Introduction. Key words Development 7 Management 7 Surface water resource 7 Groundwater resource 7 Irrigation

Transcription

1 Water resources development and management in the Cuddapah district, India M. Ramakrishna Reddy 7 N. Janardhana Raju 1 7 Y. Venkatarami Reddy 7 T.V.K. Reddy Received: 10 June Accepted: 15 November 1998 M. Ramakrishna Reddy Department of Civil Engineering, KSRM Engineering College, Cuddapah, India N. Janardhana Raju (Y) 7 Y. Venkatarami Reddy T.V.K. Reddy Department of Geology, Sri Venkateswara University, Tirupati , India 1 Present address: Institut für Umwelt-Geochemie, Im Neuenheimer Feld 236, D Heidelberg, Germany Abstract Intensive application of surface water in command areas of irrigation projects is creating water logging problems, and the increase of groundwater usage in agriculture, industry and domestic purposes (through indiscriminate sinking of wells) is causing continuous depletion of water levels, drying up of wells and quality problems. Thus the protect aquifers to yield water continuously at economical cost, the management of water resources is essential. Integrated geological, hydrological (surface and groundwater) and geochemical aspects have been studied for the development and management of water resources in droughtprone Cuddapah district. The main lithological units are crystallines, quartzites, shales and limestones. About ha of land in the Cuddapah district is irrigated by canal water. A registered ayacut of about ha is irrigated by 1368 minor irrigation tanks. A total of 503 spring channels are identified in the entire district originating from the rivers/streams, which has the capacity of irrigating about 8700 ha. The average seasonal rise in groundwater level is 7.32 m in quartzites, 5.35 m in crystallines, 3.82 m in shales, 2.50 m in limestones and 2.11 m in alluvium. Large quantities of groundwater are available in the mining areas which can be utilised and managed properly by the irrigation department/cultivators for the irrigation practices. Groundwater assessment studies revealed that 584 million m 3 of groundwater is available for future irrigation in the district. From the chemical analysis, the quality of groundwater in various rock units is within the permissible limits for irrigation and domestic purposes, but at a few places the specific conductance, chloride and fluoride contents are high. This may be due to untreated effluents, improper drainage system and/or the application of fertilisers. Key words Development 7 Management 7 Surface water resource 7 Groundwater resource 7 Irrigation Introduction The Cuddapah district has an extent of Km 2 and lies between the north latitudes 13743b and 15714b, and east longitudes 77755b and 79729b (Fig. 1). The climate of the district is hot and semiarid. The monthly maximum, minimum and mean temperatures as measured at Cuddapah are 44 7C, 14 7C and 27 7C, respectively. The annual rainfall recorded at the Cuddapah rain gauge station for 100 years ( ) is given in Fig. 2. The mean rainfall at the Cuddapah rain gauge station is 759 mm. In the following discussion this mean rainfall will be considered as normal and is expressed as 100%, periods of severe drought will be 50% of the normal rainfall, drought will be 75% of the normal rainfall, high rainfall will be 125% of the normal rainfall and extremely high rainfall will be 150% of the normal rainfall. The Cuddapah district is aptly called the district of Pennar as almost the entire district is drained by the Pennar river and its tributaries. The important tributaries joining the river from the north include the rivers Kunderu, Sagileru and Tummalavanka, while those from the south include the rivers Chitravati, Papaghni, Buggavanka, Cheyyeru and Kalletivagu. Bahuda, Mandavi, Pullangi and Gunjanaeru are the tributaries of the Cheyyeru. The rivers and streams in the district are mostly ephemeral under the influence of heavy spells of rainfall by cyclonic storms in the Bay of Bengal. The Cuddapah district was formerly divided into 12 taluks, i.e. Jammalamadugu (J), Proddutur (PR), Muddanur (M), Pulivendula (PU), Lakkireddipalle (L), Rayachoti (RY), Cuddapah (C), Kamalapuram (KA), Badvel (B), Sid- 342 Environmental Geology 39 (3 4) January Q Springer-Verlag

