Monday, March 31, 2008

module 2 POPULATION


Population Explosion
•The rapid and dramatic rise in world population that has occurred over the last few hundred years. The world's population increased from 1.65 billion in 1900 to 3.02 billion in 1960. The United Nations estimated that the population reached 6 billion in late 1999. Thus, the size of the population nearly quadrupled in the span of 100 years, a historically unprecedented rate of increase.

Population growth
Population in itself is NOT the problem. The problem is fast rate of growth of people which is giving rise to overpopulation.
Overpopulation refers to when an organism's numbers exceed the carrying capacity of its habitat. In common parlance, the term usually refers to the relationship between the human population and its environment, the earth.
Overpopulation is not simply a function of the size or density of the population. Overpopulation can be determined using the ratio of population to available sustainable resources. If a given environment has a population of ten, but there is food or drinking water enough for only nine, then that environment is overpopulated.

How to set equlibrium between population & environment ?


INTRODUCTION


Overpopulation has had a major impact on the environment of Earth starting at least as early as the 20th century. Many posit that the human population has expanded, enabled by over-exploiting natural resources, with resultant adverse impacts upon biodiversity, aquifer sustainability, climate change and even human health. There are also indirect economic consequences of this environmental degradation in the form of ecosystem services attrition.


STEPS FOR SETTING EQUILIBRIUM



  • Toward a livable future
    How people preserve or abuse the environment could largely determine whether living standards improve or deteriorate. Growing human numbers, urban expansion, and resource exploitation do not bode well for the future. Without practicing sustainable development, humanity faces a deteriorating environment and may even invite ecological disaster.

  • Taking action:

Many steps toward sustainability can be taken today. These include: using energy more efficiently, managing cities better, phasing out subsidies that encourage waste, [etc.]



  • Stabilizing population:

While population growth has slowed, the absolute number of people continues to increase (by about 1 billion every 13 years). Slowing population growth would help improve living standards and would buy time to protect natural resources. In the long run, to sustain higher living standards, world population size must stabilize.



  • Slowing population growth

Environmentalists and economists increasingly agree that efforts to protect the environment and to achieve better living standards can be closely linked and are mutually reinforcing. Slowing the increase in population, especially in the face of rising per capita demand for natural resources, can take pressure off the environment and buy time to improve living standards on a sustainable basis.3,8,11,12



  • Boost Living Standards

As population growth slows, countries can invest more in education, health care, job creation, and other improvements that help boost living standards.11 In turn, as individual income, savings, and investment rise, more resources become available that can boost productivity. This dynamic process has been identified as one of the key reasons that the economies of many Asian countries grew rapidly between 1960 and 1990.5



  • Green development

It is a land use planning concept that includes consideration of community-wide or regional environmental implications of development, as well as site-specific green building concepts. This includes city planning, environmental planning, architecture, and community building



  • Conservation & Management of Environment

Environmental sustainability is defined as the ability of the environment to continue to function properly indefinitely. This involves meeting the present needs of humans without endangering the welfare of future generations. The goal of environmental sustainability is to minimize environmental degradation, and to halt and reverse the processes they lead to.


This includes conservation of


Biome •In-situ conservation • Ex-situ conservatiosn


Water management


Natural Resource management


Conservation of atmosphere



Effects of overpopulation
•Inadequate fresh water
•Depletion of natural resources
•Increased levels of air pollution, water pollution, soil contamination and noise pollution


•Deforestation and loss of ecosystems. Changes in atmospheric composition and consequent global warming
•Mass species extinctions
•Poverty.

