Evaluation of the Impact of Water Management Technologies on Water Savings in the Lower Chenab Canal Command Area, Indus River Basin

: Traditional irrigation practices, low crop productivity, unlevelled ﬁelds, water losses taking place during conveyance and application phases, as well as low irrigation efﬁciencies are the main problems of the common farmers in Pakistan. These problems are more noticeable in the command area of Lower Chenab Canal (LCC), which is the main portion of the Indus Basin Project in Pakistan. To overcome these problems, different water management technologies such as precision land levelling (PLL), bed planting, drip irrigation systems, and watercourse improvement were introduced to farmers to increase water savings and crop yields in the area of ﬁve distributaries—Khurrianwala, Shahkot, Mungi, Khikhi, Killianwala and Dijkot—during the cropping seasons of 2008 to 2015. The use of drip irrigation resulted in savings of water and fertilizer and increased the crop yields by 30–40%. Three watercourses, one on each site of 1200 m in length, were lined, which resulted in improved conveyance efﬁciency of 15–20%. If wheat, rice and cotton in the command area of LCC are sown on precisely levelled ﬁelds and on beds, then about 2768.1 million m 3 and 3699.3 million m 3 of irrigation water can be saved. These results show the potential of water-efﬁcient technologies for saving water as well as increasing crop yields.


Introduction
Pakistan is one of the most water-stressed nations, with a per capita water availability of less than 1000 m 3 . The current proportion of agriculture towards the GDP of the country is 21%. Irrigated agriculture in the Indus Basin is the major user of water in Pakistan. About 80% of the cultivated area of Pakistan is under irrigation and about 90% of all food is produced from this area [1]. The population growth rate is very high, particularly in developing countries like Pakistan, which has placed the water supply under stress. The food requirements of this ever-increasing population demands higher food production, which will be possible through water-efficient technologies as water is the basic ingredient cotton seed under different irrigation methods showed that drip irrigation has significantly increased the yield of seed cotton over furrow irrigation. Initial investment for drip irrigation system is high but at the same time this system saves water and fertilizer and minimum labor and no investment is involved in land levelling [32]. According to [33], evaporation and percolation of irrigation water is reduced while crop development is improved by using drip irrigation system in which water is frequently applied to an area near the roots of plants. As compared to bed-furrow and sprinkler irrigation, water use efficiency and crop production is improved with drip irrigation system [34][35][36][37]. According to [38][39][40], use of drip irrigation system with mulching in recent years has resulted in better application of irrigation water along with fertilizers and pesticides.
To overcome the issues and problems of water insufficiency in the farmer field, the Government of Punjab through its Irrigation and Power Department, executed a mega project to improve the irrigation infrastructure and to introduce institutional reforms in irrigation and drainage subsectors in the Lower Chenab Canal (LCC) area of the Indus Basin. Along with these off-farm measures, it was also decided to incorporate an on-farm research and development component to effectively address the challenges being confronted regarding water management at farm level to achieve the potential crop yields on sustainable basis. The on-farm research and development project was executed on six distributaries (Khurrianwala, Shahkot, Dijkot, Killianwala, Mungi, and Khikhi) in the command area of LCC to introduce the water management techniques to local farmers.
The main thrust of the project was to address the issues of water management at the on-farm level by introducing water management technologies such as precision land levelling, bed planting, watercourse improvement and high efficiency irrigation system.
The objective of this study was to investigate the impact of these technologies on water savings and crop yields in the study area and to estimate the water savings in the whole command area of Lower Chenab Canal (LCC) using remote sensing (RS) and geographic information system (GIS).

