MAESTro knows it all!
United Nations Environment Programmes (UNEP) International Environmental Technology
Centre (IETC), based in Japan, has created a searchable electronic database on
Environmentally Sound Technologies (EST) called maESTro.
maESTro is an information tool which contains data on a wide range of
environmentally sound technologies, institutions and information sources related to water
pollution, environmental management, human settlements, hazardous substances, solid
wastes, wastewater, water augmentation and many more. EST contributors, individual users,
organizations and institutions regularly update this information.
This data is distributed free of charge on floppy diskettes, CD-ROMs and in printed
hard copy formats. This information is also accessible on the worldwide web at http://www.unep.org.ip/.
maESTro is free of charge and promotes interactive global networking.
The Water Harvesting Company of Stockholm, Sweden, has hit upon a novel
technology to store rainwater ( huge underground caverns. An environmentally sound
technique, it can greatly increase the volume of freshwater stored underground.
This technology is based upon the recognition that rarely is water shortage a question
of inadequate precipitation, but a problem of limited infiltration and storage space.
There are three major components to the Swedish technology: the collection area, the
conveyance system and the storage facility. The collection area can cover the entire
landscape, by taking advantage of the natural topography. The conveyance system is
natural: the forces of gravity ensure that water enters the geological structure
surrounding the cavern only to find its way to the lowest point in the hydraulic system.
This gravity system can be improved by drilling holes between the cavern and neighbouring
fissures. Storage depends on the size of the cavern, which is a large porous fissure that
becomes part of the geological structure.
The technology is fairly cheap and initial investments range from Rs. 2000 to Rs. 4000
($50 - $100) per cubic metre of created cavern. Thus water that would be otherwise lost to
flash floods and evaporation can be safely collected and stored underground.
world thinks of water and how to manage it.
Water is no longer being viewed for what it is - just water. A natural
resource, it is increasingly being viewed as a commodity that has to be used rationally,
priced appropriately, managed, banked, traded, sources recharged and reused as much as
possible, wherever possible.
The US: Groundwater recharge makes sense - in addition to replenishment, evaporation
losses are minimal, the chances of secondary contamination reduced, there are reduced alga
blooms and reduced pumping costs. Moreover, recharge also reduces the gradual subsidence
of land due to water extraction."Aquifer storage and recovery systems allow for the
storage of excess surface water during periods of high surface water flow and its
subequent recovery during periods of low surface flows and high demands,"says Peter
Fox of Arizona State University, Arizona. Fox is an ardent advocate of aquifer recharge.
Groundwater recharge has to be an integral part of water resource planning in
urban areas now, given the fact that traditional means to meet growing water demand in
urban areas requires the exploitation of surface and subsurface resources to the maximun
extent possible, adds Fox.
The most common way of aquifer recharge is the use of recharge basins where water is
allowed to collect on large pieces of land that allow the stored water to percolate
through. This however is land intensive. Technologies are now available where the water
can be recharged into an aquifer by injecting into wells that are dug above an aquifer and
the water percolates into it or through a direct injection well that ends in an aquifer.
Arizona is moving towards a groundwater banking system. Entities that recharge
groundwater receive credit for the amount of groundwater they are recharging, which they
can then sell to groundwater users. The Groundwater Management Act (GMA) has established a
goal of zero groundwater mining by the Year2025. The GMA has established a system of
ground water management systems combined with a system of penalties and incentives.
Groundwater users are penalised on an escalating scale for withdrawing groundwater without
recharging it. The penalties force the groundwater user to either recharge groundwater or
purchase groundwater from a ground water supplier.
Mexico: In Monterrey, Mexico, ground and surface water resources are in short supply,
unable to meet the demands of heavy industry manufacturing plants. To meet their demands,
industries on their own, or in a consortium have constructed wastewater treatment plants
that provide treated effluent for industrial process water.
Wastewater is purchased from the city, pumped from the sewer into a treatment plant and
the treated water distributed to industries. While individual industry owners reuse the
treated water on their own plant property, in places where there is a consortium, the
treated water is distributed through a water distribution network.
With the construction of 3 large wastewater treatment plants in the city by the
Monterrey Water and Wastewater Authority, virtually all the wastewater from the city is
treated and reused either directly for non potable use or indirectly for potable water use
throughout the city.
It is possible to harness runoffs from very large wadis or dry river beds.
Using low technology. Too erratic to warrant high engineering investment, this technology
makes use of the construction of dykes all along the seasonal stream, so that each one
will detain only a small part of the flood: the rest of the water will flow past and be
diverted to the next dyke and so on. These dykes would allow the percolation of large
amounts of water, enriching any existing underground storage.