Remedies of Effects of overpopulation
•Water conservation & management
•Sustainable development
•Pollution control
•Natural & artificial regeneration of forests
•Social Awareness

Poverty & Population
•High infant and child mortality High rates of infant mortality are caused by poverty. Rich countries with high population densities have low rates of infant mortality.
•Increased chance of the emergence of new epidemics and pandemics]
•Starvation, malnutrition or poor diet with ill health and diet-deficiency diseases (e.g. rickets). Famine is aggravated by coupled with inflation in some regions and a resulting low level poverty. Rich countries with high population densities do not have famine .Poverty of capital formation. Poverty and inflation are aggravated by bad government and bad economic policies. Many countries with high population densities have eliminated absolute poverty and keep their inflation rates very low]
•Low life expectancy in countries with fastest growing populations
•Unhygienic living conditions for many based upon water resource depletion, discharge of raw sewage and solid waste disposal
•Elevated crime rate due to drug cartels and increased theft by people stealing resources to survive
•Conflict over scarce resources and crowding, leading to increased levels of warfare



Family Welfare
Introduction
Welfare of each citizen is the AIM of family welfare Department. It is tried to achieve mainly through saving the lives of mothers and children and improving their health status as well as checking the population growth
India launched the National Family Welfare Programme in 1951 with the objective of "reducing the birth rate to the extent necessary to stabilise the population at a level consistent with the requirement of the National economy. "The Family Welfare Programme in India is recognised as a priority area, and is being implemented as a 100% Centrally sponsored programme. As per Constitution of India, Family Planning is in the Concurrent list. The approach under the programme during the First and Second Five Year Plans was mainly "Clinical" under which facilities for provision of services were created. However, on the basis of data brought out by the 1961 census, clinical approach adopted in the first two plans was replaced by "Extension and Education Approach" which envisaged expansion of services facilities along with spread of message of small family norm.

Implementation of Family Welfare Programme

• Under the Guidance of Secretary & Commissioner (Family Welfare), Commissioner (Health) and Additional Director (Family Welfare) and through primary health care approach Family welfare department is striving to achieve complete welfare of the citizen by organizing and implementing RCH programme through out the state.
•The state Family Welfare department is also carrying out special schemes like Integrated Population Development Project, link couples, rapid referral services, moped loans, National Maternity Benefit Schemes etc. The department is actively working for polio eradication and Intensive Pulse Polio Campaign and surveillance for polio cases are being carried out.



Women & Child Welfare
•The Department of Women and Child Development was set up in the year 1985 as a part of the Ministry of Human Resource Development to give the much needed impetus to the holistic development of women and children. With effect from 30.01.2006, the Department has been upgraded to a Ministry under the independent charge of Smt. Renuka Chowdhury, Minister of State for Women and Child Development.

Mandate
•The broad mandate of the Ministry is to have holistic development of Women and Children. As a nodal Ministry for the advancement of women and children, the Ministry formulates plans, policies and programme; enacts/ amends legislation, guides and coordinates the efforts of both governmental and non-governmental organization working in the field of Women and Child Development. Besides, playing its nodal role, the Ministry implements certain innovative programme for women and children. These programme cover welfare and support services, training for employment and income generation, awareness generation and gender sensitization. These programme play a supplementary and complementary role to the other general developmental programme in the sectors of health, education, rural development etc. All these efforts are directed to ensure that women are empowered both economically and socially and thus become equal partners in national development along with men.

Policy Initiatives
•For the holistic development of the child, the Ministry has been implementing the world's largest and most unique and outreach programme of Integrated Child Development Services (ICDS) providing a package of services comprising supplementary nutrition, immunization, health check up and referral services, pre-school non-formal education.
• Ministry is also implementing Swayamsidha which is an integrated scheme for empowerment of women. There is effective coordination and monitoring of various sectoral programme. Most of the programmes of the Ministry are run through non-governmental organisations. Efforts are made to have more effective involvement of NGOs. The major policy initiatives undertaken by the Ministry in the recent past include universalisation of ICDS and Kishori Shakti Yojana, launching a nutrition programme for adolescent girls, establishment of the



Disaster Management


•Emergency management (or disaster management) is the discipline of dealing with and avoiding risks. It is a discipline that involves preparing for disaster before it happens, disaster response (e.g. emergency evacuation, quarantine, mass decontamination, etc.), as well as supporting, and rebuilding society after natural or human-made disasters have occurred.
•In general, any Emergency management is the continuous process by which all individuals, groups, and communities manage hazards in an effort to avoid or ameliorate the impact of disasters resulting from the hazards
•Disaster management is a multidisciplinary area in which a wide range of issues that range from forecasting, warning, evacuation, search, and rescue, relief, reconstruction and rehabilitation are included.
It is also multi - sectoral as it involves administrators, scientists, planners, volunteers and communities.


