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Irrigation Scheduling in Branch Canals and its Interconnection with Canals Performance, Water Saving,

and Farmers’ Practices

El-Gamal, T. T1 and Fawzy, G.2 Abstract

Irrigation scheduling has a serious effect on branch canals performance. It is obvious that the branch canal is not able to convey enough water to irrigate its entire cultivated lands at once and so scheduling the irrigations between sub-branches, Meskas or farmers is a crucial topic. The current study investigates the current situation of irrigation scheduling or irrigation distribution through the day. Most of the farmers tend to irrigate on forenoon hours while stopping the irrigation during night. Focusing the irrigation in a certain period of the day has its negative effect on tail farmers who might face a water shortage during these periods. On the other hand, ignoring the irrigation during night hours could increase escape flow. Irrigation Improvement Project (IIP) was conducted to improve the equity of water distribution and increase irrigation efficiency through branch canals in Egypt. Constructing single lifting points and downstream control gates in conjunction with the establishment of water users associations are the tools to achieve IIP targets. IIP should affect irrigation distribution and its side effect in different ways. Downstream control gates should stop escape flows from branch canals. Single lifting points with the rule of water users associations should affect spreading the irrigation schedule through the day. An evaluation program has begun few years ago by Water Management Research Institute to evaluate the impact of IIP on irrigation performance and farmers’ social status. Based on the outcome of this program, the current study aims to investigate irrigation distribution through the day in both improved and unimproved canals. Irrigation distribution in both systems and at different branch canals locations was described and compared. The effect of the irrigation scheduling on canal performance and on water saving was assessed. Different fields’ irrigation data and farmers’ questionnaires, which define the irrigation times and the percentage of night irrigation for some selected areas in both improved and unimproved canals, were used in the study. In addition, the study used different measurements on branch canals including water levels recording and flow calculations. The results showed that the irrigation is spread more during summer seasons and in improved canals. However, the difference in irrigation distribution is not statistically significant. The difference between irrigation scheduling at different locations in both improved and unimproved canals are not significant. Regarding canals performance, the availability of the water levels at tail regions has a rotational trend that is change over few days more than a quick change between day and night hours. Considering escape flow, improved canals did not stop it. However, it

1 Researcher, Water Management Research Institute, National Water Research Center, Delta

Barrage, Egypt P. C. 13621/5 Tel. (+202) 2189458 Fax. ((+202) 2189561; email: telgamel@yahoo.com

2 Associate Professor, Water Management Research Institute, National Water Research Center, Delta Barrage, Egypt P. C. 13621/5 Tel. (+202) 2189458 Fax. ((+202) 2189561; email: gmfawzy@hotmail.com

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seems that the magnitude of the escape flow is less than expected. On the other hand, escape flow ratios have the rotational trend over days more than a quick change between day and night hours. The reasons that bush the farmers to irrigate during night in improved canals are the implementation of the internal rotation “Motarefa”, the suitability of the weather and the existence of the rotational system at the end of branch canals

Keywords: Irrigation scheduling, night irrigation, water saving, irrigation practices

1. Introduction One of the significant irrigation phenomena is the tendency of the farmers to

irrigate during specific hours of the day while ignoring the irrigation during night hours. This tendency has its negative effect on the availability of water for tail farmers during day hours. On the other hand, ignoring the irrigating during night could increase escape flow losses. Improved canals were designed to use the night period, with its low consumption, to fill branch canals so that the canals could face high consumption during day hours. Downstream control gates should completely stop escape flow. Applying the continuous flow should insure the availability of the water through all parts of branch canals, which should increase the tendency of the irrigation during day hours in tail regions as in head regions. From the other side, having a big cultivated area served by the same lifting point with the implementation of an internal rotation between lifting points “Motarefa” might enforce farmers to irrigate during night especially during high consumption periods. Although many improved canals were handed over, none of the canals could be considered as a completely improved canal due to different implementation and operation obstacles. The continuous flow was not truly implemented at any improved canal. Most of downstream control gates are out of order. Re-modeling problems and the increase of rice ratio than the design quota are among the obstacles the face the improved canals. All of these obstacles limited the influence of IIP on irrigation distribution and so decrease the difference between irrigation distribution in improved and unimproved systems.

