Not just the gradual depletion of groundwater in South and Southwest areas of National Capital Territory (NCT) is major cause of concern but quality of groundwater in these areas has also become another cause of worry.
According to a report of Central Ground Water Board (CGWB), the chemical quality of groundwater in NCT Delhi varies with depth and space while brackish ground water mainly exists at shallow depths.
CGWB hydrogeologits have observed in groundwater studies the thickness of fresh water zones is limited in most parts of Southwest area, in the floodplains of Yamuna, in general, fresh water aquifers exist down to 30-70 m.
“The fluoride contamination in groundwater has been noticed in samples of groundwater collected from Southwest district. The high fluoride levels are mostly found in areas where groundwater is brackish to saline in nature while nitrate concentration has also reported in areas where domestic effluent is discharged in to open drains,” the report stated.
In Delhi, depth to fresh saline water interface in ground water of NCT has found at maximum depth in Chattarpur basin and the in the area adjacent to Delhi Ridge near Samalkha and Bijbasan.
According to the report, hydraulic conductivity and continuous source of fresh water from the perennial river has accumulated fresh water thickness in the aquifer in the range of 30 to 50 m.
The Delhi Ridge in general has fresh Ground Water at all explored depth. The area adjacent to the ridge receive continuous recharge fro Delhi ridge and has high lateral permeability on account of faults and coarser nature of sediment.