ASSESSMENT OF SHALLOW GROUNDWATER QUALITY: CASE STUDY OF MONA SCARP

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1 ASSESSMENT OF SHALLOW GROUNDWATER QUALITY: CASE STUDY OF MONA SCARP Shahid Ahmad, M. Munir Ahmad, M. Yasin, Ghani Akbar and Zahid Khan Water Resources Research Institute, NARC, Park Road, Islamabad ABSTRACT A case study of Mona SCARP was conducted by adopting participatory interactive dialogue and diagnostic analysis approach. Evaluating farmer s perception and laboratory analysis in thirteen selected villages of the MONA SCARP area made the assessment for shallow groundwater quality. The average numbers of private tubewells were 83 per village and varied from 3 to 400. About 67% farms had access to conjunctive use of water, as water from both canal and tubewells was available. In addition, 10% farms have had access to tubewells water only. Therefore, 77% farms were using tubewell water. According to the farmer s perceptions, 100% villages have fresh groundwater to a depth ranging between 7.5 to 30 m. Furthermore, groundwater quality beyond 30m depth was brackish. This showed that the depth of skimming well would be even less than 30m to have uninterrupted supply of fresh groundwater and avoiding intrusion of saline water. The total dissolved solids (TDS) of 56 handpumps varied from 242 to 2349 ppm and ph varied from 7.1 to 7.8 in the selected villages. The probability analysis indicated that there was only 10% chance that TDS were higher than 1083ppm. Thus, at 90% probability the TDS was less than marginal quality. The depth of hand pumps in the area varied from 6.1 to 16.8 m. Moreover, water quality of 35 private tubewells as a function of depth was also assessed. The depth varied between 12.2 to 46 m showing the shallow depth of pumping of tubewell water, which is mainly due to high watertable and the availability of thin layer of the fresh groundwater. The shallow depth of private tubewells was a good indication of the thin layer of fresh groundwater. The TDS of these tubewells varied from 155 to 3040 ppm in the selected villages. There was 80% probability that the TDS were less than 905 ppm. Thus, there was hardly 20% chance of having marginal to brackish quality groundwater. In addition, there was 90% probability that ph was less than 7.5. PRA study revealed that groundwater is a function of depth and farmers are well aware of this fact. Thus, a team of experts, having experience in participatory interactive dialogues can use PRA approach coupled with properly designed checklist. Furthermore, the diagnostic analysis (with chemical analysis of the groundwater samples) confirmed the results of the PRA study that quality of groundwater up to a depth of 30 m was fresh to useable. Thus quality of groundwater is a function of depth in the Study Area as the correlation was reasonably strong. 1. INTRODUCTION Shortage of canal water is one of the major limitations in the Indus Basin Irrigation System (IBIS) for increasing agricultural productivity on sustained basis. The earthen canal system and inefficient conveyance resulted in waterlogging and salinity. The area affected by waterlogging and salinity was around 42% of the IBIS by the end of 1979 (WAPDA 1979). The Salinity Control and Reclamation Projects were initiated during 60s and until mid 90s around 38 projects were completed. These projects were very successful in the freshwater zone, but in the brackish zone, the use of poor quality water resulted into secondary salinization and sodification of soils (WCD 2000). At present there are over 500,000 tubewells in the country. The ground water use had reached a maximum level of 61 billion 1

2 m 3 during and then started decreasing. In billion m 3 water was pumped annually (GOP 1998). Increasing use of groundwater has changed the irrigation environment. The advantages are evident for the farmer, as groundwater allow irrigation at times and with amounts as desired by the farmer. Especially in areas with insufficient canal water, use of groundwater seems profitable. A side effect of the extraction of the groundwater by tubewells is a decrease of groundwater levels, which is positive in areas where fields are waterlogged or salinized due to capillary rise from shallow groundwater (IWASRI, 1991). Farmers participation has been emphasized to improve performance of irrigation and