Survival of life on earth depends on the availability of natural resources. The use of these resources has an impact on the environment around us. Water usage leads to its pollution. Coal, oil, minerals and metals are being depleted by increasing usage. A high level of irrigation, unless accompanied by proper drainage, make the soil saline or water-logged. Combustion of fuels results in greater accumulation of carbon dioxide leading to global warming. This use and depletion of resources has an Impact on our environment. About sixty per cent of the land area in the States is under one or other type of agriculture. This is above the national average of 51%. A portion of this land is marginal for agriculture and requires higher inputs but gives lower yields. As subsistence farming is economically nonviable, this land is soon degraded and the soil is eroded. Land that cannot support agriculture could well be suitable for forestry and pasture.
Irrigated land has been rendered saline or water-logged due to water use. Thus in the upper Krishna Project about 71,000 ha, have become either saline or alkaline. In the command area of the Tungabhadra reservoir about 33,000 ha, are either saline or water logged; 24,455 ha are saline or waterlogged in the Malaprabha and Ghataprabha (command) area and 16,500 ha, in the Cauvery basin. Remedial measures are being undertaken in some areas at a high cost.
Pasture lands in the State have been steadily decreasing. During 1956 to 1983, pastures came down by 31% while animal units increased by 30%. Overgrazing is bound to follow together with compacting of the land cattle paths. As a result of the expansion of agriculture and its allied activities, the natural vegetation in the plains has suffered the most. In fact the characteristic vegetation of this habitat namely the scrub forest has almost vanished. The wild life too has practically been wiped out in this tract except in isolated pockets. Similarly in the Western Ghats, the fragmentation of natural vegetation has already reached alarming proportions and this would have serious consequences on the rate of extinction of species. The wild life has been decimated in many parts of the State and its numbers are rapidly dwindling due to loss of habitat, constant fragmentation and illegal killing.
The forest areas in the Western Ghats are being converted into plantations of cardamom, cocoa, rubber, coffee and tea. Simultaneously timber and fuel wood species are replacing the rich tropical forests. These plantations while being commercially remunerative, can cause great harm to the bio-diversity and habitat of the flora andfauna. Vast forest areas have been submerged by hydel projects on the west-flowing rivers. Resettlement of the people displaced by development projects has further reduced the forest area by honey combing the forests with human settlement. Silting is the most serious problems with tanks and reservoirs. The capacity of the tanks goes on decreasing every year, the tank irrigating less and less land, ultimately becoming altogether useless for irrigation when the sluices can no longer be opened. The solution proposed for the silting problem is afforestation of the catchment to the extent possible, banning cultivation in the foreshore lands and construction of small checkdams upstream to trap the silt.
The exploitation of renewable and non-renewable natural resources is likely to have an environmental impact. Increased production of minerals will vary with the location, method and magnitude of operations. Area surrounding the mines will also be affected by the works as well as workers. So the extent and mode of mining must be regulated by ecological considerations for the long term utilisation of resources.
Pollution is the introduction of extraneous materials into environment adversely affecting its normal use. Water pollution is caused mainly by discharge of waste waters into natural water courses and water bodies. Water is being polluted by industries and human habitations. Industrial effluents can cause organic, chemical and even hazardous pollution. In order to control this pollution, effluent standards have been prescribed industry-wise. Thermal pollution caused by water with temperatures above the ambient water temperature is also to be controlled. The Water (Prevention and Control of Pollution) Act was enacted
by Parliament on 23rd March 1974, The greatest water pollution in the State is caused by Urban Agglomerations. It is obligatory on the authorities to treat the sewage before discharging it.
However 139 of the 172 Municipalities do not have functional underground drainage or sewage treatment plants.