2 Fig. 1 Location map of the study area with river-stream pattern davattom (S), Rajampet (R) and Koduru (KO). The classification of the district into taluks was abandoned in 1985 in favour of mandals for effective administration. The villages of 39 modern mandals prior to 1985 belonged to the same taluk, whereas the villages in 11 mandals were split between two taluks (Table 1; Fig. 3). Basinwise hydrogeological studies of the Cuddapah district have been carried out by some researchers (Janardhana Raju 1991; Siddiraju 1993). Geology and hydrogeology Fig. 2 Annual rainfall in the Cuddapah rain gauge station ( ) The geological succession of the rock formations was originally documented by King (1872) and later modified by Murthy and others (1978). The geological succession of the Cuddapah district is given in Table 2. The general strike direction of rock formations are N W S E and dipping towards NE. These rocks, and the mineral deposits in them like chrysotile asbestos, barytes, steatite, clay minerals and lead-zinc mineralization, have been extensively studied by a number of scientists (Krishnaswamy 1981; Sivarami Reddy 1990). Raghu (1990) has extensively studied biogeochemical aspects of baryte mining areas in Mangampeta and Vemula in the Cuddapah district. Hydrogeologically the district is mainly divided into granites, quartzites, shales and limestones. The groundwater in all the rock formations occur in un- Environmental Geology 39 (3 4) January Q Springer-Verlag 343

3 Table 1 List of mandals in the Cuddapah district 1. Peddamudiam (J) 18. Galiveedu (L&RY) 35. B. Mattam (B) 2. Rajupalem (PR) 19. Chinnamandyam (RY) 36. B. Kodur (B) 3. Duvvur (PR) 20. Sambepalle (RY) 37. Kalasapadu (B) 4. Mydukur (PR) 21. Tsundupalle (RY) 38. Porumamilla (B) 5. Chapad (PR&KA) 22. Veeraballe (RY) 39. Gopavaram (S&B) 6. Proddatur (PR) 23. Rayachoti (RY) 40. Badvel (B&S) 7. Jammalamadugu (M&J) 24. Lakkireddipalle (L&RY) 41. Atlur (S) 8. Mylavaram (J&M) 25. Ramapuram (L&RY) 42. Siddhavattam (S) 9. Kondapuram (M) 26. Chintakommadinne (C) 43. Vontimitta (S) 10. Muddanur (M&KA) 27. Pendlimarri (C) 44. Nandalur (RJ) 11. Thondur (PU) 28. Veerapunayunipalle (KA) 45. Rajampet (RJ&KO) 12. Simhadripuram (PU) 29. Yerraguntla (KA) 46. Penagalur (RJ) 13. Lingala (PU) 30. Kamalapuram (KA) 47. Chitvel (KO) 14. Pulivendula (PU) 31. Vallur (C) 48. Pullumpet (KO) 15. Vemula (PU) 32. Cuddapah (C) 49. Obulavaripalle (KO) 16. Vempalle (PU&L) 33. Chennur (C) 50. Koduru (KO) 17. Chakrayapet (L) 34. Khajipet (C) Table 2 Geological succession of the Cuddapah district System Series Stages of formation Recent and sub-recent Superficial deposits Alluvium and soils Unconformity Kundair series Nandyal shaly limestones Koilkuntla limestones Kurnool group Late Proterozoic ( m.y.) Jammalamadugu series Auk shales Narjee limestones Banaganapalle quartzites UUUnconformity Krishna series Srisailam quartzites Unconformity Nallamalai series Cumbum shales and phyllites Cuddapah super group Bairankonda quartzites Middle Proterozoic ( m.y.) Unconformity Chitravati series Pullumpet (Tadipatri) shales Nagari quartzites Unconformity Papaghni series Vempalle dolomites&shales Gulcheru quartzites Eparchean unconformity Archeans (2400 m.y.) Crystallines Granites, gneisses and schists confined and semi-confined aquifer conditions. The occurrence and movement of the groundwater depends on bedding planes, weathered, fractured, fissured and fault zones. The permeability of all formations depends on secondary porosity, except for alluvium where the porous materials (gravel and sand) act as highly permeable. Alluvium mainly occur along the river and stream courses and the occurrence of the groundwater is in unconfined nature. The carbonate formations (limestones and dolomites) have generally medium high permeability by fractures, joints and karst. The net work of fractures and joints in dolomitic limestones favours the penetration of water and the formation of phreatic aquifers. Karst springs (cave springs) are also observed in the limestone areas, which yield substantial amount of water. Hydrogeological conditions prevailing in the district indicate that the quartzites are more water bearing formations than the shales. The contact zones of trap sills in the south-western parts of the district are found to yield a good quantity of water. Further detailed hydrogeological conditions are discussed under the groundwater resources. 344 Environmental Geology 39 (3 4) January Q Springer-Verlag