drainage systems in various parts of the world (FAO 1980). There were many reasons for transferring responsibility and authority of irrigation management to end-users, but the key factor had been the need to reduce public spending in irrigation development and maintenance and to enable re-allocation of funds to other more pressing uses (FAO 1993). Furthermore, the theoretical and empirical research studies conducted in the past recommended active involvement of farmers in the day-to-day management of irrigation systems. Participation in management of irrigation systems is not enough, in addition to management farmers have an important role to play in decision making related to quality and quantity of groundwater (Turral 1995). In, Pakistan, responsibility of groundwater development and management has been shifted gradually from public to private sector. Groundwater development and management is presently being carried out by farmers through private (individual) and community (Farmers Organisations) tubewells. Groundwater quality depends on the climatic parameters, nature of the surface flow, topography, extent of seepage and irrigation with amendment practices. The groundwater in the Indus basin contributes around 35% to the total water available for agriculture and water quality of the 60 percent area is marginal to brackish (World Bank 1997). The native groundwater that existed in the pre-irrigation period (early 19 th century) was salty because of the underlying geologic formation being of marine origin. Now, this native salty groundwater is overlain by fresh groundwater due to seepage from rivers and canals of the IBIS. Thus, shallow fresh groundwater zone occurs between the native pre-irrigation and the present day water tables (WAPDA 1988). In the Indus basin, near the rivers and canals, the fresh surface water seepage has improved the quality of the native groundwater to 120 to 150 m depths. However, in some areas, the thickness of the shallow groundwater zone ranges from less than 60 m along the margins of Doabs (area enclosed between two rivers) to 30 m or less in the lower or central parts of Doabs. Recently, it has been estimated that nearly 2000 billion m 3 of fresh groundwater (mostly in the form of a thin layer) is lying on salty groundwater. The concern on quality of these waters is becoming increasingly important in the faces of ever-growing population, accelerated agricultural activity and expanding industry. For successful crop production on sustainable basis without deteriotating soil health, the quality of groundwater is the main concern. Therefore, this study was conducted in the Mona SCARP area. 1.1 Selection of Locations Historical data were used to conduct a spatial and temporal analysis for groundwater quality of SCARP tubewells in the Mona Unit to identify potential locations using GIS (WRRI 2000). The criteria for selection of sites was based on the following elements: 2

3 Deep groundwater quality beyond 30 m depth should be saline, saline-sodic or sodic. This was verified by the quality of SCARP tubewells for which sufficient data were available. Location is part of the Mona Unit and part of the cluster but meeting the above mentioned quality considerations. Proximity to the Mona Field Office and accessibility especially during the rainy season to avoid problems associated with waterlogging. Based to the GIS study, thirteen villages were selected which represent freshwater, marginally saline, marginally saline-sodic and hazardous quality of deep groundwater (Table 1). Table 1. Classification of SCARP Tubewells in selected villages based on spatial analysis of deep groundwater in the Mona SCARP, Bhalwal, Sargodha, Pakistan. Number Name of Village Number of SCARP Classification of Tubewells Based on Deep Tubewells Installed Groundwater Quality 1 Head Faqerian 26, 28, 29 Marginally sodic 2 Jalar Waraichan 30, 31, 32 Marginally saline-sodic 3 Ratho Kala 33,34, 37 Marginally saline-sodic Hazardous saline marginally sodic 4 Chak #1 69 Freshwater (Very Good) 5 Thathi Noor 39, 40, 41, 44 Marginally saline hazardous sodic 6 Chak #6 ML 45 Marginally saline hazardous sodic 7 Moza Dohri 27, 68 Freshwater (Very Good) 8 Nabi Shah Bala 39, 94 Marginally saline-sodic 9 Dhera Ranjha 80 Marginally sodic 10 Chak #15 NB 81, 82 Marginally sodic 11 Chak #17 NB 84 Marginally sodic 12 Bonnga