water and carbon case studies Flashcards
the river eden
about
north west england, between mountains of the lake district and the pennines
source: pennine hills in south cumbria
mouth: solway firth at the scottish border
rural but flows through the city of carlisle
the upland areas that drain into the river carlisle experience extreme weather that can cause flooding downstream
carlisle is particularly vulnerable because its at the confluence of the eden, patteril and caldew rivers and is fairly low lying
the river eden
characteristics
rainfall is higher than the national average because of the relief of the area: mountainous terrain encourages orographic rainfall
high rainfall means lots of water enters the river channels
long and narrow which increases lag time
slopes are steep which reduces lag time and increases peak discharge
the river eden
rock types
highest ground is igneous rocks which are impermeable, infiltration is slow and surface run off is high reducing lag time
rest is limestone and sandstone which are permeable
when precipitation falls in these areas infiltration is quick and there is little surface run off increasing lag time and the amount of water in ground stores increases
the river eden
land use changes
farming
intense farming caused soils to become more compacted e.g. heavy machinery or trampling livestock
2000-2009 30% increase in number of cattle in the eden valley meaning more land is likely to have been trampled
compaction reduces infiltration so surface runoff is higher which means water levels rise quickly during rainfall increasing the risk of flooding
the river eden
land use changes
construction
built up areas increasing e.g. eden gate development
surfaces in built up areas are impermeable which reduces infiltration flows and increases size and speed of surface run off flows
some new developments near carlisle built on floodplains which has created a flood risk to property and required the construction of flood defences
building on floodplains can also cause flooding downstream as water that would naturally infiltrate on floodplains flows downstream instead
the river eden
land use changes
deforestation
much of the original forest cover in the eden basin is gone due to deforestation for timber and land for farming giving way to large areas of grassland and heathland
trees increase infiltration and decrease run off so fewer trees means more runoff, flashier flood hydrographs and a greater risk of flooding
the river eden
climate change
climate change is predicted to change rainfall patterns in the uk
e.g. parts of western uk could get up to 35% more winter rainfall by 2080
increased winter rainfall in the eden basin would increase run off and flood risk
effect of precipitation on the eden basin
storm desmond
december 2015 storm desmond caused flooding in cumbria, some of the worst occurred in the eden basin
shap (village in eden basin): 262.6mm of rainfall in 48 hours, nearly 50mm more than the average rainfall for the whole of december
2000+ properties flooded in carlisle alone
the amazon rainforest
about
worlds largest tropical rainforest
hot, very wet climate and vegetation is very dense
many groups of indigenous people
home to many endangered species
the amazon rainforest
the water cycle
water cycle causes the amazon to be very wet, there is a lot of evaporation over the atlantic ocean and the wet air is blown towards the amazon. this contributes to the amazon’s very high rainfall
warm temps mean evaporation is high in the rainforest itself which increase the amount of precipitation
rainforest has a dense canopy which means that interception is high and as a result less water flows into rivers than might otherwise be expected and does so slowly
affects the amazon environment: it is populated by species that are adapted to high humidity and frequent rainfall
the amazon rainforest
the carbon cycle
carbon sink: stores carbon in vegetation and soil
increasing concentration of co2 in the atmosphere has led to increased productivity in the amazon rainforest because the vegetation is able to access more co2 for photosynthesis, the amount of biomass is increasing
as a result co2 sequestered by the amazon rainforest has increased, making it an even more important carbon store
it has been suggested that even though trees are growing more quickly they are dying younger
as a result we may not be able to rely on the amazon rainforest to continue to be such an effective carbon sink in the future
the amazon
effect of deforestation on the water cycle
1) no tree canopy to intercept rainfall so more water reaches the ground surface
too much water to soak into the soil, instead water moves to rivers as surface run off which increases the risk of flooding
2) reduces the amount of evapotranspiration
means less water vapour reaches the atmosphere, fewer clouds form and rainfall is reduced which increases the risk of drought
the amazon
effect of deforestation on carbon cycle
1) without roots to hold the soil together, heavy rain washes away the nutrient rich top layer of soil, transferring carbon stored in the soil to the hydrosphere
2) less leaf litter so humus isnt formed. the soil cant support much new growth which limits the amount of carbon that is absorbed
3) trees remove co2 from the atmosphere and store it so fewer trees means more atmospheric co2 which enhances the greenhouse effect and global warming
the amazon
effect of climate change
1) in some areas temp is increasing and rainfall is decreasing which leads to drought, the amazon had severe droughts in 2005 and 2010
2) plants and animals living in tropical rainforests are adapted to moist conditions so many species die in dry weathe. frequent or long periods of drought could lead to extinction of some species.
drought can also lead to forest fires which can destroy large areas of forest, releasing lots of co2 into the atmosphere
3) predicted that a 4 degree temp rise could kill 85% of the amazon rainforest which would result in lots of carbon being released into the atmosphere as the dead material decomposed, and less carbon dioxide being taken in from the air by trees for photosynthesis
attempts to limit human impacts on the amazon
selective logging
only some trees (oldest) are felled, most are left standing
this is less damaging to the forest than felling all the trees in an area
if only a few trees are taken from each area the forest structure is kept, the canopy is still there and the soil isnt exposed
this means the forest is able to regenerate so the impact on the carbon and water cycles is small
