Roots of water scarcity
#GS3 #Environment #WaterStress
Nature-based solutions like planting of trees and restoration of forests are often touted as the panacea for water conservation. This is because forest watersheds - lands covered by forests which drain all the water flowing through them into waterbodies like rivers or lakes - provide a whopping 75 percent of the world’s accessible freshwater resources. But many organisations implementing this crucial nature-based solution have been unable to differentiate between restoration of forests and planting trees.
Issue in India
- In India, afforestation was one of the interventions of the Union Government’s Jal Shakti Abhiyan, launched in July 2019, to make the country’s most waterstressed districts water secure.
- Under this programme, district administrations were encouraged to undertake planting of trees in a big way.
- It must be noted that simply planting trees will not conserve water. In fact, trees can suck up water and release it through evapotranspiration—water lost by trees to the atmosphere through tiny openings on the underside of their leaves known as stomata.
- According to Wildlife Institute of India, when sparsely vegetated land is converted into forest, there is a reduction in blue water (available for human use) and increase in green water (part of water available for plant use). Trees can consume more water than other shorter vegetation.
What should be done?
- First thing that should be noted is that of scale. In general, forest expansion of 2 sq km or more can increase the possibility of rainfall. Trees transport water to the air, and water vapour moves to another location, which can be far from the afforested area.
- The second aspect is what kind of tree species must be planted for water conservation. Invariably, fast growing broad leaved species such as eucalyptus and poplar consume more water as compared to needle-leaved species, such as casuarina and pines.
- The third aspect is that of site characteristics. Areas with varying ecology, soil and patterns of precipitation have different responses to large-scale plantations.
- Natural ecosystems, especially evergreen systems found along the Western Ghats, are much better at conserving water as they have complex root systems, which can hold large amounts of soil together and that can, in turn, hold large quantities of water in place.
- They also slow down the flow of water streams through them which helps the soil absorb and hold more water.