Abstract:
A lake bank filtration (LBF) scheme comprising
of nine tubewells on the bank of the lake Naini in
Nainital, India exists in landslide debris while most bank
filtration sites globally are in alluvial aquifers. The water
quality and stable isotopes (d18O and d2H) have been
studied to assess the proportions of bank filtrate drawn by
the wells. Results show that of the nine wells, two wells
perennially abstract mainly bank filtrate, three abstract
predominantly bank filtrate during non-monsoon but
groundwater during monsoon, and four wells largely abstract
groundwater perennially. Bank filtrate proportion in a
well is not dependent on its distance from the lake. Also,
more than one groundwater stream appears to be contributing
to the well field. Such anomalous hydrology is
likely due to hydrogeological heterogeneity in the landslide
debris or drainage from fractures and faults in the underlying
geology. The study shows that an LBF well in a
landslide deposit can sustainably deliver water of drinking
quality at a short distance of *5 m and travel time of *2
to 3 days from the lake.
