It is predicted that the 21st century would witness hydropolitics that could even result in wars for water at all levels (international, national and regional). The hydrosphere presently holds about 1,384,120,000 km3 of water in solid, liquid and gaseous states, of that most of which is stored in the oceans. Only 2.6 percent is fresh water, of this, 77.23 percent is frozen in ice caps, icebergs, and glaciers. Groundwater found up to a depth of 4kms that accounts for another 22.21 percent of fresh water. The remaining little water is stored in the soil, lakes, rivers, the biosphere and atmosphere. Therefore, fresh water is the precious commodity for all terrestrial life on earth.
The protection of freshwater sources like lakes, tanks, rivers, streams and groundwater from pollution is fundamental to food production, public health and health of all living species. Toxic pollutants released into the freshwater due to the so-called developmental activities by human beings can render water unfit for supporting life.
Water environment and pollution studies are carried out by several scientists (Mortimer (1942), Anderman (1973), Gibbs (1973), Golterman (1975), Trutt (1975), Stevenson (1975), Zafar (1976), D’Itri (1977), Dunne (1978), Jackson (1979), Gulati (1980), Satyamohan (1980), Hammer (1981), Faust (1981), Achammamba (1984), Sinha (1986), Welch (1992), Kodarkar (1995), Sastry (1996) and Wilby (1997)). On environmental pollution too several scientists have worked (Carson (1962), Sandbach (1982), Chand (1989), Alloway (1993), Baird (1995)).
The major problem associated with industrial activity in Patancheru area is the deterioration of quality of water from its industrial wastes. The chemicals from a wide range of industries including pharmaceutical industries release chemical wastes into the environment thereby polluting the water environment. In Figure 5.1 location of tanks, streams, settlements and industries are shown. The practice of using drainage system and tanks for disposal of industrial effluents resulted in devastation of surface and groundwater environments, in Nakkavagu basin.
The areas other than Patancheru industrial area within Nakkavagu basin, which are affected by water pollution include Chitkul, Chidruppa, Sultanpur, Eardanoor, Arutla, Baithole, Gandigudem, Pocharam, Ganapathigudem, Ismailkhanpet, Inole, Lakdaram, Bachuguda and Peddakanjerla.
5.2 NAKKAVAGU BASIN
In water pollution impact assessments, the basins are considered as units, because the movement of surface and ground waters is mainly restricted to the basin alone till they join a higher order basin.
The Nakkavagu basin is the sixth order basin, since the Nakkavagu stream is a sixth order stream. The catchment area of Nakkavagu basin is 734 square kilometers; it appears polygonal in plan (Figure 5.2). The catchment area lies mainly in the Medak District and partly in Rangareddy District. Nakkavagu originates to the south of Patancheru near Kollur and joins Manjira River near Gaudcherla village after travelling a total distance of 35kms. Initially Nakkavagu is known as ‘Maisammavagu’, from Kardanoor it is popularly known as Nakkavagu. A major tributary of Nakkavagu is Pamulavagu, a fifth order stream, which flows from the north-east direction of the basin and joins Nakkavagu at Bachuguda village of Patancheru Mandal. The Nakkavagu initially travels north up to Bachuguda village, after the confluence of Pamulavagu it travels in the north-north-west direction up to Chidruppa, from here it takes a turn in the north-west direction and forms a ‘S’ shaped meandering loop before joining with Manjira river at Gaudcherla. Manjira River ultimately ends up in Godavari River at Kandukurthi Bridge in Nizamabad District. Nizamsagar is the reservoir constructed over Manjira River at the border between Medak and Nizamabad Districts.
Nakkavagu has largely dendritic drainage pattern. This kind of drainage pattern is very commonly associated with areas of uniform lithology, horizontal or very gently dipping strata, and low relief. They comprise a multitude of small branch streams, which join each other, usually at fairly acute angles, to nourish a large trunk stream. While the drainage density depends on the permeability of the underlying rock and precipitation. Drainage density is high on north-eastern portion of Nakkavagu basin that is to the right of Nakkavagu stream. Rain water flows in Nakkavagu normally for a period of 4 to 6 months during Monsoon and Post-monsoon periods, and the rest of the year industrial effluent flows along the water course. Presently the water flowing in Nakkavagu in any given season is more, in comparison to the flow conditions before industrialisation. Since all the industrial effluents will finally end up in the Nakkavagu.
