Hydraulic and hydro-salinity behavior of skimming wells under different pumping regimes

Hydraulic and hydro-salinity behavior of skimmingwells under different pumping regimes

Muhammad Mazhar Saeeda,*, M. Ashrafb, M.N. Asgharc

aCentre of Excellence in Water Resources Engineering,

University of Engineering and Technology, Lahore 54890, PakistanbPakistan Council of Research in Water Resources, House no. 3, Street no. 17,

F-6/2, Islamabad, PakistancInternational Water Management Institute, Multan Road, Chowk Thokar Niaz Baig,

Lahore 53700, Pakistan

Accepted 16 December 2002

Abstract

Skimming wells are meant to extract top fresh water layer in the fresh-saline aquifer. Their

development in the Indus basin occurred through private sector in a technological vacuum. As a

result, these wells have some technical, environmental and social constraints, which hinder the

sustainability of these wells. As an initial step to improve the well technology, the hydraulic and

hydro-salinity responses of the fresh-saline aquifer under different pumping regimes need to be

monitored. The present paper reports the hydraulic and hydro-salinity behavior of the Indus basin

aquifer in Pakistan under field conditions at farmers’ wells. Two sites, having 6- and 16-strainer wells

were monitored during July 2000–December 2001. The 6-strainer well was operated for 4 h with

single-, 4- and 6-strainer arrangements and the spatial behaviors of specific drawdown were observed

under these arrangements. The 16-strainer well was monitored continuously for the above period. The

well discharge, pumped water quality and pumping duration was recorded of every pumping event

under farmer’s practice to extract groundwater. The rainfall and temporal water table fluctuation was

also recorded at this site. The impact of 24 years of well operation on groundwater quality was

observed by comparing the hydro-salinity profiles of 1974 and 1998 under 3-strainer well. The results

showed that the specific drawdown was higher for single-strainer and it decreased with the increase in

number of strainers in skimming wells and hence reduced the chances of saline-upconing. Each

strainer in multi-strainer well contributes equally in well discharge provided the horizontal distances

among the strainers are equal. The pumped water quality in fresh-saline aquifer was a very sensitive

function of fresh water recharge and pumping duration. It was observed that with the increase in daily

operation from 2 to 12 h per day, the pumped quality deteriorated three-folds and there was also 30%

reduction in well discharge due to high suction lift. It was observed that continuous operation of a

3-strainer well having discharge of 14 lps over the 24 years had raised the fresh-saline interface

Agricultural Water Management 61 (2003) 163–177

* Corresponding author. Tel.: þ92-42-6822024/6822558/6821100; fax: þ92-42-6822024.

E-mail address: [email protected] (M. Mazhar Saeed).

0378-3774/03/$ – see front matter # 2003 Elsevier Science B.V. All rights reserved.

doi:10.1016/S0378-3774(03)00026-X

(iso-concentration line of 1.5 dS/m) to 9 m. Keeping in review the observations, it is recommended

that the daily operation of 4–6 h keep the water quality within marginal limit (<1.5 dS/m) and the

pumping operation is also cost-effectivewithonly 15–20%reduction in well discharge for thestudy area.

# 2003 Elsevier Science B.V. All rights reserved.

Keywords: Skimming wells; Fresh-saline aquifer; Indus basin; Saline-upconing; Intermittent pumping; Hydro-

salinity

1. Introduction

Worldwide, excessive over-pumping is the most common cause of salt-water intrusion in

coastal and inland fresh-saline aquifers. In coastal aquifer, there is a direct contact between

inland fresh water and marine saline water at a sloping interface. In inland aquifer, the

fossil saline groundwater is overlain by fresh water accumulated as a result of recharge

from precipitation, irrigation systems and natural streams. Exploitation and mining of fresh

water resources in these aquifers take place regularly for irrigation purposes and to mitigate

droughts, especially in (semi) arid regions. Over-exploitation in these aquifers induces low

piezometric head resulting in upward movement of saline water, called saline-upconing

(Reilly and Goodman, 1987). Various skimming techniques are being used to extract salt-

free water and hence to avoid saline-upconing in these aquifers. These include conven-

tional shallow wells, multi-strainer (multi-point) wells, radial collector wells, scavenger

wells, dug wells and re-circulation wells (Sufi et al., 1998). These techniques are referred as

skimming wells. Skimming well is a general term used to represent a well in which the

depth of the well is defined by taking into consideration the thickness of the overlying fresh

water layer and with an intention to extract relatively fresh water without saline water

intrusion from fresh-saline aquifer (Saeed et al., 2002c).

