# Groundwater Quality Mapping using Geographic Information System: A Case Study of District Thatta, Sindh

Ghulam Shabir Solangi, Altaf Ali Siyal, Muhammad Munir Babar, Pirah Siyal

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Ghulam Shabir Solangi, Altaf Ali Siyal, Muhammad Munir Babar, Pirah Siyal. Groundwater Quality Mapping using Geographic Information System: A Case Study of District Thatta, Sindh. Mehran University Research Journal of Engineering and Technology, 2017, 36 (4), pp.1059-1072. hal-01705672

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# Groundwater Quality Mapping using Geographic Information System: A Case Study of District Thatta, Sindh

GHULAM SHABIR SOLANGI*, ALTAF ALI SIYAL*, MUHAMMAD MUNIR BABAR*, AND PIRAH SIYAL**

RECEIVED ON 21.04.2017 ACCEPTED ON 29.05.2017

## ABSTRACT

Access to safe and affordable drinking water for all is an important goal of SDGs (Sustainable Development Goals). Degradation of water quality of coastal aquifers is a major concern throughout the world including the Indus River delta. Looking at the present changing climate scenario, the study was conducted to assess and map the spatial variation in the groundwater quality of district Thatta using GIS (Geographic Information System). The groundwater samples from hundred (100) randomly selected hand pumps of the district were collected such that all union councils of the district were sampled. The water samples were analyzed for different physicochemical parameters, i.e. taste, color, odor, pH, turbidity, EC (Electrical Conductivity), calcium, magnesium, total hardness, chloride, total dissolved solids, and arsenic using standard laboratory techniques. The results of water analysis revealed that 85% of the groundwater samples had TDS (Total Dissolved Solids) concentration beyond the permissible limit described by WHO (World Health Organization). Whereas, all the groundwater samples had chloride concentration beyond permissible limit of 250 mg/l. Analysis for arsenic revealed that only 20% of groundwater samples had a concentration higher than the safe limit of 10 ppb. The study indicated that in most of the areas, the groundwater quality was not as per drinking standards prescribed by WHO, hence was not suitable for drinking purpose. The GIS maps of groundwater quality parameters were prepared using spatial interpolation Kriging tool. These maps provide the visual analysis and interpretation of spatial variability of different groundwater quality parameters, hence are supportive in monitoring and managing the vulnerability of groundwater contamination.

**Key Words:** Coastal Aquifers, Arsenic, Chlorides, Physicochemical Properties, Geographic Information System.

## 1. INTRODUCTION

Groundwater is considered as one of the most vital renewable and extensively circulated resources of the earth which are also an important source of water supply throughout the globe [1]. It is used for domestic, agriculture, industrial and

many other human needs. Human health is directly associated with groundwater; therefore, its quality is of a prime importance for human health [2]. In areas where potable water resources are limited, an accurate and reliable estimate of sustainable use or yield is critical [3].

Corresponding Author (E-Mail: siyal@yahoo.com)

<footnote>* US-Pakistan Center for Advanced Studies in Water, Mehran University of Engineering & Technology, Jamshoro.</footnote>

<footnote>** National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro.</footnote>
Specifically, optimal or sustainable groundwater resource
userequires setting upper limits on water withdrawal (or
sustainable yield) to avoid compromising the source [4].
Estimates reveal that in Pakistan 30% of all diseases and
40% of all deaths occur due to use of contaminated water
while every fifth person experiences illness because of
contaminated water [5]. It is also reported that more than
three million people encounter the water-borne diseases
every year while 0.1 million die [6].

