Groundwater Quality from Basaltic Aquifers
Dr. S. K. Vadagbalkar, Associate Professor and Head, Dept. of Geology, Dayana...
material, with closely spaced fractures. 2) Middle part of the flow with massive, compact basalt
without fractures or ve...
Groundwater table fluctuations in basaltic aquifers are dramatic. During the precipitation,
literally the dug well/bore ...
The quality of groundwater is specified with chemical, physical and biological analysis.
A complete chemical analysis of...
degraded or smells objectionable i.e. common man relies on his senses. In severe cases, such
objectionable water may not...
a reliable source of drinking water, think of the quality of water which we are getting. The wells
nearby and such pollu...
sugarcane cropping in the surrounding area, of these industries to meet their demand as raw
material. Heavy use of ferti...
where the wells are unlined or are insufficiently protected, get affected easily by contaminants. It
serves to them for ...
should occur, or to forecast the contaminant dispersion than to decontaminate an aquifer. The
complexity of the problem ...
the stream/river in which the load is to be disposed, and within the limits of its natural
purification capacity.
If su...
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Groundwater Quality from Basaltic Aquifers, Dr. S. K. Vadagbalkar, Associate Professor and Head, Dept. of Geology, Dayanand Institution, Solapur - 413 002.


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Basaltic aquifers-shallow and deep, from Deccan Trap regions in parts of Maharashtra state, are considered as a case study to understand the quality of waters. Based on the research articles, news, from scientific journals, reports of government and non-government social organisations, communications, newspaper articles and news, attempts have been made to prepare a concise reconnaissance review article.

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Groundwater Quality from Basaltic Aquifers, Dr. S. K. Vadagbalkar, Associate Professor and Head, Dept. of Geology, Dayanand Institution, Solapur - 413 002.

  1. 1. 1 Groundwater Quality from Basaltic Aquifers Dr. S. K. Vadagbalkar, Associate Professor and Head, Dept. of Geology, Dayanand Institutions, Solapur - 413 002 Email: vadagbalkar@gmail.com Member, Ujani Janhit Sansad, Solapur (Cell No-098906 27900) This article is referred for National River Policy Documents under leadership of Dr. Rajendrasinghji, President, Jal Biradari, Jaipur, Rajasthan; which was submitted to Hon‟ble Prime Minister Dr. Manmohan Singh. Abstract: Water is the essence of life on the „water planet‟ Earth. Its position as a geofactor is well known in the development of any country truly with the quantity and quality. Most of the water acts as renewable source. Large amount of freshwater available for various utility purposes is in form of underground storage. i.e. groundwater. As it is hidden below the surface, it is most ignored and presumed by the masses towards its availability in safe form. In general the groundwater available in most of the areas in the country is fresh with exceptions of coastal and waterlogged areas of high irrigation, in some parts of inlands, where saline or brackish groundwater are reported. But with the increasing human activities and additions of wastes – (sewage and domestic) from urban and rural settlements, industrial sectors and agricultural discharges into surface waters, which further infiltrate to groundwater, are contaminating and heavily polluting, both the waters at alarming rate. It is important to note that groundwater contamination is largely irreversible and the present technology for controlling the pollution and aquifer cleaning at subsurface level is highly expensive and also has limitations. Surface water and groundwater are interrelated and inter dependent, the contamination of groundwater is mainly connected with surface water and ground conditions available. However, the gravity of the problem is still not seriously accepted by the authorities and populations. Based on the research articles, news, from scientific journals, reports of government and non-government social organizations, communications and news paper articles etc., attempts have been made to prepare a concise reconnaissance review article. Basaltic aquifers-shallow and deep, from Deccan Trap regions from different parts of Maharashtra state, are considered as a case study to understand the quality of waters. Geological and Hydrological properties of Basaltic Aquifers: Maharashtra state is one of the leading states of India bounded by north latitudes 16º 4‟ and 22º 1‟ and east longitudes 72º 6‟ and 80º 9‟ covering an area of about 3,07,690 Sq. Km. There are total 31 districts and 303 tahsils. It is one of the leading states in the country with respect to groundwater utilisation for domestic, industrial and agriculture. The groundwater is made available through large diameter dug wells and bore-wells intersecting the shallow as well deeper aquifer zones. Nearly 82% of the area constitutes part of the major continental tholeiitic basalts-lava flows of Creataceous-Miocene age referred as Deccan Traps in Indian stratigraphy. Flood basalts owe their great thickness mostly to the accumulation of large number of thin and thick lava flows. The different lava flows and flow units can be separated on the basis of their lithological characters. In general the top of the flow is marked by vesicularity, flow breccias, clinkery surface, shrinkage fractures and red bole layer. The vesicles are rounded, irregular or tubular and are generally filled with secondary minerals giving rise to amygdaloidal form at places. In a single lava flow the various flow units separable are as follows :- 1) Upper part of the flow with vesicular, amygdaloidal basalt with or without red bole and/or brecciated and tuffaceous
