The Importance of Groundwater

Design of groundwater recharge structures
Recharge of aquifers
In places where the withdrawal of water is more than the rate of recharge an imbalance in the groundwater reserves is created. Recharging of aquifers are undertaken with the following objectives: 

• To maintain or augment natural groundwater as an economic resource
• To conserve excess surface water underground
• To combat progressive depletion of groundwater levels
• To combat unfavourable salt balance and saline water intrusion

Design of an aquifer recharge system
To achieve the objectives it is imperative to plan out an artificial recharge scheme in a scientific manner. Thus it is imperative that proper scientific investigations be carried out for selection of site for artificial recharge of groundwater.

The proper design will include the following considerations:

Selection of site: Recharge structures should be planned out after conducting proper hydro-geological investigations. Based on the analysis of this data (already existing or those collected during investigation) it should be possible to:

  n Define the sub-surface geology.
  n Determine the presence or absence of impermeable layers or lenses that can impede percolation
  n Define depths to water table and groundwater flow directions
  n Establish the maximum rate of recharge that could be achieved at the site.

Source of water used for recharge: Basically the potential of rainwater harvesting and the quantity and quality of water available for recharging, have to be assessed.

3. Engineering, construction and costs

4. Operation, maintenance and monitoring

Design of recharge structures and settlement tank

For designing the optimum capacity of the tank, the following parameters need to be considered:

1.) Size of the catchment

2.) Intensity of rainfall 

3.) Rate of recharge, which depends on the geology of the site

The capacity of the tank should be enough to retain the runoff occurring from conditions of peak rainfall intensity. The rate of recharge in comparison to runoff is a critical factor. However, since accurate recharge rates are not available without detailed geo-hydrological studies, the rates have to be assumed. The capacity of recharge tank is designed to retain runoff from at least 15 minutes rainfall of peak intensity. (For Delhi, peak hourly rainfall is 90 mm (based on 25 year frequency) and 15 minutes peak rainfall is 22.5 mm/hr, say, 25 mm, according to CGWB norms).

Illustration For an area of 100 sq. m., volume of desilting tank required in Delhi = 100 x 0.025 x 0.85                                                             = 2.125 cu. m. (2,125 litres)

Design of a recharge trench
The methodology of design of a recharge trench is similar to that for a settlement tank. The difference is that the water-holding capacity of a recharge trench is less than its gross volume because it is filled with porous material. A factor of loose density of the media (void ratio) has to be applied to the equation. The void ratio of the filler material varies with the kind of material used, but for commonly used materials like brickbats, pebbles and gravel, a void ratio of 0.5 may be assumed.
Using the same method as used for designing a settlement tank:
Assuming a void ratio of 0.5, the required capacity of a recharge tank
        = (100 x 0.025 x 0.85)/0.5
        = 4.25 cu. m. (4,250 litres)

In designing a recharge trench, the length of the trench is an important factor. Once the required capacity is calculated, length can be calculated by considering a fixed depth and width.

Climate Change Will Strave Us of Chocolates!

Chocolate lovers, embrace those chocoholic fixes now. A recent report from the International Center for Tropical Agriculture predicts it could become a luxury product if West Africa's temperatures rise thanks to climate change.
The world's $9 billion chocolate industry gets almost half of its cocoa from West African farmers in Ghana and Cote d'Ivoire (Ivory Coast), reports Thinkprogress.org.
According to the International Center for Tropical Agriculture, if Ghana and the Ivory Coast experience a 2.3 Celsius degree jump in temperature by 2050, the climate won't be suitably cool enough to grow the crop.
This is a problem, given these farmers financially rely on cocoa as their sole crop. "Many of these farmers use their cocoa trees like ATM machines," said CIAT's Dr. Peter Laderach, the report's lead author, in a press statement. "They pick some pods and sell them to quickly raise cash for school fees or medical expenses. The trees play an absolutely critical role in rural life."
The research, commissioned by the Bill & Melinda Gates Foundation, used the combined results of 19 climate models to assess the impact of climate change on cocoa production.
As early as 2030, farmers will begin to see an impact on the crop, notes Scientific American.

 

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Solar Decathlon 2011

Fire up those photovoltaics, ladies and gents ... the 2011 Solar Decathlon is upon us.

Thanks in part to a thankfully-not-drastic location change, an unfortunate last-minute dropout and a freak earthquake, the road leading to this year's edition of the U.S. Department of Energy's biennial solar-powered home showdown has been somewhat dramatic. Still, the show must go on as 19 fiercely competitive collegiate coteries descend on Washington, D.C.'s West Potomac Park later this month to see which team has created the most attractive, livable, affordable and efficient solar-powered home.

Like Olympic decathlons, each hardworking team must submit their home to 10 different point-based contests — ranging from Market Appeal to Engineering to Architecture — to help determine which eco-abode will take top honors. The magic number is 1,000, with each contest worth a maximum of 100 points. (2009's top scorer was Team Germany with 908 points.)

