Tuesday, October 22, 2019
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Posted at: Mar 25, 2019, 8:08 AM; last updated: Mar 25, 2019, 8:08 AM (IST)

Reinventing water cycle

Unplanned urbanisation, massive deforestation, burning of fossil fuels and resultant rising temperature have collectively disturbed the water cycle. Policy-makers and scientists need to take immediate measures to fix it, writes SS Kukal

Of the numerous cycles that nature has blessed humanity with, water cycle is the most crucial one for survival. This renewable cycle provides the mankind and other living beings the all-important water, without which life cannot even be imagined.

The fundamental part of the water cycle is evaporation, a constantly occurring phenomenon that involves the formation of vapours from the surface of water bodies and the canopy of plants through heating. These vapours rise and accumulate in the earth's atmosphere in the form of clouds, which condense and fall back onto the earth in the form of rain or snow. The fresh water and snow replenish various water sources (including groundwater) and glaciers.

Not too long ago when humans had affinity towards nature, a vast expanse of forests and other vegetation existed and the weather patterns were consistent too. But the large-scale migration of people from rural to urban areas over the past decades stretched the towns and cities to unimaginable limits, thus leading to an alarming decline in the green cover. This rapid urbanisation and massive deforestation along with the burning of fossil fuels and crop residue have caused an unprecedented rise in temperature.

All these factors have collectively disturbed the evaporation component of the water cycle. As such, the once well-defined seasons — winter, spring, summer and autumn — are no longer the same and weather continues to spring surprise every now and then. The surprise comes in the form of harsh and extended winter, rains accompanied by storms and floods and summer bringing along unbearable heat and droughts.

Major contributors

Unplanned urbanisation has led to the replacement of porous soil surface with concrete structures, which have almost zero-infiltration capacity. The concrete jungles, as the modern day cities and towns have come to be known, hinder recharge of groundwater — also an important component of the water cycle.

The large-scale deforestation in mountainous areas is leading to higher water run-off rate, thus depriving the hilly terrain of rainwater that would have seeped into the soil. The rising mercury, which has been breaching past records almost every year, is another contributing factor since the rate of evaporation is directly proportional to atmospheric temperature.

A disturbed water cycle has, in turn, led to a change in the rain pattern. Compared to the past, rainfall now is high in intensity but for a shorter duration, which aggravates soil erosion and runoff intensity. A data analysis by experts at the Punjab Agricultural University (PAU), Ludhiana, pointed out that about 18-54 per cent of the rainfall over the past few years has been categorised as "extreme".

Countering the problem

It is important that policy makers along with scientists frame short and long-term strategies to fix the disturbed water cycle. For this, an integrated approach has to be adopted, which mainly has to comprise the following measures:

Cities and towns have been expanding at an unprecedented pace and Punjab alone has witnessed 4 per cent (from 34 to 38 per cent) growth in urban population between 2001 and 2011. The urbanisation has mostly been unplanned and is leading to concretion of the soil surface, which blocks the passage of rainwater into the soil for groundwater recharge. Thus, measures need to be adopted to fix the problem (see box).

A recent study by the Central Ground Water Board showed that 'depth to ground water' level in most parts of Punjab ranged from 10 to 20 metres below ground level (mbgl), but the ratio is more than 20 mbgl around cities such as Jalandhar, Ludhiana, Amritsar, Patiala, Fatehgarh Sahib, Nawanshahr and Sangrur. The higher the mbgl, the more need for groundwater recharge. 

Need for afforestation

The cities in our country have little vegetation left in the form of trees or shrubs. Thus, the concept of ‘urban forestry’ needs to be followed to check the rapid growth of cities as well as to decrease urban pollution, facilitate better groundwater recharge and counter runoff losses.

  • Policies need to be framed at municipal corporation level to plant trees in private properties. Area-specific afforestation has to be planned by civic bodies in association with the Department of Forestry and Natural Resources, PAU.
  • The government should invest in research and other infrastructure to identify urban-specific tree and shrub species, which can bear the brunt of rapid urban growth.
  • Ornamental plant species that can help mitigate pollution need to be identified and planted in residential areas--PAU scientists have been working on this aspect. The natural vegetation in rural areas has been replaced by monotonous cropping system. It is, therefore, imperative to make strategies for rural afforestation as well.
  • Trees have to be planted on roadsides, banks of canals and other water bodies, fields and irrigation channel boundaries, public places, common land, residential, farm houses, etc.
  • It should be made mandatory to create dedicated biodiversity parks on at least 1-2 ha of common land in every village where inherent species are planted.
  • At the same time, fast-growing trees also need to be cultivated under different soil and climatic conditions.

