■ USE AUTOMATIC WATERING SYSTEMS THAT USE SOIL MOISTURE AND
WEATHER REPORT DATA: Systems are currently available that only
automatically water when the soil moisture falls below a certain level.CASE STUDIES
ASWAN HIGH DAM, EGYPT: Completed in the 1970s, the Aswan High Dam in
Egypt was built to supply irrigation water. The water that is available is only
half of what was expected due to evaporation and seepage losses in unlined
canals. Several other problems were encountered: First, the elimination of
nutrients onto farmlands now requires the use of expensive fertilizers. Second,
the depletion of nutrients into the Mediterranean caused a decline in certain
fish catches. Third, large amounts of standing water caused the proliferation
of snails and ultimately resulted in a debilitating disease known as
schistosomiasis, with some areas having infection rates of 80%.
BANGLADESH: In the 1960s, thousands of wells were dug in Bangladesh by
foreign governments and humanitarian organizations in an effort to supply
freshwater to the population. Shortly thereafter, arsenic compounds from the
soil began to leach into the groundwater. Arsenic poisoning began to appear
among the population, with millions of people showing symptoms.
CATALINA ISLAND, CA: Catalina Island is one of only a handful of sites that use
the process of reverse osmosis to obtain drinking water from seawater.
Reverse osmosis is a water purification technology that uses a semipermeable
membrane to remove ions, molecules, and larger particles from drinking
water. Ocean water is pumped through seawater wells to a desalination plant,
located in the city of Avalon. The plant’s maximum daily output is about
325,000 gallons.