Land is the principle resource in the world. Land degradation means the loss in capacity of land to support growth of useful plants on a sustained basis. It is a complex phenomenon. Natural calamities like landslides in the hills, drought in most of the terai have frequently occurred. Most of all, flooding has become the major cause of land degradation leading to the poor socio-economic conditions and the deterioration of the natural ecosystems.
Removal of top fertile layer of soil by water is a critical problem in the mid hills. In the past, the perennial streams of clean water trickling from the hills supported good agriculture in the plains. In less than 30 years, unrestricted tree felling, cutting, overgrazing, random cultivation on steep slopes without proper terracing has aggravated the soil loss. Apart, from the loss of productive top soil it has further damaged the land and water resources due to siltation of dams and deposition of thick and sandy plains of the Tarai Rivers.
Rivers in Nepal have damaged more than 400,000 hectares of productive agricultural lands. The extent and severity of damage have increased year after year due to frequent changing nature of mountain- rivers, farmlands near river bank are washed away by flooding, crops are ruined and width of rivers widen every year during monsoon.
Nepal’s rivers carry around 336 million tons of soil per year to the main river systems entering India. The productive of riverside lands has been seriously affected by silting, flooding, and deposition of pebbles. Furthermore, the river damaged the areas of middle mountains of Nepal suffer from excessive grazing pressures of domestic animals. The natural succession has been inhibited by excessive grazing pressure as well as flash floods during the Monsoon.
In Nepal land degradation has been occurred in all the physiographic regions of the country. Indiscriminate felling of trees and clearing forest areas for agriculture has given rise to the scarcity of the essential needs of rural people such as fuel, wood and small timber. These activities along with populations’ pressure and improper land use patterns have led to serious environmental degradation. In Nepal land degradation includes physical, biological and chemical degradation.
Both the natural conditions and human activities have contributed to the degradation of land. Fragile geological structure, forest fire, avalanches and dry landslides are some of the major cause of land degradation whereas deforestation, overgrazing, farming on the steep slope, construction works and excessive use of chemical fertilizers are some major examples of human induce cause.
Increasing population, fragile economy and sometimes farm policies and fuel to it. In its natural condition land is covered by forest trees and other natural vegetation. Trees leave control the speed of the raindrops and allow them to go down to the land surface slowly, which is the favorable condition for the growth of plants and micro organism in the soil.
When trees are felled and the roots mats are destroyed, the soil is the subject to soil erosion by full force of the rains. Heavy rain removes nutrients by washing away the thin top layer of soil and by leaching nutrients deed into the sub-soil thus making it unavailable to plants roots. Air is as much important to soil quality as mineral nutrients and compacted soil poses serious threat to environment in the form of land degradation.
Forest help to maintain the temperature at a lower level and prevent them from rising. In the absence of forest, the entire heat that is not absorbed by the atmosphere but strike the earth’s surface are reflected by the earth’s surface, leading to a rise in atmosphere temperature. The heavy grazing pressure on grazing lands in the mountain areas has speed up the soil erosion, which led to increased run off and compaction of soil.
Cultivation on steep slope without taking considerations of improved farming such as terracing in steep slope, use of organic manures and so has contributed to the soil erosion which has resulted in high water turbidity, which further leads to the harmful effects to the aquatic flora and fauna including fish species. Development activities such as construction of roads, buildings, dams and so have further added fuel to it.
All these activities have resulted in the poor socio-economic status and imbalance in the natural ecosystems. Decreased land productivity and wash away of agricultural land due to flooding have given rise to the poor socio-economic status of rural people in Nepal. The productivity of riverine ecosystems has decreased.
It is clear that due to the lack of effective implementation of counter measures, the land degradation problem is increasingly becoming a challenge for the economy and natural ecosystems in Nepal.
It is realized that the balance between the land degradation and restoration rates should be maintained so as not to further degrade the land. The effective implementation of land restoration measures with full fledged political and bereaurocratic commitments and sound technology are urgently required.