5.2.1 Drainage System
Drainage of Nakkavagu is highly altered by the interference of man through many centuries. The flowing waters are tamed through construction of a series of tanks and channels. The characteristics of the drainage system of Nakkavagu is given below:
a) The drainage pattern is mainly considered as sub-parallel and dendritic which is characteristic in granitic terrain.
b) Radial drainage is observed on the north of Lakdaram cheruvu, streamlets radiating from kopje like granitic structure (Figure 5.2(a)).
c) A tributary of Nakkavagu emerging from Peddacheruvu outflow, flows parallel to Nakkavagu for a distance of about 6 kms before joining with Nakkavagu near Baitul village (Figure 5.2(e)). The semi-parallel drainage system observed at many places along Nakkavagu can be attributed to the paleo-flow channels of Nakkavagu. For example the stream of Arutla and another stream north of Bachuguda (Figure 5.2(d) & 5.2(f)).
d) ‘S” shaped meandering of Nakkavagu, before its confluence with Manjira River at Gaudcherla is the prominent feature of Nakkavagu (Figure 5.2(c)).
d) The drainage is also affected by roadways, railway line, development of industries and construction of houses etc. As it is easy to alter drainage of streamlets they got most affected. The provision of culverts or bridges over larger streams lessened the alteration of natural drainage.
Artificial lake is called ‘tank’ it is locally called as cheruvu or cheru or kunta. They are largely seen in regions of uncertain rainfall. They are formed in natural hollows or depressions or sloping land by building a dam or bund on the lower side to hold water, by enclosing a semi-circular or semi-elliptical area. Some times artificial tanks are created by removing earth to create depression and then bund is laid, which are usually oblong in shape. The area irrigated by a tank is called its ayacut.
The tanks are serving two important purposes in controlling the floods and as an insurance against crop failure during drought. Water collected in the tanks is the major source of water for meeting domestic, agricultural needs of human beings and for supporting all other living things of the region. They have a prime role in the development of the region and therefore they are essential in the area.
The characteristics of the tanks in Nakkavagu basin are given below:
a) Intensive integrated watershed management was done in Nakkavagu basin, in the past. Almost all the second order and some higher order streams are tapped through construction of bunds and creation of tanks.
b) Smaller tanks are constructed in the fertile agricultural fields. The main purpose of these tanks is for recharging the groundwater and less important as a source for flow irrigation. Centuries of flooding of streams and streamlets resulted in deposition of huge thickness of alluvium. The soil in such places is highly permeable and construction of huge tanks for storage of water for flow irrigation is impossible. Therefore a series of small tanks are constructed in those regions, they are the places for recharging the groundwater aquifers. As a result groundwater raises high on the downward side of the tank. High density of dug-wells and bore-wells are found on the downward side of such tanks, for example, a number of such tanks and bore-wells are seen on the north of Nakkavagu, between Chidruppa and Tarkhanpet (Figure 5.2(i)).
c) Non-cultivable rocky wastelands at higher contour levels are selected for construction of very large tanks. These places are less permeable so there ought to be lesser leakage’s, therefore such places are put to best use by construction of large tanks for storing water example, Lakdaram tank (Figure 5.2(b)), Peddacheruvu (Figure 5.2(g)) etc. In this way the wastelands are also contributing to the economic prosperity of a region indirectly. Rocky granite areas are least useful for cultivation, so they are of least use. All the rainwater falling on such areas will ultimately move to lower reaches quickly, as a result all the water would have been wasted in the absence of tanks in such places. The wastelands increase the total availability of rainwater per unit area under cultivation, if the water falling upon wastelands is fully harvested and utilised for cultivable lands. The rocky wastelands too have a role in sustaining the agricultural activity of the region.
d) Eye like small depressions observed at many places are non-perennial water sources, at the time of rains they overflow leading to streamlets. During rainy season some of these act as percolation pits. Some of these small depressions located close to many of the villages could be the result of excavation for clay or mud and the raw material for construction purpose. Such a usage is still seen around Patancheru town, intensive brick making activity is going on around Patancheru.
