Water

• The global water cycle is comprised of many stores, the largest being oceans, which contain 97% of global water.
• Only 2.5% of stores are freshwater, of which 69% is glaciers, ice caps and ice sheets and 30% is groundwater.
• Surface and other freshwater only accounts for around 1% of global stores.
• Other surface and freshwater is made up of permafrost, lakes, swamps, marshes, rivers and living organisms.
• In polar regions, 85% of solar radiation is reflected, permafrost creates impermeable surfaces, lakes and rivers freeze, there is rapid runoff in spring, and there is a seasonal release of biogenic gases into the atmosphere.
• In tropical rainforests, dense vegetation consumes 75% of precipitation, there is limited infiltration, deforestation leads to less evapotranspiration and precipitation, there are very high temperatures and very high humidity, and there is convectional rainfall.
• The Earth consists of six cells of circulating air, which form the globe’s climate control.
• Desertification is a process caused by a combination of physical causes such as reduced precipitation and global warming, and human causes like population growth and over-cultivation.
• Mitigation and adaptation to flood risk can involve afforestation of upland areas, restricting construction on floodplains, establishing temporary extra flood plains, and more.
• Meteorological droughts have a major impact on wetlands, reducing interception due to less precipitation causing vegetation to wilt and die, impacting soil nutrients levels and the rest of the complex food web.
• Wetlands have a natural importance and value for human society.
• All drainage basins are vulnerable to surpluses in water, but some locations are more susceptible to flooding due to low-lying land, the base of a river valley and estuaries, urbanised, built environments, and small basins in semi-arid and arid regions.
• If land and sea surface temperatures continue to rise, the period between ENSO cycles could decrease.
• Wetlands contribute to human society by providing resources such as fuelwood, fisheries, and mammals and birds for tourism.
• Anthropogenic Global Warming is due to increased greenhouse gases in the atmosphere, which could lead to several different impacts directly affecting the hydrological cycle.
• Wetlands regulate conditions by providing a regular supply of groundwater and base flow of river, purifying water, and reducing flood risk.
• For the Northern Hemisphere, the Hadley Cell is a part of the ITCZ, where air rises at the Doldrums, travels upwards, then sinks as it meets the cooler air of the Ferrel Cell, causing precipitation to occur.
• The UN Water Courses Convention offers guidelines on the protection and use of transboundary rivers.
• According to the WWF, most agreements lack appropriate enforcement and monitoring in water management.
• Downstream impacts of water management can include restructuring flow, water tables, and pollution.
• Efficiency in water management can involve avoiding waste and mismanagement.
• Prior use of water, including existing historic rights and potential future use, is a tricky question in effective water management.
• Social and economic needs are also factors in effective water management, including population size, welfare of people, and development plans.
• National governments, such as the UK’s environment agency, are involved in checking compliance with EU frameworks.
• The UNECE Water Convention promotes joint management and conservation of shared freshwater ecosystems in Europe and neighbouring areas.
• Dependency on alternative sources can be a factor in effective water management.
• The criteria for effective water management can be based on natural factors such as rainfall amounts, discharge, and share of drainage basin.
• Key players in water management include the UN, the EU, national governments, and non-governmental organisations like WWF.
• The UN Environmental Commission for Europe (UNECE) Water Convention aims to protect and ensure the quality and sustainable use of transboundary water resources.
• The European Union (EU) Water Framework Directive, agreed in Berlin 2000, targets to restore river, lakes, canals, coastal waters to suitable condition.
• Anthropogenic factors influencing the Drainage Basin include Climate, Soil Composition, Geology, Relief, Vegetation, Size, Deforestation, Afforestation, Dam construction, Change in land use, Ground water abstraction, Irrigation, Urbanisation, and Deforestation.
• Stores include Soil Water, Mid-term Groundwater, Long-term River Channel, and Surface Storage.
• Slow Groundwater Flow is the gradual transfer of water through porous rock, under the influence of gravity.
• Water can sometimes become trapped within these deeper layers of bedrock, creating aquifers and long water stores for the drainage basin.
• The percolation rate is dependent on the fractures that may be present in the rock and the permeability of the rock.
• The water table is the upper level at which the pore spaces and fractures in the ground become saturated and is used by researchers to assess drought conditions, health of wetland systems, success of forest restoration programmes etc.
• Transpiration is a biological process where water is lost to the atmosphere through the pores of plants (stomata).
• Evaporation is the loss of water moisture from the surface of a body of water, the soil and interception storage to the atmosphere.
• Outputs of the Drainage Basin include three main outputs: Evaporation, Transpiration, and Stores.
• Physical factors influencing the Drainage Basin include Climate, Soil Composition, Geology, Relief, Vegetation, Size, and Cloud seeding.