Introductory Soil and Water Conservation Engineering
II Semester 3rd Feb to 30th June 2020, 2019-20
Teacher Information
Professor
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Email
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Phone
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Dr. K. C. Shashidhar
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shashidhar.kumbar@gmail.com
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9448103268
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Class-1 Reference Material
Introduction to Soil and Water Conservation
Soil and water are our precious heritage. It is obligatory on our part to protect and hand over these resources to further generations. It is estimated that about 50% of the cultivated area in India suffers from severe soil erosion and requires remedial measures. Apart from soil, water is another basic resource for increasing and stabilizing crop production in dry land areas. Rainfall is the only source of water available for crop production. Since these two basic resources play a major role in feeding the nation, we have to conserve these natural resources to sustain our food production.
Conservation: Implies utilization of resources without wasting them, so as to get high level of production indefinitely.
Soil and water conservation Engineering: May be defined as utilization of soil and water without wasting them by involving Engineering Principle, so as to get higher, sustainable agriculture production.
The productivity of some lands has declined by 50% due to soil erosion and desertification. Yield reduction in Africa due to past soil erosion may range from 2 to 40%, with a mean loss of 8.2% for the continent. In South Asia, annual loss in productivity is estimated at 36 million tons of cereal equivalent valued at US$5,400 million by water erosion, and US$1,800 million due to wind erosion. It is estimated that the total annual cost of erosion from agriculture in the USA is about US$44 billion per year, i.e. about US$247 per ha of cropland and pasture. On a global scale the annual loss of 75 billion tons of soil costs the world about US$400 billion per year, or approximately US$70 per person per year.
Only about 3% of the global land surface can be considered as prime or Class I land and this is not found in the tropics. Another 8% of land is in Classes II and III. This 11% of land must feed the six billion people today and the 7.6 billion expected in 2020. Desertification is experienced on 33% of the global land surface and affects more than one billion people, half of whom live in Africa.
Land degradation, a decline in land quality caused by human activities, has been a major global issue during this century and will remain high on the international agenda in the subsequent century. The importance of land degradation among global issues is enhanced because of its impact on world food security and quality of the environment. High population density is not necessarily related to land degradation; it is what a population does to the land that determines the extent of degradation. People can be a major asset in reversing a trend. However, they need to be healthy as well as politically and economically motivated to care for the land. Subsistence agriculture, poverty, and illiteracy can be important causes of land and environmental degradation.
Land degradation can be considered in terms of the loss of actual or potential productivity or utility as a result of natural or anthropic factors; it is the decline in land quality or reduction in its productivity. In the context of productivity, land degradation results from a mismatch between land quality and land use. Mechanisms that initiate land degradation include physical, chemical, and biological processes. Important among physical processes are a decline in soil structure leading to crusting, compaction, erosion, desertification, environmental pollution, and unsustainable use of natural resources. Significant chemical processes include acidification, leaching, salinization, decrease in cation retention capacity, and fertility depletion. Biological processes include reduction in total and biomass carbon and decline in land biodiversity. The latter comprises important concerns related to eutrophication of surface water, contamination of groundwater, and emissions of trace gases (CO2, CH4, N2O, NOx) from terrestrial/aquatic ecosystems to the atmosphere. Soil structure is the important property that affects all three degradative processes. Thus, land degradation is a biophysical process driven by socioeconomic and political causes.
Factors of land degradation are the biophysical processes and attributes that determine the kind of degradative processes, e.g. erosion, salinization, etc. These include land quality as affected by its intrinsic properties of climate, terrain and landscape position, climax vegetation, and biodiversity, especially soil biodiversity. Causes of land degradation are the agents that determine the rate of degradation. These are biophysical (land use and land management, including deforestation and tillage methods), socioeconomic (e.g. land tenure, marketing, institutional support, income and human health), and political (e.g. incentives, political stability) forces that influence the effectiveness of processes and factors of land degradation.