e) Some tanks are oblong and square shape in plan, indicating that many of these tanks are dug and constructed for the purpose of storing water. Example, Ismailkhanpet south tank (Figure 5.2(j)) and Peddacheruvu of Chitkul (Figure 5.2(g)). These tanks are usually shallow; the range between full tank level and low tank level is high. Whereas the bund constructed directly over natural depression usually appears like ‘delta’ in plan (Figure 5.2(k)), which ranges between full tank level, and low tank level is very high as a result the storage capacity is also high. The dugout tanks involve huge costs, so preference will be given for the construction of bunds along the natural valleys of the streams. Therefore, dugout tanks are found few in numbers in Nakkavagu basin.
f) Canals are dug out to divert the flood-waters from the streams they ultimately end up in the tanks, which are specially constructed for this purpose, for example Muttangi village tank (Figure 5.2(h)).
g) Two types of water outlet systems are existing for the tanks. The controlled central point of opening which is manually operated, facilitates controlled irrigation, whereas spill-way is to let out the excess waters as a security against bund failure and for filling the tanks down-stream from excess waters. A series of tanks are constructed on the down-stream to see that no water goes waste from spillways.
h) Some of the tanks of the past are silted up completely; therefore very little or no water can be stored in them. Such tank-bed areas are at present under cultivation. The soil (silt deposited in the tank bed) deposited over a period of time in these tanks is fertile.
i) In Bollaram industrial area, nearly 95 % of the tanks are of non-perennial water source category, in Bachuguda area about half of the tanks are perennial sources of water.
5.3 INDUSTRIAL POLLUTION IN NAKKAVAGU BASIN
Case studies of 10 pharmaceutical industries located in Nakkavagu basin are considered to evaluate the quantity of hazardous raw material utilised in the production (Table 5.1). The difference between the total raw material consumed and the quantity of product produced is the material that would ultimately enter into the environment of Nakkavagu basin, in the form of solid, liquid or gaseous state. Of which only a part of the material is recovered and most of the remaining wastes are the effluents, which are partially treated and are then released into the environment. Total quantity of products produced by these 10 industries is about 1881.5 tonnes and the total quantity of hazardous raw material used is about 8146 tonnes i.e. on an average about 4.3 times of hazardous raw material is utilised for every unit of the product produced. These industries are using organic and inorganic hazardous chemicals as raw material.
The hazardous and toxic chemicals identified under schedule one and part two of ‘The Manufacture, Storage and import of Hazardous chemicals Rules, 1989’, are being utilised in the production by many industries. They are, Acetone, Acetyl chloride, Ammonia, Aniline, Benzene, Bromine, Chlorine, Chlorosulphonic acid, Dimethylcaromyl, Dioxane, Ethylene dichloride, Formaldehyde, Hexane, Hydrochloric acid, Maleic anhydride, Methylene chloride, Nitrobenzene, Nitrogen dioxide, Nitrogen oxides, Phenol, Phenyl glycidal ether, Sodium cyanide, Sulphuric acid, Thionyl chloride, Toluene and Triethylamine. There are four possible potential hazardous problems associated with the use of chemicals; they are
1) Hazardous waste products.
2) These chemicals are a potential occupational hazard to the workers.
3) The containers used for storage and transport are being reused for domestic purposes. Thousands of such containers are sold every year, which are supposed to be disposed off safely.
4) They can find their way into the environment through mishandling and leakage’s etc.
5.3.1 Common Effluent Treatment Plants
There are two Common Effluent Treatment Plants (CETPs), which are established at Patancheru and Bollaram.
188.8.131.52 CETP – Patancheru
The association of industries in the year 1994 constructed a CETP at Patancheru. The effluent treatment plant is meant for treating 7,500 cubic meters per day. The total members of CETP-Patancheru are 128 industries, presently only 72 industries are contributing their effluents to CETP.
The treatment process at CETP can be grouped into three categories respectively i.e. 1) Effluent collection and equalisation 2) Physico-chemical treatment and 3) Biological treatment. The effluents reaching the CETP through tankers from the member industries are collected in sumps. Thereafter, the combined effluent is given the physico-chemical treatment comprising equalisation, decanatation and screening. The supernatant effluent from decanatation unit is pumped into biological treatment system comprising anaerobic system (USAB) and aerobic Activated Sludge Process (ASP) with secondary clarifier. The effluents are then treated in aeration tanks then the effluents are sent into secondary settling tanks. Decanter separates the sludge from secondary settling tanks and the effluents are released into the Isukavagu stream (CPCB report, 1998).