4 Fig. 3 Number of mandals in the Cuddapah district Hydrology-surface water resources Projects/reservoirs The K. C. Canal, which imports water from the Tungabhadra river, is a major surface water source to the Kurnool and Cuddapah districts. The total length of the canal is 306 Km, of which 79 Km lie in the Cuddapah district. The land irrigated in the Cuddapah district is fixed at ha. The Mylavaram reservoir is constructed across the Pennar river in the Mylavaram mandal. The Tungabhadra river and the surplus flows of the Pennar river contribute water to this reservoir. The Pulivendula branch canal project, the Tungabhadra and the Pennar waters let into the Chitravati river at Goddamarri, has an irrigation potential of ha in the Cuddapah district. Out of the 50 mandals in the district, 22 mandals receive water from the K. C. Canal, the Mylavaram reservoir and the Pulivendula branch canal. Figure 4 shows mandalwise ayacut irrigated, or about to be irrigated by these three projects. The mandals with code numbers 2 6, 26, receive irrigation water by the K. C. Canal project; 1, 2, 6 8, 29 and 30 by the Mylavaram reservoir, and 9, by the Pulivendula branch canal project. The Rajupalem and Proddutur mandals (2 and 6) receive irrigation water both from the K. C. Canal and the Mylavaram reservoir. Confluence lakes In spite of the ephemeral nature of the rivers and streams in the district, a perennial water body (source) occurs at the confluence of the major and minor streams. Such an inland body of perennial water surrounded by dry stream beds can be called a confluence lake. Even under severe drought conditions, these confluence lakes never dried up in the past. Typical examples of the confluence lakes in the district are the Gurralamadugu lake at the confluence of the Gurralavanka stream with the Chitravati river in the Kondapuram mandal, the Sangameswaramadugu lake at the confluence of the Mogamneru stream with the Papaghni river in the Veerapunayanipalle mandal and Attirallamadugu lake at the confluence of the Gunjanaeru stream with the Cheyyeru river in the Rajampet mandal. These minor streams (tributaries) are characterised by low catchment areas covered mostly by shales. As a result, the sediment carried by them is mostly composed of Environmental Geology 39 (3 4) January Q Springer-Verlag 345

5 Fig. 4 Mandal-wise ayacut irrigation by the K. C. Canal, Mylavaram reservoir and Pulivendula branch canal clay-size particles which get washed out into the main stream during floods. The main stream, on the other hand, has a higher catchment area which can contribute a sediment load with substantial concentration of sandsize particles which are deposited in the river bed during the waning stages of the flood. The bed level of the main stream after the flood will be at a higher elevation than the level of water in the confluence lake (Ramakrishna Reddy 1994). The water level in the main stream is just a few centimetres below the bed level and is still at a higher elevation than the level of water in the confluence lake. The confluence lake is mostly fed by the spring discharge from the main stream. This is the reason for the perennial nature of the confluence lakes. Spring channel irrigation The flow of water from a spring along an excavated channel/trench moved by gravity and used for irrigation of low-lying lands is called spring channel irrigation. Springs are quite common in the Karst terrain (fractured and cave springs), in quartzites (fractured and fault springs) and in the vicinity of streams and rivers. The springs originating from the rivers/streams like Papaghni, Mandavi, Bahuda, Cheyyeru, Gunjanaeru, Chitravati and Kunderu are used for spring channel irrigation, but springs are absent in the river Sagileru and the lower reaches of Pennar. Some spring channels have dried up owing to upstream construction of major tanks (the Gangavaram reservoir in the Veeraballe mandal), while others dried up due to large