Disaster Mitigation


Disaster Mitigation is any action or measure that either prevents that occurrence of a disaster or reduces the severity of its effects. The concept of Disaster Mitigation has been around for many years, even though the term may not be familiar to everyone. An example of Disaster Mitigation is the use of smoke alarms, sprinkler systems and fire escapes. Disaster Mitigation is an integral part of many data center operations, which routinely create backups of important data. Disaster Mitigation can reduce the effects of many hazards, not just fires

The disaster mitigation involves two categories and four phases each:


•Phases and professional activities - The process of emergency management involves four phases: mitigation, preparedness, response, and recovery


Phases and personal activities - The process of emergency management involves four phases: mitigation, preparedness, response, and recovery


Phases and professional activities


Mitigation
Mitigation efforts attempt to prevent hazards from developing into disasters altogether, or to reduce the effects of disasters when they occur. The mitigation phase differs from the other phases because it focuses on long-term measures for reducing or eliminating risk
Preparedness
In the preparedness phase, emergency managers develop plans of action for when the disaster strikes. Common preparedness measures include the
•communication plans with easily understandable terminology and chain of command
•development and practice of multi-agency coordination and incident command
•proper maintenance and training of emergency services
•development and exercise of emergency population warning methods combined with emergency shelters and evacuation plans
•stockpiling, inventory, and maintenance of supplies and equipment
Response
• The response phase includes the mobilization of the necessary emergency services and first responders in the disaster area. This is likely to include a first wave of core emergency services, such as firefighters, police and ambulance crews. They may be supported by a number of secondary emergency services, such as specialist rescue teams.
Recovery
•The aim of the recovery phase is to restore the affected area to its previous state. It differs from the response phase in its focus; recovery efforts are concerned with issues and decisions that must be made after immediate needs are addressed. Recovery efforts are primarily concerned with actions that involve rebuilding destroyed property, re-employment, and the repair of other essential infrastructure


Phases and personal activities
Mitigation
•Personal mitigation is mainly about knowing and avoiding unnecessary risks. This includes an assessment of possible risks to personal/family health and to personal property- example of mitigation would be to avoid buying property that is exposed to hazards, e.g. in a flood plain, in areas of subsidence or landslides
Preparedness
•Preparedness measures can take many forms including the construction of shelters, installation of warning devices, creation of back-up life-line services (e.g. power, water, sewage), and rehearsing evacuation plans.
Response
•The response phase of an emergency may commence with search and rescue but in all cases the focus will quickly turn to fulfilling the basic humanitarian needs of the affected population. This assistance may be provided by national or international agencies and organisations
•The recovery phase starts after the immediate threat to human life has subsided. During reconstruction it is recommended to consider the location or construction material of the property.
The most extreme home confinement scenarios include war, famine and severe epidemics and may last a year or more. Then recovery will take place inside the home. Planners for these events usually buy bulk foods and appropriate storage and preparation equipment, and eat the food as part of normal life.


Note •ELEMENTS OF MITIGATING STEP WILL REMAIN SAME FOR ALL THE DISASTERS-(FLOOD,CYCLONE,EARTHQUAKE,ETC )

(WITH ABOVE MENTIONED MITIGATING STEPS MENTION FOLLOWING AS PER REQUIREMENT OF THE QUESTION)

FLOODS

Floods can be caused by natural, ecological or anthropogenic factors, either individually or as a combined result.
Anthropogenic activities, such as deforestation and shifting cultivation, can also contribute to floods.