In coastal areas, up to one billion people utilize
groundwater as the major source of drinking
throughout the globe [7]. In such areas, seawater
intrusion is the main environmental issue for
contamination of groundwater [8-10]. The groundwater
becomes unsuitable for domestic, irrigation as well as
industrial purposes when mixed with salty water even
in very small quantities [11]. In coastal aquifers, increase
in seawater intrusion is an interrelated and dynamic
phenomenon which depends on different parameters
such as recharge, groundwater extraction from coastal
aquifers, and the topography of such aquifers [12-13].
The unplanned and unsystematic groundwater
withdrawal from aquifers is the primary reason of
groundwater salinization in coastal areas [14]. Because
of environmental change, sea level is rising that is also
one of the fundamental cause of seawater intrusion
and contamination of the coastal aquifers [15-16]. The
deteriorating quality of water in developing countries
has caused diarrhea [17], hepatitis E [18], dental caries
and oral hygiene [19], anemia in children [20], reducing
intelligence in children, and brain functioning and
development [21].

In Pakistan, more than 60% of the population utilizes
groundwater for drinking purpose [22] and the
degradation of groundwater is one of the significant
concerns caused by overexploitation of the groundwater
resources and discharge of untreated polluted wastes

into the water bodies. Sixty-Eight percent (68%) rural
population of Pakistan is drinking the water of poor
quality [23]. One hundred million cases of diarrheal
diseases are being registered in hospitals of Pakistan
within 1 year [24]. It is also reported that in Pakistan,
around 0.25 million children die due to drinking of
contaminated water [22]. Polluted water, purity, and
hygiene practices are the fundamental cause of most
diarrheal cases, the primary cause of around 0.25 million
children die under the age of five years annually [22].
According to a study led by UNICEF, around 20-40% of
the hospital beds in Pakistan were occupied by patients
experiencing waterborne diseases, such as, typhoid,
dysentery, cholera, and hepatitis, which are the reasons
of 33% of all deaths [25]. The accessibility of safe and
affordable drinking water significantly affects the
waterborne diseases.

The southern Sindh province of Pakistan adjoins the
Arabian Sea coast where drinking water quality is
deteriorating due to the dumping of industrial and urban
waste and use of agrochemicals and yet has limited
freshwater resources [26]. The groundwater quality is
badly affected by salinity, arsenic, fluoride and microbial
pollution, which further deteriorates in low-lying, deltaic
and floodplains of Sindh [27]. In these areas, people mostly
depend on the groundwater for drinking and irrigation
purpose because of low precipitation and reduced flow
of Indus River [28]. In the coastal areas, seawater intrusion
further degrades the quality of groundwater [2]. The
contamination in groundwater in most of the areas of the
Thatta district is due to seawater intrusion, as seawater
contains many trace metals [29]. Therefore, monitoring of
quality of drinking water is a key factor for control of
waterborne diseases in such areas.

Initial studies on arsenic distribution in the
groundwater show that high arsenic concentrations
(10-600), exceeding WHO [30] permissible limit of 10
ppb, occur in the groundwater of Tando Mohammad Khan, Thatta, Mitiari, Khairpur and other parts of Sindh province of Pakistan [30-33]. Memon et. al. [26] conducted a study in the southern districts i.e. Thatta, Badin, and Tharparkar of Sindh province of Pakistan and reported about some common diseases like gastroenteritis, diarrhea, vomiting, kidney, and skin problems found in these areas. The review of the literature indicated that so far only a few studies have been conducted on groundwater quality of Thatta district. Some studies were focused only on physicochemical parameters while in other studies only the biological parameters in groundwater were observed. However, these studies did not consider the entire district but considered only some major cities of the district only. However, detailed studies regarding the spatial variation of the groundwater quality in coastal districts of Sindh are still lacking.

GIS is an effective tool widely used for monitoring and mapping of the water quality, evaluating the spatial variability of water quality and detecting the environmental change [34]. Considering the concerns of civil society about the quality of groundwater of Thatta district, the present study was carried out. Distinctive physicochemical parameters of groundwater were analyzed and compared the standard allowable limits described by WHO to assess the quality of groundwater for drinking purpose. The study accordingly planned to assess the groundwater quality and develop a spatial distribution database using GIS interpolation techniques, based on the results of physicochemical analysis of groundwater of district Thatta. The results obtained from the study will be useful for government, policy makers as well as the public to be aware of existing groundwater contamination and will be supportive for the monitoring and managing the vulnerability of groundwater contamination in the district.