scale exploitation of groundwater in the vicinity of the springs. The spring discharge at Gandi in the Chakrayapet mandal is presently being used to irrigate 260 ha of land in the Idupulapaya village and there is gross under-utilisation of the groundwater within the aquifers underlying the spring channel. There are in total 503 spring channels in this district with a registered ayacut of about 8700 ha (Fig. 5). Tank irrigation Man-made reservoirs of small capacity (popularly known as tanks) are crucial for recharging groundwater in these regions, since streams and rivers are dry for most part of the year. Most of the villages in the district have abandoned their drinking-water tanks in favour of assured 346 Environmental Geology 39 (3 4) January Q Springer-Verlag

6 Fig. 5 Mandal-wise land irrigation by the spring channels sources of groundwater, which is free of turbidity and biological pollutants. These drinking-water tanks have been converted into percolation tanks for groundwater development. There are in total 1368 minor irrigation tanks in the district. The number of irrigation tanks in a mandal ranges from zero in the Rajupalem mandal (code nr. 2) to 215 in the Galiveedu mandal (code nr. 18) with a mean of 27. Only a few tanks are observed in the Lingala, Pulivendula, Vemula and Vempalle mandals because most of this area is occupied by the leaky Vempalle dolomitic limestones. The mandals occupied by the Archean rocks (code nrs ) have 841 tanks accounting for over 61% of the tanks in the district, and also those mandals occupied by the Cumbum formation have maximum number of tanks. The mandals occupied by the Archean granitic rocks and the dyke rocks are so rugged that the terrain is best suited for the construction of innumerable tanks generally of small size. The registered irrigated ayacut by minor irrigation tanks is over ha. The mandal-wise distribution of ayacut (Fig. 6) irrigated by tanks ranges from 34 ha in the Chennur mandal (code nr. 33) to 2278 ha in the Chitvel mandal (code nr. 47). When compared with the mandals occupied by the Archean rocks, many of the mandals occupied by the Cumbum formations irrigate more land indicating that the tanks in the latter areas are larger than those in the former areas. Lifting water for irrigation When surface water is available at a lower elevation and the ayacut is located at higher elevation (in the case of confluence lakes and depressions within rivers), it is necessary to lift water for irrigation by some mechanical device. Both the irrigation department and APSIDC have taken up 17 lift irrigation projects in 15 mandals in the district to irrigate about 4900 ha. The land irrigated in a mandal in this way ranges from 50 ha in the Lingala mandal (code nr. 13) to 834 ha in the Chapadu mandal (code nr. 5) with a mean of 326 ha. Over exploitation of groundwater in the sandy alluvium of the main stream leads to the drying up of the confluence lakes and failure of the projects using those waters. Environmental Geology 39 (3 4) January Q Springer-Verlag 347

7 Fig. 6 Mandal-wise land irrigation by the minor irrigation tanks Hydrology Groundwater resources Groundwater conditions in Archean rocks The groundwater in Archean rocks occur in the weathered, jointed, fissured and fractured zones under the water table and in semi-confined conditions. The occurrence and the movement of groundwater in these rocks is dominantly controlled by the depth of weathering and fractured zones. The depths of weathering varies from m and the depth of fractured zones varies from m. Numerous dykes were found to play a vital role to control the movement of groundwater. Groundwater in granitic rocks is developed by means of dugwells, dugcum-borewells and borewells.the depth of dugwells ranges from 3 18 m with yields ranging from lph and the depth of borewells ranges from m and the yield ranges from lph. Groundwater conditions in the Cuddapah group of rocks The Cuddapah group of rocks mainly comprise of quartzites, shales and limestones. Groundwater occurrence and movement is controlled by the depth of weathering, occurrence of bedding planes, fractures, faults and the presence of solution channels or cavities in limestones. Janardhana Raju and others (1996) have utilised integrated geological, hydrological and electrical resistivity surveys to delineate groundwater potential zones in the Upper Gunjanaeru catchment in the Cuddapah district. Hydrogeological conditions have indicated that the Pulivendula quartzites are more water-bearing formations than the Tadipatri shales. Janardhana Raju and Reddy (1998) have studied the extent of the influence of the fracture pattern from remote sensing and delineated the nature of subsurface lithology with the help of vertical electrical resistivity soundings for groundwater in the Pullumpet (Tadipatri) shales of the Upper Gunjanaeru river basin. They observed two sets of lineament directions, one set is N E; S W, and another set is NO7-307W; SO7-307E 348 Environmental Geology 39 (3 4) January Q Springer-Verlag

8 and N W; S E, which are the major sources of surface and groundwater flows. The contact zones of trap sills are found to yield good quantity of water in the Cuddapah district. Groundwater is developed by means of dugwells, dug-cum-borewells and borewells. The depth range of dugwells varies from 8 to 15 m bgl and borewells m and yield ranges from 840 to 5500 lph and lph respectively. Alluvium comprising of gravel, sand, silt and clay is found along the river and stream courses. The thickness of the Pennar alluvium varies from 1 to 16 m. Maximum alluvium thickness (120 m) is observed in the southern part (Gunjanaeru) of the Cuddapah district (Janardhana Raju and others 1996). The groundwater occurs under the water table conditions and the depth of dugwells range from 5 to 8 m, yielding upto 8500 lph. Groundwater conditions in the Kurnool group of rocks The geological formations in the Kurnool group comprise of Banaganapalle quartzites, Auk shales, Panyam quartzites, Koilakuntla limestones, Nandyal shales and conglomerates. Groundwater in these group of rocks is controlled by the presence of bedding planes, joints, faults, fissures and solution cavities. The depth of dugwells vary from 8 to 18 m and the depth of borewells ranges from 40 to 70 m. The yields of the dugwells vary from 840 to 5000 lph and borewells yield from 1100 to lph. Artificial recharge of groundwater There has been a continuous decline in the groundwater levels in the district particularly in upland areas far away from rivers and streams. The groundwater depletion is mainly due to the frequent drought periods, over-exploitation of groundwater and the annual increase of groundwater structures. Because of these problems the irrigation department has taken up artificial recharge programmes to improve the groundwater levels by the construction of check dams and percolation tanks. Approximately 15% of drinking water in Germany is produced by artificial recharge methods (Schottler 1996). A check dam is a masonry structure of small length and low height constructed across a stream to arrest surface runoff of the stream. The check dams not only provide surface water for irrigation by gravity flow but are also useful for artificial recharge for groundwater development. There are 342 check dams spread over 49 mandals to provide an indirect ayacut of 2994 ha in the district (Fig. 7). If a check dam is not holding enough surface water for irrigation by gravity flow, and no water could be obtained through the sluices, it is called a percolation tank. It has an indirect ayacut of 100 ha created by pumping groundwater from wells downstream of the tank. A percolation tank is essentially the same as that of a normal tank without sluice, supply channel and/or an identified ayacut. There are 34 percolation tanks spread over to 23 mandals to provide an indirect ayacut of 4630 ha in the district. Water table fluctuations Water levels fluctuate annually in almost all the wells in the district.the annual rise in groundwater level is due to infiltration/percolation from rainfall and locally by seepage of water from surface storage tanks. Water levels usually begin to rise in July and continue until November. The period during which the groundwater levels rise corresponds to the period of monsoon months. Water levels usually decline during dry months until the end of June. In order to study the seasonal fluctuations of watertable and secular