Some mitigation measures for floods
Structural measures:
1. Prevention of over-bank spilling by the construction of embankments and floodwalls.
2. Improvement of flow conditions in the channel and anti-erosion measures.
3. Improved drainage.
4. Reservoirs for impounding monsoon flows to be released in a regulated manner after the peak flood flow passes.

non-structural measures :
1.Flood forecasting and warning services.
2.Disaster relief, flood fighting and public health measures.
3.Flood insurance.
4.Maintaining wet lands.
5.Flood forecasting and warning services.

Protection measures from damage to building:
-To avoid residing on river banks and slopes on river sides and the sides of gorges.
-To build at least 250 meters away from the sea coast/ river banks.
-To build proper drainage system in all flood prone areas, so that the water can be drained off quickly to prevent accumulation.

Cyclones:
Cyclones pose a major threat to life and property in many parts of the world. Every year these sudden, violent cyclones bring widespread devastation to coastlines and islands lying in their erratic paths.

Protection measures for damage to building
-Site selection
-Platforms and orientation
-Foundations
-Wall openings
-Glass panelling
-Roof architecture

Syllabus of EM

Course Contents

Module I: Introduction
NGOs and Environmental Activism. Ecosystems: Types of Eco-Systems, Geosphere – Biosphere and Hydrosphere introduction. Major issues of Biodiversity, Biosphere reserves, National Parks and sanctuaries, Natural Resources.

Module II: Population Growth and its effects on the environment:
Problem of Population growth, poverty and environment, Population Explosion, Family Welfare Programme, Women & Child Welfare. Natural Disasters: Floods, earthquakes, cyclones, land slides, disaster management.

Module III: Resources: Renewable and non-renewable
Defining resources, classification of resources, soil and land degradation, economic development and resources use, natural resources accounting. Energy needs, renewable and nonrenewable energy resources, introduction to solar energy and its availability, wind power and its potential, hydropower as a clean source of energy, coal, oil, natural gas etc. introduction to biofuel.

Module IV:Pollution and Solid Waste
Water Pollution: Water resources of India, Hydrological Cycle, methods of water conservation and management, river action plan, ground and surface water pollution. Recycling and management of water and wastewater (domestic and industrial). Air Pollution: Air pollution and air pollutants, sources of air pollution and its effected on human health and vegetations. Green house effect, global warming and climate change. Ambient air quality standards, steps taken by Government to control air pollution. Noise pollution and its impacts on human health.
Solid Waste: Municipal Solid Waste Management, segregation, disposal methods, composting, land fill sites etc. Hazardous waste management, biomedical waste management.

Module V: Environmental Impact Assessment (EIA) and Environmental Management System (EMS):
Introduction to EIA, its impact and case study, notification of MOEF, introduction to ISO 9000 and 14000 standards, environmental information system (EIS), role of information technology in environment. Forest / Dams: Forest degradation and management, hazard based environmental issues, Fast depletion of forest resources and their regeneration, environmental issues related to Mega Hydroelectric Projects / Dams, resettlement and rehabilitation of people; its problems and concerns.

Module VI: Indian and International efforts for environmental protection
Legal framework: Constitutional provisions, the Indian Penal Code, Role of Judiciary in Environmental Protection, Emergence of Environmental Issues, Stockholm Conference on Environment, 1972 and Agenda 21. International Protocols, WTO, Kyoto Protocol, International Agreement on Environmental Management.

Sunday, March 30, 2008

Module 1 Eco-System

Geosphere
•The term Geosphere is often used to refer to the densest parts of Earth, which consist mostly of rock and regolith . In modern texts, geosphere refers to the solid parts of the Earth and is used along with atmosphere, hydrosphere, and biosphere to describe the systems of the Earth. In that context, some geologists prefer "lithosphere" over geosphere, but these words can be used interchangeably .
•The term originally applies to the four nested geospheres identified solid (earth), liquid (water), gas (air), and plasma (fire). The nested geospheres then include the asthenosphere, lithosphere, hydrosphere, atmosphere, and the ionosphere or plasmasphere. The dense geosphere is also subdivided into the crust, mantle, and core. The outer core is unusual in that it is considered to be a liquid, yet it is a part of Earth's interior. The term Geosphere is often used to refer to the densest parts of Earth, which consist mostly of rock and regolith .