  2. 2. 2 material, with closely spaced fractures. 2) Middle part of the flow with massive, compact basalt without fractures or very less fractures. 3) Lower part of the flow with massive, compact basalt with widely spaced fractures. On regional scale the lava flows are horizontal in nature and exhibit stepped terrace appearance, but show variation on local scale with gentle dips at places. The variations are mainly traceable in thickness of flow units, laterally and vertically. Weathering in basalts horizontally and at depth varies with the conditions of climate, topography, lithological variations as flow units, depth, texture, soil cover and chemical composition. The bottom of the flow when exposed at or near the surface due to cuboidal nature of jointing, spheroidal weathering dominates, resulting in formation of large or small core stones. When the rocks are exposed near the surface, then due to weathering and stress release, sheet joints and open fractures are developed, which may extend at depth, interconnecting vertically the different lava flow units and/or lava flows occasionally. Otherwise, normally the fracture pattern of one flow is not continued in the second flow at depth. The interconnection of pores/fractures near the surface, in weathered mantle and flow contacts and various flow units, make the basalts good aquifer and reservoirs. The open fractures and its networking may act as conduit to give rise to transmission or percolation of sufficiently large amount of surface water at depth and in lateral extension to provide good storage facilities. As the conditions of primary and secondary porosity in basalt vary from place to place they vary widely in permeability too. The formations are thinner or thicker, vertically and also laterally. The lateral gradations are of great significance with respect to the occurrence and movement of groundwater. Sediments or former erosional /depositional surfaces and ash or altered glassy zones between the lava flow units, greatly modify the porosity and permeability of basaltic aquifer, essentially at depths. Sealing of fractures due to siltation, mineralization, precipitation of salts etc. in geologic time, reduces the porosity and permeability of the aquifer. Similarly as the fracture intensity decrease with depth along with the compaction, the movement and availability of groundwater retards. There are important differences in the same formation at different horizons and in different localities. The primary and/or secondary openings are irregularly distributed and/either are interconnected or remain isolated horizontally and also vertically. Erratic pattern of weathering, variations in flow units and their thickness and haphazard interconnections or isolations of pores and fractures, lead to the heterogeneous nature of aquifer characters, in basalts. And therefore it is commonly observed that some wells / bore wells may yield negligible, in spite of deeper penetration, in respect to near by wells / bore wells yielding high with either partial or deeper penetration. However, it is nature‟s gift that these rocks will definitely yield either small or large but reliable amounts of water to dug wells. i.e. seasonal availability, even at high altitudes. Deeper excavation of dug wells below the aquifer act as storage in critical time at least to fetch water for drinking. Due to multi layer aquifer system, existence with the presence of multiple lava flow units at depth, the bore wells penetrating at deeper depth upto100mts. (300 feet), from the surface is yielding sufficiently good amount of water in large parts of Deccan Traps in suitable morpho geological conditions, intersecting two or three lava flows. In basaltic aquifers large amount of water is available under unconfined conditions compared to confined conditions. Many times even at confined conditions large amount of water is available under special conditions. Due to such erratic occurrences, many researchers accept the concept of leaky aquifer, in between the unconfined and confined conditions. Dating of the water available at depth is not available for basaltic aquifer, but probably the waters accumulated at depth in large amount may be during the suitable conditions in the past during geological time and hence can be termed as "Fossil Water” i.e. stored water. This may be considered as mining of water. With the highest and continuous rate of pumping out of water, for use from such deeper aquifers has resulted in total evacuation and the bores are abandoned. Delineation of such characteristics, though complex, seriously needs the immediate attention.