trends, hydrographs in different formations has been prepared (Fig. 8). The analysis of data revealed that the average seasonal rise in water level is 7.32 m in quartzites, 5.35 m in crystallines, 3.82 m in shales, 2.50 m in limestones, and 2.11 m in alluvium. From the hydrographs, an overall decline trend of groundwater levels is observed in quartzites, crystallines and shales. Whereas in the case of the limestones and alluvium there is no steep decline in groundwater levels, which indicates nearly stable groundwater conditions. The groundwater conditions in different rock formations of the Cuddapah district are presented in Table 3. Table 3 Groundwater conditions in different rock formations of Cuddapah district. (Source: AP State Groundwater Department) Location Geological formation Diameter of well (m) Depth of well (m bgl) Staticwater level (m) Post water level (m) Discharge (Lpm) Drawdown (m) Boppapuram Cumbum shales 11.5! Dodugunuru Cumbum shales Medidinne Auk shales Kothapalle Tadipatri shales Machenapalle Nandyal shales Gollapalle Narji limestones Arakatavemul Koilkuntla limestones Vanipenta Nandyal shalylimestones Thallapuram Alluvium Paidala Alluvium Environmental Geology 39 (3 4) January Q Springer-Verlag 349

9 Fig. 7 Mandal-wise land irrigation by the check dams Fig. 8 Hydrographs of observation wells in different rock formations in the Cuddapah district Groundwater assessment for the Cuddapah district has been made on the basis of the norms recommended by Groundwater Estimation Committee (CGWB 1986). Groundwater balance studies revealed that the recharge and draft are million m 3 and million m 3, respectively. The recharge is determined by considering recharge from rainfall, surface water bodies and recharge through the applied irrigation. The draft is based on the number of energised wells and extent of area irrigated. Nearly 584 million m 3 of groundwater is available for future irrigation to bring more land under irrigation by way of sinking more bore/dugwells in the Cuddapah district. Janardhana Raju and others (1994) have applied GEC norms for the assessment of groundwater balance in the Upper Gunjanaeru river basin, Cuddapah district. From their studies it is evident that 1933 ha7m of net groundwater is available for future irrigation in the river basin. 350 Environmental Geology 39 (3 4) January Q Springer-Verlag

10 Water management in Mangampet baryte mining areas Mangampet baryte mine is a opencast mine in Cuddapah district presently with a depth of more than 80 m bgl. Large quantities of groundwater is accumulating and creating problems in the deep mining zones. Hence the management of the groundwater that inundates the opencast mine is of utmost importance. Groundwater occurs mainly in the fracture zones of bedded barytes and within the cavernous dolomitic limestones in immediate contact with the underlying baryte deposits. Large-scale blasting works carried out for the removal of overburden and mining of baryte result in the development of new fracture openings, which act as conduits for groundwater movement. These fractured aquifers get recharged by the flood discharge of a major stream (flowing west of the Anantarajupalle village in a general north-easterly direction) and this groundwater infiltrates/percolates into the deep opencast baryte mines. In spite of bailing large quantities of groundwater with high capacity pumps, mining has to be virtually stopped for a few months every year during rainy season. The entire water collected in a baryte mine is presently pumped out into the nearby Surabhikunta tank, located south-west of the mining area. As a result, this tank is perennial and is able to irrigate paddy in its entire ayacut round the year. From the studies, it indicates that the direction of groundwater flow in the baryte mining area is from south-west to north-east. It is not desirable to pump mine water into the Surabhikunta tank located towards the south-west of the mining area. The water that is pumped into the tank acts as a source of artificial recharge of groundwater (flowing in a north-east direction) and enters once again into the mines. It is therefore necessary to pump out the mine water through the pipe lines into the minor