Rainwater harvesting

The rainfall pattern in Punjab is such that 80 per cent of it is received in just two-and-a-half months. More so, half of this may occur in just a month and one-fourth within a week. At present, most of the rain is wasted as runoff water, which finds its way into oceans. It is, therefore, both a challenge as well as an opportunity to harvest rainwater.

  • Civic bodies should make it mandatory to have a mechanism for rooftop rainwater harvesting (RWH) in all residential and commercial buildings.
  • No alternate option for the RWH be provided to the residents (as is the norm currently) and the house plan should be approved only if the system is in place —PAU has worked out RWH systems under different situations.
  • The harvested rainwater can either be used to recharge groundwater or stored in reservoirs, which can be used for non-drinking purpose.
  • There should be a green belt on all main and connecting roads to facilitate infiltration. Under no circumstances should the green belt be made impervious through tiling or plastering. If tiling has to be done, porous tiles should be used. 
In rural areas, most of the rainwater gets accumulated in village ponds or inundates the fields. It can be utilised in several ways:

  • Excess rainwater should be stored in dug-out lined or unlined reservoirs, depending upon the purpose for storage. The unlined reservoirs can help recharge groundwater while the lined ones can facilitate stored water for micro-irrigation.
  • Farmers should install groundwater recharge structures designed by the PAU and the Punjab Department of Soil and Water Conservation. The excess rainwater diverted out of fields can be used for groundwater recharge.
  • Village ponds, an integral part in rural set-up, should be excavated for increasing seepage rate as these ponds are natural points of groundwater recharge. 
  • Drains in rural areas need to be revived to divert excess runoff and canal water during rainy season for groundwater recharge or for lift irrigation system.

Recycling waste water

Almost entire waste water from houses and commercial set-ups flows down the sewers into streams, rivers and ultimately the oceans. This water, which otherwise pollutes the good-quality groundwater, can be recycled after treatment and used for non-drinking purpose. The industry, in particular, should adopt in situ treatment and recycling of waste water and ensure zero discharge of industrial effluents into water bodies.

The water supply to every sector in this part of the country is being supplied almost free of cost, which leads to non-judicious use of water, something that needs to be checked.

The municipal water supply to residential, public and commercial consumers should be metered and water be charged as per actual use by consumers. This will lead to water conservation.

The installation of submersible pumps in residential houses needs to be banned completely. Efforts have to be made to supply canal water for drinking purpose.

There should be a separate supply lines of water for drinking and non-drinking purpose. The treated sewage water can be supplied for non-drinking purpose.

The households should install urinals in their toilets at least for male members to avoid the flushing of huge amount of water after urination.

In rural areas, agricultural water supply, be it from surface or groundwater sources, should be charged in terms of actual usage. Farmers need to be made aware of advanced techniques of irrigation, which can help save water. For efficient use of groundwater for irrigation, 24-hour power supply should be ensured.

Farmers should irrigate their fields only after going through the weather-based agro-advisory issued by the PAU scientists twice a week. This will help them utilise rainwater instead of surface or groundwater for irrigation.

As our water sources are on the constant decline, their judicious use becomes imperative for every individual. Moreover, since managing the water cycle is an integrated approach, it is important the government strategises the water cycle management with the help of scientists, policy-makers and those implementing their decisions.

Replenishing groundwater in urban areas

  1. Civic bodies need to mandatorily mark land for a ‘seepage belt’ (grassed strip of land surface) in every urban residential colony
  2. It should rather be a prerequisite for approving construction maps 
  3. Cementation of open space between the front and rear boundaries of a house and adjoining metalled roads in urban areas should be strictly prohibited— this area should be maintained as green belt
  4. These belts need to be provided with grass cover but if that can't be done, interlocking tiles with holes at centre should be used; these allow infiltration
  5. Urban households must be educated against cementing their compounds; these should rather be converted into lawns so that rainwater can seep in.
Figuring it out 

Rapid growth: 4%growth (from 34 to 38 per cent) in Punjab’s urban population in a decade from 2001 to 2011

Extreme pattern: 18%to 54% of rainfall over past few years has been categorised as ‘extreme’ (as per PAU data) 

Erratic rainfall: 80% of rainfall in Punjab is received in a mere two-and-a-half months; half of this in just a month 

(The author is Dean, Faculty of Agriculture, PAU, Ludhiana)


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