Engineers fear the
unpredictable and often leave large, seasonal and unpredictable streams with catchment
areas of 100,000 hactares or more untouched. The excuse: lack of adequate
hydrological data, large volumes of water and sediment and the high cost that accompanies
the harnessing of water under these conditions. This is where size comes in. It is
possible to harness water on a small scale, on large streams. All in a modular manner,
making use of only a small portion of the flood at a time.
The main specification is that the width of the spillway equal the narrowest part of
the wadi. The next step is to build a series of L- shaped ponding dykes, one leg being
perpendicular to the line of flow and connecting with the bank and the other parallel to
the line of flow, adjacent to the spillway channel.. The length of the dyke is as long as
is needed to leave an adequate channel for the spillway. The height of the dyke should be
sufficient to hold 2 m head of water, allow for a flow of 1 m deep in the spillway with 1
m freeboard- a total height of 4 m. The longitudinal wing extends upstream upto a point 2m
higher than the base line of the perpendicular dyke.
To divert water from the spillway channel into the dyke, a diversion ditch is
constructed which then allows for water to fill in the pond. Once filled excess water
drains back into the spillway channel leaving a 2 m water column of water behind to
percolate into the ground. If a series of such dykes are constructed, each one will detain
only a small part of the flood water and the rest will flow past and be diverted into the
next dyke and so on. In this way, it is possible to capture medium sized floods
Germany: Germany appears to have realised the potential of harvesting rainwater.
"Rainwater utilisation is now recognised as an advanced, ecologically and permanently
safe operating system,"says Klaus Konig from Professional Association for Water
Recycling and rainwater catchment systems, a NGO from Uberlingen, Germany. In Germany, in
the nineties, several thousand rainwater utilisation installations have been installed. To
ensure the quality of rainwater collected and that the potable water system is protected
and secure from possible contamination by individual installations, there now exist
legally binding regulations within the German potable legislation. For instance, no
connection may be made between the rainwater system and the potable water system.
In The Berlin Communal Dwelling Rainwater Utilisation Project, the rainwater from all
the roof areas is disposed off through the public rainwater sewers of the Berlin Water
Companies, into separate sewers. Along with the outflow from streets, parking spaces and
pathways, it is then tranferred into a 160 cubic metres capacity cistern. After simple
treatment, the water is used for toilet flushing and gardening.
In Germany, hectic efforts are on to develop an efficient ceramic toilet that uses only
3 litres of flushing water. All rooms in the Arabella hotel in Berlin are equipped with
water saving toilet system, which has a split operation panel. For flushing faeces,
4litres are used, while for flushing urine, the quantity of water is reduced to 2.5
Singapore: In Singapore, the Public Utilities Board (PUB) is the national water authority.
It has proven to be an efficient organisation providing reliable potable water at the most
ecoomical cost. Programmes of water literacy, peoples participation and reliable
water meters that are regularly monitored coupled with a responsive group of public
engineers has been the formula adopted. Plumbers are given licenses to ensure good quality
of plumbing work. All water fittings and pipes are inspected by the PUB before
installation. All accounts are metered, even temporary ones at worksites. These metres are
checked monthly. The billing is computerised and any fluctuations are automatically
detected by the computer. Customers are advised to check for leaks if the readings are
abnormally high. They are also encouraged to take their own readings. Replacement of mains
have reduced leakage problems and improved water quality.
Water demand management included the implementation of water conservation measures,
tariff restructuring, legislative measures and educating the public.
Israel: The million dollar question is: how does Israel survive with less than 300 cubic
metres of water per capita per year when international organisations define arid countries
with less than 1000 cubic metres per capita per year as highly stressed countries where
water becomes a severe constraint to growth.
"The answer lies in water demand management," reveals S Arlosoroff, a retired
World Bank Water expert. The management has succeeded- Israel now has a GDP of $ 16000 per
capita per year, it produces most of its food, with the exception of grains, it even
exports agricultural produce, supports the water requirements of industry and the people
are able to maintain a high standard of living- all with a very limited supply of fresh
The management package includes a cocktail of legislative, institutional, economic and
technological measures, focussing on water demand management increased efficiency use of
water in agriculture, reuse of most of treated sewage effluents as well as integrated use
of surface and ground water resources. "By the year 2020, Israel will be reusing
70-75 % of treated effluents,"predicts Arlosoroff.
Source: All inputs below are based on
the 3 day symposium on Efficient Water Use in Urban Areas- innovative ways of
finding water in cities, held in Japan between 8-10 June, 1999. The symposium was
organised by United Nations Environment Programme - International Environmental Technology
Centre, Kobe, Japan