Minhas 8 Saline Zone 13 Sakacar (Jurra) Saline Zone 2. MATERIALS AND METHODS An explicitly participatory methodology for the target group appraisal and analysis was adapted for this study. This involved field visits each to the thirteen selected villages, as well as dialogues with the farming community groups in these villages. The participatory and diagnostic approach was designed to increase understanding of relationships, processes and impacts in the area. In each village, the team held dialogues and conducted field visits with a range of local groups and structured interviews of selected farmers and sampling of groundwater for quality analysis. A wide range of participatory methods was used including seasonal analysis, scorings, structured interviews and sampling. The team on every afternoon arranged discussions to establish trustworthiness of the findings. Six essential elements of the Participatory and Diagnostic Approach methodology used in the Study Area are: a) a defined methodology and systemic learning process; b) multiple perspective; c) group learning process; d) context specific; e) structured interviewing and sampling; f) facilitating experts and stakeholders; and g) leading to sustained action. The participatory methods used in these systems of learning and action can be structured into three classes: a) methods for group and team dynamics; b) methods for sampling; and c) methods for structured interviewing and participatory dialogues. It is the collection of these methods into unique approaches, or assemblages of methods, that constitute different systems of learning and action. The techniques used under each method are presented in Table 2. 3

4 Participatory Rural Appraisal (PRA) was conducted in thirteen villages (Figure 1) to validate the GIS based spatial analysis but it was not possible to document the farm level conditions and to evaluate the quality of shallow groundwater by collecting samples from private hand pumps and tubewells. This was possible only through structured interviews of selected farmers and survey to collect samples of shallow groundwater for quality analysis. Thus diagnostic analysis was conducted in seven villages. In these seven villages around 58 farmers were interviewed and groundwater samples of hand pumps were collected. In addition to this, 35 farmers were interviewed and groundwater samples of their private tubewells were collected for quality analysis. Seven villages namely Head Faqerian, Jalar Waraichan, Ratho Kala, Chak #1, Thathi Noor, Chak #6 ML and Moza Dohri were selected for diagnostic analysis to assess the groundwater quality. Table 2. Participatory appraisal and diagnostic methods for alternative systems of learning and action. Group and Team Dynamics Methods Sampling Methods Interviewing and Dialogues Team contact Transect walk Semi-structured and Team reviews and Random selection of farms structured interviewing discussions Collection of water samples of Direct group dialogues Interview guides and all the hand pumps and wells Checklists Rapid report writing Work sharing Process notes Team involved in study was composed of seven members. Four members were located full time in the Study Area. The team leader and one of the members have already experience of the methodology. Therefore, after developing the checklist and structured questionnaire, these were used in the field for pre-test. Participatory and diagnostic questionnaire and checklist were prepared to focus methods of group and team dynamics and structured interviewing. The questionnaire and Checklist include all elements relevant to land use system and ground water quality in the selected villages. 3. RESULTS AND DISCUSSION 3.1. Participatory Rural Appraisal Water Availability from Different Sources Results of the Participatory Rural Appraisal (PRA) indicated that six out of thirteen villages were having 100% farms commanded by both canal and tubewells. Only one village was exclusively commanded by tubewells. Therefore, twelve out of thirteen villages had access to canal water. In the thirteen selected villages 23% farms were exclusively commanded by canal water only, thus these farms did not have access to groundwater and did not have flexibility in availability and use of water. However, these are potential farms for installation of tubewells in the future (Table 3). About 67% farms had access to conjunctive use of water, as water from both canal and tubewells was available. In addition, 10% farms were having access to tubewell water only. Therefore, 77% farms were using tubewell water (Table 3). These farms might require some sort of support for the use of skimming wells technology, because these villages have varying degree of groundwater salinity. Furthermore, wide variability in number of private 4

