Project Report

Depleting Groundwater Levels and Increasing Fluoride Concentration in Villages of Mehsana District, Gujarat, India:
Cost to Economy and Health

 

Report Prepared by
S.K. Gupta and R.D. Deshpande

 

Sponsor

Habitat and Environment Committee
(HEC) of the Habitat International coalition (HIC)
S/C Enda TM/Rup-BP, 3370 Dakar-Senegal

 

 

 

(May, 1998)

Project Report

Depleting Groundwater Levels and Increasing Fluoride Concentration in Villages of Mehsana District, Gujarat, India:
Cost to Economy and Health

 

Executive Summary

It is well known that trace elements are essential and beneficial to human health in minute concentrations, as they play an important role in many metabolic processes and act as cofactors. However, exceeding their permissible intake is known to be toxic and has adverse effects on general body metabolism. One such trace element, which is ubiquitously distributed in soil, earth and water is fluoride. It is a fact that low amount of fluoride (0.3-1.0 mg/l) in drinking water is helpful in the prevention of dental caries and in treatment of osteoporosis. However, high intake of fluoride (>1.5 mg/l) in drinking water for a prolonged period is known to cause damage to the teeth enamel and eventually leads to skeletal complications that result in fluorosis.

Mehsana district in north Gujarat is located within the latitudes 230 03íN to 240 09íN and longitudes 710 23íE to 720 52íE. The region is rich in agricultural production but is largely dependent on groundwater, both for irrigation and drinking water requirements. During the last decade, large scale exploitation of groundwater for irrigation has led to fall in groundwater table at a rate of approximately 3m/yr, though groundwater mining condition have now been there for the last two decades. As a result, residents of the region face the following problems:

  1. Fluorides and other dissolved salts in drinking water have shown progressively increasing trend and have exceeded the safe limit in past two decades
  2. Chemical quantity of groundwater is also showing adverse impact on soil fertility and crop growth.
  3. With progressive decline of groundwater table, more electric power is required to lift the same quantity of water.
  4. The process of deterioration of groundwater quality continues unabated and progressively increasing proportion of the population is seen to the affected by fluorosis.

In the present area, with groundwater as the primary source for drinking and irrigation, it is necessary that all aspects related to the problem be fully investigated and a quantitative appraisal made to help long term planning. To make a comprehensive review of this multifaceted problem, Water Resources Research Foundation (WRRF), approached the Habitat and Environment Committee (HEC) of the Habitat International Coalition (HIC) with the present project proposal. Following is a report of the investigations, largely based on study of published and unpublished reports with various departments of the Govt. of Gujarat and in the research journals.

Geologically the area comprises un-consolidated alluvial sediments derived by fluvial transport from north-eastern catchment of Aravalli hills and are partly mixed with blown sands from southwest. The deposition took place during last 200 kyr (Late Quaternary). The site of deposition was the Cambay basin which was formed during Tertiary due to block faulting and has been a tectonically active region ever since. The earlier stages of deposition experienced sea level fluctuations, while the later stages witnessed a rather arid environment with large scale contribution of aeolian sands. Neo-tectonic movements also accompanied the sedimentation process (Patel, 1986). Thus the deeper layers have fluvio-marine origin, while the upper layers have fluvio-aeolian characters. The thickness of sediments is more than 1,000m and comprises alternate layers of clay, silt, sand and gravel that show pinching and swelling structure of layers. Recent work (Prasad et al, 1997) has shown that the mainland of Gujarat was separated from the Saurashtra by a narrow, shallow sea-link joining the Gulf of Kachchh with the Gulf of Khambhat (see Figure 7) until about 65-70 kyr ago. The sea then receded during the period of last major glaciation and the sedimentation front advanced westwards filling the former sea corridor.

Due to their high permeability, the coarser layers comprising of sandy and gravelly horizons formed the aquifers which are separated by semi-permeable silty and clayey horizons. Brackish to saline conditions are observed in deeper aquifers which are generally found below 250m depth but occasionally even at much shallower depths. The continuity of aquifers occasionally gets disrupted due to pinching of layers or fault displacement. According to Patel (1986), the lower aquifers are hydro-statistically under artesian conditions. The general gradient of aquifers is towards west and these merge in eastern direction, where along the foot hill zone of Palanpur-Kheralu, these are exposed and receive natural recharge. Towards their western extension, the deeper aquifers abut against a thrust plane near Radhanpur-Viramgam belt. Along this belt, tubewells tapping the deeper artesian aquifers show free flow at ground, have high temperature and saline water (see Figure 6). Recently, excess dissolved helium has also been recorded from groundwater of those wells.

