NEED FOR GROUNDWATER UTILIZATION AND MANAGEMENT IN AURANGABAD CITY, MAHARASHTRA ABSTRACT

Transcription

1 NEED FOR GROUNDWATER UTILIZATION AND MANAGEMENT IN AURANGABAD CITY, MAHARASHTRA S.M.Deshpande Junior Geologist, Groundwater Surveys and Development Agency, Shivajinagar, Pune ABSTRACT Aurangabad city is famous for its water supply schemes of historical importance. Initially the town received its water supply from springs or wells, connected with small underground masonry pipes. These systems were designed to supply sufficient water through out the year. The city still depends upon some of these sources and of these four are still in a working order. However, with increasing population and urbanization the geographical area of the city has also increased manifold, demand supply calculations were to be regularly revised. The water supply network has been upgraded accordingly and new dependable source from the Jayakwadi Major Irrigation Project has been tapped to fulfill the demand. Due to rainfall variability Jayakwadi reservoir is facing problems of assured inflow and is not getting filled up to the capacity every year. This ultimately is affecting water supply of the city and also causing distress among farming communities. Besides this, tremendous amount of energy is required for pumping, which is increasing the cost of water supply to the city. In view of these facts and considering the availability of groundwater resources within city limits it is now very essential to think about development and management of groundwater dependant sources to supplement the city water supply. There is scope for groundwater based water supply schemes, as around 18 Mm 3 of groundwater resource are available and is economical than the surface water. The domestic requirement of around 40-50% of the present population can be catered though groundwater. Geology of the city is favorable for artificial groundwater recharge, hence groundwater management measures like rainwater harvesting by different ways and means are very much essential.

2 INTRODUCTION Aurangabad city is famous for its water supply schemes of historical importance. Initially the town received its water supply from springs or wells, connected with small underground masonry pipes locally called as Nahar. These systems were designed to supply sufficient water through out the year. The city is still getting water supply from four such Nahars. Many areas in the city are totally dependent upon these Nahars for the domestic water supply. One such Nahar is supplying water to the famous Panchakki (water grinder), which is a famous archeological monument in the city. The peculiar feature of these Nahars is that they are all rainfall dependent. However, with increasing population and urbanization the geographical area of the city has also increased manifold, demand supply calculations were to be regularly revised. The water supply network has been upgraded accordingly and new dependable source from the Jayakwadi Major Irrigation Project has been tapped to fulfill the demand. Due to rainfall variability Jayakwadi reservoir is facing problems of assured inflow & is not getting filled up to the capacity every year (Commission, 1999). This ultimately is affecting water supply of the city and also causing distress among farming communities. Besides this, tremendous amount of energy is also required for pumping, treating and supplying water from Jayakwadi reservoir, which is 45 kms from the city. In view of these facts and considering groundwater resources it is now very essential to think about development and management of groundwater dependant sources to supplement the city water supply. Present Status Demography: The total population of the urban agglomeration of Aurangabad city is 9,20,979 (GoM, 2001) out of which Aurangabad Municipal Corporation (AMC) population is 9,01,542. The details of the population & households are as given in Table-1. Table-1: Demography of Aurangabad Urban Agglomerations (2001 census) Sr. No. Particulars Aurangabad Municipal Corporation Aurangabad Cantonment Total in Aurangabad Urban Agglomerations 1 Area (sq.km) Population 9,01,542 19,437 9,20,979 3 Number of house holds 1,16, ,19,592 Rainfall: The average annual rainfall in Aurangabad is mm. About 83% of annual rainfall is received during June to September. The variation in rainfall from year to year is large. Aurangabad falls in drought prone area hence is characterized by the erratic behavior of the rainfall. On an average there are 46 rainy days in a year. Physiography: Aurangabad is situated on both the sides of Kham River. It stands in the Dudhana valley between Lakenwara range on north and Satara hills on south. Along the base of higher range soil is shallow and rocky, while towards the center it deepens and becomes rich and fertile. The area is mostly highly dissected or moderately dissected plateaus with insignificant valley fills (CGWB, 2001). Drainage Characteristic: The Aurangabad urban agglomeration is a part of Godavari basin, which is drained by the Kham and Sukhana Rivers. Harsul and Sangvi reservoirs are constructed across the two tributaries of Kham at the upstream side of the city area. The Sukhana River drains the eastern part of the city consisting of Maharashtra Industrial Development Corporation (MIDC) and Chikhalthana areas. The Sukhana reservoir is constructed at downstream and is located just outside of the city area across this river. The drainage pattern of both the rivers is dendritic. The Kham River has complex drainage course, which takes many right angle turns and also meanders invariably. The drainage course