## 2. MATERIALS AND METHOD

### 2.1 The Study Area

Thatta district comprises of four talukas viz. Thatta, Keti Bander, Ghorabari, and Mirpur Sakro. It spreads over a geographical area of about 8390 square kilometers (839100 hectares). As per the 1998 census, the total population of these four talukas was 0.6 million. The district is situated where the Indus River flows into the Arabian Sea, having Latitude of 23°56'54" to 25°26'40"N and Longitude of 67°8'58" to 68°20'59"E. It lies in the southwestern part of Sindh province of Pakistan (Fig. 1). Jamshoro district is in North and West, Sujawal and Tando Muhammad Khan districts in the East, Karachi district lies on the West while district Hyderabad shares Northeast boundary of the district Thatta. The climate of the district is dry with an average annual rainfall about 220 mm [35] most of which falls during monsoon which spans from June to September. The temperature ranges between 23.8-28.7°C [35-36]. The agriculture in the area depends on both the surface water (Indus River canals) and groundwater. It is a part of Lower Indus alluvial and a deltaic plain covered by thick alluvial deltaic sediments which host the aquifers in the area [37]. Its soil constitutes fine-grained sediments, rich in organic matter containing a high amount of arsenic, which is supposed to become part of aquifers by various geochemical processes [38-39]. Most of the residents of the district use groundwater extracted from the hand-pumps drilled into shallow aquifers down to 5-12 m for their drinking and other daily water use.

### 2.2 Analysis of the Groundwater Samples

The groundwater samples were collected from randomly selected 100 hand pumps installed at public places i.e. schools, bus stops, restaurants as well as at the residential places. These hand pumps were extensively used by the people for extracting groundwater for their domestic use. Groundwater sampling locations were recorded using the handheld
Garmin GPS (62s). Thus, about three samples from each of the 27 union councils of the district were collected as shown in Fig. 2. The groundwater samples were collected in one-litre polythene bottles by observing standard sample collection methods. The bottles were washed and rinsed properly with distilled water to remove any possible contamination. During the study, it was learned that the installation depth of hand pumps varied from 5-15 m throughout the district. According to the depth of hand pumps, the purging process was applied. If the hand pump was bored at 10 m depth, it needed 30 strokes for its purging. After purging, the polythene bottles and their caps were washed with the same water and then samples were collected in bottles for getting maximum accuracy in results. The samples were collected from July-December 2016. All the collected groundwater samples were coded, sealed and preserved properly, then shifted to the laboratory for physicochemical analysis.

<figure><img src="image_2.png" /><figcaption>FIG. 1. LOCATION MAP OF THE STUDY AREA</figcaption></figure>

## 2.3 Water Quality Parameters

The groundwater samples were analyzed for different physicochemical parameters viz. taste, color, odor, turbidity, pH, EC, TDS, C1 (Chloride), Ca (Calcium), Mg (Magnesium), TH (Total Hardness), and arsenic using available standard laboratory methods. The results of groundwater quality parameters were compared with permissible limits prescribed by WHO for the safe drinking water. Materials and methods used for determining groundwater quality parameters of Thatta district are described in Table 1.

## 2.4 Preparation of Groundwater Quality Thematic Maps

ArcGIS 10.3.1 was used to develop spatial distribution groundwater quality thematic maps of the district for various physicochemical parameters. The resulting analysis of physicochemical parameters was stored in MS Excel spreadsheet along with location coordinates. The excel sheet was imported in ArcMap 10.3.1 through

<figure><img src="image_3.png" /><figcaption>FIG. 2. GROUNDWATER SAMPLING LOCATION</figcaption></figure>
add option. The spatial variation of each of the groundwater quality parameter was interpolated for the whole district using spatial interpolation "Kriging" tool and then extracting the AOI (Area of Interest) using "Extraction by mask" tool. Thus, spatial distribution thematic maps of the groundwater of district Thatta for various physicochemical parameters viz. taste, pH, color, odor, turbidity, electrical conductivity, calcium, magnesium, total hardness, chloride, total dissolved solids, and arsenic were prepared.

