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Exo-genetic Forces leading to Weathering Erosion Processes
The geological phenomena and processes that originate externally to the Earth’s surface derived through the strength of the earth. They are genetically related to the atmosphere, hydrosphere and biosphere. Comet and meteoroid impacts, the tidal forces of the moon, radiation from the sun etc. are the factors of exo-genetic forces.
•    The processes which results in general the lowering of land surface through various factors are known as Denudation. Denudation includes all the processes that wear away or rearrange landforms on the surface of the earth.

WEATHERING•    A general term which describes the general process by which rocks are broken down at the earth’s surface into sediments, clays, soils and substances that are dissolved in water.
•    The process of weathering typically begins when the earth’s crust is uplifted by tectonic forces. After the physical breakup and chemical decay of exposed rocks by weathering, the loosened rock fragments and alterations products are carried away through the process of erosion.
•    Erosion relies on transporting agents such as wind, rivers, ice, snow and downward movement of materials to carry weathered products away from the source area. As weathered products are carried away, fresh rocks are exposed to further weathering. Over time, that mountain or hill is gradually worn down.
•    Weathering of rocks is influenced by
1.    Rock Structure (folds, faults, joints, voids),
2.    Climate (temperature, precipitation),
3.    Topography (rainfall depends on topography),
4.    Natural vegetation binds the rocks, decayed organic matter to the formation of carbon dioxide humid acids by penetrating its roots into the earth’s surface.
a)    Physical Weathering
•    When rock is broken and disintegrated without any chemical alternation, the process is called as physical weathering. Physical weathering is caused by:

1.    Frost Action: The repeated action of water freezing in pores of cracks of rocks, or growth and melting of ice crystals in the pore spaces of soils and rocks fractures, disintegrates even the hardest rocks like granite. Frost action occurs predominantly in cold climates.
2.    Temperature: In dry cloudless regions (deserts) a marked diurnal range of temperature leads to mechanical weathering (exfoliation – onion skin weathering). After sunset, sounds like ‘pistol-shots’ are commonly heard in deserts.
3.    Salt Crystal Growth: In the arid climates, as the water evaporates, crystals form from dissolved minerals.

b)    Chemical Weathering:

•    It results from chemical reactions between minerals in rocks and external agents like air or water. Oxygen oxidizes minerals to alteration

products whereas water can convert minerals to clays or dissolve minerals completely.
•    It mainly occurs in the hot and humid climates where heat and moisture are in abundance.
•    Chemical weathering processes :
1.    Hydration: Once minerals have experienced hydration, they become more susceptible to chemical weathering, especially those of carbonation and oxidation.
2.    Oxidation: Oxygen dissolved in water reacts with certain rock minerals, especially iron to form oxides.
3.    Carbonation: Carbon dioxide (CO2) is introduced into a fluid. This is more prominent in karsts (limestone) regions.
4.    Solution: Solid rocks like calcium, potassium, sodium magnesium, etc. get dissolved in water.
5.    Hydrolysis: Water combines with rock-minerals to form an insoluble precipitate like clay mineral.
c)    Biological or Organic Weathering:•    It is the disintegration of rocks as a result of the action by living organisms. 

•    Microscopic organisms like algae, moss, lichens and bacteria can grow on the surface of the rocks and produce chemicals that have the potential of breaking down the outer layer of the rock.
•    They eat away the surface of the rocks. These microscopic organisms also bring about moist chemical micro-environments which encourage the chemical and physical breakdown of the rock surfaces.
d)    Differential Weathering:
•    The difference in rates of weathering due to different types of rocks,
textures or other characteristics is referred to as differential weathering forming unique landforms including pedestals, waterfalls and monadnocks.

•    Climate can also produce differential weathering responses for the same rock type such as limestone weathers more quickly in wet climates than dry climates.

Preamble and Values in Constitution

•    The Preamble to the constitution embodies the essence of the entire constitution and is like an introduction and preface of a book. It explains the purposes and objectives with which the constitution has been written and hence provides the guideline to the constitution.
•    The Objective Resolution , proposed by Pandit Nehru and passed by the Constituent Assembly, ultimately became the Preamble to the Constitution of India.