3 indicates the influence of fractures on the drainage. Drainage density of the Kham drainage is more than that of the Sukhana drainage indicating comparatively low porosity (CGWB, 2001). Watersheds: Aurangabad Urban area is mainly falling within the GV-49 watershed and partly in GP-10 watershed delineated by Groundwater Surveys and Development Agency (GSDA) (Plate-I). The northern part of these watersheds is hilly. The southern part of GP-l 0 watershed is peneplain and used to be agriculture land prior to be declared within the Municipal area. The urbanization is yet to bloom in this area and most of the land is used for agriculture. Water Supply Scenario: The present water supply is MLD (0.156 Mm 3 /day). This supply is from Jayakwadi major irrigation project that is located at 45 kms away from the city. Due to growth in population of the city, the demand of water supply is projected to 220 MLD for the year Accordingly the yearly demand of city upto the year 2016 is worked out as 80.3 Mm 3. The reservation for water supply in Jayakwadi dam is made for the yearly demand to the extent of 113 Mm 3. Hydrogeology: Basaltic lava flows known, as Deccan traps are the only water bearing formations in the area. The weathered and fractured mantles of the traps are forming water table aquifers in the area where ground water occurs under phreatic conditions. The vesicular part of the flow and also the jointed/ fractured basalt form the aquifer in the area. Depth to water level is shallow during post monsoon and generally varies between 3-6 m bgl and during pre monsoon 6-10 m bgl (CGWB, 2001). Similarly the specific yield of the aquifer is low i.e indicating low storage capacity. There are around 750 bore wells drilled by AMC in city areas mostly fitted with hand pump. Besides these there are 16 community dugwells of AMC to tap ground water resources in the area. In addition to above a number of private dugwells and borewells are present to provide alternative to pipe water supply at individual level. In many areas the high yielding borewells are used exclusively for supplying the groundwater by the tanker. Groundwater marketing is a common practice in such areas. Groundwater Resources: The quantitative assessment has been done watershed wise and it is updated from time to time. Major part of the city falls within GV- 49 watershed and remaining in GP-l0. Details of groundwater assessment in both these watersheds are as per latest groundwater assessment of Maharashtra State given in Table-2. Table-2: Watershed wise Groundwater Resources (GSDA, 2004) Parameters/Watershed Waterhsed GV-49 (NC) Watershed GP-10 (NC) Net annual recharge (Mm 3 ) Net annual withdrawal (Mm 3 ) Net annual balance (Mm 3 ) No.of Existing wells with pump set Development stage % Category of watershed Critical Semi-critical NC Non Command The groundwater development in non-command of watershed GV-49 is more than GV-10, which is less urbanized. The study reveals that groundwater utilization in Aurangabad city area has increased in the last decade. Similarly the water levels also show declining trends indicating immediate need for groundwater management. Groundwater Development Possibilities The hydrogeological situation prevailing in Aurangabad municipal area is favorable for groundwater development barring few localities, which can be utilized for domestic purpose. Precise locations of potential areas favorable for groundwater occurrence and pin pointing of favorable sites of wells and bore wells need to be looked into carefully. According to preliminary estimates, aquifer of one-meter thickness is likely to yield around 3 Mm 3 of groundwater in

