5.5 irrigation methods

types of irrigation methods

furrow, drip, flood, and spray

furrow irrigation

trench dug along crops and filled w water

easy and inexpensive; water seeps into soil slowly

~66% efficient, 33% lost to runoff and evap

• less efficient

drip irrigation

most efficient, but more expensive

over 95% efficient

holes in hose allow water to slowly drip out

avoids waterlogging and conserves water

large scale very expensive, home garden good

flood irrigation

floods entire field; easier but more disruptive to plants

can watering the soil & drown plants

~80% efficient; 20% lost to runoff evap

spray irrigation

ground/surface water pumped into spray nozzles

more efficient than flood/burrow (less water loss)

more expensive (requires energy for pumps & movement of sprinklers) have to buy medical equipment

waterlogging and solution

overwatering saturates the soil, filling all soil pore space w water, depriving roots of oxygen

solution: drip irrigation, or soil aeration (poke holes in soil to allow air in & water to drain through soil), can stunt growth or kill crops

soil salinization and solution

salinization: salt buildup over time bc groundwater used for irrigation naturally has small amounts of salt

water evaporates, salt is left behind in soil, overtime it can reach toxic levels, dehydrating plant roots & preventing growth

solution: drip irrigation, soil aeration, flushing w fresh water, switch to freshwater source

global human water use

industrial: power plants, metal/plastic manufacturing

municipal: households (toilet, shower, drinking water)

agriculture: water for livestock, irrigation water for crops

aquifers & groundwater

groundwater: h2o stored in pore spaces of permeable rock and sediment layers

aquifer: useable groundwater deposits for humans

• replenished by groundwater recharge(rainwater percolating down thru soil into aquifer)

unconfined aquifers recharge quickly bc they have constant additions of water percolating down = easier to extract

depletion of aquifers causes

saltwater intrusion (near coast), cone of depression (all areas)

saltwater intrusion

excessive pumping near coast lowers water table pressure, allowing salt water to sleep into groundwater

cone of depression

forms when water table is lowered by excessive pumping, depleting water and dying nearby wells