floods downstream, protecting land from destructive erosion, acting as washlands + recharging aquifiers Chemically act like giant filters by trapping + recycling nutrients + pollutants = maintain water quality High biological productivity + support diverse food web Contribute to value for humans as they provide resources, services (hydrology within water cycle) + as carbon stores (peat) Supporting services = primary production at very high level, nutrient cycling, food chain support, carbon state, life support systems Provisioning services = fuelwood, peat, fisheries, mammals + birds as tourism Cultural services = aesthetic value, recreational use, cultural heritage Regulating services = flood control, groundwater, recharge/discharge, shorelines as change + to protect, water purification Climate change affects inputs, stores + outputs within hydrological system so, climate change = droughts will result in: reduction in inputs, reduce level of water stored in soil, rivers + lakes, increase importance of groundwater flow, cause initial high rates of evaporation
Convectional rain
associated with intense thunderstorms which occur widely in areas with ground heating. Common in tropical areas/uk in the summer. When land becomes hot the air above it becomes warmer, expands + rises. As it rises the air cools and is ability to hold water vapour decreases. Condensation occurs and clouds develop. If air continues to rise = rain falls. Further ascent causes more expansion + cooling = rain takes. Earths hot surface heats air above Heated air rises, expands + cools; condensation takes place. Rising warm air Cool air descends and replaces warm air
Intertropical Convergence Zone (ITCZ)
belt of low pressure that circles the earth, generally near the equator where the trades winds meet
Residence time
can be compared, average time a water molecule will spend in that reservoir/store. These impact on turnover within water cycle system. Groundwater if deep seated can spend 10,000 years beneath earth's surface. Ancient ground water under Sahara Desert, result of former pluvial periods = fossil water, isnt renewable or reachable for human use. Ice core data suggests water in Antarctic is 800,000+ More accessible stores ie, soil moisture is much shorter and easily lost to stores by evaporation, transpiration, groundwater flow or recharge.
Floodplain drainage
common in developed countries to provide land for agriculture + expand urban areas. Drainage process reduces natural storage capacity of floodplain especially where natural wetlands are lost. Land may shrink as dries out getting lower = more susceptible to flooding. Flood mismanagement can occur as alterations @ one point in drainage basin causes negative consequences further downstream. Hard engineering of River Mississippi, research suggests that channelisation, straightening of river by cutting through meanders + construction of artificial levees to increase rivers capacity + velocity have increased flood risk. River engineers claim natural forces overwhelmed effects of 1993 flood but conversation groups/residents on floodplain clam levees + artificial channels constricted river = increasing effects.
Orographic
concentrated on the windward slopes + summits of mountains. when air is forced rise over barrier ie, mountain it cools and condensation takes place = rain. The leeward (downwind) slop receives little rain which is known as rain shadow effect.
Urbanisation
creates imperable surfaces that reduce infiltration + increase surface runoff and throughflow through artificial drains; stream + river discharge often increases rapidly. Case study = Carlisle, Manchester
Water stress
demand exceeds availability, less than 1,700m3 water per capita per annum. If country's water to consumption exceeds 10% of its renewable freshwater supply, difficulties in obtaining new quantities.
Water transfer schemes
diversion of water from 1 drainage basin to another (inter-basin transfer). Done by diverting river or constructing large canal to carry water from area of surplus to area of deficit. UK water transfer = wet north west + dry south east (increased climate change) water grid planned but costs + difficulty of achieving of co-operation with private companies. Welsh reservoirs to Liverpool + Birmingham, Lake District to Manchester.
Maximum annual temperatures
high temps = maximum evapotranspiration, precipitation at a minimum and = plants to use up soil moisture store. River levels fall/crops need irrigation
Dam construction
increases surface water stores + evaporation and reduce downstream river discharge. Case study = lake nasser behind aswan dam estimated to have evaporation looses of 10-16 billion cubic metres each year. 20-30% of water volume from Nile
Dam construction =
increases surface water stores + evaporation and reduce downstream river discharge. Case study = lake nasser behind aswan dam estimated to have evaporation looses of 10-16 billion cubic metres each year. 20-30% of water volume from Nile
Geopolitical issues nile
large no of borders is key issue. Colonial history plays part in boundaries. 300 million people live in the area but expected to increase to 600 million by 2030 = 2030 further pressure. Egypt dependent on nile for 95% of water needs but Kenya + Rwanda need supplies in order to develop industries ie, crop irrigation + HEP production. African nations may not have water scarcity issues (physical) they may have economic water scarcity ie, they lack funds + tech to exploit supplies. Demands of rising population + climate change could mean Nile Basin nations could be water scarce by 2025
Throughflow
lateral transfer of water down slope through the soil via natural pipes + percolines
Water scarcity
less than 1,000m3 water per capita per annum. Physical scarcity, difficulty accessing water. Economic scarcity, can't afford access to water. Imbalance between demand + supply.
