Fresh Water Habitat and Their Degradation, Nepal Drinking Water Quality Standard, Ecological Importance of Freshwater Ecosystem

Freshwater habitat and their degradation

Human activities are disrupting and degrading many of the ecological and cultural services provided by the freshwater rivers lakes and the wetlands. Such activities affect the freshwater system in four major ways.First, the dams and the canals get fragment i.e about 40% of the world's 237largest rivers alter and destroy the terrestrial and the aquatic wildlife habitats along the rivers and coastal deltas and the estuaries by reducing the water flows and increasing the damage from the coastal storms. Second flood control levees and dykes built along the rivers disconnect the rivers from their floodplains, destroy the aquatic habitat and after or reduce the functions of nearby wetlands.For example, the 2341 mile Missouri rivers in the waste central US harnessed by the levees and a serious of the six dams, which have disrupted the seasonal variation in the flow of rivers and changed water temperature on some stretches. This hinders the growth of the Insects populations and interferes with the spawning cycle of the fishes and the feeding habits of the shorebirds and thus severely disrupts entire food webs.

The dams and the level also have interrupted by the sediments. As a result of these disturbances dozens of the native have declined and the biodiversity of the ecosystem threatened.A third major impact on the freshwater system comes from cities and farms, which add the pollutants and excess plant nutrients to the nearby stream, rivers or lakes. For example, run off of the nutrients into a lake i.e cultural eutrophication causes the explosion of the population of the algae and the cyanobacteria which deplete the lakes dissolve oxygen . when the organism dies and sink to the lake bottom, decomposers go to the work further deplete the oxygen in deeper water fishes and other species can then die off causing a major loss of biodiversity.

Fourthly many land wetlands have been drained or fitted to grow crops or have been covered with concrete and asphalt and buildings. For examples, more than half of the inland wetlands estimated to have existed in the continental US during the 1600s no longer exist. About 80% of the lost wetlands were destroyed to grow crops. The rest were lost to mining, forestry, oil and gas extraction, highway and urban development. The heavily formed US state of Lowa how lost about 99% of its original inland wetlands.

Protecting and sustaining of freshwater environment

Water is the lifeblood of the biosphere. It connects us to the one another to other forms of life and to the entire planet. But due to the different activities and disruption to the water bodies, the quality and quantity of the water are degraded day by day in the world. Experts warn that within the next 20 years more than half of the world's population could face water shortages. There are some practical solutions or protections measures that can help us and ecosystem to protect the freshwater environment.

1: protecting land to protect water

By preserving the health of land around rivers and lakes the watershed we can keep pollution out of our water.

2: keeping rivers flowing in healthy ways

We can preserve the benefits that rivers give us by preserving the pattern of high and low flow that orchestrate life inand along rivers.

3: averting water scarcity by reducing waste

We can dramatically reduce water waste by giving large users businesses forms cities tools to use water more wisely.

4: reducing the ecological impacts

5: reconnecting floodplains with rivers

6: promoting the sustainable agricultural practice.

7: protecting the coastal river and estuaries.

8: guarding freshwater ecosystem against invasive species.

Often referred to as invasive nuisance exotic or non-native species the shot way can appear being even natural but in the society, they are one of the greatest threats to biodiversity. This problem can be solved by stopping the spread of the invasive species through education, partnership and policy and restoration of the freshwater habitats.

Nepal's drinking water quality standards

Note – these standards indicates that the maximum and minimum limits.

– these standards indicate that the maximum and minimum limits.

** figures in parenthesis are upper range of the standards recommended.

Source: ministry of physical planning (Nepal gazette (BS 2063-3-12)

Ecological importance of the freshwater ecosystem

The Freshwater ecosystem is well connected with the other natural ecosystem due to their close vicinity. However, clearing can disconnect such ecosystem thereby reducing their ability to perform their ecological functions such as maintenance of biodiversity. A natural ecosystem is one that provides habitat for native flora and fauna. It must be relatively undisturbed and must not support rural-urban or industrial land use. A natural ecosystem can be terrestrial or aquatic and they are generally characterised by well-established stands of predominantly native vegetation.

According to the natural wetlands policy 2003 (Nepal), the wetlands of the country's lowlands alone support 32 species of mammals, 461 species of birds (among which 15 species are rare), 9 species of turtle and 20 species of snakes. In addition, a total of 185 species of fishes is found in wetlands of Nepal. Also about 172 species of the major wetland plants are listed by IUCN Nepal including 4 endangered macrophytes such as tree fern, orchid, screw pine and sphagnum moss. According to an estimate, a lake/pond can store water about 4 times of its volume in its surrounding land and help recharge the ground water storage. Wetlands are biological filters where plants and animals present within it help in the purification of incoming polluted water for example microbes and vegetation reduces BOD, N, P, Eicchornia absorbs heavy metals like Hg, Cd, Pb etc.

Similarly, freshwater habitat i.e swamps temporarily store a large amount of water with little increase in water level that attenuates/decreases the flood i.e as the detention basin. It is estimated in 1985 that for the Charles river catchment in Massachusetts the loss of the 8422 acres of the wetland i.e a small portion of the total catchment would result in average annual flood damage downstream of US $ 17 million. In wetlands, the decomposition of the dead organism litter and the wastes occur which are in turn used by the wetland vegetation as the source of nutrients regulating the nutrient cycle. Wetland plants regulate greenhouse gases like carbon dioxide regulating temperature precipitation and other climatic processes which in turn support the regulation of chemical composition of the atmosphere. In addition, wetland also buffers microclimate of the surrounding area locally i.e during summer days it maintains cool climate with high relative humidity around.

References:

Miller, Jr. G.T. Living in the Environment. Wadsworth Publication, 2003.

S.C., Santee. Environmental Science. India, New Center: New Center Book Agency (P) Ltd, 2004.