•    The Preamble, in brief, explains the objectives of the Constitution in two ways: one, about the structure of the governance and the other, about the ideals to be achieved in independent India. It is because of this, the Preamble is considered to be the key of the Constitution.
The objectives which are laid down in the Preamble are:
•    Description of Indian State as Sovereign, Socialist, Secular, Democratic Republic. (Socialist, Secular is added by the 42nd Amendment Act, 1976)
• Provision to all the citizens of India i.e.,
– Justice – social, economic and political.
– Liberty – of thought, expression, belief, faith and worship.
– Equality – of status and of opportunity.
– Fraternity – assuring dignity of the individual and unity and integrity of the nation.
Usefulness of the Preamble:
•    The Preamble sets out the objectives which the constituent assembly intended to achieve. As Supreme Court has observed, the Preamble is a key to unravel the minds of the makers of the Constitution. It also embodies the ideals and aspirations of the people of India.
•    The Preamble is non-justiciable in nature, like the DPSPs and cannot be enforced in a court of law.
•    The Preamble cannot override the specific provisions of the constitution. In case of any conflict between the two, the latter shall prevail.
•    The Preamble can neither provide substantive power (definite or real) to the three organs of the State, nor limit their powers under the provisions of the constitution.
•    As observed by the Supreme Court, the Preamble plays a limited and yet vital role in removing the ambiguity surrounding the provisions of the Constitution.
Whether the Preamble is a part of the Constitution or not?
•    The Supreme Court in the Keshvananda Bharti v/s State of Kerala (1973) case overruled its earlier decision (Berubari Case 1965) and made it clear that the Preamble is a part of the constitution and is subject to the amending power of the Parliament as any other constitutional provisions, subject to basic structure of the constitution.
•    However, it is not an essential part of the constitution; still it serves as an important guide to interpret the true spirit of the Constitution.
Whether Preamble can be amended or not?
•    The Supreme Court in Keshvananda Bharti (1973) case has held that, Preamble may be amended subject to basic structure of the constitution. In other words the amendment should not destroy the basic features of it.
•    In fact, Preamble has been amended by 42nd Amendment 1976 whereby three words viz, socialist, secular and integrity were added.
Significance of the Preamble:
•    The Preamble declares that it is the people of India who had enacted, adopted and given the Constitution to themselves. Thus, sovereignty lies ultimately with the people.
•    It also declares the ideals and aspirations of the people that need to be achieved.
•    Ideals are different from aspirations. While ideals have been achieved with the Constitution proclaiming India as Sovereign, Socialist, Secular, Democratic Republic’, the aspirations include justice, liberty, equality and fraternity, which are yet to be achieved. The ideals are the means to achieve aspirations.
Ideals (mentioned in Preamble):
•    The word ‘Sovereign’ emphasizes that there is no authority outside India on which the country is in any way dependent.
•    By the word ‘Socialist'(added by the 42nd Amendment Act 1976), the Constitution means that the achievement of socialistic pattern of society through democratic means.
•    India is a ‘Secular (added by the 42nd Amendment Act 1976) state’ does not mean that India is non-religious or irreligious, or anti-religious, but simply that the State in itself is not religious and follows the age-old Indian principle of “Sarva Dharma Samabhava”. It also means that the State shall not discriminate against the citizens in any way on the basis of religion.
•    The State regards religion to be the private affair of a person including the right to believe or not to believe in a religion.
•    The term ‘Democratic’ means that the rulers elected by the people only, have the authority to run the government. India follows a system of ‘Representative Democracy’, where the MPs and MLAs are elected directly by the people.
•    Efforts are being made to take democracy to the grassroots through Panchayats and Municipalities (73rd and 74th Constitutional Amendment Acts, 1992). However, the Preamble envisages not only political democracy but also social and economic democracies.
•    The word ‘Republic’ means, the head of the state is an elected representative (directly or indirectly) and not the hereditary monarch.
Aspirations to be achieved (mentioned in Preamble):
•    The Indian Constitution considers political justice to be the means to achieve social and economic justice by making the state more and more welfare oriented in nature.
•    Political Justice in India is guaranteed by universal adult suffrage without any sort of qualification, e.g. education, property, social status and tax return.
•    While social justice is ensured by abolishing any title of honour (Art. 18) and untouchability (Art.17), economic justice is guaranteed primarily through the Directive Principles.
•    The Indian Constitution guarantees six democratic freedoms to the individuals under Art-19 and Right to Freedom of Religion under Arts-25-28. Thus providing essential liberty to the society for their fullest development of intellectual, mental and spiritual thoughts.
•    Our Constitution ensures equality in the matters of status and of opportunity by declaring any discrimination illegal by the state only on the basis of religion, caste, sex or place of birth (Art-15) by throwing open public places to all by abolishing untouchability (Art-17) and by abolishing titles of honour Art-18).
•    However, various laws and regulations have been passed for the upliftment of SCs, STs, OBCs, Children and also for women (Protective Discrimination).
•    Fraternity as enshrined in the Constitution means a sense of brotherhood prevailing amongst all the sections of the people. This is sought to be achieved by making the State secular, guaranteeing fundamental and other rights equally to people of all sections, and protecting their interests. However, fraternity is an evolving process and by the 42nd amendment, the word `integrity’ was added, thus giving it a broader meaning.

