Road To Soil Erosion

Ashish Poudel

Soil is not just the mere dirt we see around. It is growing medium for plants, home to many organisms and engineering medium and construction materials for human. It is an important natural resource for all developing and developed countries. Nepal being an agrarian country has higher importance of soil resources. Though naturally and freely available, soil resources are degrading both in quality and quantity. Soil degradation is natural as well as manmade. The natural phenomenon of soil degradation occurs to complete bio-geo-chemical cycle. The most prominent phenomenon that degrades both the quality and quantity of soil is soil erosion.
Soil erosion is the displacement of the upper layer of soil by the agents like water, ice and human activities. This directly affects net productivity of soil and also the structure of soil layers called soil horizons. Nepal is very prone to soil erosion and susceptible to sediment disaster due to sloppy lands, fragile and young geography, scouring by rivers and rivulets and various human activities. More than 80 tonnes per hectare per year of soil is lost due to soil erosion. Human activities like deforestation, inappropriate land use, construction and overgrazing are some factors of human induced soil erosion in Nepal.
According to a study conducted in China, unpaved rural roads are the major cause of sediments in small watershed which degrades the water quality. The soil erosion also causes siltation in water reservoirs, degrades the ecosystem by destroying the habitat of organisms effecting biodiversity. This increases sediment disasters like floods, landslides and debris flow. Soil erosion has negative effects on infrastructures like dams, canals and and hydro power plants. Loss of soil also releases sequestrated carbon into the atmosphere thus accelerating global warming.
Construction of rural roads without proper engineering and study of site is one of the major factors contributing to soil erosion. According to statistics from Department of Roads, out of 12493.94km roads in Nepal, 1735.49km is gravel roads and 4389.47 km is earthen. Most of the earthen and gravel roads are not properly engineered and supervised. They lack proper drainage system and have high gradient. This affects the longevity of road and exacerbates soil erosion.
Constructing earthen and gravel roads haphazardly cause deforestation, denudation of site ultimately causing soil erosion. In the monsoon season the situation worsens. Due to climate change, the intensity of rainfall is higher and rainfall duration is shorter, causing more erosion than usual. Soil erosion may seem like just loss of naturally occurring soil but it has other chain effects.
The problems created by soil erosion are worse than we can imagine, and haphazard construction of roads is worsening the situation. Our nation is in crucial phase of development; the local bodies are constructing and planning to join every nooks and corner of nation by road network. Yes, development is necessary but it needs to be sustainable.
All the development works including construction of roads should be done according to standards set by the government. We should try to implement bio engineering, scientific farming techniques and other methods to check soil erosion to protect the precious gift of nature, soil. And to make the Earth a better place to live in. 

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