Since 1960s, the groundwater development in the Indus basin of Pakistan has been

proceeded at an exponential rate. A large number of public sector groundwater develop-

ment programs set the trend of deep wells, but increasingly farmers have invested in

skimming wells from their own resources. Among various types of skimming wells,

conventional shallow wells and multi-strainer wells are the most popular among farming

community for irrigation purposes in the basin (Saeed et al., 2002b). This shift from deep to

shallow wells occurred gradually without proper design and operational codes. Although,

the investigations on the design and feasibility of multi-strainer wells started in early 1970s

and the researchers such as Kemper et al. (1976), Ahmed (1979), McWhorter (1980),

Chandio and Larock (1984), and Sufi et al. (1998) worked out the design for such wells.

These codes could not get popularity among the end-users, possibly due to lack of irrigation

extension services and the complex technicalities involved in these codes. As a result, the

local drillers and farmers evolved their own technology. In each area, a limited number of

drillers operate who are the sole service providers, accustom to a certain technology.

Among farmers, there is little awareness of well technology choice. In a recent survey, it is

observed that the farmers’ skimming wells have some technical, economical and environ-

mental constraints, which hinder the sustainability of these wells (Saeed et al., 2002a).

Presently, it seems that the groundwater development in the private sector is taking place in

164 M. Mazhar Saeed et al. / Agricultural Water Management 61 (2003) 163–177

a technological vacuum. Recently, Asghar et al. (2002) developed guidelines for design and

operation of shallow wells using the data from experimental study conducted by Kemper

et al. (1976). The findings may not be used as such as the hydro-chemical composition of

the area has changed over the years due to over-exploitation. The approach should be to

improve the existing farmers’ practices rather than introducing new ones. The starting point

of any such improvement in these wells is to look at the hydraulic and hydro-salinity

responses of the fresh-saline aquifers under skimming well operations. The present paper

reports the observations made regarding the hydraulic and hydro-salinity behavior of the

fresh-saline aquifer under the field pumping conditions in the Indus basin of Pakistan.

2. Study area

The aquifer under the Indus basin consists of a thick alluvial complex of Holocene and

late Pleistocene age deposited by the Indus River and its tributaries. Hydro-geologically,

the whole of the Indus alluvial complex can be treated as a huge, single unconfined aquifer,

with hydraulic conductivity in the range of 30–60 m per day and average storage

coefficient of 0.12. The aquifer is believed to extend 300 m in depth over most of the

area (Gazdar, 1987). The main sources of recharge to the aquifer are rain, rivers and

seepage from surface storage reservoirs, canals and watercourses. Groundwater quality in

the Indus basin varies in a rather complicated way, depending on the extent of the recharge.

The general pattern is that the groundwater quality deteriorates as one traverse the basin

from upstream to downstream towards the Arabian Sea. Water quality less than 1.5 dS/m is

found in the northeastern part of the basin where the rainfall is the highest while

this increases to 4.70 dS/m in the southern part of the basin. Fresh groundwater is also

found close to the riverbeds of the Indus and its tributaries, and poor quality groundwater

in the central parts of the inter-fluvial regions, called doab (means land between two

rivers). Locally, the spatial variability in the quality of pumped groundwater is greater

than this general picture would make one think. Even wells in close proximity are known

to yield different quality waters, partly depending on the depth from which they are

pumping.

The study area is located in the Chaj doab (the land between Chenab and Jehlum rivers)

and is part of Mona Unit of Salinity Control and Reclamation Project, SCARP-II (Fig. 1).

It covers about 70,000 ha spreading over 83 villages. The soil of the area ranges from

coarse to moderately fine, with the predominance of moderately coarse texture soil class.

The climate of the area is subtropical semi-arid to subtropical semi-humid with winter

temperature ranging from 3 to 23 8C, while in summer, the weather is extremely hot with

temperature ranges from 22 to above 42 8C. The mean annual rainfall is about 600 mm and

mean annual evapotranspiration is 1612 mm.

The area is being irrigated by northern branch of Lower Jehlum (perennial) and Shahpur

Branch canals (non-perennial). The canal water is usually less than farm irrigation water

demand. Public and private tubewells augment the canal water supplies in the entire area. A

number of 138 deep tubewell were installed having depth of 60–75 m under SCARP in

mid-60s. Most of these tubewells had to close at the request of farmers due to their poor

quality water. The farmers installed their own tubewells at shallow depth of 30–40 m.