## 3. RESULTS AND DISCUSSION

The water quality maps are useful for assessing the suitability of water for drinking purpose [1]. These maps provide the visual interpretation of spatial variability of different groundwater quality parameters, hence are helpful in monitoring and managing the vulnerability of groundwater contamination.

### 3.1 Taste, Color, Odor, and pH

The results of the study revealed that about 55% of the groundwater samples of the district Thatta had bitter

and salty taste, while 16% samples had color values greater than the permissible limit of 15 TCU. However, odor and pH in most of the water samples were within the permissible limits set by WHO for human consumption. Spatial distribution of these parameters is shown in Fig. 3(a-d).

### 3.2 Turbidity

The groundwater quality analysis revealed that the turbidity in the groundwater of the study area ranged from 0.5-34.1 NTU with a mean value of 5.4 NTU while its permissible limit for drinking water is 5 NTU [30]. The suspended particles in water strengthen the connection of overwhelming metals and other dangerous minerals and pesticides, making the water cloudy and opaque, thus create human health issues [29]. The spatial distribution of turbidity in the study area is shown in Fig. 4. The Fig. 4 shows that areas near to Gharo town have some turbidity might be due to use of poor quality strainer filter material.

<table><caption>TABLE 1. WATER QUALITY PARAMETERS AND METHODS ADOPTED FOR ANALYSIS</caption><thead><tr><td>Parameters</td><td>Test method</td></tr></thead><tbody><tr><td>Colour (TCU*)</td><td>Sensory Test</td></tr><tr><td>Odour</td><td>Sensory Test</td></tr><tr><td>Taste (bitter, salty, sour and sweet)</td><td>Sensory Test</td></tr><tr><td>Turbidity (NTU*)</td><td>Turbidity Meter, Lamotte, Model 2008, USA</td></tr><tr><td>Calcium (mg/l)</td><td>3500-Ca-D, Standard method (1992)</td></tr><tr><td>Chlorides (mg/l)</td><td>Titration (Silver Nitrate), Standard Method (1992)</td></tr><tr><td>Hardness (mg/l)</td><td>EDTA Titration, Standard Method (1992)</td></tr><tr><td>Magnesium (mg/l)</td><td>2340-C, Standard Method (1992)</td></tr><tr><td>pH at 25°C</td><td>pH Meter, Hanna Instrument, Model 8519, Italy</td></tr><tr><td>TDS (mg/l)</td><td>TDS meter</td></tr><tr><td>Arsenic (mg/l)</td><td>Merck Test Kit (0-0.5 mg/L) 1.17927.0001</td></tr><tr><td colspan="2">*TCU = True Colour Units, NTU = Nephelometric Turbidity Unit (s)</td></tr></tbody></table>
## 3.3 Electrical Conductivity

EC is the most significant parameter used as the primary index to decide the suitability of water for drinking as well as for irrigation purpose [40-41]. For drinking purpose, its permissible limit is 0.7 dS/m [30]. For the study area, EC values ranged from 0.5-26.1 dS/m with an average value of 2.4 dS/m. The higher values of the EC along coastal belt might be due to the entry of highly saline water from the Arabian Sea into aquifers of the study area. Similar results were reported by Husain et. al. [27] while conducting a study in the Indus deltaic plain. Higher concentration of the conductivity increases the destructive nature of the water [29]. Fig. 5 demonstrates the spatial distribution of EC in groundwater of the Thatta district which shows the higher electrical conductivity of groundwater in almost all places of the study area.