Biosphere
•The biosphere is the part of the Earth, including air, land, surface rocks, and water, within which life occurs, and which biotic processes in turn alter or transform. From the broadest biophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, hydrosphere, and atmosphere. This biosphere is postulated to have evolved, beginning through a process of biogenesis or biopoesis, at least some 3.5 billion years ago.


HYDROSPHERE
•A hydrosphere (Greek hydro means "water") in physical geography describes the collective mass of water found on, under, and over the surface of a planet
•The Earth's hydrosphere consists of water in all forms: the ocean (which is the bulk of the hydrosphere), other surface waters including inland seas, lakes, and rivers; rain; underground water; ice (as in glaciers and snow); and atmospheric water vapor (as in clouds). The average depth of the oceans is 3,794 m (12,447 ft), more than five times the average height of the continents
•The abundance of water on Earth is a unique feature that distinguishes our "Blue Planet" from others in the solar system. Approximately 70.8 percent (97% of it being sea water and 3% fresh water) of the Earth is covered by water and only 29.2 percent is landmass. Earth's solar orbit, volcanism, gravity, greenhouse effect, magnetic field and oxygen-rich atmosphere seem to combine to make Earth a water planet.
•The water cycle describes the methods of transport for water in the hydrosphere. This cycle includes water beneath the Earth's surface and in rocks (lithosphere), the water in plants and animals (biosphere), the water covering the surface of the planet in liquid and solid forms, and the water in the atmosphere in the form of water vapor, clouds, and precipitation. Movement of water within the hydrosphere is described by the hydrologic cycle. It is easy to see this motion in rivers and streams, but it is harder to tell that there is this motion in lakes and ponds.

Biodiversity
•Biodiversity is the variation of life forms within a given ecosystem & biome
• Biodiversity found on Earth today consists of many millions of distinct biological species, the product of four billion years of evolution.
•The most straightforward definition of biodiversity is "variation of life at all levels of biological organization". A second definition holds that biodiversity is a measure of the relative diversity among organisms present in different ecosystems. "Diversity" in this definition includes diversity within a species and among species, and comparative diversity among ecosystems.
•The 1992 United Nations Earth Summit in Rio de Janeiro defined "biodiversity" as "the variability among living organisms from all sources, including, 'inter alia', terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems". This is, in fact, the closest thing to a single legally accepted definition of biodiversity, since it is the definition adopted by the United Nations Convention on Biological Diversity

Types of Biodiversity
Biodiversity is often used by ecologists as the "totality of genes, species, and ecosystems of a region“ thus indicating the three levels at which biodiversity exisits:

genetic diversity - diversity of genes within a species. There is a genetic variability among the populations and the individuals of the same species. (See also population genetics.)

species diversity - diversity among species in an ecosystem. "Biodiversity hotspots" are excellent examples of species diversity.

•ecosystem diversity - diversity at a higher level of organization, the ecosystem. Diversity of habitat in a given unit area. To do with the variety of ecosystems on Earth.

Major issues of Biodiversity
•During the last century, erosion of biodiversity has been increasingly observed. Some studies show that about one eighth known plant species is threatened with extinction. Some estimates put the loss at up to 140,000 species per year (based on Species-area theory) and subject to discussion.The figure indicates unsustainable ecological practices, because only a small number of species come into being each year. Almost all scientists acknowledge that the rate of species loss is greater now than at any time in human history, with extinctions occurring at rates hundreds of times higher than background extinction rates
•The factors that threaten biodiversity have been variously categorized. Jared Diamond describes an "Evil Quartet" of habitat destruction, overkill, introduced species, and secondary extensions. Edward Wilson prefers the acronym - HIPPO, standing for Habitat destruction, Invasive species, Pollution, Population, and Overharvesting

Major Issues
•Destruction of habitats
• Exotic species
•Genetic pollution
•Hybridization and genetics

