Brackish water

1. BRACKISH WATER
• Brackish water, also sometimes termed brack water, is water
occurring in a natural environment having more salinity than freshwater,
but not as much as seawater.
• It may result from mixing seawater (salt water) with fresh water
together, as in estuaries, or it may occur in brackish fossil aquifers.
• Certain human activities can produce brackish water, in particular civil
engineering projects such as dikes and the flooding of coastal marshland
to produce brackish water pools for freshwater prawn farming.

2. • Brackish water, generally defined as water with TDS content between
that of freshwater (≤500 mg l−1 TDS) and seawater (33 000–48 000
mg l−1 TDS), can occur naturally as brackish groundwater in
subsurface saline aquifers, as surface water due to natural erosion, or
as a result of seawater mixing with river water (in estuaries) or
groundwater (in coastal aquifers).
• Brackish water is also the primary waste product of the salinity
gradient power process.
• Because brackish water is hostile to the growth of most terrestrial
plant species, without appropriate management it is damaging to the
environment.

3. BRACKISH WATER BODIES OF WORLD
Brackish Seas :
• Baltic Sea (the world’s largest inland brackish sea)
• Black Sea
• Hudson Bay and James Bay
• Salish Sea
• Ariake Sea

4. Brackish Lakesin World :
• Lake Turkana in Kenya and Ethiopia
• Bras d’Or Lake on Cape Breton Island in Nova Scotia, Canada
• Laguna de Oviedo in the Dominican Republic
• Lake Charles, Louisiana, United States
• Lake Manitoba in Manitoba, Canada[1]
• Lake Maracaibo in Zulia State, Venezuela
• Lake Monroe in Florida, United
• Lake Shinji in Japan
• Lake Hamana in Japan
• Lake Saroma in Japan

5. Brackish Lakes of India :
• Chilika Lake in Odisha, India
• Kaliveli Lake in Tamil Nadu, India
• The Kerala Backwaters, a series of lagoons and lakes in Kerala, India
• Muthupet Lagoon in Tamil Nadu, India
• Pulicat Lake in Andhra Pradesh, India
• The Rann of Kutch between Gujarat, India and Sindh, Pakistan

6. BRACKISH WATER HABITATS :
ESTUARIES : Brackish water condition commonly occurs when fresh
water meets seawater. In fact, the most extensive brackish water
habitats worldwide are estuaries, where a river meets the sea.
• Estuaries are a type of wetland that contains brackish water. These
are areas that are covered with water during parts of the year and are
very biodiverse areas (contain many different species).
• Estuaries and their surrounding wetlands are bodies of water usually
found where rivers meet the sea.

7. • The characteristics of each estuary depend upon the local climate,
freshwater input, tidal patterns, and currents.
• However, not all estuaries contain brackish waters. There are a small
number of ecosystems classified as freshwater estuaries. These
estuaries occur where massive freshwater systems, such as the Great
Lakes in the United States, are diluted by river or stream waters
draining from adjacent lands.
• Many plant and animal species thrive in estuaries. The calm waters
provide a safe area for small fish, shellfish, migrating birds and shore
animals. The waters are rich in nutrients such as plankton and bacteria.

8. BRACKISH WATER BODIES :
• Amazon River, empties so much freshwater into the Atlantic Ocean
that it reduces the salinity of the sea for hundreds of kilometres
• Chesapeake Bay in Maryland and Virginia. It is the drowned river
valley of the Susquehanna River. It is the largest estuary in the United
States.
• Delaware Bay, an extension of the Delaware River in New Jersey and
Delaware, the United States
• Great Bay, an extension of the Piscataqua River in Portsmouth, New
Hampshire, United States

9. MANGROVES :
• Another important brackish water habitat is the mangrove swamp or
mangal. Many, though not all, mangrove swamps fringe estuaries and
lagoons where the salinity changes with each tide.
• Among the most specialised residents of mangrove forests are
mudskippers, fish that forage for food on land, and archer fish, perch-
like fish that “spit” at insects and other small animals living in the
trees, knocking them into the water where they can be eaten.

10. • Although often plagued with mosquitoes and other insects that make
them unpleasant for humans, mangrove swamps are very important
buffer zones between land and sea, and are a natural defense against
hurricane and tsunami damage in particular.
• The Sundarbans and Bhitarkanika Mangroves are two of the large
mangrove forests in the world, both on the coast of the Bay of Bengal

11. BRACKISH WATER SEA AND LAKES :
• Some seas and lakes are brackish. The Baltic Sea is a brackish sea
adjoining the North Sea.
• The Caspian Sea is the world’s largest lake and contains brackish
water with a salinity about one-third that of normal seawater.
• Hudson Bay is a brackish marginal sea of the Arctic ocean, it remains
brackish due its limited connections to the open ocean, very high
levels freshwater surface runoff input from the large Hudson Bay
drainage basin, and low rate of evaporation due to being completely
covered in ice for over half the year.water

12. • In the Black Sea the surface water is brackish with an average salinity
of about 17-18 parts per thousand compared to 30 to 40 for the
oceans.