The upper aquifers are under semi-confined condition. They receive recharge (i) directly by seepage from the shallow unconfined aquifer, (ii) by lateral flow from the recharge zone of Palanpur-Kheralu foothill region in the east. The shallow unconfined aquifer receives direct recharge from (a) rainfall infiltration, (b) nearby stream flow and, (c) by return flow from the irrigation. As one moves westwards the groundwater progressively becomes saline.

Radiocarbon dating of groundwater from deeper aquifers showed that the groundwaters were 15-20 kyr old (Bhandari et al, 1986). This means that the water being pumped was recharged by rain 15-20 kyr ago and has been in contact with sediment grains for such a long period. It is hypothesised (Patel, 1986) that high fluoride levels in groundwater are a result of leaching of this element (along with others) from the sediments which have their provenance (source area) in the metamorphic rocks of Aravalli hills. In a groundwater mining situation, as it prevails in the Mehsana and neighbouring districts of Banaskantha, Gandhinagar and Ahmedabad, pumped water with a larger residence time in the aquifer is, therefore, likely to have higher salinity including higher fluoride. The high total dissolved solids (TDS) and fluoride contours appear to run NE-SW and there is general decrease towards the NE (Figure 6).

At places, the shallow groundwater also shows poor quality on local scale. This is attributed either to local stagnation or high concentration of toxic elements in the host sediments and, in some cases, due to industrial pollution.

The areas on the banks of the rivers draining the region, namely Saraswati, Rupen, Banas and other smaller streams get recharged during the rainy season (June to September). At such locations, groundwater levels are relatively higher and shallow aquifers supply good quality water.

The groundwater development in the region can be sub-divided in three phases

  1. Pre-1935 phase: Groundwater at shallow depth (5-10m) and obtained from dug wells by bullock and manual lifting of water.
  2. 1935-1955 Phase: Groundwater levels declined to 10-30m and dug-cum-bore wells become prevalent and diesel pump sets were used for lifting the water.
  3. Post 1955 Phase: Groundwater levels began to decline rapidly and from sixties the decline has been between 1-3m every year. Deep tubewells fitted with electric motors have been used to lift groundwater from 100-250m depth.

The deterioration in groundwater quality almost parallels the post 1955 phase, when with the advent of tubewells and electric motors the groundwater extraction went up many folds. Gradually, the soil fertility was being affected by irrigation with high TDS groundwater and several native crops disappeared. Presently, cash crops of bajari, cotton and jowar are grown in the region.

The Geological Survey of India carried out groundwater investigations in the Mehsana area as early as 1953-54. At the time of this investigation tubewell development in Mehsana district was in its initial phase. In 1969, the need for artificial groundwater recharge through wells by rainwater or water from other suitable sources to augment the natural infiltration and to improve the quality of groundwater was already being discussed.

A survey was conducted in eighteen fluoride endemic villages in Mehsana district of north Gujarat. The individuals affected with fluorosis were examined for apparent mottled teeth and skeletal complications. Samples of urine and blood of these individuals along with drinking water were collected and compared with samples obtained from Ahmedabad city. The analysis of water, urine and blood also showed significantly high fluoride levels in individuals affected with fluorosis. Several other parameters indicative of metabolic functions were analysed which clearly indicated adverse effect of high fluoride ingestion.

Government of Gujarat has identified a few schemes for solving the water supply problems of this regions. Some of the schemes are:

 

1. Dharoi Reservoir Dependent Scheme:

371 villages belonging to Kheralu, Sidhpur, Visnagar and Patan taluka, will be provided with the 68.86 MLD of water under group water supply scheme, at an estimated cost of Rs. 140 Crore (Rs. 1.4 billion).

2. Sabarmati River Dependent Scheme:

109 villages from Vijapur taluka will be provided with water drawn from Sabarmati river at an estimated cost of Rs. 36 Crore (Rs. 0.36 billion).

2. Narmada Canal Dependent Scheme:

111 villages belonging to Chanasma taluka, 118 villages belonging to Kadi taluka and a large number of villages belonging to Sami and Harij taluka will be provided with the water from Narmada main canal by constructing necessary ìoff take pointsî, storage tanks and filtration plants.