  3. 3. 3 Groundwater table fluctuations in basaltic aquifers are dramatic. During the precipitation, literally the dug well/bore wells overflows in low line and Planation areas under the suitable conditions, while they go totally dry in summer. Such heavy fluctuations in water table affect the yield and availability of water throughout the year. As the yield and availability of groundwater, varies with the change in conditions and as erratic manner, the water table contouring and basin movement of groundwater, as normally accepted by the researchers, is not true in the field. The yield of wells/bore wells even in small area varies abruptly. Therefore with the field experience and experiments, it is felt that the micro-basin approach, considering the aquifer characters, its extension - lateral and vertical, must be considered. The field observations confirm the occurrence and availability of water in pockets or small basins/chambers with or without interconnections. i.e. may be interconnected or isolated. The massive units, isolated fractures and other related features, hinder the movement of water laterally and vertically, so that storage of water and its movement are restricted. With such conditions isolated pocket occurrences of groundwater are seen in basaltic rock terrain, laterally as well vertically at depths. How ever during monsoon due to heavy replenishment on and near the surface, groundwater table continuity results. Groundwater Geochemistry: All ground waters/natural waters are in chemical sense solutions. Water being a universal solvent and with its special dipolar nature react with nearly all natural and artificial materials. Concentration of salts in groundwater depends upon the environment, movement and source of the groundwater. In real sense it is the reflection of the composition of the minerals and rocks, on which it moved. In general dissolved constituents are concentrated more in groundwater than surface water, as groundwater has greater longtime contacts with the geologic strata. Ground waters from basaltic terrain are found rich in bicarbonates and carbonates as anions and with calcium, magnesium, sodium, along with silica as cat ions. Sulphates and chlorides are other anions with varying concentrations. This reflects the basaltic composition. Most of the reactions are of hydrolysis nature, taking place between plagioclase, augite and olivine minerals of basalts and water. The concentration of any chemical constituent is directly depending upon the solubility and Eh-pH of the environment. The dissolution rate of rock forming minerals and their solubility are temperature dependent. The higher the temperature faster the dissolution. Solubility of silicates increases with increasing temperature but is not true for carbonates. When the water percolates through soil horizon, it gains CO2 from organic decomposition, to form carbonic acid, which further accelerates the dissolution reaction. As chloride and sulphate minerals are generally absent in basalts, their concentration is not represented in groundwater. However chlorides being highly soluble and may be accumulated, either from atmospheric precipitation or zeolites, remain in soluble state, transforming bicarbonate – carbonate waters to chloride waters. Sulphate and chlorides are thereby considered as index to attribute their concentration by artificial means in basaltic groundwater. Due to carbonate and alkaline elements dominance, the ground waters are of alkaline nature and thereby display pH>7. Total dissolved solids vary in concentration. Electrical conductivity and total dissolved solids are interlinked. With more amounts of salts the conductivity increases. Normally the waters are termed as hard waters due to dominance of Ca, Mg, and bicarbonates- carbonates. In temperate climate the dissolved salts of calcium precipitate in form of carbonate minerals leaving behind chloride in groundwater specifically at depth. This is reflected in calcrits modules dispersion in soils, as well chalk formation at shallow depths, sealing the fractures and pores in the basaltic aquifers. With bicarbonates the water are temporary hard, while they may get modified with time to permanent hardness, with chloride enrichment. The term salinity is used to denote excess total dissolved solid concentration i.e. salts. Sodium chloride concentration is considered as the basic factor for salinity. Dissolved salts in groundwater of normal salinity occur as dissociated ions. In additions other minor constituents are reported in elemental form.
  4. 4. 4 The quality of groundwater is specified with chemical, physical and biological analysis. A complete chemical analysis of groundwater sample includes determination of inorganic, organic and radiological parameter, as major, secondary, minor and traces constituents. The important elements and the concentrations are as follows- major constituents-Na, Ca, Mg, HCO3, SO4, Cl and Si (1 to 1000mg/l), secondary constituents -Fe, Sr, K, CO3, NO3, F and B ( 0.01 to 10mg./l), minor constituents-Al, As, Ba, Cd, Cr, Co, Cu, Pb, Mn, Li, Mo, Ni, PO4, V, Zn, U and Sb (0.0001 to 0.1mg./l), trace constituents- Be, Bi, Cs, Ga, Au, La, Pt, Ra, Ag, Th and Sn (less than 0.001mg./l). Number of researchers have reported and are working with the estimation of quality of groundwater from unconfined and confined aquifers of basalts from different region, but unfortunately this number is very small, if compared with the magnitude of the aerial distribution and variations presents in the Deccan Trap region. Probably due to analytical constraints only the major constituents are analysed and reported, with very few exceptions reporting for secondary, minor and traces. The overall review reveals