Two samples of treated effluents released by CETP-Patancheru collected in rainy season are chemically analysed (Tables 5.2). They are highly polluted and far exceed the permissible limits of industrial effluents, disposable in inland surface waters (Photo 5.1). CETP has no secure hazardous sludge disposal site. The sludge collected in the process is being dumped in the same premises, which is also a potential source for water contamination (Photo 5.2).
Table 5.2 CETP-Patancheru effluents (August, 1997) (in ppm)
As almost all the industries are not having primary treatment plant facility the effluents are being directly sent to CETP. As this facility is not equipped to treat the effluents in two stages the CETP fails to treat the effluents.
Since its inception in 1994, CETP was receiving effluents from Patancheru and other places like Jeedimetla, Kazipally, Medchal, Kothur, Bollaram and Pashamylaram, etc., it is also receiving effluents from other Districts such as Rangareddy, Hyderabad, Medak, Nalgonda, Mahboobnagar of Andhra Pradesh and Bidar of Karnataka. Although CETP is not capable of treating local industrial effluents it had been receiving the effluents across Nakkavagu basin. In addition CETP of Patancheru received effluents from non-member industries too. Therefore the impact of Pollution on Nakkavagu basin area is the net result of industries located in a far wider area than Nakkavagu basin alone.
Nine different types of industries are sending their effluents to CETP of Patancheru. They are Bulk Drugs and Drug intermediates, Pulp paper and other cellulose base industries, Metal finishing, Resins and chemicals, Pesticides, Paints, Rubber, Edible oil refineries and Textile processing. Therefore it is impossible for CETP to treat the effluents to the prescribed standard from such diverse industries. The classification of member industries of CETP-Patancheru, type of effluents, location wise and contribution of effluents are given in Tables 5.3 and 5.4
184.108.40.206 CETP – Bollaram
CETP-Bollaram is having presently 25 member industries, of which 8 member industries are from outside Bollaram IDA. The present effluent load of CETP is 340 m3/day. Some of these industries are also members of Patancheru and / or Jeedimetla CETP’s too.
The wastewater brought in tankers is unloaded into the primary clarifier, by using pumps, at the rate of 10 to 15 m3/h. Suspended solids are removed here and collected in 3 sludge lagoons. Clear wastewater flows by gravity to the holding tank where nutrients, i.e. Phosphoric Acid, Urea and Di-Ammonium Phosphate, are added. The wastewater is equalised by gentle recirculation by a pump and after equalisation fed into a chamber for digester, which is recycled back to the digesters at the rate of 40 to 50 m3/h. Wastewater at the rate of 10 m3/h is sent to first stage aeration tank for biological treatment. From the first stage of aeration tank, wastewater flows by gravity to the intermediate clarifier where micro-organisms are separated in the form of sludge and the same is returned to the first stage aeration tank and clear liquid overflows to the second stage aeration for further biological degradation. Wastewater from second stage of aeration tank flows by gravity to the final clarifier is taken to maturation ponds from where it is pumped to the oxidation ponds-cum-solar evaporation ponds. All the solar evaporation ponds are connected in series. The effluents get evaporated and the sludge collected is disposed off (CPCB report, 1998). It also receives effluents without primary treatment at various industries.
Table 5.3 Classification of Member Industries of CETP-Patancheru
Name of Products
Number of Industries
Source: CPCB Report, 1998.
Table 5.4 Location wise classification of Member industries of CETP-Patancheru and their effluent loads.
Location of Industries
No. of Industries
Effluent load (kld)
Source: CPCB Report, 1998.
The effluents released from CETP’s do not have adequate water sources for dilution in Nakkavagu and Manjira River, except to some extent. The performance of CETP’s is given in Table 5.5. CETP’s are the industries by themselves are the major contributors of pollution.
Table 5.5 Performance of CETP’s
Source: CPCB report (1998).
5.4 SURFACE WATER
The surface waters in the basin include Nakkavagu and its tributaries, tanks, ponds and other small depressions. The volume of water in many of the surface water bodies varies with seasons. The surface water bodies, which receive the effluents from industries continuously, do not show much variation. Similarly because of industrial effluents entering into Nakkavagu the flow is maintained from Kardanoor onwards, even during the peak of summer Nakkavagu never goes dry. The flow of effluents in the Nakkavagu and its tributaries is shown in Figure 5.3.