Conservation & Managementof Biodiversity
•The conservation of biological diversity has become a global concern. Although not everybody agrees on extent and significance of current extinction, most consider biodiversity essential. There are basically two main types of conservation options, in-situ conservation and ex-situ conservation.
•In-situ conservation means "on-site conservation". It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or cleaning up the habitat itself, or by defending the species from predators

• Ex-situ conservatiosn means literally, "off-site conservation". It is the process of protecting an endangered species of plant or animal by removing part of the population from a threatened habitat and placing it in a new location, which may be a wild area or within the care of humans. While ex-situ conservation comprises some of the oldest and best known conservation methods, it also involves newer, sometimes controversial laboratory methods.


Biosphere Reserve
The programme of Biosphere Reserve was initiated under the 'Man & biosphere' (MAB) programme by UNESCO in 1971
The term ‘Biosphere Reserve' should denote an area:
•which is, set aside for the conservation of the resources of the biosphere and for the improvement of the relationship between man and the environment;
•which is, to serve as sites for long term scientific research as well as education all over the world.
Biosphere Reserve Objectives
Each Biosphere Reserve is intended to fulfill three basic functions, which are complementary and mutually reinforcing:
•• A conservation function - to contribute to the conservation of landscapes, ecosystems, species and genetic variation;
•• A development function - to foster economic and human development which is socio-culturally and ecologically sustainable;
•• A logistic function - to provide support for research, monitoring, education and information exchange related to local, national and global issues of conservation and development (UNESCO, 2005 s


Protected area categories

•National Parks Conservation of species of a habitat with minimal or very low intensity of human activity. No human resides in the Park, other than a public servant on duty and permitted persons by the Chief Wild Life Warden .Its zone Core

• Sanctuaries Conservation of species and habitats by manipulative management. No human resides in the Sanctuary, other than a public servant on duty and permitted persons by the Chief Wild Life Warden. Its zone - Core, Buffer and Restoration

• Biosphere Reserves Conservation of the natural resources and for the improvement of the relationship between man and the environment therein. Both natural and human-influenced ecosystems; substantial human settlements (rural). Its zone - Core, Buffer, Restoration and Cultural


Wildlife Parks & Sanctuaries in India
The Indian wildlife heritage has a unique status worldwide. It has the second largest base of bio diversity in the world, with 441 Wildlife Sanctuaries and 80 National Parks, which have become destinations for visitors from all around the world. Accounts of man-eaters of Kumaon and other wildlife encountered by Jim Corbett, are fascinating and true, and just a glimpse of many other mysteries and delights of the Indian wildlife that is housed in the sanctuaries around the country. Another incredible feature of these amazing conservatories of exotic wildlife is that they are home to the largest number of tigers and one-horned rhinoceros in the world, as well as the almost extinct Asiatic Lion, and a large percentage of the total elephant population! Also, India's wildlife sanctuaries which cover about 90,000 sq km house more than 500 species of mammals, over 2000 species of birds, over 500 species of reptiles and amphibians and around 30000 species of insects.

Friday, March 21, 2008

MODULE 5 Deforestation

Deforestation
Deforestation is the conversion of forested areas to non-forest land for use such as arable land, pasture, urban use, logged area, or wasteland. Generally, the removal or destruction of significant areas of forest cover has resulted in a degraded environment with reduced biodiversity. In many countries, massive deforestation is ongoing and is shaping climate and geography.
Causes of deforestation
There are many causes, ranging from slow forest degradation to sudden and catastrophic
• clear cutting,
• slash-and-burn,
• urban development
• acid rain, and
• wildfires.
Deforestation can be the result of the deliberate removal of forest cover for agriculture or urban development, or it can be a consequence of grazing animals, primarily for agriculture. In addition to the direct effects brought about by forest removal, indirect effects caused by edge effects and habitat fragmentation can greatly magnify the effects of deforestation.

