The living environment: The hydrosphere

Dynamic equilibrium Human activities that alter the rates of processes in the hydrological cycle can lead to changes in residence times and quantities in the reservoirs of the cycle.

Agriculture - 70% - for irrigation Industry - 22% - cooling, warming, washing, solvent, paper Domestic use - 8% - toilets, hygiene, washing clothing

Demand for water can change over time. Demand can increase if population increases (higher birth rate V death rate or immigration). Demand can decrease if the population decreases. Also, water consumption per capita (per person) can increase if a nation becomes more affluent (increase in GDP per capita). Increased irrigation of farmland causes higher water consumption. ——————————————————— More People Increased affluence Easier to access (new technology) Increased demand for irrigation Increased Industrialisation (chemical, steel, and paper manufacturing) eg las vagas 24/ 7 in the middle of a dessert

An increase in wealth means more access to water and modern appliances that use water e.g. washing machines, dishwashers. There may also be an increase in industrialisation within developing countries. Subsistence farming may change to commercial farming requiring large irrigation schemes.

Decline in industry e.g. paper Most efficient home appliances People change behaviour Improved maintenance of pipes preventing leaks Increased water recycling Reduced irrigation as improvements in technology e.g. micro irrigation / aquaponics.

Disease (cholera) Poor hygiene Increased time collecting water (less time to access education) Lack of irrigation for crops This economically affects nations as the labour force is reduced, treatment of water becomes more expensive, and farming is reduced.

Deforestation Less interception and evaporation of water on leaves. Less transpiration from inside the leaves. This means less precipitation down wind.

• deforestation • agriculture • urbanisation • Global climate change

Agriculture Crop irrigation increases evaporation. Trampling and compaction of soil means less interception and more surface runoff into rivers / lakes.

Urbanisation Concrete / tarmac is impermeable. Less infiltration and more surface runoff into rivers. Can cause flooding. water drains (in england) link to our sewage pipes

Global Climate Change: -Temperature change affects evaporation, melting, and condensation. - Precipitation patterns change due to change in wind direction / velocity. - Melting land ice will change the flow of rivers. - increase intensity of water - increases the risk of drought - increased permafrost melt

Residence time= volume of water in the reservoir ———————————————— mean transfer rate While the hydrosphere is in an equilibrium it is dynamic. The inputs and outputs increase and decrease over time. Thus, so does the quantity of water in a given reservoir. We refer to this as the Residency Time.

Precipitation stopped by vegetation

Rain and Snow

Water moving from surface into the earth

The flow of sub-surface water through porous rock

Water that flows over the surface when it can’t percolate

Liquid turns to vapour travelling back to the atmosphere

Plant roots take water from the soil to their leaves, which evaporates from their pores

Total amount of moisture removed by processes of evaporation and transpiration

transpiration will increase with increased vegetation cover, which will depend on the type of vegetation and the season. Vegetation with a low albedo (reflectivity), such as dark forests, will absorb more solar radiation, increasing evaporation.

the rate of evaporation increases with temperature. The main energy source is solar radiation, so evaporation and temperature will increase with sunshine hours.

Wind will increase the rate of evaporation by reducing the relative humidity and preventing saturation of the air.

Will determine the amount of water available for transpiration. It is dependent on soil and rock permeability.