The industrial effluents are usually released directly into streams and tanks. Pollutants also enter indirectly, as effluent stream (Figure 5.4), through atmosphere in the form of acid rains (Figure 5.5) and dust particles brought down by rain or air, leachets from solid waste dumps, surface runoffs during rains, leakage of effluents from solar evaporation ponds etc.
The surface water pollution is dangerous to the aquatic ecosystem. Nakkavagu waters are polluted beyond sustaining any kind of life. Some of the tanks are supporting meager life forms, and some are completely devoid of aerobic fauna. The comparison between unpolluted and polluted tanks is given in Figures 5.6 and 5.7.
All the industrial effluents ultimately end up in Nakkavagu; as a result it became the most polluted stream. Nakkavagu carries the effluents to a distance of 22 kms from Kardanoor onwards up to the merging point with Manjira River at Gaudcherla. Pamulavagu a major tributary of Nakkavagu adds its effluents into Nakkavagu at Bachuguda. The flow of effluents in Pamulavagu is erratic; sometimes there is no flow at all, because of a series of tanks located across its tributaries. The industrial effluents released in Bollaram and Khazipally industrial areas gets collected and stored in the tanks like, Khazipally tank, Gandigudem tank, Asanikunta, Krishnareddipet tank, etc. Krishnareddipet tank is the largest, and is the last of the series of tanks across the Pamulavagu tributary, unless the outlet of this tank is opened rarely any water flows into Pamulavagu.
5.4.1 Flowing Waters
The quality of streams varies and it is dependent on various factors. The total dissolved solids of the effluents of Nakkavagu as analysed over a period of time are presented in Figure 5.8. This gives a general picture of the pollution in Nakkavagu over a period of time. On the whole the trend shows gradual increase in pollution since 1979 with exception of observations in 1995 and 1998.
220.127.116.11 Surface waters Analytical Results
18.104.22.168.1 Summer Data of Streams (S-Data):
The data is pertaining to 11 samples of which 9 samples represent the Nakkavagu and 2 samples represent CETP and Pamulavagu. These samples are collected in summer 1997. Basic analysis data of the samples is presented in Table 5.6 and 5.7.
These samples are compared to the standards of inland surface waters (Table 5.8). The pH of Nakkavagu waters are slightly alkaline, CETP waters are slightly acidic and the Pamulavagu waters are more alkaline. TDS, COD, BOD and SO4- parameter concentrations are very high. Cl- is nearer to the limit of 1000ppm. F is high in 4 samples that are above 2ppm. Pb is high in all the samples with an exception of one sample of Nakkavagu. Hg is very high in all the samples. As and Se are high in all the samples with an exception of one sample from Nakkavagu. Cd, Zn, Cu, B, Mn, Cr, and Fe parameters are in permissible limits.
Almost all the parameters of CETP effluents are high. Therefore, the pollution in Nakkavagu is mainly because of the release of partially treated effluents into Nakkavagu.
The correlation matrix is given in Table 5.9. The following groups of elements are strongly and positively correlated: TDS is strongly related to TH, Cd, Hg and Cr, TH is related to Cd, Hg and Cr, COD is related to BOD and Cl-, BOD related to SO4- and Cl-, and the following pairs of parameters are also strongly related SO4- – Cl-, SO4- – Zn, F- – Fe, Zn – Se, Cu – As, and As – Se.
22.214.171.124.2 Rainy Season Data of Streams (R-Data):
R-Data is pertaining to 14 samples of surface waters collected from Isukavagu, Nakkavagu, Manjira River, Nizamsagar and Godavari River. These samples are collected during the rainy season (1997). The analytical and statistical data is presented in Tables 5.10 and 5.11. The variation of TDS, COD and BOD in surface waters at various locations from source up to Godavari River is given in Figures 5.9, 5.10 and 5.11. There is only slight reduction in the above parameters as the waters of Nakkavagu flow down stream. TDS and COD values in the effluents are reduced to the permissible limits, whereas BOD is still high just before the confluence point with Manjira River. The low values can be attributed to two factors, the innate capacity of self treatment of the stream as it moves over a distance (about 22kms) and the dilution factor, as it is the rainy season freshwaters from other sources reach Nakkavagu. Total suspended solids are also high in Nakkavagu and Pamulavagu streams. The waters of Manjira and Godavari Rivers are moderately alkaline, could be the result of agricultural pollution, the excess salts from agricultural fields (the residual fetilisers etc.) might have reached through water into the rivers. Sulphates and chlorides found in the effluents are contributed by the industries as directly or indirectly through CETP’s. But after the confluence with Manjira River they are diluted to the safer limits. Throughout Nakkavagu DO is very low and it is incapable of sustaining any kind of aerobic life, and also there are few chances of survival of anaerobic life because of the toxicity of Nakkavagu waters. The concentration of Zn, Cd, Pb, Cr and Cu in Isukavagu and Nakkavagu are presented in Table 5.12 among them except Pb rest are within the safe limits.