2. Methodology The current study investigates irrigation scheduling through the day or the

density of the irrigation during each hour of the day with the magnitude of night irrigation. The study aims to measure the tendency of the farmers to irrigate during specific hours of the day and the effect of this on different irrigation phenomena. Data was collected from three different sources. It was collected and was analyzed using two different ways. In the first collection and analyzing way, the irrigation scheduling was measured from irrigation time sheets by defining the percentage of the pumps working at specific hour to the summation of pumps working during the twenty-four hours. In this way, all hours where an irrigation incident is taken place are counted. For instance, if an irrigation incidence was taken place between 7:30 AM and 9:30 AM, the counter for hours 8, 9, and 10 increases by one. This is repeated for all irrigations in the studying areas. At the end, the counter for each hour through the twenty-four hours is recorded and the percentages between the number of each hour and the total summation of the twenty-four hours are calculated as the irrigation densities during different hours. Night irrigation ratios are the summation of irrigation ratios from 5:00 PM to 5:00

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AM during winter season. During summer season, night irrigation ratios are the summation of irrigation ratios from 7:00 PM to 5:00 AM. The other way is through questionnaires that investigate night irrigation among other parameters. In both ways, the data was collected from two improved and two unimproved canals. Regarding data sources, special experiments were performed in two improved canals. Two experiments were performed on each improved canal during the period from September 2006 to July 2007. Each experiment took from four to six days. During each experiment, pump operations were collected from all lifting points on the canal. In the second source, pumps operations data was also collected from two other unimproved canals during summer 2005 and winter 2005-06. The irrigation time data was collected from some selected farmers at different locations on the canal over the whole time of both seasons. The third source is the collected questionnaires. Questionnaires were collected from farmers in the aforementioned improved and unimproved canals during summer 2006 and winter 2006-07. In this study, forenoon time’s expression is used for the irrigation between 8:00 AM and 11:00 AM. Late hours’ expression is used for the period between 12:00 AM and 5:00 AM.

3. Studying areas Among the investigated canals in the monitoring and evaluation program that

was conducted by WMRI, four branch canals [Two improved canals and two unimproved canals] were chosen for the current study. Two other canals were mentioned in the study as well. Whole details about all investigated canals could be in [3] and [4]. In El-Behira governorate (figure 1), the investigated canals include Besentway canal (improved) and El-Saraniya canal (unimproved).

El-Mahmoudia IIP subproject

El-Mahmoudia canal

El-Herfa canal

El-Berka

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El-Mahmoudia canalMonitored canalsMonitored drainsOther branch canalsOther drains

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Figure 1: El-Mahmoudia subproject with the main monitored canals

Besentway canal (Km 13.32 on El-Mahmoudia canal) serves total area of 5339 feddan. The canal has eight sub-branches, which have a big ratio of the cultivated area of the canal and more than the half of lifting points. The canal is passing through two urban areas. The first one is located between Km 2.0 and Km 4.10. The bed level at this area is much higher than the design level. The same problem

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is existed in the most of sub-branches on the canal. The head regulator was free open for entire monitoring period and the canal was controlled through the distributor. The canal has two automatic gates but both of them were out of order during the most of the monitoring time.

El-Saraniya canal off-takes from El-Mahmoudia canal (Km 44.375). It is 7.10 Km long and it has an extension that is 8.67 Km long. It has three sub-branches. The total served area for El-Saraniya and its extension is 12306 feddan. The canal is operated using the rotational system but the head should be open continuously as it has an internal irrigation rotation.

In Kafr EL-Sheikh governorate, the investigated canals are in Meet Yazid canal (figure 2). The study contains on Dakalt canal (improved) and Mars El-Gamal canal (unimproved).

Meet Yazied canalMonitored canalsMonitored drainsOther branch canalsOther drains

El-Wasat IIP subproject

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Figure 2: El-Wasat subproject with the main monitored canals

Dakalt canal (Km 41.1 on Meet Yazied canal) is about 11.4 km long and serves about 5580 feddan. The canal has three automatic regulators and new concrete tail escape. All automatic gates were out of order during the entire monitoring time. The bed level in the canal and its sub-branches was within the design bed level. The canal is under the control of the head regulator (sluice gate) for the most of the time. The canal has many sub-branches, but the number of lifting points on most of these sub-branches are small (two ~ three). Most of the direct lifting points on the mainstream of the canal are at the end reach.

Mars El-Gamal (unimproved canal) off-takes from El-Zawia canal (Km 3.70). It is 11.50 Km long and it serves around 9400 feddan. It feeds two other sub-branches and it has an internal irrigation rotation as in El-Saraniya canal.