NFHS-4 survey

•    NFHS-4 is the first of the NFHS series that collects data in each of India’s 29 States and all 7 Union Territories. Also, NFHS-4, for the first time, will provide estimates of most indicators at the district level for all 640 districts of the country included in the 2011 Census.
•    In NFHS-4, women aged 15-49 years and men aged 15-54 years are interviewed. When the survey is completed throughout the country, approximately 570,000 households would be covered for information.
•    The results from NFHS-4 in 15 States/Union Territories indicate that:
a)    Fewer children are dying in infancy and early childhood.
b)    All 15 States/Union Territories have rates below 51 deaths per 1,000 live births, although there is considerable variation among the States/Union Territories.
c)    Almost all mothers have received antenatal care for their most recent pregnancy and increasing numbers of women are receiving the recommended four or more visits by the service providers.
d)    More and more women now give birth in health care facilities and rates have more than doubled in some States in the last decade.
e)     At least 6 out of 10 children have received full immunization in 12 of the 15 States / Union Territories.
f)    Fewer children under five years of age are now found to be stunted, showing intake of improved nutrition.
g)    While this reveals a distinct improvement since the previous survey, it is found that in Bihar, Madhya Pradesh and Meghalaya more than 40% of children are stunted.
h)    Wasting is still very high by international standards in all of the States/Union Territories. Anaemia has also declined, but still remains widespread.
i)    Over two-thirds of households in every State/Union Territory have access to an improved source of drinking water, and more than 90% of households have access to an improved source of drinking water in nine of the 15 States/Union Territories.

About NFHS:
a)      NFHS will provide updates and evidence of trends in key population, health and nutrition indicators, including HIV prevalence. Moreover, the survey will cover a range of health-related issues, including fertility, infant and child mortality, maternal and child health, perinatal mortality, adolescent reproductive health, high-risk sexual behaviour, safe injections, tuberculosis, and malaria, non-communicable diseases, domestic violence, HIV knowledge, and attitudes toward people living with HIV.
b)      The information will enable the GOI to provide national and international agencies to monitor and evaluate policies and programmes related to population, health, nutrition, and HIV/AIDS.