Correlation of the parameters indicates that the TDS, TS, TSS, Cl-, SO4-, COD and BOD all are positively related to each other’s (Table 5.13). The dissolved substances such as Cl-, SO4-, etc. are responsible for the high COD and BOD in the stream waters. The negative values for Dissolved oxygen (DO) against all the above parameters indicate that they are responsible for the fall in oxygen levels in the water.
126.96.36.199.3 Winter Data of Streams (W-Data):
The water of Pamulavagu is highly acidic, whereas the waters of Nakkavagu is alkaline. TDS, Electrical Conductivity (EC) and COD parameters are moderately high as compared to the waters of Manjira River (Table 5.14). Isukavagu is less polluted before the confluence of CETP effluents. DO in Manjira River is high before the confluence of Nakkavagu effluents, but after the addition of Nakkavagu effluents, its DO is reduced by half (Table 5.15). The Table 5.16 shows strong correlation between TDS, EC and COD.
188.8.131.52 Quality of Streams
The quality of the streams as observed during the year is discrete and cannot be linked to seasons. The drainage system existing and which is used for draining the effluents from industries are not perennial. The perennial nature of the streams especially Nakkavagu and Isukavagu are because of the continuous letting out of the industrial effluents and effluents from CETP-Patancheru. The production in industries is not seasonal and the effluents are continuously let into the streams. Some of the industries are releasing their effluents at intervals in such cases the samples collected would appear more polluted. During the rainy season because of dilution the pollution levels of Nakkavagu effluents should have been low but as compared to Summer Data (S-Data) and Winter Data (W-Data) over all the parameters are high at same locations. The industrialists had the knowledge of the presence of CPCB team, as a result the quality of effluents sent to CETP during that period had been good and the industrialists restricted themselves during that period by not letting the effluents into the streams, and also during that period the treatment facility was improved a lot. There are many reasons for variation of the quality of the effluents in the streams
The quality of tanks depends upon the water entering them; these are artificial water bodies purposefully built across the streams in order to store water. They have become the traps or obstruction points to the free movement of effluents in the natural drains, which are released by industries into them. The residence time of pollutants in tanks is increasing, unless the effluents are released they remain trapped in them. But for the fear of damage to the crops, water is not being let out. They are presently appearing like ‘solar evaporation tanks’ where pollutants are getting accumulated in them.
184.108.40.206 Tanks Analytical Results
The degree of quality of some of the tanks in the region is presented in Tables 5.17 and 5.18, and Figure 5.12. Higher values of TDS, EC and COD indicate higher pollution levels in such tanks. Asanikunta, Khazipalli and Krishnareddipet tanks are the worst polluted tanks in the region. The Krishnareddipet tank is one of the highly polluted largest tanks in the region. Asanikunta and Khazipalli tanks are having highly acidic waters, which when released into streams will lead to secondary effects like mobilisation of heavy metals to less polluted areas.
The Table 5.19 shows strong correlation between TDS, EC and COD, and negative correlation between all the above parameters and DO. Therefore, the pollutants in the waters are responsible for the fall in DO in the tanks.
Groundwater potential depends upon a number of factors like climate, topography, soil characteristics, lithology, geological structures and flora of the area. Geologically Nakkavagu basin comprises mainly of Archaean granites, alluvium and partly basalts and laterites. Groundwater occurs in confined, semi-confined and unconfined conditions. The groundwater pollution depends on various factors such as depth of groundwater table, type of aquifer, permeability of the aquifer, characteristics of the soil, topography, geology of the area and concentration, dilution, dispersion and nature of pollutants.
The groundwater flow directions get established over a period of time, there won’t be much variation in the behaviour of groundwater in aquifers, unless there is a major crustal movement. As pollutants in groundwater follow the groundwater flow trends, the dispersion patterns remain the same although the concentrations of pollutants may vary.