M. Mazhar Saeed et al. / Agricultural Water Management 61 (2003) 163–177 165

Fig. 1. Location of study area in the Indus basin (above) and selected well sites in the study area (below).


As the quality of these wells depends upon the local recharge, the recent dry spell over the

past 3 years has also deteriorated the pumped water quality. Now the farmers are adopting

multi-strainer wells to further reduce the depth to 15–18 m. The water quality of these wells

still remains relatively saline compared to canal water (400–600 ppm).

3. Material and methods

Two well sites were monitored during the present study. At Tariq Farm, the farmer was

interested to install multi-strainer well. When one borehole of 7.5 cm in diameter and 18 m

deep was drilled (with 9 m screen and 9 m blind pipe), a 4-h pumping test was conducted

with this single-strainer well in October 2000. The drawdown was measured at 0.30, 2.55,

4.35, 5.98, 7.43 and 15.03 m from the pumping well (tw-2 in Fig. 2). The well discharge of

this single-strainer well was 4.5 lps. Farmer drilled three more boreholes (tw-1, tw-3, and

tw-4) of same specification to make this a 4-strainer skimming well. A 4-h pumping test

was conducted to see the response of the aquifer to this configuration. The well discharge

with this arrangement was 15 lps. The farmer was not very happy with the discharge he was

getting with this 4-strainer well. He decided to drill two more boreholes of same

specification in-between the existing ones (tw-5 and tw-6). Again a 4-h pumping test

was conducted with this 6-strainer well. The discharge of 6-strainer well was about 24 lps.

The observation wells had diameter of 2.5 cm, depth of 10 m and were screened at lower

2 m. Pumping tests data were used to evaluate the distribution of pumping stress in terms of

specific drawdown with different number of strainers.

At second well site (Akram Farm), a 16-strainer well was monitored continuously from

July 2000 to December 2001 to evaluate farmers’ practices to extract groundwater for

irrigation purposes. Each strainer was of 5 cm in diameter and 15 m deep (with 9 m screen

and 6 m blind pipe). The distance of strainers varies from 2.24 to 3.74 m from the tee-joint

(Fig. 3). The observation wells were installed close to each strainer to measure the

drawdown in each strainer in response to 4- and 6-h pumping tests. At this site, the pumping

Fig. 2. Arrangement of well points and observation wells at Tariq Farm (not to scale).


duration, well discharge and pumped water quality were monitored for each pumping event

under farmer’s practice to extract groundwater to supplement canal water. An observation

well was drilled away from the hydraulic influence of this and other neighboring wells to

monitor the temporal groundwater fluctuation at the farm. The precipitation data was also

monitored for each rainfall event at this farm.

The study area had been the site for preliminary experiments of multi-strainer skimming

wells since seventies. The very first multi-strainer well was installed at Phullarwan

Research Farm of Mona Reclamation Experimental Project (MREP) in 1974. This 3-

strainer well is still in operation with minor modifications in configuration and is used to

supplement the irrigation requirement of the farm. The strainers are of 15 cm in diameter,

20 m in depth and are at more than 7.0 m apart from each other. The record showed that the

well was operated for 3 h per day on the average and had never been operated more than 9 h

per day (Ashraf et al., 2001). The hydro-salinity status of the aquifer depth up to 40 m was

available for the year 1974 at this site (McWhorter, 1980), which showed that the fresh-

saline interface (iso-concentration line of 1.5 dS/m) was at a depth of 25 m from ground

surface. In 1998, we drilled an exploratory borehole at the same site and hydro-salinity was

measured along the aquifer depth. This site is used to evaluate the long-term impact of well

operation on the hydro-salinity behavior of the aquifer.

Fig. 3. Arrangement of well points at Akram Farm (not to scale).


4. Results and discussion

4.1. Hydraulic behavior

The idea of multi-strainer well is based on the concept that these wells have the

advantage to spatially distribute the pumping stress. It had field confirmation during the

present monitoring study. Fig. 4 shows the spatial distribution of pumping stress with

single-, 4- and 6-strainer wells at Tariq Farm. The well discharge was different for each

pumping test, so the drawdown was converted into specific drawdown (drawdown per unit

discharge) for comparison. It is evident from the figure that the specific drawdown is

more in case of single-strainer well and this decreases with the number of strainers. The

maximum specific drawdown is higher in single-strainer well. The saline water in fresh-

saline aquifers move upward to maintain the equilibrium disturbed by the drawdown

propagation around the well (Bear, 1979). The spatial distribution of drawdown helps to

minimize the chance of saline-upconing provided that the well is designed and operated

keeping in view the local hydro-geological environment.