Impact On Environment
Generally, the removal or destruction of significant areas of forest cover has resulted in a degraded environment with :
•Reduced biodiversity.
•Changed climate and geography.
•Deforestation affects the amount of water in the soil and groundwater and the moisture in the atmosphere.
•Deforestation can destroy genetic variations (such as crop resistance) irretrievably
•Deforestation lessens the landscape's capacity to intercept, retain and transport precipitation. Deforestation also contributes to decreased vapor transpiration, which lessens atmospheric moisture which in some cases affects precipitation levels down wind from the deforested area .

Long-term gains can be obtained by managing forest lands sustainable to maintain both forest cover and provide a biodegradable renewable resource. Forests are also important stores of organic carbon, and forests can extract carbon dioxide and pollutants from the air, thus contributing to biosphere stability and probably relevant to the greenhouse effect. Forests are also valued for their aesthetic beauty and as a cultural resource and tourist attraction

Economic impact
•Historically utilization of forest products, including timber and fuel wood, have played a key role in human societies, comparable to the roles of water and cultivable land. Today, developed countries continue to utilize timber for building houses, and wood pulp for paper. In developing countries almost 3 billion people rely on wood for heating and cooking. The forest products industry is a large part of the economy in both developed and developing countries. Short-term economic gains made by conversion of forest to agriculture, or over-exploitation of wood products, often leads to loss of long-term income. Both West Africa and Southeast Asia have experienced lower revenue because of declining timber harvests. Illegal logging causes billions of dollars of losses to national economies annually

Forest Regeneration
Forest regeneration is the act of renewing tree cover by establishing young trees naturally or artificially-generally, promptly after the previous stand or forest has been removed. The method, species, and density are chosen to meet the goal of the landowner. Forest regeneration includes practices such as changes in tree plant density through human-assisted natural regeneration, enrichment planting, reduced grazing of forested savannas, and changes in tree provenances/genetics or tree species. "Human-assisted natural regeneration" means establishment of a forest age class from natural seeding or sprouting after harvesting through selection cutting, shelter (or seed-tree) harvest, soil preparation, or restricting the size of a clear-cut stand to secure natural regeneration from surrounding trees. "Enrichment planting" means increasing the planting density (i.e., the numbers of plants per hectare) in an already growing forest stand.

Definition and Purposes
Technically the term “dam” relates to the barrier constructed across a stream, valley or similar natural depression for the purpose of impounding water, but popular usage includes the impounded water along with the barrier.
Apart from the obvious requirements of storage for community or stock water supply, the economic purposes served by impounding of water by dams are: land irrigation, generation of electricity by hydraulic power, amelioration of flooding by partial retention of flood waters, and improvement of natural waterway facilities for inland navigation.
Hydroelectricity is electricity produced by hydropower. It is a renewable source of energy, produces no waste, and does not produce carbon dioxide (CO2) which contributes to greenhouse gases. Hydroelectricity now supplies about 715,000 MW or 19% of world electricity (16% in 2003), accounting for over 63% of the total electricity from renewable in 2005.
Negative Impacts of Hydroelectric Projects
•The construction of large dams completely change the relationship of water and land, destroying the existing ecosystem balance which, in many cases, has taken thousands of years to create. Currently there are around 40,000 large dams which obstruct the world's rivers, completing changing their circulation systems: this is not going to occur without dire environmental impactsThroughout the past few years, the negative impacts of dams have become so well known that most countries have stopped building them altogether and are now forced to invest their money into fixing the problems created by existing dams

Greenhouse gas emissions

The reservoirs of power plants in tropical regions may produce substantial amounts of methane carbon di oxide. This is due to plant material in flooded areas decaying in an anaerobic environment, and forming methane, a very potent greenhouse gases.

Soil Erosion
One of the first problems with dams is the erosion of land. Dams hold back the sediment load normally found in a river flow, depriving the downstream of this. In order to make up for the sediments, the downstream water erodes its channels and banks. This lowering of the riverbed threatens vegetation and river wildlife. One of the reasons dams are built is to prevent flooding. However, most ecosystems which experience flooding are adapted to this and many animal species depend on the floods for various lifecycle stages, such as reproduction and hatching. Annual floods also deposit nutrients and replenish wetlands.