irrigation tank located far away to the north-west of the mining area. This strategy is highly helpful to avoid further seepage of pumped out water to enter again into the mines. Another strategy that could be adopted by the mine owners is to construct a large number of high-yielding deep borewells in and around the mining area and handover to irrigation department/ cultivators to utilise the groundwater for irrigation. Large-scale pumping of groundwater by cultivators lowers not only the groundwater levels, but also the cost of lifting water by mine owners which could be reduced drastically. Groundwater quality in Cuddapah district The major chemical constituents in the groundwater of the district are calcium, magnesium, sodium, potassium, bicarbonate and chloride (Table 4). The specific conductance ranges from 115 ms/cm at 25 7C at Ayyavanikambaladinna in limestone to ms/cm at 25 7C at Palur in shales, both located in the Jammalamadugu mandal. Out of 350 samples analysed 60 samples show specific conductance of less than 750 ms/cm and 94 samples show more than 2250 ms/cm. The remaining 196 samples fell in the range of 750 and 2250 ms/cm. According to the US salinity hazard classification, the groundwater in the district mainly falls in the medium to high salinity hazard and low to medium sodium hazard. Water of low conductivity is more suitable for irrigation than the water of high conductivity. It is observed that the quality of groundwater in the various rock units is within the permissible limits of irrigation and domestic purpose, but at a few places the specific conductance, chloride and fluoride contents are high. The high value of specific conductance is observed mostly in the water from domestic wells, apparently due to local contamination. In some places chloride concentration is more than permissible limits (250 ppm). This may be due to the domestic pollution and irrigation practices. Fluoride content is more than permissible limits (1.5 ppm) in some places, which may be due to the geological contamination (CGWB 1986). Janardhana Raju and others (1992) have studied seasonal variations of groundwater quality in the Upper Gunjanaeru river basin in the Cuddapah district. From their studies it is revealed that the pre-monsoon water has a low sodium hazard as compared to post-monsoon water and geochemical classification indicates that the groundwaters are of Ca-HCO 3 type. Quality of groundwater is deteriorating day by day because of rapid industrialisation and urbanisation. Many industries are letting out their untreated effluents into open channels, which contaminates groundwater through infiltration and percolation. Apart from this, the improper drainage system in urban areas and wastage from humans and animals are effecting groundwater quality. Application of pesticides, insecticides and fertilisers are also contributing to the groundwater pollution. Table 4 Water analysis of the Cuddapah district; EC ms/cm at 25 7C Constituent Range Mean ph Electrical conductivity Total hardness (mg/l) Calcium (mg/l) Magnesium (mg/l) Sodium (mg/l) Potassium (mg/l) Carbonate (mg/l) Bicarbonate (mg/l) Chloride (mg/l) Fluoride (mg/l) Environmental Geology 39 (3 4) January Q Springer-Verlag 351

11 Summary and conclusion The K. C. Canal Project, importing surface water from the Krishna river basin, has a capacity to irrigate ha in the entire Cuddapah district. The Mylavaram reservoir and Pulivendula branch canal project has an irrigation potential of about ha. There are 503 spring channels which are supplying surface water to a registered ayacut of 8700 ha in the district. A registered ayacut of about ha land receives surface water from the 1368 minor irrigation tanks and 17 projects involving lift of water from the confluence lakes and depressions within the major river beds has a capacity to irrigate 4900 ha. There are 34 percolation tanks spread over 23 mandals and 342 check dams spread over 49 mandals which are providing an indirect ayacut of 4630 ha and 2994 ha respectively through the artificial recharge of groundwater. From the hydrographs, the overall decline trend of groundwater levels are observed in quartzites, crystallines and shales, whereas nearly stable groundwater