LAKE BANK FILTRATION INDUCED TRANSPORT OF MICROORGANISMS

Abstract

The water-supply system at Nainital is quite different in India and this is quite similar in Europe, where the water supply is met with bank filtration mechanisms. At Nainital, Uttarakhand the nearby lake area where out of 12 tube wells there are 8 tube wells which are in good operating condition and are located at a distance of less of than 100 m from the lake and are being used to extract the lake water and as well subsurface ground water flowing towards the lake. The study carried out is mainly to analyse the water quality and transport induced by lake bank filtration in reduction of bacteriological load in the tube well water. The water samples were collected in the month of January, February, March and May 2011 and some parameters such as pH, TDS, Conductivity, DO and Temperature were determined at the site and some were determined in the lab. The aquifer parameters were also determined at the selected tube wells by pumping test along with hydraulic gradient to estimate travel time from the lake to the tube wells. Results clearly indicate the possible increase in contamination in the tube well water in the coming future if the heavy pumping of water from the tube well is carried out in the same trend as of today. The lake bank filtration is an effective filtration mechanism compared to other in reducing the contamination load and as a result of pumping test, the higher transmissivity and higher hydraulic conductivity of tube well 5 region indicates the subsurface water flow extraction high at the region. The bacteriological study is of total-fecal colliform and chlorophyll-a, where in the winter the colliform found to be higher in the lake compared to summer. The less amount of colliform and chlorophyll-a are found in the tube wells closer to the lake.