Study Area
The current study was carried out in the command area of the Lower Chenab Canal (LCC), which is located in Rachna Doab, an area between two rivers-the Ravi and Chenab Rivers-which are tributaries of the Indus River. Rachna Doab lies in the heart of Indus Basin in Pakistan. It constitutes the single largest irrigation system in Punjab, Pakistan, with a gross command area of about 1.5 million hectares and culturable command area of 1.24 million hectares. It is one of the oldest and most developed cultivated areas in Punjab, Pakistan. The climate of the area has large seasonal variations in temperature and rainfall. The summer season is hot and lengthy, which starts in April and ends in September, with an average temperature of 35 • C, ranging from 21 • C to 49 • C. The winter season is short (December to February) and temperature varying from 5 • C to 27 • C with average temperature of 16 • C and sometimes minimum temperature falls below 0 • C during nights. The average annual rainfall in this area is around 500 mm with about 75% of annual rainfall during the monsoon season, which spans from June to September. The main crops in the area are rice, wheat, cotton, maize, sugarcane, vegetables, and fodder which are grown in two growing seasons i.e., Rabi (winter) and Kharif (summer).
The Lower Chenab Canal takes its water from River Chenab at the Khanki Head works. The main branches of LCC are the Upper Gugera (UG) Branch, the Lower Gugera (LG) Branch, the Burala Branch, the Rakh Branch, and the Jhang Branch. The project was implemented on six distributaries of Lower Chenab Canal (Figure 1) from 2008-2015. The whole area of the project was suffering from severe shortage of irrigation water supplies with marginal to low quality groundwater before start of the project.
The main thrust of the project was to introduce the following water-efficient techniques to local farmers so that more crop yield per drop of water can be achieved.

Precision Land Levelling (PLL)
Precision land levelling is levelling the field within certain degree of desired slope using a laser-guided beam throughout the field. It reduces evaporation and percolation losses from the field by enabling faster irrigation times and eliminating depressions and pounding of water in depressions. PLL helps to save costly farm inputs such as water and fertilizers, improve crop stand and increase crop yield as much as 15 percent. PLL has huge scope in Pakistan as most of the farmer's field area is still irrigated by surface irrigation methods like flood irrigation, basin irrigation, border irrigation, and furrow irrigation. Application efficiency of these irrigation methods is between 30-50%. PLL is essential for these irrigation methods to escalate their application efficiency to 60-80% along with increase in crop yield.
Precision land levelling was one of the main water conservation technology and activities of the on-farm research & development component project. PLL was performed free of cost at the farmer's field according to their land holdings. In the distributaries selected under the project, PLL was done on 2631 hectares. Water savings and increase in crop yield from field area under PLL were calculated by comparison against the field area without PLL. In every village, some fields were intentionally left where no PLL was done. During each irrigation, the irrigation time was noted and flumes were used to measure the volume of water applied to fields with and without PLL. Water saving was calculated from the total volume of irrigation water applied to fields with and without PLL. Crop yields were estimated by taking crop samples before harvesting from an area of 1 m 2 from both the fields i.e., with and without PLL.

Bed Planting (BP)
Bed planting is another water saving technique, which is very beneficial on precisely levelled fields. Under the project, bed planting was demonstrated at various farmers' fields, which were brought under precision land levelling. Before start of the project, the farmers of the area were not aware of the benefits of the bed planting. All efforts were made by project team to convince the

Precision Land Levelling (PLL)
Precision land levelling is levelling the field within certain degree of desired slope using a laser-guided beam throughout the field. It reduces evaporation and percolation losses from the field by enabling faster irrigation times and eliminating depressions and pounding of water in depressions. PLL helps to save costly farm inputs such as water and fertilizers, improve crop stand and increase crop yield as much as 15 percent. PLL has huge scope in Pakistan as most of the farmer's field area is still irrigated by surface irrigation methods like flood irrigation, basin irrigation, border irrigation, and furrow irrigation. Application efficiency of these irrigation methods is between 30-50%. PLL is essential for these irrigation methods to escalate their application efficiency to 60-80% along with increase in crop yield.
Precision land levelling was one of the main water conservation technology and activities of the on-farm research & development component project. PLL was performed free of cost at the farmer's field according to their land holdings. In the distributaries selected under the project, PLL was done on 2631 hectares. Water savings and increase in crop yield from field area under PLL were calculated by comparison against the field area without PLL. In every village, some fields were intentionally left where no PLL was done. During each irrigation, the irrigation time was noted and flumes were used to measure the volume of water applied to fields with and without PLL. Water saving was calculated from the total volume of irrigation water applied to fields with and without PLL. Crop yields were estimated by taking crop samples before harvesting from an area of 1 m 2 from both the fields i.e., with and without PLL.