4. The typical relationship between water consumption and water supply in branch canals

Typical relationships between water consumption and water supply are presented in figure (3) based the experiments performed in Besentway and Dakalt canals during summer 2006 and winter 2006-07. Water consumptions were calculated from all pumps through the canals. Nominal pumps discharges were

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used with an average correction factor, which is the relation between total supply volume and total consumption volume all experiment days. In different experiments, the consumption is concentrated during few hours of the day while it decreases until stopping by the midnight. During the second experiment in Besentway canal (part B), water supply values were recorded using ultrasonic flow meter at the head of the canal. During this experiment, water consumption values fluctuated between 0.0 and 6.73 m3/sec. Zero values were found at the midnight and first hours of the day. Maximum consumption values were found between 8:00 and 9:00 AM. Water supply values were between 3.01 and 1.72 m3/sec. Maximum values were found at 11:00 AM and during the afternoon hours. Minimum values were found between 2:00 and 5:00 AM. The ratios between water consumption and water supply were between 0.0% and 315.0%.

Figure 3: Total consumption and water supply for Besentway and Dakalt canals

For other experiments, water supply was recorded by measuring the flow downstream the head twice a day. For the first experiment on Besentway canal (September 2006 – part A), the ratios between water consumption and water supply were between 0.0% and 329.0%. For Dakalt canal and during high consumption period (June 2007), the ratios were between 4.0% and 198.0%. During low consumption period (November 2006), the ratios were between 0.0% and 266%.

This has its affect while designing improved branch canals regarding two points. Branch canals should have enough capacity to face the high consumption during day hours until being filled again during night hours without adversely affecting tail-farmers. This was treated by enlarged the cross sections of the improved canals. On the other hand, having a low consumption during night hours

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could increase the escape flow. It was planned to treat this using the automatic control gates.

5. Irrigation scheduling 5.1 Irrigation scheduling in improved branch canals

Figure (4) presents average irrigation distribution in Dakalt during winter and summer seasons and the details about average irrigation distribution at different locations of the canal during both seasons. From the figure, the maximum irrigation density ratio during winter season was at 10:00 AM and it was 9.4%. During summer season, the maximum irrigation density ratio was 7.7% and it was at 8:00 AM. In general, irrigation is distributed more during summer season. Considering irrigation distribution at different locations of the canal during winter season, there is no clear difference between the values. During summer season, there is a difference between head and tail irrigation distribution during late hours where irrigation ratios at the head are close to zero while it is still have some considerable values at the tail. Irrigation ratios at the tail are lower than corresponding values at the head during afternoon hours.

Figure 4: Average irrigation distribution during winter and summer seasons and at different locations of Dakalt canal

Considering night irrigation ratios (figure 5) and based on collected questionnaires, about 5% of the irrigations were performed during night in winter season and about 20% of the irrigations were performed during night in summer season. The values at different locations are close to each other. Based on collected irrigation time, night irrigation ratios during winter season were between 14% and 17% and the values increase from the head to the tail. During summer season, the ratios are between 16% and 22%. The minimum value was at the middle and the maximum values were at the tail.

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Figure 5: Average night irrigation ratios in Dakalt canal during winter and summer seasons based on collected questionnaires and collected operation hours

Irrigation density curves for Besentway canal are presented in figure 6. One main characteristics of Besentway canal is the high length and bad condition of its branches. This makes the situations of some fields at head branches, which are considered at the head of the canal, worst than the situation of some fields at middle or tail branches. The maximum irrigation density ratio during winter season was 11.6% and it was at 8:00 AM. During summer season, the maximum ratio was 11.0% and it was at 9:00 AM. In both seasons, irrigation densities ratios decrease from 12:00 PM to 3:00 PM then they increase again.

Figure 6: Average irrigation scheduling during both winter and summer seasons and at different locations of Besentway canal

Considering irrigation distribution at different locations on the canal during winter season, tail-farmers focus more on irrigating during forenoon hours (max irrigation ratio is 14.7% at 8:00 AM) while stopping the irrigation completely during late hours. At the head, irrigation is distributed more. Maximum irrigation density ratio during day hours is less than the ratios at the middle and the tail. At afternoon hours where irrigation ratios decrease, the irrigation ratios at the head are higher than irrigation ratios at the middle and the tail. During summer season, maximum irrigation density ratio at the middle is higher than maximum irrigation density ratios at the head and the tail. During late hours, the irrigation stopped at the middle while there is still some irrigation at the head and the tail.

Considering night irrigation ratios (figure 7) and based on the collected questionnaires, there is no night irrigation during winter season. During summer season, night irrigation ratios are between 10% and 23%. The maximum is at the head and the minimum is at the middle. Based on collected irrigation time, the maximum night irrigation ratio is at the head (27%) and the minimum value is at

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the tail (21.7%). During summer season, the maximum irrigation ratio is at the tail (24.5%) and the minimum irrigation ratio is at the middle (9.6%).

