Dr. Roshan Raj Shrestha, Ph.D. of the NGO
Environment and Public Health Organization
(ENPHO), which is popularizing environment-friendly
technologies in Nepal like rainwater harvesting,
says that collecting rain which falls on
a roof or a sealed surface is a “simple
concept that brings a lot of benefits.”
“Rainwater-harvesting is very affordable.
Everybody is capable of using the technology.
We just need to re-popularize it,” Dr. Shrestha
said of the indigenous technology which
has been edged out of ‘Nepali's daily lives
by “modern technologies.”
He
added, “Rainwater harvesting in both urban
and rural areas must now become a mandated
public policy as well as a nationwide, community-based
system to insure long-term water supply.”
Advantages of Rainwater Harvesting
It provides additional water for a variety
of applications including agricultural,
industrial, commercial and private use.
“Everyone must realize that rainwater harvesting
provides an independent water supply and
one without cost for energy supply if gravity
flow is applied,” explained Dr. Shrestha.
Rainwater harvesting also regulates drainage
and river input; reduces soil erosion; provides
additional water for public use and emergency
response; reduces flood risk on roads and
sealed surfaces; improves liquid waste management;
and improves river management.
Rainwater harvesting promotes self-sufficiency
and instills an appreciation for this essential
and precious resource since it is harvested
independently of any central system.
Collecting rainwater not only conserves
water, it also conserves energy since the
operation of a centralized water supply
requires a high energy input for pumping
and distribution. A decentralized rainwater
supply, on the other hand, can take advantage
of gravity flow if properly designed.
Rainwater harvesting lessens local erosion
and flooding caused by drainage from construction,
road development, land use changes and area
sealing. The rain is instead captured and
stored and only gradually released at a
later time. Thus, storm water run-off, the
normal consequence of rainfall, becomes
captured rainfall and is available for a
number of productive uses.
The purity of rainwater makes it an attractive
water source for certain industries that
require pure water such as dairies. Prior
to contact with a building or the earth's
surface, rainwater is one of the purest
sources of water. However, rainwater harvesting
needs to consider and treat eventual microbiological
and chemical components, which may be dissolved
and collected from the catchments.
Rainwater harvesting is an ideal alternative
source of water, particularly in areas where
water is scarce or in places where water
supply services are not adequate.
In rain-drenched areas, rainwater catchment
systems can be used for different purposes
like flood mitigation, sewerage management
or compensating for the lack of water in
sealed surfaces. In addition, in areas with
modern water systems, rainwater could be
used as a substitute for processed potable
water for non-drinking purposes such as
flushing the toilet, watering plants, washing
laundry and other purposes.
Untapped Resource
Despite these advantages, rainwater has
become an “untapped resource” due to the
introduction of piped-in water systems.
If one were to study the actual water supply
situation versus local rainwater management,
it would become obvious that rainfall is
typically not regarded as a water resource;
instead, it as often seen as a hindrance
to certain activities such as construction.
Sealed areas, roofs of buildings and roads
are provided with collection systems for
water run off, but these systems are, the
great majority of the time, used for drainage
purposes into nearby rivers and streams.
To compound this situation, there is no
regulatory system in place to manage rainwater.
Sadly, this puts rainwater to waste. A valuable
fresh water resource before hitting the
catchments, rainfall is wasted when discharged
into the drainage system.
The government has not considered rainwater
collection as an alternative for water supply.
Everyone prefers a water service delivery
system that reaches consumers in their homes
in potable form, 24 hours a day. Water usually
comes from a river reservoir or from an
underground natural supply, processed in
a treatment plant and delivered through
a system of pipes and controls. Rainwater
harvesting can be used as a viable supplement
to such a main system, depending on an individual
household's water needs.
It's worth noting that once the Melamchi
water supply scheme comes into effect, water
in Kathmandu will be more expensive than
it currently is. Also, tariffs stemming
from Melamchi water will likely be divided
into two categories including a subsidized
monthly minimum volume and a volumetric
charge for water consumed in excess of the
minimum volume. The volumetric charge will
be much more than the subsidized tariff
and as such consumers will need to be aware
of their water usage in order to prevent
shocking bills. Rainwater harvesting can
provide a practical alternative form of
water which can be used, especially, by
those households that consume more than
the monthly minimum volume.
Kathmandu Drinking Water Situation
How do we deal with our water scarcity?
It is a challenge faced by most developing
nations, including Nepal, and Kathmandu
Valley in particular. Efforts have been
made to solve Kathmandu Valley’s water crisis
but the problem keeps on escalating. At
present, water demand is approximately 200
MLD (million liters per day) but the government
supply during the dry season is only 90
MLD (45%) and during the wet season it is
only 120 MLD (60%). In addition, waste due
to leakage is estimated at 74 MLD (37%).
Since the supply of water does not reach
a significant number of households, citizens
of the valley have to get up early in the
morning, between three and five A.M., to
extract water (using pumps hence spending
money on electricity and losing sleep) from
the main line. This process is not just
impractical but gets expensive, hectic and
time consuming.
The
current water reform plan for Kathmandu
is to bring water from the Melamchi river
basin which, if everything goes according
to schedule, should get here by 2010 AD.
Currently, residents of Kathmandu Valley
are extracting a tremendous amount of ground
water to supplement their needs by digging
deep tube wells, thereby, depleting the
ground water system. It's instructive to
note that the average annual rainfall of
Kathmandu Valley is about 1600 mm most of
which simply goes down the drain. It makes
sense to take advantage of a cost-effective
resource in the form of rainwater while
conserving the underground water table.
Re-popularizing
the Indigenous Technology
We should “re-appreciate” the culture of
rainwater harvesting. It has been part of
our ancestors' lives. Our great-grandparents
valued rainwater for good reasons. If they
practiced it for centuries, why can’t we?
The re-integration of rainwater harvesting
also means the formulation and incorporation
of a national policy. If local governing
bodies have no strict framework to follow,
they will be at a loss as to how to proceed.
A national policy is needed by the local
governments.
If the government succeeds in re-popularizing
the indigenous technology, experts say it
could save as much as Rs. 2.8 billion annually
- in Kathmandu Valley alone - besides its
environmental benefits.
“Assuming an average daily water demand
of 100 liters per capita per day, Nepal
Water Supply Corporation (NWSC) must provide
1.4 billion cubic meters of freshwater every
year for the residential, small businesses
and institutions alone in Kathmandu Valley,"
explained Dr. Shrestha. "This water
is mostly extracted from groundwater reservoirs.
The cost equivalent would be approximately
Rs. 5.6 billion a year based on the water
price of Rs 4 per 1,000 liters," he
added.
“A substitution of the public water supply
with 50 percent rainwater would not only
be very advantageous considering the economic
effects but could help secure surface and
groundwater resources and options for further
development,” stated Dr. Roshan Shrestha.
Interestingly, more than 25 plumber technicians,
who gathered in a two day training session
on rain water harvesting techniques organized
by the NGO Forum for Urban Water and Sanitation
(NGOFUWS) agreed that the reintroduction
and mainstreaming of rainwater harvesting
at both local and national levels, through
ordinances and a national law, could effectively
address Kathmandu’s growing water needs.
|