Bed Planting (BP)
Bed planting is another water saving technique, which is very beneficial on precisely levelled fields. Under the project, bed planting was demonstrated at various farmers' fields, which were brought under precision land levelling. Before start of the project, the farmers of the area were not aware of the benefits of the bed planting. All efforts were made by project team to convince the farmers and to introduce bed planting using bed-planting machine. The bed-planting machine prepares two beds and three furrows in one pass that plants four rows for wheat or two rows for cotton and maize on each bed. The bed width is 90 cm whereas the furrow is 30 cm wide and 25.4 cm deep. There is 50% savings of irrigation water and 25% increase in crop productivity under bed planting. All fields under PLL were brought under bed planting. Water savings and increase in crop yield under bed planting were calculated by comparison against conventional planting. In each village, some fields were intentionally left without bed planting and the crop was sown using conventional methods to compare with the crop under bed planting. The geometry of bed planting for different crops is shown in Figure 2a prepares two beds and three furrows in one pass that plants four rows for wheat or two rows for cotton and maize on each bed. The bed width is 90 cm whereas the furrow is 30 cm wide and 25.4 cm deep. There is 50% savings of irrigation water and 25% increase in crop productivity under bed planting. All fields under PLL were brought under bed planting. Water savings and increase in crop yield under bed planting were calculated by comparison against conventional planting. In each village, some fields were intentionally left without bed planting and the crop was sown using conventional methods to compare with the crop under bed planting. The geometry of bed planting for different crops is shown in Figure 2a

Watercourse Improvement
In Pakistan, conveyance efficiency of the tertiary level of the irrigation system, which is watercourse, is very low and a large amount of water is lost in watercourses during its route up to the farmer's field. Watercourse lining and earthen improvements ensure about 30-45% of irrigation water savings. The total length of 4496 m were lined on six watercourses, one on each selected distributary under the project.

Drip Irrigation System
Drip irrigation provides frequent and slow application of water to the soils through mechanical devices called emitters located at selected points along the water delivery lines i.e., lateral. In drip irrigation, the driving force of water movement is provided by an external energy source. The water is delivered through a closed-pipe system. This differs from surface irrigation technologies (flood, border, furrow and basin irrigation) in which the driving force of water flow is gravity, and the delivery and application structures (canals, ditches, furrows, small ponds and basins) are open to the

Watercourse Improvement
In Pakistan, conveyance efficiency of the tertiary level of the irrigation system, which is watercourse, is very low and a large amount of water is lost in watercourses during its route up to the farmer's field. Watercourse lining and earthen improvements ensure about 30-45% of irrigation water savings. The total length of 4496 m were lined on six watercourses, one on each selected distributary under the project.

Drip Irrigation System
Drip irrigation provides frequent and slow application of water to the soils through mechanical devices called emitters located at selected points along the water delivery lines i.e., lateral. In drip irrigation, the driving force of water movement is provided by an external energy source. The water is delivered through a closed-pipe system. This differs from surface irrigation technologies (flood, border, furrow and basin irrigation) in which the driving force of water flow is gravity, and the delivery and application structures (canals, ditches, furrows, small ponds and basins) are open to the atmosphere. The emitters in the drip irrigation system moistens the adjacent surface area. The percentage of the wetted surface area and soil volume depends on soil properties, initial moisture level of the soil, the applied water volume, and emitter flow rate. The drip irrigation system was one of the major activities of the project, which was installed at the project distributaries (5 acres at each distributary). Due to high initial cost of the drip irrigation system, only one drip irrigation system for row crops at each distributary of project was installed for research purposes and for demonstration to local farmers.