These schemes can provide water for drinking, but people require water for a variety of uses including agriculture and industry. Long term solutions must come from either inter-basin import of water on a large scale or local storage of annually renewable rain water in surface and underground reservoirs. Nature has endowed the Mehsana area with excellent groundwater basin capable of storing enormous quantity of water in reserve. Over the years this reserve has been drained and needs to be refilled through a programme of fresh groundwater recharge. Unfortunately the natural conditions of this area do not provide for large surface storage reservoirs by dam construction. The present sources of natural and artificial recharge contribute negligibly compared to the exploitation. Therefore, there is a need to provide drinking water from whichever surface reservoir that can be utilised for this purpose but, provision for agricultural domestic and industrial requirements must come from innovative groundwater recharge schemes and increasing the efficiency of application.

The top alluvial cover being highly porous and permeable, storage tanks can improve the recharge on a local scale. The tank supported recharge wells can enhance groundwater recharge significantly, provided such measures are taken in large numbers. Practically all villages in the area have at least more than one sufficiently large size pond for constructing such wells. The recharge capacity can be further increased when additional supply, other than rainwater, is arranged through feeder canal network. The foothills zone along Palanpur-Kheralu-Modasa is the identified natural recharge area for the deeper confined / semi-confined aquifers of Mehsana area. Specific measures must be undertaken to recharge shallow aquifers in this zone.

A pilot project for tackling the fluoride problem based on artificial recharge of groundwater using storm water runoff has been proposed for the village of Balisana in Mehsana district of Gujarat. The estimated cost of the project envisaging fluoride free potable quality water at the rate of 50 litre per person per day for human population of 12,000 plus a cattle population of 3,000 is Rs. 48.00 lakh only (=US$ 120,000.-), which is less than the estimated cost of a pipeline based group water supply scheme dependent on import of surface water.

In conclusion, it may be worth mentioning that a satisfactory resolution of the excess fluoride problem in drinking water, using storm water runoff for groundwater recharge of shallow aquifers as advocated in this chapter would additionally lead to (1) small saving in groundwater presently used in irrigation and, (2) over a period of few years, some induced recharge to deeper aquifers through leakage via intervening aquiclude layers. We also visualise a study improvement in groundwater recharge technology so that it will be possible to recharge larger amounts of storm runoff even for non-potable applications. Ultimately, the long term solution to the water problem of the region lies in conservation of rain water, both in surface and subsurface reservoirs and, renovation and reuse of waste water.

Table of Contents

Page No.

Executive Summary i

Table of Contents Viii

List of Figures xi

List of Tables xiii

Chapter: 1 Introduction 1

History of groundwater development 2

Chapter: 2 Geological Background 4

Hydro-chemical regime 18

Areas with fresh groundwater at all levels 18

Areas with fresh groundwater overlain by 18
saline groundwater

Areas with saline groundwater at all levels 18

Chapter: 3 Fluorine in Environment 20

Sources of fluorine ingestion 22

Chapter: 4 Fluoride and Biological Tissues 26

Effect of fluoride on bones, skeletal system 26
and skeletal fluorosis

Long bones 27

Short bones 27

Flat bones 27

Irregular bones 27

Characteristic structural changes in fluorosed bones 28

Dental fluorosis 28

Parts of a tooth 29

Structural parts of teeth 29

Effects of fluoride/ fluorosis on soft tissues/ 30
organs/ systems

Fluoride toxicity, fluorosis and its 31
effects on Red blood cells

Effects of fluoride poisoning on the 32
gastro-intestinal mucosa

Neurological manifestations 32

Allergic manifestations 32

Urinary tract manifestations 32

Ligaments and blood vessels calcification 32

Chapter: 5 Fluoride Toxicity Studies in 33
Mehsana District, North Gujarat

General 33

Fluoride toxicity on body fluids and metabolic 38
indicators

Genotoxic effects of fluoride in Mehsana 41

Chapter: 6 Remedial Measures 42

Schemes based on defluoridation of drinking water 42

Defluoridation of water using Nalgonda 42
technique

Mechanism of defluoridation by Nalgonda 43
technique.

Salient features of Nalgonda technique. 46

When to adopt Nalgonda technique. 46

Domestic defluoridation. 47

Fill-and-Draw defluoridation plant for 50
small community.