Depending on their inherent characteristics and the climate, lands vary from highly resistant, or stable, to those that are vulnerable and extremely sensitive to degradation. Fragility, extreme sensitivity to degradation processes, may refer to the whole land, a degradation process (e.g. erosion) or a property (e.g. soil structure). Stable or resistant lands do not necessarily resist change. They are in a stable steady state condition with the new environment. Under stress, fragile lands degrade to a new steady state and the altered state is unfavorable to plant growth and less capable of performing environmental regulatory functions.
Why Conservation
During the last century, it has been observed that the pressure of increasing population has led to degradation of these natural resources. In other words, increase in agricultural production to feed the increasing population is only possible if there is sufficient fertile land and water are available for farming. In India, out of 328 million hectares of geographical area, 68 million hectares are critically degraded while 107 million hectares are severely eroded. That's why soil and water should be given first priority from the conservation point of view and appropriate methods should be used to ensure their sustainability and future availability.
Global soil degradation map. (Source: UNEP, International Soil Reference and Information Centre (ISRIC), World Atlas of Desertification, 1997)
Water conservation is the use and management of water for the good of all users. Water is abundant throughout the earth, yet only three percent of all water is fresh water, and less than seven-tenths of freshwater is usable. Much of the usable water is utilized for irrigation. Detailed analysis will show that in about fifteen years, about two-thirds of the world’s population will be living in some sort of water shortage. Water is used in nearly every aspect of life. There are multiple domestic, industrial and agricultural uses. Water conservation is rapidly becoming a hot topic, yet many people do not realize the importance of soil conservation.
Soil conservation is defined as the control of soil erosion in order to maintain agricultural productivity. Soil erosion is often the effect of many natural causes, such as water and wind. There are also human factors which increase the rate of soil erosion such as construction, cultivation and other activities. Some may argue that since it is a natural process, soil erosion is not harmful. The truth is that with the removal of the top layer of soil, the organic matter and nutrients are also removed.
Conservation is not just the responsibility of soil and plant scientists, hydrologists, wildlife managers, landowners, and the forest or mine owner alone. All citizens should be made aware about the importance of natural resources as our lives depend on that and everyone should be involved in the process of caring of these resources properly and using them intelligently.
History of evolution of SWC programs in India.
Year SWC program
Period I: Pre-Independence period
1900 First Soil and Water Conservation Act by Punjab State
1928 Recognition of soil erosion problem by Royal Commission on Agriculture
1930 Establishment of dry land research centers (Bombay dry farming practices)
1938 Scheme for dry farming development: Emphasis on contour bunding
1945 Famine commission: SWC was considered as a component of relief measures
Period II: Post-Independence period
1950-60 Enactment of Soil and Water Conservation Acts by several states in India All India Soil Survey and Land use organization
1954 Starting of Central Soil and Water Conservation Research and Training Institute(CSWCRTI) Special schemes for drought /desert prone areas (SWC works mainly as relief programs)
1961 Launching of River Valley Schemes/projects
1975 Implementation of Operations Research Projects
Period III: Watershed development program era
1982 Launching of 46 model watershed projects (WDP) for the development of dry lands
1984 World Bank Assisted WDP in four states
1986 National Watershed Development Programs for Rain fed Areas (NWDPRA) in 16 states
1989 Integrated Waste Land Development Program (National Wasteland Development Board)
1992 National Watershed Development Project for Rain fed Areas (NWDPRA)
2001 Sujala Watershed project
Source: Shah (1999) and others
Estimates of all degraded lands (in million km 2) in dry areas (Dregne and Chou, 1994).
Continent
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Total area
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Degraded area †
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% degraded
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Africa
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14.326
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10.458
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73
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Asia
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18.814
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13.417
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71
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Australia and the Pacific
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7.012
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3.759
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54
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Europe
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1.456
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0.943
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65
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North America
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5.782
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4.286
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74
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South America
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4.207
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3.058
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73
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Total
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51.597
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35.922
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70
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