that groundwater of basaltic aquifer are potable and useful for irrigation too. Due to natural hardness and high amount of TDS at places, it requires some treatments. With the suitable treatment even it can be used in industries for special purpose. Pollution of surface and Groundwater : “Today the problem is not only one of water availability but of environmental quality and ecological balance. With increasing industrialization, urbanization and technological advances in all fields, sources of water are getting more and more seriously polluted. The survival of life on earth will be threatened if the present rate of pollution continues unabated” (Meadows et al 1974). Today the things are more worsened. As per World development resource, in India (1998) 1,760,353 kg/day of organic water pollutants are emitted, in which industry shares of emissions of organic water pollutants in % is as – primary metals (15), paper and pulp (8.4), chemicals (8.9), food and beverages (49.1), stone, ceramic and glass (0.2), textiles (12.9), others (5.6). In other report all the major 14 rivers in India are polluted, which fetch the needs of nearly 80% of the population for their drinking water supply. Surface and groundwater are two component of hydrological cycle with different but interrelated hydrologic, economic, and environmental characteristics. The complexity of the relationship between surface and groundwater makes it inevitable that changes in one point should lead to adjustment elsewhere. The surface waters are the main resource of replenishment of groundwater aquifers. Thereby degradation in surface water quality is bound to reflect in deterioration in groundwater quality. However this is not reflected in reality. Reason for this is the mechanical, chemical and biological filtration of percolating bad waters through soil and weathered zone. Due to ion exchange, bacterial decomposition and degradation of organic mater, in many types of soils, the pollutants are removed safely in a natural way or concentration of hazardous components is minimized. The ground waters from basaltic aquifers are also to be essentially related with surface water. Unfortunately gravity of the problem of groundwater contamination and its essentiality for the sustenance of life is not given much attention. En numbers of cases are reported regarding pollution of groundwater by the media in form of news/articles etc. But scientific data, or analytical and systematic reporting and follow-up are scarce. Surface water is given much more attentions than the groundwater. There are National and International programme launched for cleaning of polluted rivers or restoration of the quality of waters, on large scale. e.g. National River Action Plan (NRAP) under Central and State Pollution Boards. One way this is going to prevent the further groundwater contamination, wherever groundwater storages are linked with these river systems. The problem is critical as the common man or consumer is reluctant to know about the quality of water and simply he ignores. It is presumed that the natural gift of water, a hidden source in form of groundwater, is safe for drinking and utilisation. Essentiality of analysis for chemical quality of water is never realised seriously either by the masses or the authorities. Common public is habituated for utilisation of any kind of water, unless the water is physically
  5. 5. 5 degraded or smells objectionable i.e. common man relies on his senses. In severe cases, such objectionable water may not be used for drinking, but is used for cattle‟s, cloth washing, agriculture, cottage and small industries etc. without bothering about the serious after effects. Ground water contamination is mainly attributed to either by natural causes or by artificial causes. Natural contamination includes salinity increase i.e. increase in concentration of salts in form of total dissolved solids. With the natural solubility of chlorides and with the residence time under suitable environmental conditions the water may turn saline. Due to evaporation removal of co-existing salts also may increase the salinity. Percolation through thick soils, silt and alluvium in the flood plains of rivers also help in increasing the salinity. Thereby the waters are left with limited usage and are not potable, if the chloride concentration is more than 100mg./l. In drought prone regions of arid climate the pockets of Salinated water are common. Due to over exploitation of groundwater in the coastal region, with the disturbance of salt-fresh water balance, salt water intrusion in inland waters is frequently observed, and is reported from various isolated patches of west coast – Konkan region. Natural hazardous mineral compositions, metallic or nonmetallic, carbonaceous or organic materials may yield acidic waters, or waters with metal ions and organic composition, which are not suitable for utilisation, unless they are treated. But this problem is not attributed in Deccan trap regions. However acidic waters from some hot water springs, from Konkan region are reported. Most of these water are rich in Na-Cl alongwith few, as Na-HCO3 and Ca-Cl2 compositions. The acidity is mainly due to sulphate. Cation exchange NaCa is prominent in these waters. It is well understood that surface waters are largely contamined mainly by artificial means rather it is the result of human activities putting the wastes in the rivers intentionally or unintentionally. The contamination is physical, chemical as well biological. The suitable nature of basaltic aquifers exposed near the surface especially with open fractures/conduits are susceptible for direct contamination. Due to open fractures in jointed rocks and their interconnections, the contamination