What is lining of ponds? Explain its importance in reducingthe water losses in the field?
Pond liners need to be protected from sharp objects (for example, stones) below
the liner and from being punctured by any objects in the water body. Protection
can be provided with layers of sand, geotextiles (particularly needle-punched
nonwovens) and other materials. Pond liners are manufactured in rolls or
accordion-folded on pallets. When deployed in the field their edges and ends are
overlapped and seamed together. Methods are thermal fusion,solvents, adhesives
and tapes. The edge of the pond liner is generally rolled over the top of the soil
slope and secured in an anchor trench or it can be fixed to a vertical wall made of
wood or concrete. Box-shaped pond liners can be made for rectangular structures.
The vast majority of flexible pond liners (aka, geomembranes) are available
commercially and are manufactured using the following polymers; HDPE, LLDPE,
fPP, PVC, EPDM. They can also be manufactured with a fabric scrim between two
plys of the polymer, e.g., PE-R, CSPE-R, fPP-R and EPDM-R. Geomembranes can also
be made in-situ by spraying a polymer (polyurea, or equal) directly on a geotextile
substrate. The lifetime of these various ponds liners depends greatly on whether
they are exposed or covered.
Reducing these water losses is critical to efficient resource utilization, efficient
utility management, enhanced consumer satisfaction, and postponement of
capital-intensive additions to capacity. Wherever active water loss reduction
programs have been initiated and sustained, the gains to consumers and utilities
alike have been significant. In fact, as Frauendorfer and Liemberger point out, the
costs of improved service delivery are much lower when undertaken through
investments in non-revenue water reduction rather than through investments in
capital projects to augmentsupply capacities. This report has arrived not a moment
too early. At a time of blistering economic growth in Asia and rising competition for
scarce freshwater resources, Frauendorfer and Liemberger remind us of the
enormity of the urban water challenge in Asia, the critical role of non-revenue
water management, its constituent elements, and measures to address it. This is a
“must read” for urban water practitioners, policy makers, owners of water
companies, investors, and those of us in the development business who can,
hopefully, induce changes in Asia’s urban water management, armed with the new
insights that this paper provides.