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Arid region
The hot and arid agro eco region covers southwestern parts of the
states of Punjab and Haryana, western parts of
Rajasthan, Kachchh
peninsula and northern part of Kathiawar
peninsula in Gujarat State.
The area accounts to 31.9 m
ha, representing 9.78 percent of the total geographical area of the
country.
The region is characterized by typical hot summer and cool winter
(arid). The
mean annual precipitation is less than 400 mm. The area is under
rainfed
mono-cropping (traditional) agriculture. The resistant and short
duration rainy
season crops, such as pearl millet, "chari" (fodder), and pulses are
grown in
non-saline areas. The yields are low under average management
practices. In
areas favoured by availability of irrigation water, cotton, sugarcane,
mustard,
gram and wheat are grown.
The natural vegetation comprises sparse, sporadic tropical
thorn forest.
Recent statistics show that the forest area in the region is
drastically
reduced from 15 to almost 1 per cent.
Constraints
- Erratic and scanty rainfall leading to high water deficit.
- Soil salinity leading to frequent physiological
droughts.
- Acute drought at the time of grain formation.
- Nutrient imbalance, especially for N, P Zn and Fe.[1]
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Effect
of climate change on the region
The 500 million persons who live in the world's desert regions can
expect to find
life increasingly unbearable as already high temperatures soar and the
available water is used up or has turned salty, according to the United
Nations
Environment Programme report. It is not the physical growth of deserts
but the
rising water tables beneath irrigated soils that are leading to more
salinisation - a phenomenon already taking place across large tracts of
China,
India, Pakistan and Australia. The Tarm river basin in China,
it says, has lost more than 13,000 sq km of farmland to salinisation in
a
period of 30 years. [2]
But the greatest threat to people and wildlife living
anywhere near
deserts is climate change, which is already having a greater impact on
desert
regions than elsewhere. The Dashti Kbir desert in Iran
has seen a 16 per cent drop in rainfall in the past 25 years, the
Kalahari
a 12 per cent decline and Chile's
Atacama desert an 8 per cent drop.
The Thar desert
- which
basks in sunshine for a yearly average of 320 days - has suddenly been
transformed into a trough of death and destruction. An uninterrupted
weeklong
downpour in August caused flash floods, the worst in at least a
century.
The unprecedented event not only caused extensive damage
to life and
property, it also rendered homeless over a million people in Jaisalmer
and
Barmer districts. More significantly, it shattered the rhythm of desert
life
for communities that had combated drought and water shortage all their
life. [3]
After the surprise flooding of Barmer and other arid
parts of
western Rajasthan, Scientists believe all this water will change not
only the
look of this desert region but also its ecology.
The floods have created at least three large lakes - in
Kawas, Malwa and
Uttarlai - all in Barmer district, and each covering 7-8 sq km. NGO
field-workers involved in conservation and water harvesting estimate
that there
are more than 20 new water bodies in the Barmer-Jodhpur region. Several
water
channels or natural drains have also shown up after the flooding.[4]
Floods are always bad for this region because when water
falls on the
desert, it mixes with the sand and makes water saline and makes it
unfit to
drink.
However, scientist and meteorological experts have
different opinions.
In short, the experts say, what happened in Barmer was nothing out of
the ordinary.
To call flooding in a drought-prone region as nothing unusual might be
hard to
swallow, but meteorologists say that one has to look at the bigger
picture.
According to Nityanand Singh of the Indian Institute of Tropical
Meteorology,
Pune, rainfall has been increasing in the Rajasthan desert since 1973,
though
marginally. What has also made a difference is the decreasing rain
spells, not
just in Rajasthan but in Punjab
and Gujarat. As a
result, the
intensity of showers is greater.
Singh recalls that there were heavy floods in Jodhpur
in 1979 and 1981. He says that given the trend of weather patterns,
there could
be floods in Rajasthan every third or fourth year.
While climate experts are divided on the phenomenon of
industrial
emission-induced global climate change, they are emphatic that one
shouldn't
rush to associate the Barmer floods as a sign of a major change in
weather
patterns in the near future. [5]
Arid region with red soil and black soil
It comprises a part of the Deccan
plateau that includes the districts of Bellary,
SW parts of Bijapur and Raichur of Karnataka and Anantapur of Andhra
Pradesh.
The climate is characterized by hot and dry summer and mild winter. The
rainfall is erratic and ranges from 400 to 500 mm. The yields under
traditional
agricultural practices are very low. Groundnut, sunflower, sugarcane
and cotton
are intensively grown under irrigated conditions wherever feasible.
Constraints
- High runoff and erosion hazard during stormy cloud bursts.
- Prolonged dry spells during crop growing period
resulting in
occasional crop failure.
- Narrow range of workable soil moisture in Black soils.
- Subsoil sodicity affecting soil structure, drainage and
oxygen
availability, especially in subdominant black soils.
- High
subsoil density in red loamy soils limiting
effective rooting
depth.[6]
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