spread fast laterally and also vertically at depth, under suitable conditions, mainly in shallow aquifers. Therefore unconfined basaltic aquifers are found contaminated at various places, wherever the pollutant entry is feasible. Common sources of groundwater contamination include use of agricultural fertilisers and pesticides, sewage and sanitary wastes from human settlements-rural or urban, landfill sites or garbage dumps, industrial effluents and wastes, spills of chemical and organic materials during transport etc. Of these the main culprit is sewage or human wastes, which constitutes nearly 70% of the total pollution. The waste disposal from urban and rural population is directly flooded through surface drain into the nearby nala or river tributary which further joins the main river. Treatment of wastes is a costlier process and therefore panchayats or municipalties don't bother about the treatments. As in most part of the basaltic terrain arid and semi-arid climate persists, the nalas or rivers actually act as sewage water carriers. Only during monsoon or when the water is made available through dams/canals etc. the dilution will occur. Due to such prevailing conditions the surface water is no way serving the purpose of drinkable water, unless treated scientifically and systematically. Intensity of the problem enhance with the down stream direction. The human waste is mainly of organic composition, which is degraded and decomposed with oxygen and microorganisms available in fresh or river water. Within the natural limits, the waste can be diluted and made harmless i.e. natural purification. But with continuous addition of the load, the balance is disturbed and total collapse of the natural purification process takes place giving rise to anaerobic conditions. These results in poisonous methane, ammonia, hydrogen sulphide and similar gaseous production, alongwith accumulation of organic carbon and carbon compounds. i.e. As organic matter is decomposed under anaerobic conditions, foul smelling gases and other products of decomposition accumulate and cause problems of odour, taste and colour. This is a common site with in a village or town (small or large.), wherever surface drains of sewage accumulates or are stored or stagnant. As stated earlier, our nearly 80% population of rural and urban areas directly depend upon river waters as
  6. 6. 6 a reliable source of drinking water, think of the quality of water which we are getting. The wells nearby and such polluted rivers/streams is going to get the effect in their water, probably in relatively reduced concentration. Increase in concentration than normal range of TDS, TSS, BOD, chlorides, sulphates, phosphates, E.Coli. (MPN), T.Coli., organic carbon etc. indicate the sewage pollution. Reports about the degradation of water quality in surface and groundwaters around parts of Pune, Solapur, Kolhapur, Sangli, Dhule, Amaravati, Bombay, Nasik, Nanded, Aurangabad, Nandurbar, Parbhani, Jalgaon and so many others, have been reported by various workers - geologists, chemists, microbiologist members of social organisation etc. Solapur city population is supplied with drinking water from Bhima river. After the treatment the water is made available by the corporation. Pandharpur is famous pilgrimage center in Solapur district, towards the upstream side. During and after the completion of gatherings/mela of nearly quarter to half millions of devotees in Ashadhi and Kartiki periods, the human waste and garbage, accumulated and untreated, gets concentrated in the water of Bhima river. If adequate water is not available for flushing, mainly in drought conditions, the river water charged with wastes, start giving bad smell. With heavy treatment also, sometimes the corporation is not in a position to supply real potable water for few days. This is for the city where treatment is possible. What about the downstream population directly using river water or water from wells adjacent to the river flows? Large scale epidemics, cholera, typhoid, malaria, jaundice, emerge immediately after circulation of such waters, in the adjoining areas. Similar situations do exist in different parts of Maharashtra too. The second culprit is the industrial waste. With the technological advances and modernisation the socio-economic development is related with industrial growth of the country or town. Maharashtra state is also recognised a “state of industries” due to enormous development of industries mainly around Bombay, New Bombay, Thane, Raigarh, Ratnagiri, Pimpari-Chinchwad – Pune, Nasik and Aurangabad regions. The industries are of all types covering major, minor, cottage and even household. As a policy of development, industrial sectors are developed and planned in all districts and even in many talukas, under MIDC. Therefore the problem of industrial pollution in contribution of contamination of surface and groundwater, is serious in Maharashtra, which should be taken care of seriously by the government and population. With the unplanned utilisation of earth resources, to meet the demand, has given rise to serious alarming concentrations of heavy metals, metallic compounds, organic materials, particulates, non-degradable materials, hazardous chemicals, poisonous gases etc. in their discharges and effluents. Many times these effluents are coloured, irritative with bad smells and turbid in nature. Earlier these effluents were untreated, but with the awareness of citizens, implementation of laws, and check by a Central and State government environmental pollution control boards, the industries are legally cautioned for the suitable treatment of the effluents, before discharging them into the basin or channel. This has controlled nearly 