conditions exist in limestones and alluvium. Solution channels in the limestones and porous materials in the alluvium are the reasons for the nearly stable conditions of the groundwater levels. Groundwater assessment studies revealed that 584 million m 3 of groundwater is available which can be utilised for future irrigation purposes. Recommendations for future action Construction of more percolation tanks and check dams in the district would be very helpful for the artificial development of groundwater sources. Furthermore, we consider the construction of a large number of high-yielding deep borewells in and around the baryte mining area, and proper utilisation of these groundwater resources for future irrigation practices to be important. A watershed development programme is recommended to prevent soil runoff, which in turn helps infiltration of rain water and improves the groundwater sources. To control indiscriminate exploitation of groundwater, a spacing of m between the wells should be maintained. Use of sprinkler and drip irrigation is highly advisable in water scarce areas for its enormous saving potential of groundwater resources. To prevent and rectify the problems of water logging and water quality, conjunctive use of groundwater with surface water is of utmost importance. Acknowledgements The authors are highly grateful to Prof. R. Jagadiswara Rao, former Principal Sri Venkateswara University College for his critical evaluation, suggestions and constant encouragement during the preparation of this manuscript and also thankful to Dr. P. Babu Rao, Director, A. P. State Groundwater Department for supplying the data. N. Janardhana Raju is thankful to the Alexander von Humboldt Foundation, Germany, for awarding a Post-Doctoral Research Fellowship. Thanks are due to Mrs. Jeannette Forsen, Sweden, for her critical English corrections. Authors are also thankful to the anonymous reviewers whose thoughtful comments significantly improved the manuscript. References CGWB (1986) Technical report on groundwater resources and development potential of Cuddapah district, Andhra Pradesh, India Janardhana Raju N, Reddy TVK (1998) Fracture pattern and electrical resistivity studies for groundwater exploration. Environm Geol 34 : Janardhana Raju N (1991) Hydrogeology of the Upper Gunjanaeru river basin, Cuddapah district, Andhra Pradesh, India. (PhD thesis) Sri Venkateswara University, Tirupati, India Janardhana Raju N, Reddy TVK, Kotaiah B, Nayudu PT (1992) A study of seasonal variations of groundwater quality in Upper Gunjanaeru river basin, Cuddapah district, Andhra Pradesh. Fresenius Environ Bull 1 : Janardhana Raju N, Reddy TVK, Nayudu PT, Kotaiah B (1994) Estimation of aquifer parameters and groundwater balance of the Upper Gunjanaeru river basin, Cuddapah district, Andhra Pradesh. BHU-JAL News 9 : Janardhana Raju N, Reddy TVK, Nayudu PT (1996) Electrical resistivity surveys for groundwater in the Upper Gunjanaeru catchment, Cuddapah district, Andhra Pradesh. J Geol Soc India 47 : King W (1872) Kadapa and Kurnool formations in Madras Presidency. (Memoir 8) Geol Surv India Krishnaswamy VS (1981) Geological and mineral map of Cuddapah basin. Geol Surv India, Calcutta Murthy YGK, Nagaraja Rao BK, Ramalingaswamy G (1978) Status of Cuddapah basin geology with special reference to the D. S. S. Profile strip: In: Ramaswamy (1978), pp Raghu V (1990) Bio-geochemistry of Baryte mining areas of Mangampet and Vemula, Cuddapah district, Andhra Pradesh. (PhD thesis) Sri Venkateswara University, Tirupati, India Ramakrishna Reddy M (1994) Management of the water resources in the Cuddapah district, Andhra Pradesh, India. (PhD, thesis) Sri Venkateswara University, Tirupati, India Schottler (1996) Artificial recharge of groundwater in Germany state-of-the-art in research and practice. pp Siddiraju S (1993) Geohydrology and water resources of Pulang river basin, Cuddapah district, Andhra Pradesh, India. (PhD thesis) Sri Venkateswara University, Tirupati, India Sivarami Reddy K (1990) Geology, genesis and utilisation of barytes deposits of Cuddapah district, Andhra Pradesh, South India. (PhD thesis) Sri Venkateswara University, Tirupati, India 352 Environmental Geology 39 (3 4) January Q Springer-Verlag