Fill-and-Draw defluoridation plant 50
for rural water supply.

Status of Defluoridation plants in 51
Mehsana district.

Schemes based on import of surface water 51

Dharoi Reservoir Dependent Scheme 53

Sabarmati River Dependent Scheme 53

Narmada Canal Dependent Scheme 53

 

Chapter: 7 Innovative Methods 54

Tackling fluoride problem through groundwater 55
recharge

A pilot project proposal for tackling fluoride 57
problem in Mehsana district based on
groundwater recharge.

The project 57

Percolation well design 59

Project implementation 62

Project costs 62

Appendix 1 Village-Wise Distribution of 65
Fluoride in Drinking Water in
Mehsana District, Gujarat, India.

Bibliography 71

Acknowledgements 74

List of Figures

Page No.

Figure 1 Geological map of the Mehsana District. 5
From Arun Kumar (1998).

Figure 2 Subsurface cross sections across the line AAí 6
marked in Fig. 1. From Arun Kumar (1998).

Figure 3 Subsurface cross sections across the line BBí 7
marked in Fig. 1. From Arun Kumar (1998).

Figure 4 Subsurface cross sections across the line CCí 8
marked in Fig. 1. From Arun Kumar (1998).

Figure 5 Subsurface cross sections across the line DDí 9
marked in Fig. 1. From Arun Kumar (1998).

Figure 6 Hydrogeological map of the Mehsana area showing 11
groundwater potential and water quality. Modified
from Patel (1986)

Figure 7 Geographical arrangement of Saurashtra and Gujarat 12
at time of last major interglacial ~120 kyr ago.
Redrawn from Prasad (1996).

Figure 8 Depth to water table below ground level (bgl) 13
for the unconfined aquifers - Mehsana District.
From Arun Kumar (1998).

Figure 9 Water table elevation contours (amsl) for the period 14
May 1995 - Mehsana District. From Arun Kumar (1998).

Figure 10 The depth to piezometric surface (bgl) in the 16
tubewells in Mehsana District. From Arun Kumar (1998).

Figure 11 The piezometric surface elevation (amsl) in the 17
tubewells in Mehsana District. From Arun Kumar (1998).

Figure 12 Hydro-chemical conditions in Mehsana District. 19
From Arun Kumar (1998).

Figure 13 Layout plan of the Nalgonda defluoridation 44
technique. From GJTI Course Manual.

Figure 14 Defluoridation at domestic level. 48
From GJTI Course Manual.

Figure 15 Schematic diagram of Fill-and-Draw domestic 49
defluoridation unit. From GJTI Course Manual.

Figure 16 Schematic diagram of reactor used in Fill-and-Draw 52
defluoridation unit at for village level
From GJTI Course Manual.

Figure 17 Conceptual design of a percolation well 59
for groundwater recharge.

List of Tables

Page No.

Table 1: Geographical and agricultural information 1
about the project area.

Table-2: List of industries that use fluoride either as 21
raw materials in the manufacturing process
or fluoride arises as a by-product or it may
even be end product.

Table-3: Reported range of fluoride concentration in 23
certain common food items.

Table-4: Fluoride content in drinking water in a few 33
villages in the district of Mehsana.
(Source: RGNDWM survey data.)

Table-5: Fluoride affected Talukas of Mehsana District, 34
Gujarat State.

Table-6a: Status of water quality in Gujarat in terms of 35
fluoride, nitrate and salinity.

Table-6b: Status of water quality in Gujarat in terms of 36
fluoride, nitrate and salinity. Minimum and
maximum values observed in excess of ICMR
permissible standards.

Table-7: National and international standards of 37
quality of drinking water supplies.

Table-8: Comparison of body fluids and metabolic 38
function indicators between the fluorotic
subjects from Mehsana and normal individuals
from Ahmedabad city.

Table-9: Approximate Alum dose (mg/l) required 43
to obtain acceptable quality (fluoride: 1 mg/l)
of drinking water from raw water at various
alkalinity and fluoride Levels.

Table-10: Domestic defluoridation: Approximate volume of 47
alum solution (ml.) required to be added in 40 litres
of test water to obtain acceptable limit (<1.0 mg /l)
of fluoride in water at various alkalinity and
fluoride levels

Table-11: Estimate (in Rs.) for one 6.5m diameter, 9m 63
deep brick masonry percolation well

Chapter: 1