<figure><img src="image_4.png" /><figcaption>FIG. 4. SPATIAL TURBIDITY DISTRIBUTION IN THE STUDY AREA</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>FIG. 3. SPATIAL DISTRIBUTION OF TASTE (a), pH (b), COLOR (c), AND ODOR (d) IN THE GROUNDWATER OF THE STUDY AREA</figcaption></figure>
## 3.4 Calcium

The calcium is one of the fundamental parameters available in different types of rocks. Its maximum permissible limit in water for drinking purpose is 75 mg/l [30]. In the study area, the concentration of calcium ranged from 34-883 mg/l with an average value of 163 mg/l. The spatial distribution of calcium concentration in the groundwater of the study area is shown in Fig. 6. The spatial distribution indicated that calcium concentration was very high in the study area, which may be due to seawater intrusion in coastal aquifers of the study area.

## 3.5 Magnesium

Magnesium is another fundamental parameter available in different types of rocks. Its maximum permissible limit in water for drinking purpose is 50 mg/l [30]. However, in the study area, its concentration ranged from 24-156 mg/l with an average value of 56 mg/l. The spatial distribution of magnesium in the groundwater of the study area is shown in Fig. 7. The spatial distribution shows that there

<figure><img src="image_6.png" /><figcaption>FIG. 5. SPATIAL DISTRIBUTION OF EC IN THE GROUNDWATER OF THE THATTA DISTRICT</figcaption></figure>

was a high concentration of magnesium in many places of the study area which may be due to the geological formation of aquifers.

<figure><img src="image_7.png" /><figcaption>FIG. 6. SPATIAL DISTRIBUTION OF CALCIUM IN THE STUDY AREA</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>FIG. 7. SPATIAL DISTRIBUTION OF MAGNESIUM IN THE STUDY AREA</figcaption></figure>
## 3.6 Total Hardness

Hardness is an important parameter of water for its use in a domestic sector [2]. The calcium and magnesium are key parameters for total hardness. In the case of hard water, the excess use of soap is needed to achieve cleaning. Hardness affects the toxicity of many substances in the water [27]. As per WHO standards, the most desirable limit of total hardness for drinking purpose is 100 mg/l and the maximum acceptable limit is 500 mg/l [1]. According to Freeze and Cherry [42], the most desirable limit of TH for drinking water is 80-100 mg/l. In the study area, the total hardness values ranged from 57-883 mg/l with a mean value of 216 mg/l. In this case, just 11 samples out of 100 exceeded the maximum allowable limit of 500 mg/l. But according to Sawyer and McCarty [43], groundwater exceeding the cutoff limit of 300 mg/l is considered very hard. Such classification based on TH is given in Table 2.

The Table 2 shows that most the groundwater samples of the district fall in a hard water category. Around 60 samples out of 100 were considered as hard and need treatment before use for drinking purpose. The spatial distribution of TH in the groundwater of the study area is shown in Fig. 8. The spatial distribution shows that there was a high concentration of hardness especially in those places of the study area which are very close to the Arabian Sea.

## 3.7 Chloride

For potable water, maximum allowable limit of chloride concentration is 250 mg/l. In the present study,

groundwater samples were contaminated by chloride concentration from 372-6275 mg/l with a mean value of 1505 mg/l. All the groundwater samples had chloride concentration beyond the allowable limit of 250 mg/l. Chloride concentration in rainwater is usually under 10 mg/l, however, it might be high in coastal areas and in desert tracts [44]. The presence of chloride concentration beyond allowable limits in drinking water has a potential health impact, causes stomach discomfort, nose/eye irritation, and increases corrosive nature of water [29]. Fig. 9 describes the spatial variation of chloride concentration in the groundwater samples of the study area. Spatial distribution map shows that the chloride concentration in almost all places of the study area was

<figure><img src="image_9.png" /><figcaption>FIG. 8. SPATIAL DISTRIBUTION OF TOTAL HARDNESS IN THE STUDY AREA</figcaption></figure>