30% of the industrial pollution. But this is true and working for major industries. However, there are some big and small industries, which are not obeying the laws and systematically breaking rules and regulations and throwing out their effluents either as ill-treated or in mixed manner. The cottage industry, textile industries on small scale and similar others which are exempted or ignored with the views of humanity and survival strategy or similar, seriously pollute the surface and groundwater, by discharging untreated effluents. The cost effect is basic factor for non- treatment of the effluents. Other important factor is unawareness of the public or masses and reluctance of government authorities towards the gravity of the problem. In western Maharashtra, sugar industries belt is popular. The waste from these industries is many times ill-treated, especially during the peak periods of the productions. The distillery factories are also coexisting at many places. This waste is mainly of organic nature. Its increase in the river water and further entry into groundwater through dug wells, irrigation canals etc. has caused serious epidemics, jaundice etc. for rural and urban population surviving with it. This is irregularly regular phenomenon during Oct./Nov. to March/April of every year, as reported by the researchers and Journalist in parts of Pune, Nagar, Satara, Sangli and Kolhapur. But this is temporary fluctuation, in pollution level. The real pollution is from the agriculture adopted for
  7. 7. 7 sugarcane cropping in the surrounding area, of these industries to meet their demand as raw material. Heavy use of fertiliser and pesticides, especially in maintenance of quality and quantity of the sugarcane crop, alongwith limitless and unplanned use of surface and groundwater, has created a disastrous show in the deterioration of quality of water in these areas. High concentrations of potassium, sulphate, phosphates nitrates and chlorides in surface and groundwater are indicators of heavy pollution. As per one of the report, the total chemical fertiliser consumption in Satara and Sangli, during 1995-96 was 50390 and 83153 tones. The total pesticide consumption in Maharashtra, as per agriculture agency report is 711 MT/year, of which 7% each, is consumed in Satara and Sangli. This has reflected in very high organo- chlorine share alongwith very high concentration of F.coli., T.coli., Nitrogen, Phosphorous, Sulphur, Sodium, Magnesium Total dissolved solids, alkalinity, O.D., B.O.D., and COD etc. in the stretch of Krishna river near Satara and Sangli. Similar conditions are reported with varying degraded and deteriorated quality of waters in and around Mula, Mutha, Panchaganga, Bhima, Pravara, Godavari and many others. Concentration of hazardous DDT is reported from soils, vegetables, grasses, and even in milk entered through pesticides from these agriculture fields. The water of the Ulhas river draining the industrial area of Bombay is so heavy with toxic elements like Pb, Zn, Cr, Cu and Cd etc. that these elements have entered in the frameworks of even the river bed clay minerals. The water of Kallu stream and the Thane creek likewise contain high amount of toxic Hg, Cd, Pb, As and Cu have now found their way into vegetables and fodder grasses grown in the flood plain. The waters from Taloja – MIDC show high concentration of Cr, Cd, Ni, Zn, Cu, Pb, Fe, chlorides, TSS, TDS with pH variations from 4.1 to 9.4 (acidic to alkaline) and are coloured waters. Patalganga river waters near Khopoli-Raigarh district reveal the higher concentration of B.O.D., Nitrates, phosphates, chlorides, TSS and Silicates with pH 6 to 8. Another important aspect of pollution is unplanned, unlimited and unscientific, utilisation of water for irrigation in agricultural lands and misuse of lands. Irrigation by canal water is assumed to be planned and scientific. But in reality it is irregular, asymmetric, unplanned, unlimited and unscientific. Locally, with the economy and power influence tactics, the collapse of the system in many parts is observed. Getting excess water and storing it in the farms has become an habit of the farmers. Time scheduled and distribution planning therefore is completely disturbed and frequently the peripheral and tail end canal population is left without water. Excess irrigation has changed many fertile, high yielding lands into nonproductive and saline lands due to water logging. Low line and planar regions, under irrigation schemes are mainly suffering with this complex problem, because of inadequate sub-drainage. Due to near surface or on surface water table, transport of salts/solutes is prohibited, and thereby more dissolution of salts from soils occur, reflecting in increase in salinity. Evaporation further precipitates salts on the surface. Soil degradation as a result of salinisation is also reported from drought prone regions and rain fed agriculture zones of arid climate. In Maharashtra soils from some parts of Pune, Ahmednagar, Aurangabad, Nashik, Parbhani, Nanded, Tapi and Purna basin area, Kolhapur, Sangli, Satara and Solapur are reported degraded mainly due to water logging and excess irrigation and are reported for reduction in their crop yield. Chlorides, sulphates and sodium get enriched in degraded soils. Co-operating with the above processes, other minor, but important locally, at many places are the leachates transport from garbage sites, landfills, sanitary wastes, leakages from septic tanks, oil tanks, buried under the surface, old abandoned wells or abandoned quarries, ponds and lakes connected to open drainage or sewage, mine waters, surface and street wash during stormy rains, soil erosion, rock exposures etc. are involved in direct or indirect pollution of groundwater. The bore-wells surrounding these sites will receive the pollutants if proper care is not taken mainly through shallow unconfined aquifers. Getting drainage water or polluted water through water supply pipes, mainly due to leakages, occasionally forms a news. In rural areas
