Access to Freshwater

Human Uses Domestic Agriculture Industry Electricity Transportation Drinking, washing, cleaning Agriculture Irrigation, drinking for animals 10x higher than domestic use! Industry Manufacturing, mining, cooling Electricity Dam! Transportation Ships on lakes and rivers Boundaries Rivers and lakes mark boundaries between nation states

Water Needs **The UN now uses the term “water crisis” to refer to our current situation It isn’t that there isn’t enough water world wide, but that it isn’t evenly distributed! Up to 40% of humans alive today deal with some level of water scarcity

Sustainability of freshwater resource usage Sustainable use would allow for full natural replacement of the resources exploited and full recovery of the ecosystems affected by their extraction and use Sources of Freshwater Surface Water Rivers, streams, reservoirs, lakes Aquifers Groundwater that can be extracted directly from the surface or via wells.

During a drought, what will happen to the water table?

Aquifers Aquifer: A layer of porous rock adjacent to a layer of impermeable rock Only refilled in places where the porous rock is exposed at the surface and infiltration from precipitation Flow is VERY slow Some “fossil aquifers” are no longer exposed at the surface and therefore are never recharged

2 types of aquifers Renewable aquifer: (Recharges slowly) Natural recharge: replenished naturally by precipitation and percolation Lateral recharge: Recharged from the side by nearby streams and lakes Nonrenewable aquifer: (fossil) very little recharge, deep underground (mining) Formed tens of thousands of years ago Ex. Ogallala, under the Great Plains

Freshwater Issues Climate Change Low water levels in lakes and rivers Disrupts weather patterns altering water supply Low water levels in lakes and rivers Can make navigation impossible affecting economy Slow water flow Causes deposition of sediments which fills the streams and eliminates wetlands Pumping too fast from aquifers Cone of depression Pollution Irrigation degrades soil Evaporated water leaves dissolved minerals on surface causing salinization Thermal Pollution Warm water outflow from power plants affects dissolved oxygen

WITHDRAWING GROUNDWATER Most aquifers are renewable resources unless: water is removed faster than replenished If they are contaminated Groundwater depletion is a growing problem mostly from Irrigation. Effects of Groundwater Over pumping Subsidence: Land can sink which can lead to sink holes Sink Hole Salt Water Intrusion: When the water table is lowered the normal interface moves inland

Possible Solutions Increase Supply Reduce Domestic Use Reservoirs, desalination plants, rainwater collection, artificially recharge aquifers Reduce Domestic Use Low flow toilets, faucets, etc. Closed system car washes Grey water recycling Water from sink could be used in toilet! Irrigation Drought resistant crops, efficient irrigation methods Reduce pesticide/fertilizer use Treat polluted industrial water Regulate maximum temperature of cooling water