Crop Classification in LCC Command Area
Spatial information on different crops grown in the command area of LCC was collected from the MODIS satellite at a resolution of 250 m. Satellite images (MODIS MOD13Q1) of the LCC command area were obtained during Rabi (2007Rabi ( & 2016 and Kharif (2007Kharif ( & 2016 i.e., before and after the study period (Table 1). During Rabi and Kharif seasons in 2007 and 2016, extensive field visits were conducted in the villages under study to get the information about the crops grown. The coordinates recorded with GPS device in the fields in different villages of the study area were used to develop signature files of different crops grown in the study area. The satellite images obtained before and after the study period for Rabi and Kharif seasons were classified by using the developed signatures files of different crops of the study area. Image classification was carried out by supervised classification using maximum likelihood classifier in ERDAS 2014 and image processing software (ArcGIS) was used to estimate the area under different crops in LCC command.

Land Cover/Land Use Change
The current study was conducted on six distributaries of branches of Lower Chenab Canal (LCC). After the introduction of water-efficient technologies such as precision land levelling, bed planting and drip irrigation system in the villages under study, of six distributaries of LCC, the cultivation of wheat, cotton and vegetables have increased in the whole command of LCC (Figures 5 and 6).

Precision Land Levelling (PLL)
Precision land levelling was done on an area of 2631 hectares at six distributaries selected under the project. Water savings and increase in crop yields for different crops i.e., wheat, cotton and rice from area under precision land levelling (PLL) were calculated by comparison against the area

Precision Land Levelling (PLL)
Precision land levelling was done on an area of 2631 hectares at six distributaries selected under the project. Water savings and increase in crop yields for different crops i.e., wheat, cotton and rice from area under precision land levelling (PLL) were calculated by comparison against the area

Precision Land Levelling (PLL)
Precision land levelling was done on an area of 2631 hectares at six distributaries selected under the project. Water savings and increase in crop yields for different crops i.e., wheat, cotton and rice from area under precision land levelling (PLL) were calculated by comparison against the area without precision land levelling. Wheat was grown at all distributaries whereas cotton was grown at Mungi, Killianwala and Khikhi distributaries. Rice was grown on only Khurrianwala and Shahkot distributaries. Comparison of yield for wheat, cotton and rice under PLL and without PLL is shown in Figure 7, whereas average water saving from precision land levelling of wheat, cotton and rice is given in Tables 2-4 Figure 7, whereas average water saving from precision land levelling of wheat, cotton and rice is given in Tables 2-4 respectively. So, the total water savings from precision land levelling from villages under study was 4.3 million m 3 . If all the crops in the command area of LCC will be sown on laser-levelled fields, then a huge amount of irrigation water (about 2768.1 million m 3 ) can be saved including 1384.7 million m 3 from rice, 699.2 million m 3 from wheat and 684.2 million m 3 from cotton. Rice was mainly cultivated at the Upper Gugera and Rakh branches and cotton was mainly cultivated at the Lower Gugera and Burala branches while wheat was evenly cultivated at all five branches of the LCC. The detail is shown in Figure 8 for wheat, cotton and rice.  So, the total water savings from precision land levelling from villages under study was 4.3 million m 3 . If all the crops in the command area of LCC will be sown on laser-levelled fields, then a huge amount of irrigation water (about 2768.1 million m 3 ) can be saved including 1384.7 million m 3 from rice, 699.2 million m 3 from wheat and 684.2 million m 3 from cotton. Rice was mainly cultivated at the Upper Gugera and Rakh branches and cotton was mainly cultivated at the Lower Gugera and Burala branches while wheat was evenly cultivated at all five branches of the LCC. The detail is shown in Figure 8 for wheat, cotton and rice.

