This is based on the Rally for Rivers Draft Policy Recommendations for river revitalization, which was formulated after consultation with various experts from diverse fields relating to forestry, soil, agriculture, governance, finance, corporate, education and development. Today, after much deliberation and science, World Communities are also arriving at the understanding that massive afforestation is the single-most effective solution to our present air, soil and water situations. The recent ETH Zurich report, UNEP directives for planting of a Trillion Trees and the Bonn Challenge all point to the same science and solution.
The Science: India’s rivers are essentially rainfed. Rainfall enters rivers and streams through two main mechanisms: surface flow over land and through underground flow. Rain seeps into soil and becomes groundwater, which then gradually flows underground and enters streams, rivers etc. Trees helps rain seep into soil by creating a network of well-connected, minuscule channels in the soil. Additionally, plant debris helps soil become porous. Once water is absorbed by soil, just as rainwater percolates downward, water can percolate horizontally as well. This underground “water flow” feeds water into streams and rivers.
The basic science projects that 10,000 trees retain 37.85 million litres of water per year. By extrapolation, 242 crore trees will retain 324 TMC of water per year, which is about 41% of the Cauvery’s annual flow.