5 tubewells was observed at the village level, and it varied from as low as 3 to as high as 400 with an average of 83 per village. Depth of private tubewells in the selected villages varied from 15 to 40 m with an overall average of 30 m for the study area. Table 3. Water availability from different sources in selected villages at the Mona SCARP, Bhalwal. Village Water Availability from Different Sources (% Farms) Canal Canal + Tubewell Tubewell Ratho Kala Thathi Noor Jalar Waraichan Head Faqerian Chak No. 6ML Nabi Shah Bala Dhera Ranjha Chak No. 15NB Chak No. 17NB Bonnga Minhas Sakacar (Jurra ) Moza Dohri Chak No Average The wide variability in number of private tubewells in the selected villages was due to the following reasons: variability in quality of groundwater and depth of thin layer of freshwater; size of landholdings; cropping pattern and cropping intensity; farmers' investment capacity level; tenancy rules; and location of the farm in relation to the recharge source (canal, Mogha, watercourse) Water-table Depth and Groundwater Quality There was only one village where water-table depth was more than 3 m. Thus according to WAPDA's criteria, only one village was not waterlogged. Rest 12 villages were having some degree of waterlogging. Three villages were under severe waterlogging as water was on the surface during the monsoon season. The rise in water table was mainly due to poor performance of the SCARP tubewells. High water table in the study area demands installation of skimming wells (shallow tubewells or dugwells) to have direct impact on lowering of water table. Groundwater quality in the selected villages was a function of depth. In all the thirteen villages, groundwater to a depth of 7.5 m was of fresh quality. About 62% villages had freshwater to a depth of 15 m. About 46% villages had fresh groundwater in the depth ranging from 15 to 30 m. Furthermore, in all the thirteen villages groundwater quality beyond 30 m depth was brackish (Table 4). The conclusion of the PRA study was that groundwater is a function of depth and farmers are well aware of this fact. Thus, a team of experts, having experience in PRAs and participatory interactive dialogues can use PRA approach coupled with properly designed checklist. 5

6 Table 4. Groundwater quality as a function of depth in selected villages at the Mona SCARP, Bhalwal. Village Groundwater Depth (m) < > 30 Ratho Kala Fresh Fresh Fresh Salty Thathi Noor Fresh Salty Salty Salty Jalar Waraichan Fresh Salty Salty Salty Head Faqerian Fresh Fresh Fresh Salty Chak No. 6ML Fresh Salty Salty Salty Nabi Shah Bala Fresh Fresh Fresh Salty Dhera Ranjha Fresh Fresh Fresh Salty Chak No. 15NB Fresh Fresh Salty Salty Chak No. 17NB Fresh Fresh Salty Salty Bonnga Minhas Fresh Salty Salty Salty Sakacar (Jurra ) Fresh Salty Salty Salty Moza Dohri Fresh Fresh Fresh Salty Chak No. 1 Fresh Fresh Fresh Salty Fresh Water Percentage Diagnostic Analysis Study Water Table Depth and Groundwater Quality of Hand Pumps About 56 hand pumps were selected in the Study Area to evaluate depth of private hand pumps installed by the farmers for domestic water use. The depth of hand pumps in selected seven villages varied between 6.1 to 16.8 m. The shallow depth of pumping was mainly due to high water table and the availability of thin layer of fresh groundwater. The average depth of hand pumps in the Study Area was around 8 m and it is a good indication of the thin layer of fresh groundwater. The total dissolved solids of 56 hand pumps varied between 242 to 2349 ppm with an average of 778. The ph of shallow groundwater varied between 7.1 to 7.8 with an average of 7.3. Therefore, the shallow groundwater in the Study Area was normally non-sodic, whereas salinity varied considerably in the Study Area. Average total dissolved solids of shallow groundwater in five selected villages (Head Faqerian, Jal Waraichan, Ratho Kala, Chak #1 and Thathi Noor) varied