286
through certain processes depending on the use. Water used in agriculture goes
through riparian vegetation to be filtered before it returns to the reservoir. Water
used in mining and other industrial applications such as animal growing and slaughtering operations, is collected in a pond to let the particulate matter settle before it
returned to the environment through agricultural watering or evaporation. Water
used by residential and business consumers is processed at a wastewater treatment
plant before it is returned to the environment.
Huge volumes of raw freshwater are exclusively provided by the Earth’s water
cycle that distills and transports the water from oceans to continents, delivering it as
rain and snow, especially in humid regions and in high-elevation locations within
arid regions. Freshwater extracted from rivers, lakes, or aquifers is the main input to
the water production system. Uniquely for water infrastructure, the output is largely
the same as the input, although there may be some losses and quality transformations in the process. Electricity is the other major input, to run pumps. Raw freshwater is mostly produced for irrigation of crops. Water quality testing is usually not
conducted for raw water, but this is changing because of the threat of bioaccumulative environmental contaminants that could concentrate in irrigation-fed crops and
be passed along to people via the food supply chain.
Raw freshwater is produced in higher volumes and masses than any other commodity, so transportation requires highly specialized infrastructure; in this case,
concrete-lined canals are the solution of choice, although large pipelines and tunnels are sometimes used. Gravity-driven flow is preferred, but sometimes large electrically powered pumping stations are needed when canals lift water, such as the
Central Arizona Project in the USA which lifts Colorado River water thousands of
vertical feet over hundreds of miles of canals. Canals suffer losses from evaporation
and leakage, but these losses are usually small, under a few percent of total flows.
Raw freshwater for irrigation is used almost exclusively in the growing season.
Crops demand water every few days, but storage is not required because canal systems are designed to constantly switch deliveries between distribution systems to
maintain constant flows. Canal systems are often coupled with large storage reservoirs on rivers, and the dams of those reservoirs are capable of storing the river’s
flow during flood seasons and releasing that water to canal systems during the growing season. This storage strategy allows growing season demands to be satisfied
with flood season flows, maximizing the utilization of river flows across the water
year. A typical water year starts at the end of the summer growing season, when the
water balance in the system is at its annual minimum (Fig. 10.7).
A few raw water systems are coupled with mass storage systems that use raw
water transfers to maintain local water balances in areas where water consumption
exceeds the local hydrologic system’s sustainable rate of supply. For example, the
Central Arizona Project in the USA pumps excess Colorado River water into the
aquifers under Phoenix utilizing a legally defined water banking infrastructure to
keep those heavily utilized aquifers sustainably recharged. The owners of the water
are then entitled to withdraw it from the aquifer later, for example if it is needed
during a drought emergency. Snowpack and glaciers on high mountains is an important natural storage infrastructure that effectively provides the same services as
B. L. Ruddell et al.
through certain processes depending on the use. Water used in agriculture goes
through riparian vegetation to be filtered before it returns to the reservoir. Water
used in mining and other industrial applications such as animal growing and slaughtering operations, is collected in a pond to let the particulate matter settle before it
returned to the environment through agricultural watering or evaporation. Water
used by residential and business consumers is processed at a wastewater treatment
plant before it is returned to the environment.
Huge volumes of raw freshwater are exclusively provided by the Earth’s water
cycle that distills and transports the water from oceans to continents, delivering it as
rain and snow, especially in humid regions and in high-elevation locations within
arid regions. Freshwater extracted from rivers, lakes, or aquifers is the main input to
the water production system. Uniquely for water infrastructure, the output is largely
the same as the input, although there may be some losses and quality transformations in the process. Electricity is the other major input, to run pumps. Raw freshwater is mostly produced for irrigation of crops. Water quality testing is usually not
conducted for raw water, but this is changing because of the threat of bioaccumulative environmental contaminants that could concentrate in irrigation-fed crops and
be passed along to people via the food supply chain.
Raw freshwater is produced in higher volumes and masses than any other commodity, so transportation requires highly specialized infrastructure; in this case,
concrete-lined canals are the solution of choice, although large pipelines and tunnels are sometimes used. Gravity-driven flow is preferred, but sometimes large electrically powered pumping stations are needed when canals lift water, such as the
Central Arizona Project in the USA which lifts Colorado River water thousands of
vertical feet over hundreds of miles of canals. Canals suffer losses from evaporation
and leakage, but these losses are usually small, under a few percent of total flows.
Raw freshwater for irrigation is used almost exclusively in the growing season.
Crops demand water every few days, but storage is not required because canal systems are designed to constantly switch deliveries between distribution systems to
maintain constant flows. Canal systems are often coupled with large storage reservoirs on rivers, and the dams of those reservoirs are capable of storing the river’s
flow during flood seasons and releasing that water to canal systems during the growing season. This storage strategy allows growing season demands to be satisfied
with flood season flows, maximizing the utilization of river flows across the water
year. A typical water year starts at the end of the summer growing season, when the
water balance in the system is at its annual minimum (Fig. 10.7).
A few raw water systems are coupled with mass storage systems that use raw
water transfers to maintain local water balances in areas where water consumption
exceeds the local hydrologic system’s sustainable rate of supply. For example, the
Central Arizona Project in the USA pumps excess Colorado River water into the
aquifers under Phoenix utilizing a legally defined water banking infrastructure to
keep those heavily utilized aquifers sustainably recharged. The owners of the water
are then entitled to withdraw it from the aquifer later, for example if it is needed
during a drought emergency. Snowpack and glaciers on high mountains is an important natural storage infrastructure that effectively provides the same services as
B. L. Ruddell et al.