The water cycle describes the existence and movement of water on, in, and above the Earth. Earth's water is
always in movement and is always changing states, from liquid to vapor to ice and back again.
1.
What is the water cycle?
Evapotranspiration
The water cycle describes the existence and movement of water on, in, and above the Earth. Earth's water is
always in movement and is always changing states, from liquid to vapor to ice and back again. In general, evapotranspiration is the
sum of evaporation and transpiration.
Evapotranspiration is defined as the
Precipitation water lost to the atmosphere from the
ground surface, evaporation from the
Precipitation is water capillary fringe of the groundwater
released from clouds in the table, and the transpiration of
form of rain, freezing rain, groundwater by plants whose roots
sleet, snow, or hail. It is tap the capillary fringe of the
the primary connection in groundwater table.
the water cycle that The transpiration aspect of evapotranspiration is essentially
provides for the delivery of evaporation of water from plant leaves. Transpiration accounts
atmospheric water to the for about 10 percent of the moisture in the atmosphere, with
Earth. Most precipitation oceans, seas, and other bodies of water (lakes, rivers,
falls as rain. streams) providing nearly 90 percent, and a tiny amount
coming from sublimation (ice changing into water vapor
Infiltration without first becoming liquid).
Anywhere in the world, a portion of the water that
falls as rain and snow infiltrates into the subsurface Evaporation
soil and rock. How much infiltrates depends greatly
on a number of factors, such as ground cover or soil Evaporation is the
type. process by which water
changes from a liquid to a
Some water that infiltrates will remain in the shallow gas or vapor. Evaporation
soil layer, where it will gradually move vertically and is the primary pathway
horizontally through the soil and subsurface material. that water moves from the
Eventually, it might enter a stream by seepage into liquid state back into the
the stream bank. water cycle as
atmospheric water vapor.
Some of the water may infiltrate deeper, recharging ground-water Studies have shown that
aquifers. If the aquifers are porous enough to allow water to move freely the oceans, seas, lakes, and rivers provide nearly 90
through it, people can drill wells into the aquifer and use the water for percent of the moisture in theatmosphere via
their purposes. Water may travel long distances or remain in ground- Storage evaporation, with the remaining 10 percent being
water storage for long periods before returning to the surface or seeping contributed by plant transpiration.
As a part of the water cycle, Earth's surface-water bodies are generally
into other water bodies, such as streams and the oceans.
thought of as renewable resources, although they are very dependent on
A very small amount of water vapor enters the
other parts of the water cycle. The amount of water in our rivers and lakes is
atmosphere through sublimation, the process by which
always changing due to inflows and outflows. Inflows to these water bodies
water changes from a solid (ice or snow) to a gas,
Runoff will be from precipitation, overland runoff, ground-water seepage, and bypassing the liquid phase. Sublimation is a common
tributary inflows. Outflows from lakes and rivers include evaporation and
When rain hits saturated or way for snow to disappear quickly in arid climates.
discharge to ground water. Humans get into the act also, as people make
impervious ground it begins to great use of surface water for their needs. So, the amount and location of
flow overland downhill. It is easy surface water changes over time and space, whether naturally or with human
to see if it flows down your help.
driveway to the curb and into a Condensation
storm sewer, but it is harder to
notice it flowing overland in a Condensation is the process in which water vapor in the air is
natural setting. During a heavy changed into liquid water. Condensation is responsible for the
rain you might notice small formation of clouds. These clouds may produce precipitation,
rivulets of water flowing downhill. which is the primary route for water to return to the Earth's
Water will flow along channels as surface.
it moves into larger creeks,
streams, and rivers. Condensation is responsible for your glasses fogging up when
you go from a cold room to the outdoors on a hot, humid day,
for the water that drips off the outside of your glass of soda,
and for the water on the bathroom mirror after you take a
shower.
Adapted from the USGS (http://ga.water.usgs.gov/edu/watercycle.html)
Visit www.RIStormwaterSolutions.org for more resources
2.
Where Does the Water Go?
When rain falls on impervious
surfaces, such as streets, it
travels across the surface and
down the gutters and enters
storm drains, or catch basins.
The point where the runoff leaves the
storm drain system is called the
“outfall.” Unlike sewer systems, which
The water cycle has four main parts: carry wastewater to sewage treatment
precipitation (rain), storage plants, the storm drain system
(puddles, lakes), evaporation (water releases untreated water directly into
going into the air), and stormwater wetlands, streams and the ocean.
runoff. Runoff occurs when the rain From the catch basin, the water
flows over the land until it reaches a enters a pipe. Catch basins are
storm drain other water body. connected to each other by these
pipes. The runoff travels down
the pipes by gravity, flowing to
the lowest point in the system,
Catch basins are often the where the water exits the
first step in stormwater system.
treatment. They trap
debris such as sand and
gravel. The area below Pipes for storm drain
the pipe inlet/outlet is systems can be
called the “sump”. The Catch basins are connected by
made of different
sump allows for some pipes to other catch basins,
materials. The most
contaminants to settle to picking up water from each
common materials
the bottom of the catch basin as it travels through the
are corrugated
basin, making the catch system.
metal, PVC, and
basin one method of concrete. Pipes
treating polluted runoff. also come in many
sizes, depending on
the flow. Generally,
the pipes are small
The catch basins at the beginning of
are vacuumed the system, and
out periodically gradually get bigger
by large vacuum towards the outfall.
trucks.
Adapted from the USGS ??????????????????
Visit www.RIStormwaterSolutions.org for more resources
3.
Rhode Island Watersheds
What is a Watershed?
A watershed, or drainage basin, is the area of land and all waterways that drains
into a particular body of water. All rainfall and melting snow travel to the nearest
waterbody that lies at the lowest point of a watershed.
Watersheds come in all shapes and sizes. They can be as small as a footprint or
large enough to encompass multiple states. Everyone lives in a watershed, and
most are interconnected, eventually draining to the ultimate water bodies – the
bays or oceans. There are about 14 different watersheds in Rhode Island, each
named for the body of water that they drain into (i.e. Hunt River Watershed).
When a watershed becomes developed, the water cycle in that
The Mississippi River watershed area is altered. With more impervious cover (hard surfaces
encompasses 2/3 of the United States. that don’t allow water to soak through), comes an increase in
Stormwater runoff from this watershed is so runoff and pollutant loading.
extensive that a large dead zone (hypoxic
zone) forms where the river drains into the
Gulf of Mexico. The dead zone is so low in
oxygen, that it cannot support life.
+1-315-636-4485
+91 98151-74050 