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Cities And Climate Change

Cities worldwide are failing to take necessary steps to protect residents from the likely impacts of climate change, even though billions of urban dwellers are vulnerable to heat waves, sea level rise and other changes associated with warming temperatures.
A new examination of urban policies by Patricia Romero Lankao at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., in conjunction with an international research project on cities and climate change, warns that many of the world's fast-growing urban areas, especially in developing countries, will likely suffer disproportionately from the impacts of changing climate.
Her work also concludes that most cities are failing to reduce emissions of carbon dioxide and other greenhouse gases that affect the atmosphere.
"Climate change is a deeply local issue and poses profound threats to the growing cities of the world," says Romero Lankao. "But too few cities are developing effective strategies to safeguard their residents."
Romero Lankao's studies appear this month in a special issue ofCurrent Opinion in Environmental Sustainability and in a synthesis article in an upcoming issue of European Planning Studies.
The research was conducted in association with the United Nations Human Settlements Programme (UN-HABITAT) and funded by the National Science Foundation (NSF), NCAR's sponsor.
"Cities are major sources of greenhouse gases, yet at the same time urban populations are likely to be among those most severely affected by future climate change," says Sarah Ruth, program director in NSF's Division of Atmospheric and Geospace Sciences, which funds NCAR.
"The findings highlight ways in which city-dwellers are particularly vulnerable, and suggest policy interventions that could offer immediate and longer-term benefits."
Romero Lankao, a sociologist specializing in climate change and urban development, surveyed policies in cities worldwide while drawing on a number of recent studies of climate change and cities.
With more than half the world's population living in cities, scientists are increasingly focusing on the potential impacts of climate change on these areas. She concluded that cities are falling short in two areas: preparing for the likely impacts of climate change and cutting their own greenhouse gas emissions by reducing fossil fuel use. 

Polluters of New South Whales Beware!

New laws will require polluters in New South Wales to immediately notify state agencies of incidents, as the State Government responds to a chemical leak in Newcastle two months ago.

Premier Barry O'Farrell announced an inquiry after the toxic chemical chromium V1 escaped from Orica's Kooragang Island ammonium nitrate plant on August 8.
The leak fuelled community anger, particularly over the time it took for Orica to notify agencies of the incident and for the Government to pass on the information to residents in the neighbouring suburb of Stockton.
Today the Premier released the report by former department head Brendan O'Reilly and said the Government would adopt all its recommendations.
"This report makes clear that as a result of particularly the communication problems, the delays in communicating the incident to the appropriate authorities, delays between authorities, delays with the Government, delays with the public, the people of Stockton went through enormous stress," Mr O'Farrell said.
In the report Mr O'Reilly says it is likely between 10 and 20 kilograms of the chemical escaped beyond the Orica site.
The report criticises Orica over the initial delay of more than 16 hours before it notified anyone of the leak.
"The delay by Orica in notifying the incident had a direct impact on whether the incident was treated as an emergency," Mr O'Reilly said.
"To the residents of Stockton and neighbouring communities the lack of communication represented a period of six days of uncertainty.
"They have every right to express their anger, concern and frustration that at the end of the day, despite the legislation, the Government and company plans, policies and procedures, they were let down."
In response the Government will introduce legislation next week to toughen the state's pollution laws.
Under the changes pollution incidents must be reported within an hour, and the fine for failing to do so will be doubled to $2 million.
The Government is also planning to re-establish the Environmental Protection Authority as an independent regulator and create an industry-funded network of environmental monitors.
The legislation will also broaden the agencies who must be notified.


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Blame The Cities

Speaking on the theme ‘Cities and Climate Change’ on Monday, Urban Designer and Planner and adjunct faculty at RV School of Architecture Brinda Sastry said it was imperative to concentrate on making cities resilient. Incidently, it is also the theme of World Habitat Day on Monday.

The UN General Assembly designated the first Monday of October every year as World Habitat Day. The idea was to reflect on the state of our towns and cities and the basic right of all to adequate shelter.

“While cities occupy only two per cent of the surface area, they are responsible for 75 per cent of energy consumption and 80 per cent of greenhouse gas emissions,” she said. To combat this, the cities need to be planned in a sustainable and green way, which can be done by sharing knowledge between government, city planners, civil societies and scientific communities.

One of the examples in making a resilient city is the change in land use pattern. Concentrating and preserving natural environment will help mitigate problems of deforestation for agriculture or construction activities.

“Land use patterns will be important factors in determining the emissions from the cities. Designing multi-transport roads and using building materials that are renewable would go a long way in reducing carbon emission in the long run, Sastry said. India is the second most vulnerable country to climate change, as per the study conducted by Maplecroft, UK-based risk advisory company.

Housing issue for poor
The International Co-operation Division of BMS Education Trust in collaboration with UN Habitat organised a seminar on the occasion of World Habitat Day. Sate Housing Department, Rajiv Gandhi Rural Housing Co-operation Limited and Karnataka Slum Development Board participated in the seminar.

Prof Dr Ing H R Viswanath, executive chairman, International Co-operation Division, BMS Education Trust, drew attention to the theme - Cities and Climate Change – which had become a prominent development challenge of the 21st century.




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Paris Goes Green!

The French capital rolled out the first of its new eco-friendly electric "bubble cars" on Sunday at the launch of a car-sharing plan it hopes will spark a quiet transportation revolution.

Hot on the wheels of Paris' self-service bicycle program known as Velib', comes Autolib'. As with the 20,000 cycles at hundreds of stations across the city since 2007, anyone wishing to get from Point A to Point B in the French capital will soon be able to pick up an electric Bluecar at one location and drop it off at another.



By 2013, city officials plan to have between 3,000 and 5,000 environmentally friendly Bluecars stationed at more than 1,000 locations across the city, with the aim of cutting noise and air pollution as well as reducing traffic by discouraging private car ownership.

During an unusually sunny early autumn lunchtime on the Avenue Trudaine in Paris' family-friendly 9th arrondissement, curious onlookers gathered Sunday around a line of Bluecars brought out for a two-month trial in preparation for the official launch in early December.

On a nearby cafe terrace bemused diners watched the electric cars, which, contrary to their name are not blue but unpainted aluminium, zip up and down the avenue. There were no complaints about fumes or noise because there were none.

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