By Naba Bhattacharjee
The ground shattering loud noise of truck mounted water drills are a common sight in all localities of Shillong. On enquiry it is learnt that a number of such water drill infrastructure are stationed at Shillong since over a decade with couple of months advance booking necessary to engage one. This is a clear evidence of the extent to which ground water is being harnessed within Greater Shillong areas. It is not always need based but an “additional security” of ensuring excess, far beyond ones requirement. This is a very dangerous trend for the future. India is among the countries that will be worst hit by water scarcity with an estimated 100 million people facing drought conditions, reflecting ominous portent of a dry and barren future.
Meghalaya together with other north eastern states of the country, particularly the hills are perilously poised. It will not take long compared to the plains, for the situation to take an abrupt turn for the worst. It is not a question of non-availability of water but total ignorance and lack of initiative to conserve water, resulting in bulk of the rain water flowing down the hilly terrain into the plains. The severe water crisis at Sohra especially during dry months, in spite of being one of the highest rainfall locales in the world, is definitely a forewarning of the approaching danger. Ground water exploitation particularly energized mechanical in nature with capacity of output ranging from 2500 ltrs per hour and above to need to be regulated strictly, if not totally banned, except for community supply schemes in selected rural areas where no other feasible source of supply is viable.
A major segment of Shillong’s population is provided with surface water, emanating mostly from springs, streams and rivulets originating or flowing through the catchments. However, with ecological degradation of majority catchments in and around Shillong, the output from this primary source has been rapidly declining. The major source of piped water supply is GSWSS which is augmenting its generation and distribution to cover more areas under a scheme approved under JNNURM. The surface water generated and distributed through the network of Civic bodies is improving to meet the demand of Shillong and its suburbs although the situation deteriorates to a stage of water scarcity in many areas of the capital during dry months. In order to overcome such stress conditions, an increasing number of residents are taking recourse to harnessing of ground water by establishing bore or deep tube wells. This development which was more evident in areas located outside municipal jurisdiction due to absence of government supply, is gaining momentum with SMB jurisdiction. Groundwater, as a natural resource can augment supply during the water scarcity periods. In order to maintain this potential, a hydraulic equilibrium must be established between availability and utilization. Groundwater exploitation increasingly became inevitable in certain localities due to scarcity of regular supply of piped surface water. However, with present easing of the situation, measures must be initiated at this stage to ensure that no over exploitation of this source is allowed.
Wells were unheard of in Shillong even in the eighties. Such wells basically cater to the need of an individual settlement, harnessing far in excess to actual water requirement. The result is over exploitation of ground water without any initiative for augmenting natural infiltration of rainwater or surface run off into the underground formation. The proliferation of energized wells has to be restricted, since such wells have depleted ground water all over the country ranging from 1 to 3 meters a year depending on their location. In hilly terrain, the decline shall be much higher. Such wells can be allowed, if matching replenishment measures are ensured. Over extraction of ground water, lead to intrusion of polluted water into aquifers, resulting in problems of excess iron besides arsenic and fluoride. Ground water is facing an equally serious threat from contamination by various effluents together with fertilizers and pesticides from farm run-offs. Recycle of effluents, domestic sullage and sewage not only conserve vast volumes of water, but also protects the environment by reducing pollution.
The best way to replenish a bore well is through rain water. Infiltration of rainwater or surface run off into the underground formation is facilitated by different artificial methods like water spreading; recharge pits, trenches, shafts or direct diversion to existing wells. The choice and effectiveness of a particular method is governed by local hydro-geological formation, soil status and end use. Rooftop rainwater harvesting system is most feasible and appropriate from the point of availability, technical suitability and economic viability. Moreover, instead of the common approach of canalizing rooftop run-off to drains, the outlets must be connected to existing wells to serve as recharge points. All such steps should be aimed at maintaining the water table at a pre-determined constant level to which extraction has to be limited. This can be achieved through a law which shall provide for monitoring of all existing energized wells, including approval for establishing new ones, subject to suitable arrangement(s) made in the ground, well in advance for recharge.
A check and balance approach is essential if we want to ensure an optimum water table and also avoid serious health hazards arising due to arsenic or fluoride contamination of ground water. A strategy to implement ground water recharge needs to be launched with concerted efforts of Government, Civic Bodies and stakeholders. In fact Umpling Dorbar had initiated strict regulation on bore wells during 2005-06. The recently modified building bye-laws of Meghalaya Urban Development Authority have rightly made rain water harvesting mandatory for all new construction. It needs to be taken a step ahead for existing buildings to follow suit with specific technical guidelines on how to execute the concept. And above all a realistic appraisal of ground water potential of Greater Shillong Urban Agglomerate has to be undertaken with assistance from Central Ground Water Commission, followed by “water zoning” to identify areas where and to what extent harnessing of ground water is feasible and areas where the same is not recommended. On completion of the exercise, a procedure must be adopted for regulation by concerned agencies like MUDA/SMB/PHED of granting permission by clearly specifying bore size, discharge rate, output etc allowed to an applicant based on the findings.
(The author is an environmentalist)