Bed Planting
Bed planting is a proven technology for water saving. Water can be saved efficiently from bed planted fields only if area is properly levelled. All fields under PLL were brought under bed planting. Increase in crop yields and water savings for wheat, cotton and rice under bed planting at the distributaries of the project was calculated by comparison against the conventional planting. The yield has been increased from 8% to 16.6%, 8.6% to 14.5% and 25.1% to 28.1% for wheat, cotton, and rice respectively. Yield comparison of wheat, cotton and rice at the project distributaries under bed planting and conventional planting is shown in Figure 9, whereas average water savings from bed planted field of wheat, cotton and rice is given in Tables 5-7 respectively. Total water savings from bed planting of wheat, cotton and rice at villages of study under project was 7.8 million m 3 . If wheat, cotton and rice in the whole command area of LCC will be sown on beds, then about 3699.3 million m 3 of irrigation water can be saved including 1431.7 million m 3 from wheat-planted fields, 1339.2 million m 3 from rice planted fields and 928.4 million m 3 from cotton planted fields ( Figure 10).

Bed Planting
Bed planting is a proven technology for water saving. Water can be saved efficiently from bed planted fields only if area is properly levelled. All fields under PLL were brought under bed planting. Increase in crop yields and water savings for wheat, cotton and rice under bed planting at the distributaries of the project was calculated by comparison against the conventional planting. The yield has been increased from 8% to 16.6%, 8.6% to 14.5% and 25.1% to 28.1% for wheat, cotton, and rice respectively. Yield comparison of wheat, cotton and rice at the project distributaries under bed planting and conventional planting is shown in Figure 9, whereas average water savings from bed planted field of wheat, cotton and rice is given in Tables 5-7 respectively. Total water savings from bed planting of wheat, cotton and rice at villages of study under project was 7.8 million m 3 . If wheat, cotton and rice in the whole command area of LCC will be sown on beds, then about 3699.3 million m 3 of irrigation water can be saved including 1431.7 million m 3 from wheat-planted fields, 1339.2 million m 3 from rice planted fields and 928.4 million m 3 from cotton planted fields ( Figure 10).

Watercourse Improvement
Watercourse lining and earthen improvements ensure about 30-45% water savings. Before lining, conveyance efficiency and losses of selected watercourse at each distributary were determined by measuring discharge at different point using a cutthroat flume. The conveyance efficiency and losses of selected watercourses is given in the Table 8. After the lining, the convey efficiency improved to more than 95% and conveyance losses reduced to minimum.

Drip Irrigation System
Drip irrigation is a much-needed technology for the near future, keeping in view the existing water shortage scenario under increasing cropping intensity and area of agriculture of the country. Drip irrigation model farms on five acres, one on each selected distributary of the project, were established and different crops were grown at these farms for dissemination purpose. The data regarding water savings and increase in crop yields from these drip irrigation systems showed that there was savings of not only water (60-80%) but also fertilizer, and a 30-40% increase in crop yield. The drip irrigation systems at Khurrianwala, Killianwala and Mungi distributaries were installed for row crop i.e., maize. Comparison of water savings and increase in crop yield for drip irrigation and bed planting during different years is shown in Table 9. The drip irrigation systems at Shahkot, Dijkot and Khikhi distributaries were installed for fruit crop i.e., Citrus. These drip systems were installed during the last year of project that's why yield comparison at these sites could not be possible.

