Organic effluents such as domestic sewages are a serious problem and the discharge of small quantities of sewages into the aquatic systems can actually increase the productivity of ecosystems, however, excessive quantities will deplete oxygen content, causing severe threat to aquatic life. As a result, the presence of organic and inorganic pollutants in aquatic system continues to be one of the most important environmental issues of the world
Runoff from such concretized surfaces has a high velocity in flow during and after rainfall, which increases storm water in drainage systems in built-up areas. This increases peak flow and overland flow volume and decreases natural groundwater flow as percolation is near impossible and evapotranspiration. Urban runoff has increased pollution and contamination of water bodies in the environment, which leads to serious environmental consequences (Parkinson, et al, 2010). The traditional model of storm water management is based on a misconception by people which the main aim is to drain urban runoff as quick as possible from the environment through channels and pipes and this increases peak flows and costs of storm water management in urban system. This type of solution has been observed to promote or transfer flood problems from one section of the basin of an urban area to another section.
Being long- lasting under natural conditions, the pesticide goes on increasing in soil and water with successive applications. Serious cases of fish mortality have occurred following leaching of pesticides from agricultural fields to nearby rivers after rainfall. Most of the pesticides, being fat soluble, reach the adipose tissue of animal’s including man. On fat breakdown, the pesticides are released in the blood stream producing toxic
Rivers serve as a daily part in humans since ancient times. As industrialization from humans increase, freshwater bodies receive more and different kinds of pollution. Rivers are highly vulnerable to pollution because it is on the receiving end of drainage systems of any catchment area (Bredenhand). As pollution is introduced in water bodies, physical, chemical, and biological changes occur. Continuous increase of urban communities beside water bodies such as rivers results in shortage of clean water supply.
Wastewater: A Resource and a Problem? With increasing urbanization and population in Kathmandu valley consisting of the three historic cities: Kathmandu, Bhaktapur and Lalitpur, the gap between supply and demand for water is expanding and is reaching worrying levels that in some parts of the periphery (peri-urban) areas is creating a threat to the local ecosystems, groundwater aquifers and human health. Globally, scientists are exploring ways to conserve water and reuse urban wastewater for various purposes like, irrigation and other ecosystem services. Generally, wastewater consist of liquid wastes produced by industrial and commercial sources, and households. Currently, Kathmandu valley is experiencing water scarcity due to depleting groundwater and surface water resources caused by over-exploitation of various industries such as, Brick Kilns, Garment industries, water tankers and other commercial industries.
The Biggest Threats to Fresh Water Supplies Fresh water shortages are often associated with distant arid regions plagued by war and famine. But water shortages are now threatening many in the First World, although taps may not have gone dry as of yet. The water crisis is a global phenomenon, and will affect people from all walks of life if we continue to squander our resources and pollute our reserves. Here are some of the greatest threats to our precious water. Population Growth Growing populations are placing greater pressure on water sources and are also leading to greater pollution of the reservoirs that still exist.
With the explosion of population, many pollutant such as water bottles, crisp packages, cans are directly being thrown by human. In many cities and towns, drains are pouring water wastage directly into the river. And it is increasing day by day. River pollution is very harmful for river ecosystem. Due to pollution, there is reduction in the oxygen level.
Literature survey The concept of wastewater treatment first emerged in the 19th century (Esrey , 1998). The primary aim was to prevent the outbreak and spread of water borne diseases (Esrey , 1998). Pollution is a serious concern in the world and with the increasing population size and expansion industrialisation, it has become very control pollution naturally. One of the biggest contributors to pollution is domestic and industrial waste water (Esrey , 1998). Urbanisation and industrialisation has resulted in an increase in the amount of wastewater discharged into the environment.
Every living thing has its own influence on its surrounding, especially human. Human is a creature at the top of the food chine; therefore, the environmental impact by human is inevitable. As technology developed, urban area expanded, and human population increased, our environment got worse. This phenomenon happened in my hometown, Lishui. In this city, local inhabitants’ activities created water, land and air pollution caused insufficient resources, and destroyed habitat and biodiversity.
Due to rapid urbanisation process, the city is emerging as most populated city and this trend generates numerous economic and social externalities and social cost such as deterioration of environmental quality, increased pollution and congestion. Water logging due to storm water is one of the major problem of Mehsana city and intensity of this problem is increasing day by day. Causes of water logging in term of its topography, carrying capacity of the drainage line and the obstruction of natural drainage due to built structure will be assessed. SECOND STAGE:- LITERATURE STUDY In this stage we referred numbers of research paper related to storm water logging, ArcGIS software, DEM, drainage network design, run-off calculation of the study area and some other research paper related to our topic. We have studied water logging problem of different areas due to storm water and design of drainage network in that area.