Impact assessment of viaduct construction on groundwater recharge in NCT Delhi

Abstract

To answer the question of apprehension of impact of construction of metro viaduct on rainfall recharge, DMRC, New Delhi has referred the task to the National Institute of Hydrology, Roorkee for a scientific study. To attain the envisaged objectives and also derived scope, a comprehensive analysis of data related to meteorological, land-use and land cover (LULC), soils properties, rainfall and groundwater recharge components, impact of elevated metro rail corridors including assessment, etc. have been carried out. The database, information, field and laboratory experiment results have been analyzed using advanced tools and techniques. All related maps have been prepared as per geographical coordinate systems in the ArcGIS framework and hence, has the relevance to the actual field conditions. Studies find out that a very good scope exists to use the surface area of elevated metro rail corridors and elevated stations for capturing rainwater and conserving the harvested rainwater for artificial groundwater recharge by devising appropriate engineered recharge system. The advantages of these elevated metro rail corridors are: not in contact with natural soil surfaces; not influenced by natural surface hazards/contamination, and major anthropogenic activities and routine human interventions; and largely free from pollution originating from motor vehicles. The quality of the captured rainwater from the elevated metro rail corridors has been found much better than the motorable flyovers/ over bridges. Analyzed quality of rainwater has been found suitable for groundwater recharge.