4 sq km of urban areas of this city. The phreatic aquifer has thickness of around 5-7 m; therefore groundwater availability at the end of monsoon is around 18 Mm 3 (CGWB, 2001). However, some of the city areas due to local variation in topography and geology may not have uniform availability of groundwater. At present maximum groundwater development in the city is through private interventions and the use of community wells are very low. The studies carried out indicate that during normal rainfall conditions existing groundwater resources can be locally developed and utilized for domestic purpose (other than drinking) in following manner. Period June to September October to January February to May Groundwater that can be Available Population covered (Approx) 6.0 Mm lacs 50 lpcd 8.4 Mm lacs 70 lpcd Per capita requirement Considered 3.6 Mm lacs 100 lpcd The chemical analyses carried out by GSDA indicate that barring few localities most of the areas are suitable for drinking purpose. Groundwater Augmentation and Recharge Potential The groundwater availability for city area is estimated 18 Mm 3 which is equivalent to 30% of the annual requirement of civil water supply. At present though the water level trends are declining, normal water levels are regained every year indicating favorable storativity of the aquifer. However, due to increasing urbanization along with cement constructions and hard surfaces over the land effective recharge area is decreasing. Now around 60% of the city area is covered with buildings, cement covers and roads. This has started reducing the natural groundwater recharge within the watersheds. It is estimated that the natural 15% of groundwater recharge has reduced to around 6 to 7%. So 8 Mm 3 of groundwater will be replenished naturally every year under normal rainfall conditions. Hence to augment optimum groundwater, supply driven groundwater management measures for artificial groundwater recharge, like roof top rainwater harvesting, trenches, shafts, (location specific structures) etc are very much essential. If rooftop rain water harvesting is to be considered as a sole measure for replenishment of this deficit of 10 Mm 3 of groundwater then the roof top area required would be around 15 sq km. Therefore, the rooftop rainwater harvesting measures need to be undertaken on mass scale. The major users like industries, institutions, big apartments and buildings, hotels, complexes specially those using the groundwater, as supplementary or sole source for their need should be compelled for roof top rainwater harvesting measures. This will ensure adequate replenishment of groundwater and also help to improve the quality of groundwater. The city areas like CIDCO, Mukundwadi, Garkheda, Jawahar Colony upto Padampura, Gulmandi, Mitmita, etc have good groundwater potential (Plate-II) and groundwater marketing is on a large scale. Hence in these areas along with groundwater development artificial groundwater measures need to be taken on priority. The AMC has already initiated the steps to promote the roof top rainwater harvesting measures by giving 5% discount on the annual property tax. There are some areas in the city, which are not having the existence of aquifer. So in such areas promoting roof top rainwater harvesting measures means simply wasting the investment.

5 CONCLUSIONS AND RECOMMENDATIONS The population rose in the city from around in 1951 to around 6 lacs in 1991 i.e. nearly ten times increase in 40 years. The water supply network has been upgraded accordingly. However, developing and using the groundwater resources locally can very well reduce the dependability on surface water and will reduce the energy cost also. There is scope for groundwater based water supply schemes as around 18 Mm 3 of groundwater resource are available. The domestic requirement of around 40-50% of the present population can be catered though groundwater. Therefore pipe water supply network and groundwater based community water supply scheme needs to be undertaken judiciously so as to tackle the prevailing scarcity more effectively. The use of old Baudis (Community Wells) has been discontinued which needs to be promoted. To augment groundwater, recharge measures like roof top rainwater harvesting should be made mandatory to institutions, industries, commercial complexes and housing societies etc. Similarly the construction of roadside trenches, shafts etc need to be promoted. These artificial recharge measures can help in reducing the salt concentration and fulfill demands for selective use of groundwater for domestic and washing can be increased in the area. In the areas where groundwater marketing is a common practice enactment of making groundwater recharge by any means is a must. REFERENCES CGWB, Urban Hydrogeological Studies in Aurangabad City, Maharashtra. Central Groundwater Board, MOWR, Commission, A Report of Maharashtra Water and Irrigation Commission, Irrigation Department, Government of Maharashtra GOM, Socio Economic Review of Aurangabad District. GSDA, Estimation of Groundwater Resources in Maharashtra (as per GEC 1997), Groundwater Surveys and Development Agency, GoM Pl

6 Plate - II