Figure 7: Average night irrigation ratios in Besentway canal during winter and summer seasons based on collected questionnaires and collected operation hours

5.2 Irrigation scheduling in unimproved branch canals Besides the improved canals that were presented in the previous sub-section,

irrigation distribution was also measured at two unimproved canals during summer 2005 and winter 2005-06 [Mars El-Gamal in Kafr El-Sheikh and El-Saraniya in El-Behira]. Irrigation time data was collected from some selected farmers at head, middle and tail of the canals. The data was collected through the whole seasons. Figure (8) presents the data for Mars El-Gamal canal.

Figure 8: Average irrigation scheduling during both winter and summer season and at different locations of Mars El-Gamal canal

As in the improved canals, the highest irrigation ratio during winter season is higher than the highest irrigation ratio during summer season. The highest ratios were 16% and 13.8% during winter and summer seasons respectively. Considering irrigation density ratios at different locations of Mars El-Gamal canal during both seasons, there is no clear difference between the locations. During winter season, highest ratios at the middle and the tail are high than the highest ratio at the head. All highest ratios are between 9:00 and 10:00 AM. During late hours, values are close to zero. During summer season, highest irrigation ratios at the head and the tail are higher than the highest irrigation ratio at the middle. For all locations, irrigation ratios decrease between 2:00 and 3:00 PM then it increased again. During both seasons, the differences between locations are minors.

Considering night irrigation ratios in Mars El-Gamal canal (figure 9) and based on collected questionnaires, there is no night irrigation during summer

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season. During winter season, night irrigation ratios were between 1.7% at the middle and 5% at the head. Regarding collected irrigation time and during winter season, night irrigation ratios were between 3.3% at the middle and 6.7% at the head and the tail. During summer season, the ratios are between 14.4% at the middle and 15.9% at the tail.

Figure 9: Average night irrigation ratios in Mars El-Gamal canal during winter and summer seasons based on collected questionnaires and collected operation hours

Irrigation scheduling trend is the same for El-Saraniya canal but the ratios are in general lower than the corresponding values of Mars El-Gamal canal (figure 10). El-Saraniya has the same phenomenon of Besentway canal regarding the bad conditions of its extension and its branch (Sidi Gaze). The other phenomenon is the high dependence on drainage water especially at the tail. 68.5% of the irrigations at the tail during summer season were from the drain. The value decreased to 41% during winter season. Regarding irrigation distribution, maximum irrigation density ratio during winter season was 14% while it was 11% during summer season. Regarding different locations on the canal, there is no specific difference between irrigation ratios at these locations during winter season. During summer seasons, the highest ratios at the head and the tail are higher than the highest ratio at the middle. From afternoon to the end of the day, there is a considerable difference between the head and the tail. During these hours, the irrigation ratios at the head are lower than other locations until 3:00 PM then they begin to be higher than the irrigation ratios at the tail until the end of the day.

Figure 10: Average irrigation scheduling during both winter and summer seasons and at different locations of Saraniya canal

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Night irrigation in El-Saraniya canal (figure 11) based on collected questionnaires is found only at the tail (17.1%) during winter season. During summer season, night irrigation ratios are between 23.4% at the middle and 35.9% at the tail. Based on collected irrigation time, night irrigation ratios during winter season were between 5.6% at the middle and 7% at the head. During summer season, the ratios were between 6.3% at the tail and 16.1% at the middle.

Figure 11: Average night irrigation ratios in El-Saraniya canal during winter and summer seasons based on collected questionnaires and collected operation hours

5.3 Analyzing irrigation scheduling results The data was collected from different sources and using different ways.

Irrigation time sheets were collected for all pumps in Dakalt and Besentway experiments while they are collected for some selected farmers in Mars El-Gamal and El-Saraniya canals. On the other hand, Dakalt and Besentway experiments were performed for few days while data collection for Mars El-Gamal and El-Saraniya canals were collected for the entire seasons. Night irrigations defined from irrigation sheets were defined based on the irrigation ratios of different hours. It means that many irrigations could be counted partly in night irrigation ratios. For questionnaires, the farmers defined the number of the night irrigation and the number of total irrigations. Even this could lead to some difference between the results, but on the other hand, it will draw a general figure that is not restricted by the collection method. Considering the previous resources, it is clear than the irrigation is focused during forenoon hours. During late hours, the irrigation ratios are zero or very close to zero. This is true in improved and the unimproved canals and it is true during summer and winter seasons. Based on statistical analysis (comparing means using One-Way ANOVA and Duncan checks), there is no significant difference between average values for different canals during both seasons. In addition, there is no significant difference between different locations at different canals during both seasons. There is significant difference between night irrigation ratios at different locations based on collected questionnaires such as El-Saraniya canal during winter season. However, the result of the site is questionable.