<table><caption>TABLE 2. GROUNDWATER CLASSIFICATION BASED ON CONCENTRATION OF TOTAL HARDNESS</caption><thead><tr><td>Total Hardness (mg/l)</td><td>Classification</td><td>No. of Samples</td><td>Samples (%)</td></tr></thead><tbody><tr><td>0-75</td><td>Soft</td><td>03</td><td>03</td></tr><tr><td>75-150</td><td>Moderately hard</td><td>26</td><td>26</td></tr><tr><td>150-300</td><td>Hard</td><td>60</td><td>60</td></tr><tr><td>&gt;300</td><td>Very hard</td><td>11</td><td>11</td></tr></tbody></table>
beyond the allowable limits. The presence of higher
concentration of chlorides in the groundwater samples
of the study area can be used as an indication of seawater
intrusion in the district [45].

3.8 Total Dissolved Solids

The concentration of TDS in water is a general sign used
to decide the suitability of water for drinking as well as
irrigation purpose. The maximum permissible limit of TDS
in water for drinking purpose as per WHO standards is
500 mg/l. For the present study, only 15% of groundwater
samples had TDS concentration within the allowable limit
of 500 mg/l and the rest (85%) had very high concentration
of TDS ranged up to 16704 mg/l with a mean value of 1517
mg/l. The highest value of TDS (16704 mg/l) was observed
in the union council of Keti Bandar. The presence of a
very high concentration of TDS indicates excessive entry
of ionic matter and salts into the aquifers of the district. A
few processes may be responsible for increased
percentages of dissolved minerals in groundwater
including seawater intrusion [45]. The higher

<figure><img src="image_10.png" /><figcaption>FIG. 9. SPATIAL DISTRIBUTION OF CHLORIDE IN THE STUDY AREA</figcaption></figure>

concentration of TDS causes undesirable taste,
gastrointestinal irritation, corrosion or incrustation [27].
The spatial distribution of dissolved solids in the
groundwater of district Thattais shown in Fig. 10. Spatial
distribution map shows the highest values of TDS in many
places of the study area which are probably close to the
Arabian Sea.

3.9 Arsenic

Analysis of groundwater samples revealed that about 20% of groundwater samples were contaminated with arsenic ranged up to 150 ppb, whereas according to WHO [30], its maximum acceptable limit for drinking water is 5-10 ppb. The presence of arsenic concentration in groundwater in some areas of the district reflects an alarming situation for the people of the area who use toxic groundwater. The alarming results of arsenic concentration in groundwater indicated a nonlinear trend but its concentration varied considerably from location to location. The presence of arsenic contamination beyond permissible limit causes cancer, liver,

<figure><img src="image_11.png" /><figcaption>FIG. 10. SPATIAL DISTRIBUTION OF DISSOLVED SOLIDS IN THE STUDY AREA</figcaption></figure>
cardiovascular, neuropathies and ocular diseases [46]. One of the possible sources of arsenic pollution of groundwater might be due to the topographical arrangement of sub-strata of the area which contains adequate amounts of the arsenic component. Areas having aquifers with arsenic enriched geological formation might have groundwater contaminated with arsenic. Fig. 11 demonstrates the spatial variation of arsenic in the groundwater of the study area. The spatial distribution shows that in some union councils such as Buhara, Gaarho, Sukhpur, Mahar, Kotri Allah Rakhio Shah, Karampur, Ghulamullah, Chhatochand, Uddasi, Mirpur Sakro, etc. of the district, the arsenic concentration was beyond the permissible limits set by WHO [30].

## 3.10 Overall Groundwater Quality with Respect to WHO's Permissible Limits

Overall summary of groundwater analysis with different water quality parameters lying beyond WHO's permissible limits is given in Table 3.