  8. 8. 8 where the wells are unlined or are insufficiently protected, get affected easily by contaminants. It serves to them for both agricultural and domestic use including drinking. Use of such untreated and contaminated water is the root cause for the spread of epidemic, skin diseases and water borne diseases, in rural population of Maharashtra. Over exploitation of water in some parts of Maharashtra is also another significant problem now realized by the Central and State groundwater boards. The recent survey reports state that out of 1503 watersheds in Maharashtra, 34 are dark i.e. the stage of groundwater development is more than 85 %. This may lead to the total exhaustion and further may help in subsidence and landfalls as feared by the scientist, and may cause irreversible damage to the water-bearing zone. In coastal areas such precaution is specifically necessary to avoid saline water intrusion in inland aquifers of Konkan belt. There are reports for saline intrusion in few isolated patches, along West Coast region. Indirect impact of deforestation, use of mechanized equipments, mismanagement, misuse in agriculture- land use and crop pattern, is also reported for helping in contamination of groundwater. Deeper and slope ploughing, non-hiding straw, bare soils at certain times, use of grass land for agriculture, etc. tend to reduce the organic content of the soils, break its structure, thereby exhausting it and making it prone to erosion. This facilitates the direct infiltration of polluted water mainly contaminated with fertilizers. It also adds in turbidity, by increasing TSS. In summarization, the most important causes of pollution are: 1. The discharge of untreated or insufficiently treated domestic sewage and industrial waste water (Pollution of bacterial, organic and heavy metal etc.) 2. Storage of domestic and industrial wastes on insufficiently safe dumps. (Pollution by seepage (leachates) water.) 3. Irrigation (discharge of salt etc. into groundwater reservoirs and surface water through unsuitable irrigation and drainage methods). 4. Excessive use of fertilizers and inefficient use, unsuitable storage and disposal of pesticides (discharge of nitrate, pesticides, herbicides, etc.) 5. Deforestation and ploughing-up of grasslands (pollution of outlets with nutrients and suspended matter.) 6. Overuse of the groundwater (salt water contamination of groundwater bodies in coastal areas, subsidence and consequent changes in the behavior of surface run off, rising salt content and ultimately, drying up of the surface water body or aquifer at depth.) It is necessary to realize that some pollution is also directly received through atmosphere, in form of gaseous dissolution in rainwater. Acid rains from highly polluted (atmospheric) areas are now common. Acid rains have been reported from Chembur- Bombay, which is identified as critically polluted area which need special attention or control of pollution, by Central and State pollution control boards. Fly ash deposition from thermal power station-Parali is considered as one of the important source of pollution for -air and water, in adjoining areas. Radioactive waste from atomic reactors and their disposal sites are also matter of great concern. However, much elaborative as well determinative work is awaited in this direction. Mitigation of pollution / contamination : Pollution removal is always more difficult and more expensive than prevention. Many times the attempts made may not restore the originality, even after huge expenditure. Attempts have been made in the western countries in this direction, but the success achievement is relatively low. For developing country like India, huge expenditure in pollution treatment is not a priority as other basic needs and problems need more attention and budget. Therefore it is important to think about the preventive measures, since it is still easier to avoid that pollution
  9. 9. 9 should occur, or to forecast the contaminant dispersion than to decontaminate an aquifer. The complexity of the problem attends when the deeper aquifers are polluted. In every treatment process, basically it is essential to understand, the toxicity of each pollutant. General outline of the pollution control includes physical, chemical and biological processes. Physical processes are filtration and transport processes, which include sorption (Adsorption or ion exchange), volatilization, diffusion and advection. Chemical processes are solubility (chemical equilibrium), oxidation and reduction, hydrolysis, hydration and photolysis. Interaction of soil, rocks and minerals with water, form the compounds or complexation, either immiscible or miscible. Biological processes are primarily bio-transformation, biodegradation and bio accumulation, supplemented with biotechnological processes. Preventive and remedial measures suggested: Priority should be given not to allow the deeper aquifers to get contaminated. As shallow unconfined aquifers are normally susceptible to contamination, the source of pollution must be controlled by arrest of contamination spread/plume dispersion by using abstraction of natural or artificial impervious material in form of walls, covers, grouting layers etc. and then removing the contaminant/plume by pumping on the surface and then may be used after proper treatment. In case of dug wells proper lining must be provided for the formations vulnerable to contamination (soil, weathered mantle, open fractures, loose alluvium etc.). If not found suitable then the extraction from dug well should be abandoned and be refilled and closed. In case of bore wells a proper case must be used to avoid the entry of undesirable waste. If required the upper aquifer may be completely detached by putting full length casing for vulnerable upper zone. Direct entry of surface water/recharge water, if contaminated, into dug wells or bore wells, must be protected by filtration. Constructions of protective walls, for dug wells and cement grouting or cover, sloping away from the bore pipe, for bore well is essential. The surrounding must be kept clean and free from trees, huts (population) cattle fields etc. when it is going to be used for drinking purpose. Washing of cloths and utensils, bathing etc. also be strictly avoided. Salinated water either from deeper aquifers or from water logged areas should be carried on the high land areas and then used or spread. This will reduce the salt concentration, and also its use will recharge the upland areas and help in crop production. Sub drain and also large amount of water should be provided for salt removal from saline lands. The evaporated salt may be collected (hand or machine picked) from the surface and used elsewhere. The crop pattern should be managed with salt tolerance. To avoid salinity and water logging, the canal must be lined. Literally washing or cleaning of contaminated unconfined aquifer can be worked out by flooding them with extra water. (may be brought from adjacent basin or dam). This helps in dilution of the concentration. Similar process is worked out by nature during monsoon when the rivers and dug wells in Deccan Trap are over flooded. Aeration of aquifer by oxygen rich air and/or disinfectant gases, use of disinfectant chemicals and biodegradable chemicals to the affected aquifers of small dimensions may serve the purpose temporarily or permanently. Drainage water, effluent and similar waste waters must be treated, with help of minor to medium size treatment plants placed at different localities to cope up with the surrounding population and environ conditions and then must be reused and recycled and the excess may then be flown to surface drain. Over loading of wastes should be avoided. Disposal of the waste must be after proper determinations of capacity of acceptance of waste water load, the quantity of water available in
  10. 10. 10 the stream/river in which the load is to be disposed, and within the limits of its natural purification capacity. If surface water pollution is protected and prevented it is as well the protection and prevention of ground water contamination. The maintenance of minimum continuous natural flow of any river, even after dam, is essential to minimize the effect of pollution. Regular analysis of the samples of groundwater and surface water is essential. The data collected should also be regularly analysed, assessed, monitored and if required scientifically treated. Collection of Hydrogeological data, regular monitoring of the movement and availability of water from the aquifer and mapping should form the data base, for micro-level basin (hydro geomorphic and litho unit) and stream or river basins. A generalized methodology for monitoring groundwater quality, if adopted with modification as per requirement, may help in solving the pollution problem to greater extent. Select the area or basin to be monitored. 1. Identify all sources and causes of pollution. 2. Identify potential pollutants in the sources and causes of pollution. 3. Define groundwater usage in terms of location, type of use and quantity. 4. Define the local Hydrogeological situation. 5. Evaluate the existing groundwater quality. 6. Evaluate the infiltration rate of pollutants at ground surface. 7. Evaluate the mobility of pollutants from ground surface to the water table. 8. Evaluate the attenuation of pollutants with in the saturated zone. 9. Priorities the sources and causes of pollution in terms of their importance or potential impact on groundwater quality. 10. Determine monitoring activities already in existence. 11. Determine the methods locations and frequencies for monitoring. 12. Select and implement the monitoring programme on prioritized basis. 13. Review and interpret monitoring data. 14. Summaries and transmit monitoring information to appropriate public agencies and private organizations. Conclusion: Overall review reveals that, groundwater and surface waters, adjacent to the industries, open sewage drains or dumps, agricultural extract etc. are essentially getting contaminated due to sensitive vulnerability of soil, weathered and fractured rock layers from shallow depth in Deccan Traps. This must be protected from the source of pollution and dispersion of pollutants. Preventive measures will only safeguard the water reserves underground. The laws and regulations will have their impact only when there is proper disciplined, rude and curt implementation, by the authorities. Heavy punishment and penalization to the law breaker/environment destroyer is a time demand. But the real requirement is the awareness, in public and their full participation in at least, protecting the environmental degradation, posing threat to air, water, and land at local levels. This will solve the problem to larger extent. Ultimately it is important that, the individual is responsible for the good or the bad, as collectively, individuals form the society. It is painful and bitter to accept, “we know the things but we don’t act on them”. We are reluctant to accept the fact that we are the custodians of nature and have to hand over the surrounding in better manner, to our future generations, to live happily.