between 415 to 773 ppm. The ph of these hand pumps varied between 7.1 to 7.5. Thus the shallow groundwater of hand pumps in these villages was of fresh quality (non-saline and non-sodic). Average total dissolved solids of shallow groundwater in the Chak #6 ML and Moza Dohri varied between 917 to 1387 ppm. The ph of these hand pumps varied between 7.2 to 7.3 (Table 5). Thus the quality of shallow groundwater of hand pumps varied from fresh to brackish quality. Table 5. Average water table, hand pump depths, and shallow groundwater quality in selected villages at the Mona SCARP, Bhalwal. Village Water Table Depth Depth of Hand Pump Water Quality (m) (m) TDS (ppm) ph Head Faqerian Jalar Waraichan Ratho Kala Chak #1 (Phularwan) Thathi Noor Chak #6ML Moza Dohri

7 Variability of Shallow Groundwater Quality of Hand Pumps Total dissolved solids of shallow groundwater from 56 private hand pumps were used to have correlation as a function of water table depth or hand pump depth. The correlation of the quality of shallow groundwater to water table depth or hand pump depth was reasonably strong in most of the villages (Table 6). However, in some of the villages, the quality of groundwater varied even within same level of depth. Table 6. Correlation of total dissolved solids with water table and depth of hand pumps and private tubewells in selected villages at Mona SCARP, Bhalwal, Pakistan. Correlation for Hand Pump Correlation for Private Tubewells Villages PrivateTubewell Water Table Depth Hand Pump Depth Water Table Depth Depth Ratho Kala Thathi Noor Jalar Waraichan Head Faqerian Chak No. 6ML Chak No Moza Dohri Probability analysis of total dissolved solids and ph was conducted for selected 56 hand pumps in the Study Area. Probability analysis indicated that there was only 10% chance that total dissolved solids were higher than 1083 ppm. Thus at 90% probability the total dissolved solids were less than marginal quality. There was 25% probability that the total dissolved solids were less than 435 ppm. Therefore, the probability was very high for having good quality of shallow thin layer of groundwater. The probability analysis of ph indicated that there was hardly 10% chance of having ph of more than 7.5. Thus, there was hardly any chance of having sodic water in the shallow depths (Table 7). Table 7. Variability of shallow groundwater quality of hand pumps in selected villages at Mona SCARP, Bhalwal, Sargodha, Pakistan. Probability TDS PH (%) (ppm) Minimum Maximum Shallow Groundwater Quality of Private Tubewells About 35 private tubewells were selected in the Study Area to evaluate depth of private tubewells installed by the farmers for irrigation purpose. The depth of private tubewells in the selected five villages varied between 12.2 to 46 m. This showed that depth of private tubewells varied considerably in the selected villages. The shallow depth of pumping was mainly due to high water table and availability of thin layer of fresh groundwater. The 7

8 average depth of private tubewells in the Study Area was around 30 m. The shallow depth of private tubewells was a good indication of the thin layer of fresh groundwater. Average total dissolved solids of private tubewells in Head Faqerian, Ratho Kala, Chak #1 and Thathi Noor varied between 568 to 747 ppm. The ph of these tubewells varied between 7.3 to 7.4. Therefore, the quality of water was good for the tubewells selected in these villages. Total dissolved solids of private tubewells in Chak #6 ML and Moza Dohri varied between 683 to 2155 ppm. The average ph was around 7.4. Thus the quality of shallow groundwater was fresh to brackish (Table 8). Table 8. Water-table depth, private tubewells depth and shallow groundwater quality in selected villages at the Mona Unit, Bhalwal, Sargodha, Pakistan. Village Water-table Depth Depth of Tubewell Water Quality (m) (m) TDS (ppm) PH Head Faqerian Ratho Kala Chak #1 (Phularwan) Thathi Noor Chak #6ML Moza Dohri Variability of Shallow Groundwater Quality of Private Tubewells Total dissolved solids of shallow groundwater from 35 private tubewells were used to have correlation as a function of water table depth or tubewell depth. The correlation of quality of shallow groundwater with water table depth or tubewell depth was stronger than the hand pumps. This was mainly due to the reason that depth of private