The study of the earth’s geology related to the environmental science is known as environmental geology. The environmental geology is an applied science concerned with the practical application of the geology in solving the environmental problems arising time and again. It is a multidisciplinary field which is closely related to the engineering geology and to the lesser extent, to the environmental geography. Each of these fields involves the study of the interaction of the humans with the geological study of the interaction of humans with the geological environment including the biosphere, the lithosphere, the hydrosphere, and to some extent to the atmosphere. The environmental geology includes:
The main cause for degrading the environment today is human. Human is only responsible for degrading the environment by all anthropogenic means. It is also believed that to a large extent, the environment crisis has uplifted in the world due to the result of the deforestation. The process of urbanization and the industrialization has also added a milestone to the degrading condition of the environment. Deforestation upsets the hydrological, climatical and the ecological balance of the environment. Every sort of imbalance arising in nature has its root cause as deforestation. Soil erosion and the landslides are also intimately related to the deforestation. Besides, the artificial cause of the soil erosion is excessive grazing, over- farming, over-exploitation of the fuelwood, unplanned settlement etc.
Mining activities, deforestation, roads on hilly areas, farming and the settlement without scientific consideration has highly accelerated the landslide. Landslides in the hilly areas not only damage the landscape of the place but also cause the loss of the many life and the property. The fertile land is also converted to the bare land as fertile soil is washed down leaving the bare and rocky terrain in the area.
The over-use of the chemicals in industries and farming mine-explosions, extensive use of the petroleum and coal, unnecessary use of polyethene plastics, pesticides, fertilizers, insecticides etc the contamination of the sewages and dust to water resources, unplanned settlements, city industries, and related noise and wastes; has made air, water, and the land pollution collectively. The pollution affects the health, welfare and the quality of the life of the people.
The drought, floods, earthquake, energy crisis, nuclear site disasters, malnutrition and the other related both natural and artificial disasters are accelerating by men’s unscientific activities on the earth. Therefore, it is the time to be conscious to every step for us to protect our existing environment. Every activity where the man involves should not degrade and deteriorate the environment.
From the time of the stone age, human’s are making the use of the natural resources from the iron and from the bronze age they started exploiting the various types of the natural resources like minerals, water, rocks etc. and making multiple uses of these resources. On today’s context, the rocks and minerals are used in the construction materials, decorative stones, ornaments, industrial chemicals and the fossil fuels. Therefore, to fulfill the present public demands all these natural resources are so much exploit and use that they are creating the adverse effect on the natural environment.
Mainly in the environment two types of mining activities are carried out:
The open cast mining brings the visible changes in the landscape such as deforestation, soil erosion, landslides and lowering of the ground level etc. Besides dust, smoke, and other harmful gasses emission from the mining region causes air pollution. The operation of the compressions, drilling, sawing, polishing etc. as a result causes the contamination of the surface water as well as the ground water.
Underground mining is responsible for the subsidence of the ground. The flow of underground may be mixed with the contamination with harmful chemicals and the sludge produced. Besides the blasting during mining causes the noise pollution in an area that adversely affect the people and the species of organism settling in that area.
The geological agents that are responsible for the environmental changes are the landslide, soil erosion, glacier, river flooding, wind in the desert area, earthquake, volcanoes etc.
The most serious hazard in Nepal is a landslide. The outward and the downward motion of the slope forming material under the influence of the gravity by falling, sliding or flowing along the surface of separation at a faster rate is called the landslide. A landslide occurs when the shearing stress exceeds the capacity of underlying support.
The causes of landslide are as follows :
b. Improper land uses pattern.
c. Agricultural practice on the steep slope.
d. Irrigation on steep and vulnerable slope.
e. Grazing for construction material without considering the condition of the train.
f. Construction activities like construction of the roads, canals, slope cutting actions.
The Himalayas of Nepal has young, immature and rugged terrain. The fragile geomorphic and geologic condition of the Himalayas is highly susceptible to the factors causing landslides. The streams and the rivers with the light gradient are the most important agents of the mass wasting of the land.
The Siwaliks range has the young topography with the loss and the unpacked sediments. Sandstones, mudstones, shale layers, conglomerate are the materials contained by sidewalks which are vulnerable to the rapid weather. Conglomerate, in particular, is unconsolidated, loose and can be easily weathered. The southern slope of Siwalik is sloppy and the place receives rainfall of 1000 to 1500 mm causing the soil triggering to the landslide.
The Mahabharat range has the easily weathering rocks like Phylite, slate which cause loose compaction of soil and the steep land. Also, it is drained by big rivers like Koshi, Karnali that cut deep narrow gorges. But some parts with dolomite, gneisses are stable.
The midland region has deeply weathered rocks, thick soil covers. The high rainfall occurs in this region. The rivers in the bottom of the valley deeply involve cutting the base of the slope, improper irrigation practices. The deforestation in this region has made the region more vulnerable to the landslide.
Keller, E.A. Environmental Geology. Columbus, Ohio: Charles E. Miller Publishing Company, Bell and Howell Company, 1985.
Mahapatra, G.B. Textbook of Physical Geology. Shahadra,Delhi-110032: CBS Publishers and Distributers Pvt.Ltd., 1992.