Tag Archives: travel time of contaminant to borehole water intake

Urban gate-guarded communities’ water supply woes: Bangalore (India) vis-avis Lagos communities (Nigeria)

People who live in urban gate-guarded communities are affluent and can afford the cost of providing necessary amenities for their families. In Nigeria, the attraction of such highbrow communities usually centers around three considerations: adequate security, water supply and uninterrupted power supply.

These same considerations apply in India.

People who live in Bangalore, a gate-guarded community, are rich IT professionals, hence the reference to it as India’s “Silicon Valley”. They want and can afford the best for their families. In Nigeria the population of such communities is mixed consisting of successful young professionals and entrepreneurs.

What got this blogger interested in this topic was the short video provided by the BBC News on Bangalore, the ‘Indian silicon valley’. As a result of the increasing population pressure, the water supply in this community has reached breaking point.

This situation is the subject of the BBC video, Bangalore water woes: India’s Silicon Valley dries up. The web link to the the BBC video:

(http://www.bbc.com/news/av/world-asia-india)

And the subtitles of each frame are given below:

  • This is the first city in India which has actually physically run out of water.
  • Morning rush hour and these tankers take over Bangalore streets.
  • They are carrying precious commodity – water.
  • If we don’t supply water then there is no water for them.
  • Earlier these used to be wetlands.
  • At that time we were getting water at a depth of 300 feet.
  • Now it is 1,400 t0 1,500 feet.
  • Thousands of tankers haul millions of litres of water across Bangalore daily.
  • Bangalore is one of India’s fastest growing cities, its Silicon Valley.
  • But its traditional water sources are drying up and are also contaminated.
  • So many people now depend on water delivered by private tankers controlled by cartels sometimes called “water mafia”.
  • I would think in some form it does operate like a cartel but it’s something nobody wants to talk about openly.
  • Software professional Subir Bose lives in an upmarket gated complex.
  • Like the other 200 families here, he’s at the mercy of tanker operators.
  • Yes we are still getting water but the quality of water is suspect.
  • The negotiations have become tougher with them because the rates are going higher.
  • Bangalore has 400,000 bore wells diminishing its ground water.
  • It is estimated that about 400 t0 500 million litres of water must be extracted every day.

Mr. S. Vishwanath, a conservationist, says in conclusion of the video that “So if bore wells dry out the city starts to lose its lifeline. So the crisis is how to revive and keep these bore wells alive. Bangalore has been in water management since 1890s. So it needs to start to become a pioneer once again to solve the crisis that grips it”.

Currently the situation in Nigeria, i.e. heavy dependence on water tankers in high brow communities, is not caused by population pressure on the groundwater resources. Rather, it is caused by not paying due attention to proper water supply borehole location vis-à-vis location of onsite sanitation, poor borehole construction practices and skimping on borehole cost which is necessitated by having to drill down to up to 200 to 300 meters as noted by a Nigerian news-site, Naij.com, which states that if people in gate-guarded communities in Lagos want to have access to potable water without depending on groundwater they have to buy water from water tankers or drill deep boreholes.

In the case of Bangalore, the exponential increase in the number of boreholes necessary for the exploding population of this affluent community and the lowering of the water table to a point where groundwater abstraction cost becomes prohibitive has resulted in huge dependence on water tankers which calls for proper management of the groundwater resources in order to wean it from dependence on water tankers.

Lagos Island, where the highbrow communities are located, is characterized by:

  1. Shallow water-table.
  2. Absence of centralized sewerage system, hence the use of septic tank system for the disposal of household and human wastes.
  3. These septic tanks are usually about 3 meters deep.
  4. High cost of drilling deep boreholes (200-300 meters deep) which many household cannot afford.

P.S. Ola, O.M. Bankole and A.Y.B. Anifowose (2010) describe the area as having a complex lithology of alternating sequence of sand and clay deposits  up to a depth of about 270m. They delineated seven aquifer horizons at the following depths: 3-10m; 40-70m; 60-100m; 110-140m; 150-180m; 178-210m and 212- 240m, corresponding to aquifer thicknesses of 15-25m, 15-30m; 10-45m; 20-40m; 10-42m; 10-30m and 20-45m respectively.

If above four characteristics are considered each on its own or jointly for example, two of them, especially ‘1’ and ‘3’, they may be responsible for why water supply boreholes in Lagos Island area cannot be relied upon as a source of potable water for the following reasons:

  • Pathways through contamination from on-site sanitation can reach groundwater supplies are through the main body of the aquifer and pathways created by the design and construction of the water supply boreholes. These are called localized pathways.
  • As indicated above these areas are in the unconsolidated recent sediments. Aquifer vulnerability with respect to its contamination in Lagos Island will be a function of the intrinsic characteristics of this geologic terrain.  This vulnerability is dependent on travel time for water to move from ground surface to the water table. It is necessary to note that the water table of the near surface aquifer in this area is shallow. The greater the travel time the greater the opportunity for containment attenuation, hence the need for reliance on deep boreholes, and in addition great lateral distances between on-site sanitation and water supply boreholes will also offer the opportunity for containment attenuation. The latter requirement to ensure long travel time is a luxury in these areas because of the ubiquitous presence  of septic tanks.

Most of the gate-guarded communities on Lagos Island claim to have central water supply equipped with water treatment plants. The prices of properties are really high and one would expect that such communities would have top quality communal services, but some do not.

A company called Neighbourhood Review provides information on some of the Lagos communities, such as Greenland Estate, Cooperative Villa Estate, Femi Okunnu Estate, Cadogan Estate, Igbo Effon Estate, Royal Garden Estate, Thomas Estate,  Marshy Hills Estate and Chevy View Estate to mention a few.

Here are two of the reviews:

“Cooperative Villa Estate: The estate has a water supply unit but was not functional at the time of this review. All houses in the estate have their boreholes and reservoirs.

Femi Okunnu: The estate has a water supply unit but was not functional at the time of this review. All houses in the estate have their boreholes and reservoirs”.

Lessons learnt in the case of Bangalore are summarized above by Mr. S. Vishwanath, a conservationist, who recommends adequate water resources management. While in the case of Lagos Island, transparency concerning claims on infrastructural provision by the estate developers is necessary, especially with respect to provision of communal services.

Finally, there is a need for proper water supply borehole construction and effective public awareness concerning borehole location vis-à-vis on-site sanitation.

 

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