Spatial correlation between various groundwater quality parameters was tried to develop but in almost all the cases a non-significant trend was observed. However, there was a strong relation between Calcium and TH with a coefficient of determination of R² = 0.96 regression with regression Equation(1) as shown in Fig. 12.

$$TH = 58.574 + 0.9748 \times Ca \quad (1)$$

<figure><img src="image_12.png" /><figcaption>FIG. 11. SPATIAL ARSENIC DISTRIBUTION IN THE STUDY AREA</figcaption></figure>

<table><caption>TABLE 3. GROUNDWATER SAMPLES WITH VARIOUS WATER QUALITY PARAMETERS BEYOND WHO'S PERMISSIBLE LIMITS IN DISTRICT THATTA</caption><thead><tr><td>Parameter</td><td>Permissible Limit</td><td>Total No. Of Samples</td><td>No. of Samples Beyond Permissible Limit</td></tr></thead><tbody><tr><td>Taste (Bitter, Salty, Sour and Sweet)</td><td>Unobjectionable</td><td>100</td><td>55</td></tr><tr><td>Color</td><td>15 TCU</td><td>100</td><td>16</td></tr><tr><td>Odor</td><td>Odourless</td><td>100</td><td>11</td></tr><tr><td>Electric Conductivity</td><td>0.7 dS/m</td><td>100</td><td>88</td></tr><tr><td>pH at 250C</td><td>6.5-8.5</td><td>100</td><td>09</td></tr><tr><td>Total Dissolved Solids</td><td>500 (mg/l)</td><td>100</td><td>85</td></tr><tr><td>Chloride</td><td>250 (mg/l)</td><td>100</td><td>100</td></tr><tr><td>Calcium</td><td>75 (mg/l)</td><td>100</td><td>85</td></tr><tr><td>Magnesium</td><td>50 (mg/l)</td><td>100</td><td>52</td></tr><tr><td>Total Hardness</td><td>500 (mg/l)</td><td>100</td><td>11</td></tr><tr><td>Turbidity</td><td>5 NTU</td><td>100</td><td>30</td></tr><tr><td>Arsenic</td><td>10 (ppb)</td><td>100</td><td>20</td></tr></tbody></table>
<figure><img src="image_13.png" /><figcaption>FIG. 12. CORRELATION BETWEEN CALCIUM AND TOTAL HARDNESS</figcaption></figure>

4. CONCLUSIONS

The groundwater quality analysis of Thatta district indicated that 55% of the groundwater samples had bitter and salty taste, while 16% water samples had color values greater than the permissible limit of 15 TCU. Similarly, 85% of the total samples had TDS beyond permissible limit of 500 mg/l, while 30% samples had turbidity values beyond permissible limit of 5 NTU. However, all the groundwater samples had chloride concentration beyond the WHO's permissible limit. The calcium concentration was also more than the permissible limit of 75 mg/l in 85% samples, while 52% samples showed higher values of magnesium. Based on total hardness, only 03 samples were considered as soft, 26 moderately hard, 60 hard and 11 very hard. However, odor and pH in most of the groundwater samples were within unobjectionable limits for human consumption. Analysis for arsenic revealed that 20% of groundwater samples had a concentration higher than the safe limit of 10 ppb, which is an alarming situation for the people of the district who use such toxic water for drinking purpose.

GIS maps of groundwater quality for various
physicochemical parameters also indicated that in most
of the areas of the district, especially coastal areas, the

groundwater was not satisfying the water quality
standards set by WHO, hence not suitable for drinking
purpose. Proper treatment before use for drinking purpose
is recommended.

ACKNOWLEDGEMENT

The US-Pakistan Center for Advanced Studies in Water,
Mehran University of Engineering & Technology,
Jamshoro, Pakistan, is gratefully acknowledged for
funding the project "Climate Change: Assessing impact
of seawater intrusion on Soil, Water and Environment in
Indus Delta using GIS and Remote Sensing tools" under
the Applied Policy Research Grants.

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