Human impact on the stores and transfers of the water cycle
da Izzy Glass
1. Water abstraction (the extraction of water from river or groundwater aquifers)
1.1. Water that is abstracted for irrigation, industry and domestic purposes have significant effects on water cycle. Abstraction can result in low flow conditions in rivers, which can have harmful impacts of ecosystems.
1.2. Aquifers can become depleted. And become contaminated by inflowing saltwater if the water table drops below sea level. (issue in London).
2. Example. Irrigation in middle East
2.1. Irrigation has significant impact on water stores and transfers. In Middle East , water is being abstracted from underground aquifers, that were formed thousands of years ago. In danger of becoming depleted as the rate of recharge is slower than rate of use.
3. Example. Land drainage in UK.
3.1. Low land (somerset levels) were once submerged. Land is now highly productive farmland, still vulnerable to flood.
3.2. Drainage of peatlands have impact on water and carbon cycles- the water table is lowered, changing rates of evaporation and infiltration. Dry peat is vulnerable to erosion. Peatlands: thick deposits of partly decomposed vegetation and act as carbon stores.
4. Land use change
4.1. Urbanisation
4.1.1. Replacement of vegetated ground with impermeable concrete and tarmac. Watter cannot infiltrate soil. Increasing overland flow and flooding more likely. Soil water and groundwater stores are reduced.
4.2. Deforestation
4.2.1. Removal of trees, leading ton surface run off and soil erosion. Reducing soil water stores. Run off percentage high, evapotranspiration less.
4.3. Afforestation
4.3.1. Run off percentage low so precipitation is lost or stored before it reaches river channel. Flooding is much less likely.