Species Extinction
As fisheries become an increasingly important source of food supply, more attention is being paid to the harmful effects of dams on many fish and marine mammal populations. The vast majority of large dams do not include proper bypass systems for these animals, interfering with their lifecycles and sometimes even forcing species to extinction.
Changes to Earth's RotationNasa geophysicist have found evidence that large dams cause changes to the earth's rotation, because of the shift of water weight from oceans to reservoirs. Because of the number of dams which have been built, the Earth's daily rotation has apparently sped up by eight-millionths of a second since the 1950s. Chao said it is the first time human activity has been shown to have a measurable effect on the Earth's

Animal diseases
Animals are subject to a similar range of water related diseases as humans. They may also act as reservoirs for human water-based infections and infections with water-related insect vectors. The promotion of animal husbandry as a secondary, income generating activity for farmers in newly irrigated areas should be carefully evaluated for its possible environmental and health risks.

Aquatic weeds
The main problems of aquatic weeds are that they reduce the storage and conveyance capacity of reservoirs, canals and drains and increase water loss through evapotranspiration. Most irrigation schemes suffer infestations of exotic species. They are difficult and expensive to control, though the use of linings, shade and intermittent drying out can compliment traditional techniques of mechanical removal, careful herbicide application and the introduction of weed eating fish and insects.

Resettlement and Rehabilitation of people( its problems and concerns.)
•Towns and forests located in areas that will be inundated will have to be demolished and removed in order to increase navigability on the river. The loss of forests and agricultural lands will lead to erosion and the build up of sediment at the base of the river and reservoir. This could lead to increased flooding upstream. Sediments and silt contain valuable nutrients necessary to agricultural production. The blocking of sediments behind the dam means that these nutrients may not reach fertile farmland downstream of the dam. This could reduce the fertility of the land.
•The destruction of the villages also leads to problems of pollution. The Yangtze River is already polluted from the shipping of coal, acid rain, and its central location in Chinese industrial activity. Pollutants from towns and waste dumps that will be inundated will add to this pollution. Some funds were set up to aid in cleaning the area for the reservoir, but only the future will show whether a sufficient job was done. Water moves slower in the reservoir and some are concerned that the pollution will sit and worsen water quality of the river.

Population change
Irrigation projects tend to encourage population densities to increase either because they are part of a resettlement project or because the increased prosperity of the area attracts incomers. Major changes should be anticipated and provided for at the project planning stage through, for example, sufficient infrastructure provision. Impacts resulting from changes to the demographic/ethnic composition should also be considered. Training is an important component if new skills are expected.

Income and amenity
The most common socio-economic problems reducing the income generating capacity of irrigation schemes are:
• the social organization of irrigation operation and maintenance (O&M): who will carry out the work (both operation and maintenance); when will irrigation take place (rotation schedules); Poor O&M contributes significantly to long-term salinity and water-logging problems and needs to be adequately planned at the design stage.
• reduced farming flexibility. Irrigation may only be viable with high-value crops thus reducing activities such as grazing animals, operating woodlots etc.
• insufficient external supports such as markets, agro-chemical inputs, extension and credit facilities

Human migration
•Human migration (outside of the nomadic way of life) and displacement are commensurate with a breakdown in community infrastructure which results in a degree of social unrest and may contribute to malnutrition and an increased incidence of disease. Large, new irrigation schemes attract temporary populations both during construction and during peak periods of agricultural labour demands and provision for their accommodation needs to be anticipated. The problems of displacement during project construction or rehabilitation can usually be solved by providing short-term support.

Resettlement
•Often the most significant social issue arising is resettlement of people displaced by the flooding of land and homes or the construction of canals or other works. This can be particularly disruptive to communities and, in the past, insensitive project development has caused unnecessary problems by a lack of consultation at the planning stage and inadequate compensation of the affected population. Technical ministries should seek expert assistance at an early stage. Community re-establishment often includes, for example, pilot farms, extension services and credit schemes.