Discussion
Water scarcity is a consistent problem in the country, especially in the irrigated areas of the Lower Chenab Canal (LCC). According to [41], there is an intense scarcity of irrigation water in the command area of the LCC, which is threatening irrigated agriculture. The main cause of this problem is the mismanagement of available resources of irrigation water. This key crisis is the reason that government is focusing on management of irrigation water at farm level through different water-efficient technologies. Under the on-farm research and development project, water-efficient techniques such as precision land levelling, bed planting, and drip irrigation systems were introduced to farmers of six distributaries in the command area of the LCC.
LU/LC of different crops on the branches of the LCC has changed a lot after the promotion of water-efficient technologies. The cultivation of wheat, cotton and vegetables increased a lot especially because of promotion of precision land levelling and bed planting and drip irrigation (Tables 10 and 11). According to [42], the acreage under wheat and sugarcane during the Rabi season 2007-2008 was 497,214 hectares and 126,883 hectares, respectively, which was almost the same as reported in Table 8 for wheat and sugarcane. The acreage reported in Table 9 for rice, cotton, and sugarcane is in accordance with the area reported by [42] for rice, cotton and sugarcane during the Kharif season 2007 i.e., Rice cultivated area was 252,756 hectares, cotton cultivated area was 76,740 hectares and the sugarcane cultivated area was 198,419 hectares.
Precision land levelling has resulted in 22% savings of irrigation water along with 10% higher production in the rice-wheat system [8]. Precision land levelling not only curtailed the cost of operation but also helped in uniform crop stand through better application of fertilizer. The farmers of the villages under study have now become aware of the advantages of precision land levelling. They are now levelling their lands every year for irrigation water savings and better crop production. If all the crops in the command area of LCC will be sown on laser-levelled fields then about 2768 million m 3 of irrigation water can be saved and used to irrigate more area.
Bed planting is another proven technology for savings of irrigation water. Bed planting is useful only on precisely levelled fields. During this study, higher water and fertilizer use efficiency was achieved in bed-planted fields. Bed planting has resulted in 30-50% savings of irrigation water and 20-25% increase in crop yield. According to [20], furrow irrigation under raised bed technology saved more than 30% of irrigation water against traditional flood irrigation. Bed planting is a new technology for the farmers of the command area of LCC. The need is to focus on this technology and 3699 million m 3 of irrigation water can be saved by sowing crops on beds in the command area of LCC. The drip irrigation system is the most efficient water-saving technology that used irrigation water, fertilizers and other nutrients the most efficiently for better crop production. The most efficient water saving technology (drip irrigation) helped small farmers of the study area to improve their livings by using agricultural inputs (water and fertilizers) more efficiently. Drip irrigation also helped the farmers to improve the quality and yield of crops especially vegetables. During the last 30-40 years, numerous efforts were made to introduce drip irrigation system in Pakistan, but no remarkable attainment were observed [43,44]. The high initial cost of drip irrigation systems impeded the adoption of it on a large scale in Baluchistan [45]. During the last few years, the government of Punjab, through its Agricultural Department, has started a project wherein drip irrigation systems are being installed on 48,562 hectares of land on a cost-sharing basis [46]. To lower the burden of the high initial cost of drip irrigation systems on farmers and to promote the adaptation of drip irrigation systems in the whole country, such projects needs to be started whereby drip irrigation systems should be installed on a cost-sharing basis.

Conclusions
This study was conducted in the villages where the project was successfully implemented from October 2008 to June 2015 in the command area of the Lower Chenab Canal, in the main part of Indus Basin, Pakistan.
From the findings of the seven-year study, it can be concluded that water-efficient techniques have a huge scope in the command area of the Lower Chenab Canal. The cultivated area of cotton, wheat, and other crops (vegetables and maize) is increased by about 200%, 37% and 19%, respectively, after the introduction of water-efficient irrigation techniques especially precision land levelling and bed planting. Besides the increase in crop yield, a huge amount of irrigation water (2768.1 million m 3 ) from precision land levelling and (3699.3 million m 3 ) from bed planting can be saved by adopting these water savings irrigation technologies in the whole command area of the Lower Chenab Canal.
On basis of the findings of this study, the water-efficient irrigation technologies-precision land levelling, bed planting, watercourse improvement, and drip irrigation-needs to be adopted for water savings and better crop yields in all of the irrigated districts in Punjab.
Author Contributions: All authors were involved in the intellectual part of this paper. X.L. and A.B. designed this research. M.R. conducted the research and wrote the manuscript. L.A. and S.H. helped in the data arrangement while K.J. helped in data analysis. X.L. helped revise the manuscript and also provided many suggestions. All the authors have read and approved the final manuscript. Acknowledgments: The authors thanks the R&D Component of On-Farm Water Management Project, WMRC, UAF for providing relevant data.

Conflicts of Interest:
The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.