The shorelines and beaches in India serve multidimensional needs such as recreational purpose, seaport for maritime commerce, residential and commercial structures, etc. With the growth of population in the coastal zone, more competing pressures are being put on the shores and beaches. Developmental activities along India’s coastal areas have increased extensively in recent decades and this trend is expected to continue. Due to this the erosion rate has increased.
Causes of coastal erosion
a)     lobal warming
b)    Reclamation of land in certain areas, land erosion;
c)    Economic activities of construction etc. in the coastal zone areas.
d)    Abrasive action along sand and gravel moved by the waves.
e)    Destruction of mangroves, which act as a natural safeguard.
f)    Flooding of river during monsoon also lead to inundation and causes sea erosion.
g)    Worldwide increase in the scale and density of human occupation across shoreline.
Impact of coastal erosion
•    Immediate Effects 
a)    Removal of small islands.
b)    Loss of beach sediments.
c)    Destruction of existing habitats of shore flora and fauna.
d)    Weakening and destruction of sea walls, revetments, bulkheads and other coastal defences.
e)    Loss of agricultural land.
f)    Deposition of sediment on productive lands.
g)    Damage and destruction of jetties.
h)    Damage and destruction of boat-launching facilities, septic tanks, water tanks, and building foundations.
i)    Disruption of communications caused by collapse of seafront, bridge, road, and railway foundations.
•    Secondary Effects 
a)    Loss of income for those who are dependent on coastal areas.
b)    Reduction of protection against future storms.
c)    Creation of unstable cliff slopes.
d)    Pollution of beaches caused by broken sewer lines.
e)    Silting and invasion of saline water behind breached defences.
f)    Flooding of land areas behind breached defences.
g)    Scarcity of drinking water
Mitigation measures
a)    Offshore breakwaters to reduce the face of tidal surges before these reach the land.
b)    Seawalls to reduce flooding inland; including the initial surges.
c)    Construct concrete floodwalls to direct floodwaters away from populated areas.
d)    Bulkheads, to-hold landfill in place.
e)    Revetments, usually, large- stones, on relatively flat slopes to slowdown flooding.
f)    The “Soft” Engineering Approach includes: Sand fills; Sand fences; Beach grasses and Salt marshes.
g)    The “passive” or non-structural approaches include using zoning regulations to limit -development.
h)    Using building codes to reduce damage from flooding and winds.
i)    Afforestation programme with suitable species.
j)    In all vulnerable coastal areas the Coastal Zone Management should be effectively introduced.
k)    The traditional knowledge of the local people should be tapped and used for sustainable development.

Rain Water Harvesting

Rainwater Harvesting is a process involving collection and storage of rain water (with the help of artificially designed system) that runs off natural or man-made catchment areas e.g. roof top, compounds, rock surface or hill slopes or artificially repaired impervious/semi-pervious land surface.
i.    The cost of recharge to sub-surface reservoir is lower than surface reservoirs.
ii.    The aquifer serves as a distribution system also.
iii.    No land is wasted for storage purpose and no population displacement is involved.
iv.    Ground water is not directly exposed to evaporation and pollution.
v.    Storing water under ground is environment friendly.
vi.    It increases the productivity of aquifer.
vii.    It reduces flood hazards.
viii.    Effects rise in ground water levels.
ix.    Mitigates effects of drought.
x.    Reduces soil erosion.
Rain Water Harvesting Techniques:
There are two main techniques of rain water harvesting.
1.    Storage of rainwater on surface for future use.
2.    Recharge to ground water.

Urban Areas:
Roof top rain water/storm runoff harvesting through:
(i)    Recharge Pit
(ii)    Recharge Trench
(iii)    Tubewell
(iv)    Recharge Well
Rural Areas:
Rain water harvesting through:
(i)    Gully Plug
(ii)    Contour Bund
(iii)    Dugwell Recharge
(iv)    Percolation Tank
(v)    Check Dam/Cement Plug/Nala Bund
(vi)    Recharge Shaft
Examples of Traditional water harvesting system in India
–    Trans-Himalayan Region
•    Zing -Tanks for collecting water from melted ice in Ladakh.
–    Western Himalayas
•    Kul -Water channels in mountain areas Jammu, Himachal Pradesh.
•    Naula -Small ponds in Uttaranchal.
–    Eastern Himalayas
•    Apatani -Terraced plots connected by inlet and outlet channels in Arunachal Pradesh.
–    Northeastern Hill Ranges
•    Zabo -Impounding runoff  in Nagaland
•    Bamboo drip irrigation – Water from streams in the hills is brought to the plains via bamboo pipes for drip irrigation in Meghalaya
–    Brahmaputra Valley
•    Dongs -Ponds in Assam
–    Indo-Gangetic Plain
•    Dighis -Small square or circular reservoir fed by canals from rivers in Delhi
–    Thar Desert
•    Baoris / bers -Community wells in Rajasthan
•    Tankas -Underground tank Bikaner in Rajasthan
–    Central Highlands
•    Johads -Earthen check dams in Alwar district, Rajasthan
Rain water harvesting not only provides the most sustainable and efficient way of water management but also opens the vista of several other economic activities leading to Empowerment of people at grass root. For this Government should come out with appropriate incentive structure and logistics support to make it a real success.

credits: iasscore


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