Watch this video about modern irrigation methods to introduce this unit: DEFINITIONS Supply: an amount or store of something (food, water, power, gas, electricity, etc.) that can be provided or used if necessary. (suministro) Dams: a barrier to obstruct or control the flow of water, built across a stream or river (presa) Reservoir /ˈrɛzəˌvwɑː/ : a natural or artificial place where water is collected for use, supplying a community or region. (pantano) Spillway: a passageway through which extra water escapes from a reservoir, lake, or the like. (desagüe, aliviadero) Well: a hole drilled into the earth to obtain a natural deposit, as water or petroleum. (pozo) Aquifer: any geological formation containing or conducting ground water, esp. one that supplies the water for wells, springs, etc. (acuífero) Silt: earth carried by moving water and deposited as a sediment. (limo) Dew: moisture condensed from the atmosphere, esp. at night,