Context

Increased sediment deposits and changes in land use showed the degradation of soil during the last four millennia. Human activities such as agriculture and deforestation intensified global soil erosion 4,000 years ago, according to a study.

About

• While weathering of soil and erosion has, known to be controlled by changing climatic patterns and tectonic impacts of the planet, the new study suggests a role of human practices and land use-change.
• Soil erosion has direct impacts on climate and society, as it decreases the productivity of ecosystems and changes nutrient cycles.
• Max Planck Institute, a Germany-based non-profit, used radiocarbon dating techniques recorded temporal changes of soil erosion by analysing sediment deposits in more than 600 lakes worldwide. To understand the cause they analysed pollen fossil records and observed a decline in the tree cover.
• Changes in land cover were identified as the main driver of soil erosion in 70 per cent of all studied watersheds. This suggests that human practices intensified soil erosion much before the advent of industrialisation.
• Socio-economic developments during human settlements also correlated with sediment accumulation in lakes, a proxy for soil erosion.

Wetlands in Kashmir shrinking due to urbanisation

• An analysis of land cover data shows that the catchment of Narkara wetland in near Srinagar is now predominantly an urban setting.
• Wetlands are an integral part of the fragile ecosystem in north-western Himalaya. Jammu and Kashmir has several wetlands but those located close to urban areas are showing signs of deterioration due to land use change.
• This reduction is attributed to barren lands and agriculture being taken over by built-up area.
• The reckless urbanisation both within Narkara and its catchment not only affects the hydrology and ecology of this important semi-urban wetland but also increases vulnerability of people to flooding in this part of Himalaya because wetlands act as natural sponges and flood protection system.
• The gradual squeezing of wetlands is affecting their buffering capacity to withhold flood waters and storm water runoff.
• The catchment of Narkara is predominantly a semi-urban setting with settlements, agricultural fields and table lands locally called karewas, which are barren denuded landscapes. The wetland is a breeding ground for water fowl species that migrate from Russia and Central Asia during winters.