Environmental Engineering the application of engineering principles and knowledge to the problems created by man's occupancy and exploitation of the physical environment. It involves studies of hydrology, topography, engineering geology and agricultural engineering. Bangladesh has a tropical monsoon climate but there are significant differences in rainfall, temperature, and exposure to climatic hazards within the country. The heavy rainfall comes in June to October, when major rivers bring in large volumes of water from upper catchments areas in India. When cyclones and tidal waves occur in the bay of bengal, those affect coastal as well as interior regions severely. In fact, the country is quite prone to natural hazards.
Bangladesh is one of the most densely populated countries of the world. A majority of the poor people live in rural areas and earn their livelihood from agriculture and related sectors. Hence, environmental changes or their consequences are a major concern in the country, particularly for rural agricultural development.
Degradation due to organic refuges Housing and drainage wastage, excrement of human beings and animals and their sewage water, organic matters from industries, their solid and liquid wastage, etc are the main elements of organic refuges. Leaching water of these wastage ultimately falls into the sources of water and thus deterioration of environment for human beings, animals and fish are occurring constantly. The use of engineering technologies like dustbins, modern drainage linings, sanitary latrines etc are not yet widespread, even in urban areas. Sanitary latrines are gradually being introduced, but only in advanced rural areas can they be seen. A number of NGOs and the Public Health Engineering Department are working to make people more aware about deteriorating environment.
Degradation due to agricultural activities Agriculture and water are intimately connected. Rainfall, soils, temperature and availability of water are crucial for agricultural production. But the interventions of modern agricultural technologies have cast impact on the agricultural environment. Some of the effects are friendly, but some have also proved to be hazardous to the soil, water, as well as to the total rural health environment.
The use of chemical fertilisers has resulted in a decrease in the use of organic manures. In fact, this has decreased soil fertility, increased chemical fertiliser requirement and consequently reduced the benefit derived from fertilisers by way of depleting plant nutrients. Spraying insecticides and pesticides over standing crops ultimately contaminate the soil and water. This not only destroys harmful insects and pests, but also kills useful soil microbes which slowly retard the biological nutrient replenishment of aquatic animals. On the other hand, exploiting groundwater can be a blessing to agricultural productions, but it can also prove to be as a severe threat to the environment. For instance excessive arsenic in drinking groundwater as well as probability of subsidence due to excessive underground resource withdrawal are harmful consequence of excessive use of groundwater through tubewells.
Degradation due to other activities Scarcity of agricultural land resulting from population pressure in the floodplain has caused a heavy influx of settlers to hilly and forest areas. Improper use of sloping areas and clearing of forests cause severe soil erosion and loss of fertile topsoil. Mining of sand and extraction of gravel from many sites for construction also have negative environmental effects. Apart from loss of land, the most adverse effect on land is local drainage congestion due to unplanned rural network and other projects.
These harmful practices have been affecting the environment adversely. But the engineering techniques of dealing with the situation have not been effective. GO-NGOs and some other foreign organisations are trying to build up awareness as well as taking measures against environmental degradation. But these measures have been provisional and inadequate. Certainly, the country needs to take vigorous initiatives for environmental protection immediately. [MA Hamid]