On the other hand, there was an increase in hydro-salinity with the number of strainers,

contrary to the basic theme of multi-strainer well. The pumped water quality was 0.85 dS/m

for single-strainer, 2.41 dS/m for 4-strainer and 3.50 dS/m for 6-strainer well. These

observations may not be linked with the well configuration rather these could be in

response to local hydro-geological conditions of the aquifer. The low hydro-salinity level in

single-strainer well was due to fact that the fresh water layer was exploited first time at

this site and low discharge did not disturb thin fresh water layer. After the installation of

4-strainer well, and then 6-strainer well, these wells were operated continuously for

irrigation purposes and well discharge had also increased. This resulted in exploitation of

already accumulated fresh water and wells started to discharge underlying saline water.

The source of fresh water recharge in the area was north branch of Lower Jehlum canal,

which flows at a distance of 2.0 km from the test site. The canal remained close during the

time of pumping test with 4- and 6-strainers wells. After extracting already accumulated

fresh water layer, the well started discharging the deep saline water, and hence skimmed

water quality deteriorated with 4- and 6-strainer wells. This would not be the case if there

were proper recharge to the aquifer as the skimming well are meant to capture the fresh

water recharge.

Once establishing the fact that multi-strainer wells have advantage over the shallow

conventional wells, it is worth to see how these strainers behave in multi-strainer wells.

Theoretically, if the distance of each strainer from the tee-joint is same, each strainer will

contribute equally provided the medium is homogeneous and the same type and quality

material is used in each strainer. Any variation in well discharge contribution can be

attributed to variable frictional losses in strainers, and field heterogeneity. Fig. 5 represents

the drawdown in each strainer at Akram Farm with 16-strainer well during 4- and 6-h

pumping test. The specific drawdown varies slightly. The reason for this variation might be

the small differences in lengths (2.24–3.74 m) of joining pipes and also minor differences

in frictional head losses. This trend would have been clearer with the larger variation in

distances from the tee-joint but no such field situation was available to monitor. Practically,

if the strainers are at varying distances from tee-joint, the nearer strainer will contributes


Fig. 4. Comparison of specific drawdown in wells with different configurations.

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more to well discharge and hence will have more drawdown. This may expose the well

screen to air and hence suction break may occur at this strainer causing operational

problems in centrifugal pumping system.

4.2. Hydro-salinity behavior

The sustainability of fresh groundwater resources mainly depends upon the proper

skimming techniques. The objective of any skimming technique would be to extract fresh

water with minimal disturbance of underlying saline water. The pumped water quality in

skimming wells mainly depends upon the hydro-geological conditions of the aquifer,

design and operation of wells. Among the hydrological conditions, the thickness of fresh

water, source of fresh water recharge, hydraulic parameters of the aquifer, and existence of

natural barrier to prevent saline-upconing are important.

The quality of pumped groundwater is directly related to the amount of recharge

available from the deep percolation of conveyance and distribution system, as well as the

field irrigation losses and rainfall. Fig. 6 shows the depth of water table behavior,

distribution pattern and amount of rainfall, and change in pumped water quality at

16-strainers well. The impact of rainfall (fresh water recharge) on the water table and

pumped water quality is pronounced. The water table showed a declining trend during

relatively dry period (from October 2000–July 2001) and the quality of skimmed water

also deteriorate in this period. The water table and pumped water quality started

improving in response to fresh water recharge to the aquifer (after July 2001). Due to

Fig. 5. Contribution of individual strainer to well discharge in 16-strainer well.


Fig. 6. Depth to water table behavior, distribution and amount of rainfall, and changes in pumped water quality

from 16-strainer well.


shallow water table (maximum 4.0 m), the impact of recharge to both water level and

water quality of the aquifer is quick. Inter-well spacing also plays an important role in

groundwater quality. With the same amount of fresh water recharge, if the wells are

spaced closely, they will share the recharge and hence small amount of fresh water will be

available for each well.