Groundwater pollution takes place because of percolation of the pollutants into the saturated zone (Figures 5.13 and 5.14). As the flow of groundwater is controlled by many factors, the pollutants also disperse in those directions. The concentrates of pollutants reaching the groundwater do not remain the same as at the surface, some of the pollutants get absorbed and / or adsorbed. It also depends upon the solubility of the pollutants in water. At higher alkalinity the groundwater precipitates the heavy metals and other elements. Clay is almost impermeable so they may trap some of the pollutants in the ground.
5.5.1 Groundwater in Granites
Granites are plutonic crystalline igneous rocks. The nature and depth of weathering, joints, fractures and other structures mainly control the movement and occurrence of groundwater. The geological structures like joints, faults, lineaments etc., in the sub-surface granites, act like conduits for the movement of pollutants to far off distances.
The probable dispersion patterns of polluted water are shown in Figure 5.15.
The weathered product of granite is locally known as ‘morum’, water potential is high in such weathered zones. Wells are dug up to depths of 15 to 50 feet below ground level (bgl) in weathered zones. The bore-wells, which reach fractures or joints in granites, are good sources of water and even more better if the fractures or joints are interconnected (Figure 5.16). Bore well depths in the area, on an average in the range of 30 to 100 feet below ground level. Sometimes water flowing in a certain fracture follows considerable distance without any loss. Surprisingly pollutants dissolved in water also get transported too far of without getting diluted because of such fractures (Figure 5.15(d)). The pollutants also get trapped by dykes (Figure 5.17) and also between the open spaces between granites (Figure 5.18). For tracking dispersion pattern and rate of dilution of pollutants require proper understanding of geological structures. Basalts and laterites are mainly located to the south-western parts of Nakkavagu basin; the percentage of basalt and laterite coverage is very less. The groundwater potential of the three Mandals of Nakkavagu basin is given in Table 5.20.
Table 5.20 Groundwater Potential
Name of Mandal
Source: A.P. State groundwater department reports, 1988-1991 Hyderabad.
5.5.2 Groundwater Analytical Results
220.127.116.11 Summer Data (S-Data):
S-Data is pertaining to 6 samples of which three are borewell samples and three are of openwells. The basic analysis data and statistical parameters are presented in Tables 5.21 and 5.22 respectively.
The samples are compared to the inland surface water samples of EPA (Table 5.8). TDS is high in Pocharam borewell (BP1) and the open well (OB5). COD and BOD are also very high in all the borewells and openwells, with an exception of openwell (OB4). Hg is very high. As and Se are found high in the openwell samples OB5 and OB6.
The samples are compared to the drinking water standards (Table 5.23). Hg is about 10 to 300 times high in all the wells. Cl is found high in all the well samples and very high in openwell samples. As, Se, SO4 are found high in the openwells. Pb is high only in one openwell sample (OB4). TDS is found exceptionally high in all the openwell samples and in one borewell sample (BP1). Cd is found high in the Borewells (BP1 and BG2) and in the openwells (OB5 and OB6). Zn is high in all the samples except in one borewell sample (BB3). Cu is found high in BB3, OB4, OB5 and OB6. Mn is found high in BG2 and OB5 samples. Cr and Fe are within the safer limits.
The correlation matrix is given in Table 5.24. The following groups of elements are strongly and positively correlated: TDS is strongly related to TH, B and Cr, TH is strongly related to Cl-, Cu, As, Se and Cr, Cl- is related to Cu, As, Cr and Se, B is related to Cr and Fe, Cu is related to As and Se, As is related to Se and Cr, and the pairs of parameters are also strongly related COD – BOD, SO4- – As, F- – Se, Se – Cr.
18.104.22.168 G1 and G2- Data.
The groundwater data’s (G1 and G2) pertaining to the year 1991 is considered to understand the dispersion pattern of pollutants in the ground.
G1 data of 26 samples represent 14 villages adjacent to Nakkavagu, which are located in the polluted zone. Analysis of these samples is presented in Table 5.25 and statistical parameters are in Table 5.26. Except three wells, all other wells have alkaline waters. TDS and TH values are higher in many well samples, but they are well within permissible limits for inland surface waters of EPA (Table 5.8). SO4- and Cl- are within the limits. Some villages are showing high concentrations of F and Mn. Fe concentration is high in some cases.
