Explain any one theory for design of arch dam.
Answers
An arch dam is a concrete dam that is curved upstream in plan. The arch dam is designed so that the force of the water against it, known as hydrostatic pressure, presses against the arch, compressing and strengthening the structure as it pushes into its foundation or abutments.
The Green Revolution has transformed India to a food grain surplus country from a deficit one. No other activity has such immense impact on the socio-economic development of the people as the Green Revolution. Intensification of agriculture over the years has led to overall degradation of the fragile agro-ecosystem. High cost of production and diminishing economic returns from agricultural practices are affecting the socio-economic condition of farmers. Loss of soil fertility, erosion of soil, soil toxicity, diminishing water resources, pollution of underground water, salinity of underground water, increased incidence of human and livestock diseases and global warming are some of the negative impacts of over adoption of agricultural technologies by the farmers to make the Green Revolution successful. Indiscriminate and disproportionate use of chemicals pollutes the soil, air and water and feed and fodders offered to animals. This may be one of the important etiologies of increased productive and reproductive health problems of livestock. Various scientific studies and surveys conducted on fertilizer and pesticide residues during last 45 years indicate the presence of residues of fertilizers and pesticides like nitrates, organochlorines, organophosphates, synthetic pyrethroids and carbamates at higher level than permissible limit in milk, dairy products, water, fodder, livestock feeds and other food products. As urea, a nitrogen-rich fertilizer is used much more than the recommended 4-to-1 ratio to potassium; it is contributing to the global warming. The extent of systematic damages caused in the process of Green Revolution to the soil, groundwater, and ecosystem needs to be quantified. It could lead to irreversible consequence to the life of the people who are benefited once if the timely, adequate and sustainable measures are not taken up to mitigate the harm done by the Green Revolution.