The effect of daily operational hours on the quality of pumped water and well discharge

was monitored for 16-strainers well and is shown in Fig. 7. With the increase in daily

operation hours from 2 to 12 h per day, the quality of pumped water deteriorated three-folds

Fig. 7. Effect of daily operational hours on the pumped water quality and discharge.


and the well discharge decreased from 5 to 30%. In another observation at the same site,

Ashraf et al. (2001) monitored the well for 70 days during 1999. During this period, the

well was operated for 41 days with an average pumping time of 6 h per day. The quality of

the pumped water reduced from 1.2 to 0.90 dS/m at the end of the observation period.

Similarly, 3-strainer well at Phullarwan Farm was also monitored for 97 days during 1998–

1999, in which, the well was operated for 71 days with an average pumping time of 5 h per

day (Ashraf et al., 2001). The well discharge was about 17 lps. The pumped water quality

showed an improvement from 1.72 to 1.45 dS/m during the monitoring period. The

improvement in salinity level of the pumped water was most probably due to the pumping

of salts from the shallow aquifer layer and the replenishment of the groundwater from

seepage of irrigation water and rainfall that contributes to groundwater. A total of 130 mm

rainfall was recorded during the observational period.

Previously, Kemper et al. (1976) conducted field experiments with 3-strainers well at

Phullarwan Farm in which the well was operated continuously for 15 days at a rate of

14 lps. The hydro-salinity of the pumped water increased from 1.40 to 1.97 dS/m and this

had also moved the fresh-saline interface (iso-concentration line of 1.50 dS/m) from 25 to

16 m from the ground surface. After 164 days of recovery period, the saline interface could

recede only 3 m. Hafeez et al. (1986) also reported that in another experiment with the

same 3-strainer well at Phullarwan Farm, the hydro-salinity increased from 1.2 to 1.9 after

32 days of continuous operation. Under continuous pumping, when the water table

becomes steady state, a part of the pumped water comes from the underlying saline water

and a part from the recharge due to the hydraulic gradient. However, if the water is pumped

intermittently, the aquifer will be recharged only from the adjoining area due to the

Fig. 8. Temporal changes in hydro-salinity (dS/m) profile under 3-strainer skimming tubewell at Phullarwan

Farm.


hydraulic gradient that developed near the well and the chances of withdrawal from

underlying saline water is minimal. From Fig. 7, if the farmer operates his well for 4-6 h per

day, the pumped water quality will remain less than 1.5 dS/m with only 15–20% reduction

in discharge, making tubewell operation cost-effective and application of pumped water

will be less harmful to soil and crop.

The long-term operation of skimming well may pose salinity hazards even if the well is

properly design and operated. Fig. 8 shows the comparative overlay of the hydro-salinity in

1974 and 1998 under the 3-strainer skimming wells at Phullarwan Farm. The analysis

showed that the fresh-saline interface has moved up from 25 to 16 m, reducing the

thickness of available fresh water layer by 9 m. This change in hydro-salinity profile is

attributed to localized disturbance of equilibrium between fresh water and saline water in

the aquifer. Such changes at localized scale have a collective impact on the regional fresh

water resources. The regional changes in the distribution of various quality water in

response to SCARP tubewell operation has already been reported for the study area

(MREP, 1997). The findings revealed that the area with very fresh groundwater (<500 ppm)

has reduced about 23% during last 32 years (1965–1997), clearly indicating the reduced

availability of fresh water in the region (Fig. 9).

5. Summary and conclusions

Two pumping sites having 6- and 16-strainer skimming wells were monitored in the

Indus basin with an intention to evaluate the hydraulic and hydro-salinity behavior of

fresh-saline aquifer under different pumping regimes. Single-, 4- and 6-strainer wells

Fig. 9. Spatial distribution of groundwater quality in the study area (a) in 1965–1966 and (b) in 1997.


having diameter of 5 cm and depth of 18 m were operated and the spatial drawdown

behavior was observed under 4 h pumping operation. The results showed that the specific

drawdown is higher for single-strainer well and the effect of single-strainer is also more

pronounced near the well. The specific drawdown decreases with the number of strainers,

signifying the advantageous role of multi-strainer well in spatially distributing the pumping

stress. Moreover, the strainers contribute equally to the well discharge when they are placed

at equal distance from the tee-joint.