The data is compared to the drinking water standards in Table 5.23. In nine samples TDS is very high which represent the seven villages Baithole, Lakdaram, Sultanpur, Inole, Chitkul, Arutla and Ismailkhanpet. Chloride is very high in majority of the villages. Fluoride is around 1.5ppm in majority of cases. Mn is exceptionally very high in Bachuguda, Pocharam, Lakdaram, Chidruppa, Eardanoor and Baithole villages, and high in Lakdaram, Sultanpur, Peddakanjerla and Ganapathiguda villages. Nitrate is found high in 12 cases representing 8 villages, Lakdaram, Chidruppa, Sultanpur, Inole, Chitkul, Arutla, Bollaram and Madharam.
The correlation coefficients are shown in Table 5.27 and the correlation matrix plot in Figure 5.19 reveals that there is strong positive correlation of TDS, Cl-, Ca, Fe, and also between the following pairs of parameters TDS – NO3-, Cl- – NO3-, Ca – NO3- and Fe – NO3-. This indicates that all the parameters are associated with TDS, which were released directly, or indirectly by the industries as effluents. The cluster analysis, based on the similarity measures, also indicates that a strong grouping of all the parameters (Figure 5.20). The linkage of these parameters shows that there is a strong relation of TDS with rest of the parameters. The extent of groundwater pollution is also shown diagrammatically in Figure 5.21. The distances indicate that the degree of pollution is exceeding in one case at Peddakanjerla.
The analytical data is subjected to R-mode factor analysis. A three-factor model is chosen for interpretation. The factor loadings plot (Figure 5.22) indicate the following groups of parameters (TDS, Cl-, Ca, and Fe), (TH and Alkalinity (ALK)), and (Mn and F-). NO3- can be associated with first group as it is located close to it, SO4- and COD are slightly independent, but they are close to the first two groups. Overall, all the above parameters are the constituents in the industrial effluents. pH and Mg are independent. Probably Mg is contributed by the natural hardness in the groundwaters as magnesium carbonate, in addition to the contamination from industrial effluents. The characteristic Mn and F association and in confirmation with the samples, which are contributed from the industrial pollution and also the natural contamination from deep fractures, that entered into the groundwater.
G2-Data is pertaining to 41 samples representing 13 villages adjacent to Nakkavagu and its tributaries, which are located in the highly polluted zone. Basic analytical and statistical data of the groundwater samples are presented in Table 5.28 and 5.29 respectively.
When compared to the inland surface waters (Table 5.8), the TDS values are exceeding in 6 cases that is 2100. Carbonate Hardness (CH), CaCO3, and EC are also high in samples with high TDS.
The data is compared to the drinking water standards in Table 5.23. Nitrate is well with in the limit, exceptionally high in two samples of Peddakanjerla. Nitrite is high in as many as 11 samples representing the following villages, Eardanoor Tanda, Arutla, Chidruppa, Lakdaram, Ganapathiguda, Kardanoor, Inole and Peddakanjerla. TDS is also very high in about 11 samples of 7 villages Baithole Tanda, Baithole, Arutla, Lakdaram, Kardanoor, Ganapathiguda and Peddakanjerla. In majority of the cases Cl- is very high, whereas F is very high in Eardanoor and Inole villages.
Clustering of the associated parameters are shown in Table 5.30 and Figure 5.23. There is very strong correlation between TDS, Electrical Conductivity (EC), Carbonate hardness (CH), Cl- and Calcium Carbonate (CaCO3). Therefore carbonates and chlorides are the major constituents of TDS released by industries. The dendrogram shows the association of parameters (Figure 5.24).
Clustering of villages with similar groundwater pollution is shown in Figure 5.25. In the dendrogram, the degree of pollution among the samples are showing less variation except for the last four cases, showing very high variation from rest of the samples. The four samples are from Ganapathiguda and Arutla and two samples are from Peddakanjerla.
In the Figure 5.26 generated after R-mode factor analysis the cluster of parameters are grouped as (EC, TDS, CH, NO3-), (Cl-, TH, CaCO3), these parameters are mainly the constituents of the industrial effluents. pH, F and NO2- are independent. Fluoride can be attributed as mainly a geological contaminant from deep fractures. Nitrite could be a factor contributed from agricultural sources i.e. use of nitrogen fertilisers.