Abstract:
About half of the water is lost through conveyance system in channels, distributaries, minors and water courses etc. Various alternative materials had been tried from time to time keeping the low constructian cost, durability and impermeability of lining material so as to minimse the seepage losses. In the recent past low density polyethylene ( LDPE) film as a canal liner has been highlighted in India. The same has been tested world over for the past 25 years and found effective in checking seepage. In view of this, U.P. Irrigation Research Institute, Roorkee has taken up systematic studies in semi field and field conditions.
During the experimentation under semi field conditions, it was found that LDPE film eovered with clay tiles was able to save upto 30% water additionally by way of reducing the seepage losses compared to clay tile lining without buried LDPE film. Generally the type of soil and lining material are not vital factors when the channel is lined with LDPE film except for expansive soil. Proper compaction,
even surface and pebble free suhgrade are of prime importance for LDPE film lining. Also it was found that all portion of the wetted perimeter of the channel should be covered with LDPE film.
In the field channels, a substantial reduction in seepage losses has been observed wherever the channels are lined with LDPE film. On some of the minors of Upper Ganga Canal system in Aligarh and Bulandshahr districts the reduction in seepage losses were found to vary from 70% to 95% mainly depending on the quality of construction and thereafter its maintenance.