Percolines
lines of concentrated water flow between soil horizons to the river channel
Albedo
measure of the proportion of the incoming solar radiation that is reflected by the surface back into the atmosphere + space
Saltwater encroachment
movement of saltwater into underground sources (aquifers) of freshwater
Soil moisture recharge
occurs when potential evapotranspiration decreases so it's lower than precipitation and soil store starts to fill up again
Impact of history nile
original agreements for sharing Nile's water was bilateral, Egypt + Sudan agreed by colonial masters. 1929 first signed gave 48 million cubic metres to Egypt + 4 billion to Sudan, 13% going to others. Issue = egypt given right of veto on any modifications in use of Nile's water in other 9 nations. 1959 = second agreement signed, 55.5 billion cubic metres to Egypt + 18.5 billion to Sudan all water effectively given to 2 countries due to evaporation losses. Increased amount to Sudan displayed increased needs. Signed again by colonial powers on behalf of upstream countries who felt they all had enough from other sources. Ethiopia refused to recognize legitimacy of agreement. Historic agreements = unfair allocation. Ethiopia major production of water but low capture
Cyclonic rain
period of sustained, moderately intensive rain, associated with passage of depressions. Happens when warm air, which is lighter/less dense is forced to rise over cold, denser air as it rises air cools and ability to hold water vapour decreases. Condensation occurs and clouds + rain form. Warm air forced to rise when undercut by colder air.
Soil moisture utilisation
potential evapotranspiration increases & exceeds precipitation (more water evaporating from ground surface & transpired by plants than falling as rain. Water also drawn up from soil by capillary action.
water budget equation
precipitation = evapotranspiration + runoff +/ - period of time
Soil moisture surplus
precipitation greater than potential evapotranspiration. Surplus of soil moisture for plants, runoff into streams + recharging groundwater supplies. Soil @ field capacity
Water insecurity
present + future supplies can't be guaranteed so need for physical, political or economic solutions
Integrated water resource management
process that promotes coordinated development + management of water, land + related resources in order to maximize economic + social welfare in equitable manner without compromising sustainability of ecosystems. River basin treated holistically = to protect environmental quality of rivers/catchment + maximum efficency of usage + equitable distribution Main features = Freedom from corruption Environmental protection of all supplies, ecosystems Food + water security for poor Effective dialogues between users + providers Good governance w/ decentralisation of decision making linked to national strategies Appropriate choices regarding water use in economic productivity Effective regulation + planning of use Cash recovery of schemes via effective planning
Water budget
shows annual balance between inputs (precipitation) + outputs (evapotranspiration + channel flow) Can be expressed as = Precipitation (P) = channel discharge (Q) + evapotranspiration (E ) + change in storage (S) Gives direct comparison of natural water supply + demand, makes it possible to identify time periods when precipitation exceeds evapotranspiration (= positive water balance). Or, times when there's negative water balance (evapotranspiration exceeds precipitation) + increased drought risk. Soil moisture budget graph shows annual changes in precipitation + potential evapotranspiration, allows assessment of the impact on soil moisture availability in different climates. Useful for understanding vulnerability of terrestrial ecosystems + challenges for agriculture (especially climate change) -
water budget graph
shows the relationship between precipitation and evapotranspiration and how this affects soil moisture
Soil moisture deficiency
soil water store used up by high rates of evapotranspiration + low precipitation. Plants only survive if adapted or irrigated
Importance of the tropics
steep angle of the sun over tropical oceans allows intense solar radiation causing high evaporation. Trade winds transfer water vapour towards International Tropical Convergence Zone. There, strong, convectional current lifts the air so it cools + condenses into clouds = heavy rain/storms. Most of global rainfall created in ITCz = the biggest flux of transferring water from sea to land
Surface run-off
the movement of water that's unconfined by a channel across the surface of the ground. (overland flow)
Saturated overland flow
upward movement of the water table into the evaporation store
Green revolution
use of high yield varieties of crops along with use of agrochemicals + irrigation to increase yields/improve food supplies
Virtual water =
water transferred by trading in crops + services that require large quantities of water by their production. Importing a tonne of wheat from water rich area, water stressed area can save 1000 cubic metres of water