13. BRACKISH MARSH :
• Brackish marshes develop from salt marshes where a significant
freshwater influx dilutes the seawater to brackish levels of salinity.
This commonly happens upstream from salt marshes by estuaries of
coastal rivers or near the mouths of coastal rivers with heavy
freshwater discharges in the conditions of low tidal ranges.
• The salinity levels in brackish marshes can range from 0.5 ppt to 35
ppt. Marshes are also characterised by low-growing vegetation and
bare mud or sand flats.

14. • In terms of biodiversity, a brackish marsh serves a unique ecological
niche. Its vegetation is a byproduct of its salinity levels.
• High salinity serves as an evolutionary barrier for most plants,
creating a less diverse number of plant species as an ecosystem
moves from fresh to saltwater. Thus, there are only a few colonies of
saltwater native plants in freshwater and almost no freshwater plants
in saltwater ecosystems.
• Intertidal salt and brackish marshes are found throughout the Pacific
coast, from Kodiak Island and south-central Alaska to the central
California coast.

15. BRACKISH WATER FOR IRRIGATION :
• Brackish water can be directly used for irrigation if there is no fresh
water or fresh water resources are very scarce with the following
considerations:
• The soil salinity and solution concentration should not exceed the
limit of crops salt tolerance after irrigation.
• Brackish water should not be used to irrigate crops at seedling stage
in order to avoid the hazards to crop growth.
• If brackish water is directly used for irrigation, the following measures
should be taken: leaching out of accumulated salt, applying organic
fertilizers, constructing proper drainage system, reducing leakage.

16. • If brackish water is directly used for irrigation, the following measures
should be taken: leaching out of accumulated salt, applying organic
fertilizers, constructing proper drainage system, reducing leakag
• Effective results can be achieved by using brackish water to irrigate
wheat, cotton, corn and other crops timely and properly in the
growing seasons.
• Rotated interval irrigation with brackish and fresh water can be used
with brackish water for salt-tolerant crops or crops at the salt-tolerant
growth stages and fresh water for salt sensitive crops or crops at salt
sensitive growth stages.
• The timing and amount of possible substitution varies with the quality
of the two waters, the cropping pattern, climate, certain soil
properties, and the irrigation system.

17. • Whatever salt buildup occurs in the soil from irrigating with the
brackish water can be alleviated in the subsequent cropping period
when a more sensitive crop is grown with the low-salinity irrigation
water.
• The maximum soil salinity in the root zone that results from
continuous use of brackish water does not occur when such water is
used for only a fraction of the time.
• Furthermore, yield of the sensitive crop is not likely to be reduced if
proper pre-plant irrigations and careful management are used during
germination and seedling establishment to leach salts out of the seed
area and shallow soil depths.

18. • Subsequent in-season irrigations will leach the salts farther down in
the profile ahead of the advancing root system and reclaim the soil
before the brackish water is used again to grow a suitably tolerant
crop.
• This cyclic use of low- and high-salinity water prevents the soil from
becoming excessively saline, while permitting substitution of brackish
for better quality water for a substantial fraction of the irrigation
water used over the long period.
• The application time and volume change with mineralization of water,
crop patterns and water supply conditions.
• Irrigation with mixed brackish and fresh water can improve the
irrigation water quality and increase the amount of irrigation water.

19. USES OF BRACKISH WATER :
• Brackish groundwater is used for drinking purposes in many foreign
countries.
•Salty water pumped from underground sources is being used for
cooling by power generators in the U.S. In 2005, more than 95% of the
saline water drawn from groundwater storage was used by the
thermoelectric-power industry.
• Use of brackish water reverse osmosis in the petrochemical industry.
Feed water from the field is brackish and also typically contains residual
oils, hydrocarbons, solids, and other contaminants. All of these
impurities must be removed before any desalination process can take
place.

20. • Brackish water can be treated to provide a source of reliable drinking
water, more companies and communities are investigating brackish
water desalination as a practical means to avert water scarcity.
Brackish water desalination has filled the need for an alternative
source of fresh water in some areas of the U.S. where seawater
desalination has been controversial and has been challenged by
officials or the public.
• It can be used for agriculture, industrial purposes and domestic
purposes.
• Brackish water is the Breeding grounds for many fish, with species
such as snappers, halfbeaks, and tarpon spawning or maturing among
them. Besides fish, numerous other animals use mangroves, including
such species as the saltwater crocodile, American crocodiles etc can
also breed in mangroves.

21. AREA OF BRACKISH WATER IN INDIA ( 2018)
• Characteristics Area in Thousand Hectares
Orissa 430
Kerala 240
West Bengal 210
Gujarat 100
Tamilnadu 60
Andra Pradesh 60