Water!Surface Water, Ground Water,

and Treatment SystemsTEKS 7.8C

The effects of human activity on groundwater and surface water

in a watershed.

The History of Water• Water is continually moving around, through, and above the

Earth as water vapor, liquid water, and ice.

• Water is continually changing its form.

• The Earth is pretty much a "closed system," like a terrarium. That means that the Earth, as a whole, neither gains nor loses much matter, including water.

• Although some matter, such as meteors from outer space, are captured by Earth, very little of Earth's substances escape into outer space. This is certainly true about water. This means that the same water that existed on Earth millions of years ago is still here.

• Thanks to the water cycle, the same water is continually being recycled all around the globe. It is entirely possible that the water you drank for lunch was once used by Mama Allosaurus to give her baby a bath.

The Water Cycle• Earth's water is always in

movement on, above, and below the surface of the Earth.

• Since the water cycle is truly a "cycle," there is no beginning or end.

• Water can change states among liquid, vapor, and ice at various places in the water cycle, with these processes happening in the blink of an eye and over millions of years.

Distribution of Earth’s Water

So That Means…

Of all the water on Earth, humans cannot use 99% of it. Of the 1% we can use, 99% is ground water, and 1% is surface water.

Surface Water

• Surface water is any water that is on the surface of the Earth.

• This includes rivers, streams, creeks, lakes, and reservoirs.

Clear Creek near IH-45 and 518.

Watersheds• A watershed is the area of

land where all of the water that falls in it and drains off of it goes into the same place (in our case, Clear Creek).

• The word watershed is sometimes used interchangeably with drainage basin or catchment.

• The watershed consists of surface water -- lakes, streams, reservoirs, and wetlands--and all the underlying ground water.

Clear Creek tributary near Blackhawk Road.

Harris County Watersheds

You are here!

Kemah

Clear Creek Watershed

You are here!

Kemah

Drainage Area:197 square miles

Watershed Population (Harris County):118,026

Open Stream Miles:154 miles

Primary Streams:Clear CreekTurkey CreekMud Gully

All About the Clear Creek Watershed

• The Clear Creek watershed is located in southern Harris County.

• The watershed encompasses portions of Harris, Galveston, Brazoria and Fort Bend counties; 16 cities including Houston, Brookside Village, Pearland, Friendswood, League City, Pasadena, and the Clear Lake Area communities.

Clear Creek tidal area. Near IH-45 and

FM 518.

Environment of the Clear Creek Watershed

• Clear Creek between Clear Lake and the City of Friendswood is in a natural state.

• Its bottom elevations are below sea level and subject to tidal influences.

• A number of natural and recreational parks have been developed along the creek.

• Much of the channel upstream of this line also supports heavy vegetative growth.

Clear Creek from Challenger Seven Memorial Park

Flooding in the Clear Creek Watershed

• Flooding occurs frequently along various reaches of the main channel and its tributaries.

• Storm surge has also caused flooding within the watershed and has the potential to extend upstream from Kemah to I-45.

Land Use in the Clear Creek Watershed

• Development activity has historically been concentrated in the lower end of the watershed around Clear Lake and several smaller cities in the mid and upper portions of the watershed.

• However, in recent decades, development activity has increased throughout the watershed and is expected to continue.

As development continues, there is a great need for

systems that reduce flooding.

Flood Reduction Measures in the Clear Creek Watershed

STRUCTURAL TOOLS• Channel modification is a

man-made change to a channel's characteristics, typically for the purposes of reducing flood damages by increasing its overall conveyance capacity.

• This can be accomplished by widening and/or deepening the channel, reducing the friction by removing woody vegetation, or by occasionally adding concrete lining.

Flood Reduction Measures in the Clear Creek Watershed

STRUCTURAL TOOLS• A stormwater detention basin

is a large, usually excavated area of land, frequently adjacent to a channel, which is designed to receive and hold above-normal stormwater volumes.

• The detained stormwater then slowly drains over time out of the detention basin as water surface elevations in the receiving channel recede.

Flood Reduction Measures in the Clear Creek Watershed

STRUCTURAL TOOLS• Bypass channel

construction involves building a new channel that is attached to an existing channel and, as mentioned, conveying the excess stormwater runoff around its original path.

Flood Reduction Measures in the Clear Creek Watershed

NON-STRUCTURAL TOOLS• Buyout and demolition of

structures that were built deep in flood prone areas where structural projects to reduce flood levels are impractical is a non-construction solution.

• Once a flood prone house is bought and demolished, it will never incur flood damages again. The District actively pursues voluntary buyout opportunities.

Uses of Surface Water• The main uses of

surface water include drinking-water and other public uses, irrigation uses, and for use by the thermoelectric-power industry to cool electricity-generating equipment.

Surface Water Withdrawals, 2000.

Total Fresh Surface Water Withdrawals, 2000

Fresh Surface WaterCategories by Use, 2000

27,300

59

80,000

747 2,64014,900

1,240

135,000

Ground Water• Below a certain depth, the ground that is permeable

enough to hold water is saturated with water. • The upper surface of this zone of saturation is called

the water table.• The saturated zone beneath the water table is called

an aquifer, and aquifers are huge storehouses of water.

Ground Water• Groundwater is the part of precipitation that seeps down

through the soil until it reaches rock material that is saturated with water.

• Water in the ground is stored in the spaces between rock particles (no, there are no underground rivers or lakes).

• Groundwater slowly moves underground, generally at a downward angle (because of gravity), and may eventually seep into streams, lakes, and oceans.

Unsaturated soil

Saturated soil

Aquifers• Aquifers are underground

reservoirs. • Almost no bacteria live in

aquifers. Many pollutants are filtered out as the water passes through the soil on its way to the aquifer.

• To tap the groundwater in an aquifer, wells are dug until they reach the top layer of the aquifer, the water table.

• When a lot of water is pumped from an aquifer, or when there is a dry spell, the water table sinks lower.

Aquifers

• Wells can be drilled into the aquifers and water can be pumped out.• Precipitation eventually adds water (recharge) into the porous rock of

the aquifer. • The rate of recharge is not the same for all aquifers, though, and that

must be considered when pumping water from a well. Pumping too much water too fast draws down the water in the aquifer and eventually causes a well to yield less and less water and even run dry.

Water Treatment

Alum and other chemicals are added to water to attract dirt particles.

Coagulated particles sink to the bottom. Clear water moves on to filtration.

The water passes through filters, some made of layers of sand, gravel, and charcoal that help remove even smaller particles.

A small amount of chlorine is added or some other disinfection method is used to kill any bacteria or microorganisims that may be in the water.

Water is placed in a closed tank or reservoir in order for disinfection to take place. The water then flows through pipes to homes and businesses in the community.

Bibliography

• http://ga.water.usgs.gov/edu/mearth.html

• http://www.gma.org/katahdin/aquifer.html

• http://www.hcfcd.org/photogallery.html#• http://water.epa.gov/learn/kids/drinkingw

ater/watertreatmentplant_index.cfm