At the second site, a 16-strainer well was monitored from July 2000 to December 2001

continuously for every pumping event under farmer’s practices to extract groundwater for

irrigation purposes. The well discharge, pumped water quality and pumping duration were

recorded for pumping events. The temporal water table fluctuation and rainfall data was

also available at this site. The analysis of temporal water table fluctuation, rainfall and

pumped water quality suggested that the water quality is a sensitive function of rainfall

(or fresh water recharge). Daily operational hours affect the water quality and quantity

significantly. When the operational hours increased from 2 to 12 h per day, the pumped

water quality deteriorated three-folds and well discharge decreased from 5 to 30%. For

the study area and areas having identical agro-climatic and hydro-geologic conditions,

4–6 h daily operation would keep the water quality within marginal limit and well

discharge reduction will be 20%. With this operational strategy, the application of pumped

water would be less harmful to crops and soils and also the well operation would be

cost-effective.

The results of the comparative study at Phullarwan Farm revealed that the interface had

move up to 9 m above its initial position under 3-strainer well after 24 years of well

operation. At regional scale, there was 23% reduction in areas having very fresh water

(<500 ppm) in the MREP area after 32 years of SCARP tubewell operation. This shows that

while making decision regarding the design and operation of skimming wells, various

factors such as hydro-salinity in the aquifer, useable limit of pumped water quality, and

economics of the operation must be taken into account. Furthermore, the rate of recharge is

also important parameter that affects the operational strategies of these wells.

References

Ahmed, N., 1979. Groundwater Resources of Pakistan. Shahzad Nazir, Lahore, Pakistan, p. 810.

Asghar, M.N., Prathapar, S.A., Shafique, M.S., 2002. Extracting relatively-fresh groundwater from aquifers

underlain by salty groundwater. Agric. Water Manage. 52, 119–137.

Ashraf, A., Aslam, M., Saeed, M.M., Shafique, M.S., 2001. Effect of intermittent punping on the water quality of

multi-strainer skimming wells. In: Proceedings Second National Seminar on Drainage in Pakistan.

University of Agriculture, Faisalabad, Pakistan, 18–19 April, p. 200–211.

Bear, J., 1979. Hydraulics of Groundwater. McGraw-Hill, New York, p. 414.

Chandio, B.A., Larock, B.E., 1984. Three-dimensional model of skimming well. J. Irrigation Drain. Eng. ASCE

110 (3), 275–288.

Gazdar, M.N., 1987. Groundwater and environment: Pakistan scenario. In: Proceedings of the International

Conference on Groundwater and the Environment. University of Kebangsaan, Malaysia, H12–21.

Hafeez, A., Piracha, Z.A., Ahmed, N., 1986. Multi-strainer tubewells for skimming top layer of fresh water

underlain by saline aquifer. Publication no. 152, Mona Reclamation Experimental Project, WAPDA Colony,

Bhalwal, Pakistan, p. 50.


Kemper, W.D., Jahangir, M., McWhorter, D.B., 1976. Skimming well report: Field studies. Publication No. 67,

Mona Reclamation Experimental Project, WAPDA Colony, Bhalwal, Pakistan, p. 24.

McWhorter, D.B., 1980. Summary of skimming well investigations. Water Management Technical Report No.

63. Water Management Research Project, Engineering Research Center, Colorado State University, Fort

Collins, Colorado, USA, p. 77.

MREP, 1997. Project profile. Mona Reclamation Experimental Project, WAPDA Colony, Bhalwal, Pakistan,

p. 46.

Reilly, T.E., Goodman, A.S., 1987. Analysis of saltwater beneath a pumping well. J. Hydrol. 89, 169–204.

Saeed, M.M., Ashraf, M., Bruen, M., 2002a. Diagnostic analysis of farmers’ skimming well technologies in the

Indus Basin of Pakistan. Irrigation Drain. Sys. 16, 139–160.

Saeed, M.M., Ashraf, M., Asghar, M.N., Bruen, M., Shafique, M.S., 2002b. Farmers’ skimming well

technologies in the Indus basin: practices, problems, perceptions and prospects. Working Paper 40, Pakistan

Country Series No. 11, International Water Management Institute (IWMI), Lahore, Pakistan, p. 52.

Saeed, M.M., Bruen, M., Asghar, M.N., 2002c. A review of modeling approaches to simulate saline-upconing

under skimming wells. Nordic Hydrol. 33 (2/3), 165–188.

Sufi, A.B., Latif, M., Skogerboe, G.V., 1998. Simulating skinning well techniques for sustainable exploitation of

groundwater. Irrigation Drain. Sys. 12, 203–226.


Hydraulic and hydro-salinity behavior of skimming wells under different pumping regimes

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