tubewells was more than the hand pumps. Total dissolved solids of private tubewells varied between 155 to 3040 ppm with an overall average of 862. Except one village (Chak #6 ML) the quality of private tubewells in terms of salinity was very good. The ph of these tubewells varied between 7.1 to 7.9 with overall average of 7.4 for the selected 35 tubewells. The probability analysis of total dissolved solids and ph was conducted for the 35 selected private tubewells. There was 80% probability that the total dissolved solids were less than 905 ppm. Thus there was hardly 20% chance of having marginal to brackish quality groundwater. In addition, there was 90% probability that ph was less than 7.5. This showed that there was 80% chance of having nonsaline and non-sodic water (Table 9). Table 9. Variability of shallow groundwater quality of private tubewells in selected villages at Mona Unit, Bhalwal, Pakistan. Probability TDS PH (%) (ppm) Minimum Maximum

9 The variability of total dissolved solids for hand pumps and private tubewells was compared to have assessment of very shallow and shallow depths of groundwater (Figure 2). There was only 10% probability of having marginal to brackish quality groundwater for the hand pumps, whereas this probability was increased to 20 % for the private tubewells. Figure Probability of shallow groundwater of handpumps and private tubewells in selected villages at Mona SCARP. Total Dissolved Solids (ppm) Handpumps Private Tubewells Probability The conclusion of the diagnostic analysis (with chemical analysis of the groundwater samples) confirmed the results of the PRA study that quality of groundwater upto a depth of 30 m was fresh to useable. Thus quality of groundwater is a function of depth in the Study Area as the correlation was reasonably strong. 4. CONCLUSIONS Based on this study the following conclusions and recommendations can be drawn: 1. The conclusion of the PRA study was that groundwater is a function of depth and farmers are well aware of this fact. Thus, a team of experts, having experience in PRAs and participatory interactive dialogues can use PRA approach coupled with properly designed checklist. 2. The analysis of farmer s perceptions for the thickness of fresh groundwater layer indicated that 100% villages in the area had a layer of fresh water ranging between 7.5 to 30 m with potential for installation of skimming dugwells or tubewells. Almost 100% villages had marginal to brackish quality groundwater beyond 30 m depth. 3. The conclusion of the diagnostic analysis (with chemical analysis of the groundwater samples) confirmed the results of the PRA study that quality of groundwater up to a depth of 30 m was fresh to useable. Thus quality of groundwater is a function of depth in the Study Area as the correlation was reasonably strong. 9

10 4. Relatively fresh quality groundwater is available at shallower depths in the areas having brackish groundwater at deeper depths that may be pumped for sustainable agriculture. 5. The variability of total dissolved solids for hand pumps and private tubewells was compared to have assessment of very shallow and shallow depths of groundwater. There was only 10% probability of having marginal to brackish quality groundwater for the hand pumps, whereas this probability was increased to 20 % for the private tubewells. 6. The depth of private tubewells varied from 12.2 to 46 m showing shallow depth of thin layer of the fresh groundwater, which is a good indication of thin layer of fresh groundwater. References 1. FAO FAO Turral GOP Agricultural Statistics of Pakistan. Ministry of Food, Agriculture and Livestock, Economic Wing, Islamabad. 5. IWASRI Control of waterlogging and salinity in Pakistan. A review of information and methods. Publication 21, IWASRI, Lahore. 6. WAPDA Review of Existing Research on Skimming Wells. IWASRI, Pub. No. 3, Lahore. 7. World Bank Staff Appraisal Report. Pakistan National Drainage Programme. Rural Development Sector Management Unit, South Asia Region. 8. WAPDA Soil Salinity and Waterlogged Soils. Atlas Master Planning and Review Division, WAPDA, Lahore. 9. WCD WCD Case Studies: Tarbela dam and related aspects of the Indus River Basin, Pakistan. Final Draft Report. World Commission on Dams and Asianics Agro- Dev. International (Pvt.) Ltd., Pakistan. 10. WRRI GIS Study of Root Zone Salinity. 10