The Water cycle exam questions

Explain why water budgets vary between different Drainage basins (6) - Answer--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 e Explain why river regimes might vary (6) - Answer--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 co