Given that, there is statistical evidence about the differences between irrigation scheduling at different canals and locations, the general observation about the effect of time, season, status and location on the irrigation scheduling could be summarized as follows:

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Regarding the irrigation time, the irrigation is focused on forenoon. Irrigation densities ratios increase suddenly at the beginning of this period then they decrease suddenly at the end of these period. This is true in both improved and unimproved canals. In Besentway canals and during summer season of Mars El-Gamal and El-Saraniya canals, irrigation ratios return to the increase after a decrease in afternoon hours.

Regarding season, the irrigation is distributed more during summer seasons than during winter seasons. This is true in both improved and unimproved canals.

Regarding the status, the irrigation is distributed more in improved canal than in unimproved canals. Maximum values of average irrigation densities ratios in the improved canals are between 9.5% and 11.6% during winter season. During summer season, the ratios were between 7.7% and 11%. In unimproved canals, the ratios were between 11.0% and 13.8% in winter season and between 13.9% and 16.0% during summer season.

Regarding the location, there is no a considerable different between irrigation distribution at different locations (head, middle and tail) during winter season except in Besentway canal, where irrigation ratios at the head are lower than irrigation ratios at the middle and the tail. During summer season, there is a considerable difference in Besentway and EL-Saraniya canals. In Dakalt canal, irrigation distribution at the tail are different the irrigation distribution at the head and the middle at afternoon and evening hours.

6. The relationship between canals operation and irrigation scheduling

The expected relationship between irrigation distribution and water supply/water surface profile through the canal is as the following: concentrating the irrigation during day hours with the amount of water supply downstream the head affects the water surface at tail regions, which forces some tail-farmers to stop irrigating during these hours and irrigate during night. This is more expected during high consumption periods. However, the previous section showed that there is no significant difference between irrigation distribution at different locations of improved and unimproved canals. To investigate the relationship between irrigation scheduling and canals operations in more details, figure (12) presents different characteristics of the summer experiment on Dakalt canal.

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Figure 12: Ratio of pumps in work in Dakalt canals and water depths in Dakalt canal during summer experiment (June 2007)

The experiment was performed between 9 and 14 of June 2007, which is among the highest consumption period in Kafr El-Sheikh irrigation directorate. In part A and considering all head and tail pumps, more than 60% of head pumps are working together during morning hours. The ratio of working pumps began to decrease until being around 1 to 2% at late hours. Regarding tail pumps, the ratios of the pumps on work were between 20% and 50% during day hours. During late hours, the ratios were very low and sometimes reached zero. This means that part of tail pumps might be restricted from working. To investigate this and considering the first few pumps at the head last few pumps at the tail of the canal (Part B), the difference is more obvious. The last few pumps at the tail never worked during the first four days of the experiment. This is because of the low water depth at the tail region. Pumps began to work from the fifth day with the increase of the water supply, which leads to an increase of water levels at the tail region (Part C). During late hours after the fifth day, around 19% of the pumps were in work. By the end of the sixth day, the ratio of working pumps reached zero again. This could be concluded in two points; the high consumption at the head could affect the tail farmers, and the farmers tend to irrigate at the late hours in the critical conditions when the water were missed for few days. However and from part D, the change in the water level has a rotational trend where the water change in a cycle of few days instead of a quick change between day and night. This is happen although Dakalt canal is an improved canal. The head is open continuously but it is not free open. To check the difference between the available water during day and night hours, figure (13) presents water levels at the beginning of the tail regions of Dakalt and Besentway canals in summer and winter months. Water levels were recorded at 5:00 AM and 3:00 PM. These two hours represent the highest and lowest water levels. As expected, there is an

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increase in the water levels during night hours. The range of the increase in the water level, with some few exceptions, is in the range between 10 and 15 cm. However, the rotational trend over the days is more obvious than the difference day and night water levels. This could be realized in Dakalt canal during both seasons and in Besentway canal during summer season.

Figure 13: Water surface profiles through Dakalt during summer and winter seasons

Considering the typical relation between consumption and supply (section 4), and considering total storage volume during the period when supply is higher than consumption with the total surface area of the canal and its sub-branches, average increase in water depth was between 13 and 17 cm during November experiment. During June experiment, average increase was between 21 and 31 cm. This average value is not constant through the whole canal because the storage volume is not uniform through the time and considering the traveling time besides the operation of the head.

7. The relationship between irrigation scheduling and escape flows

The most expected disadvantage of stopping the irrigation during night is the increase of escape flow during this period. Escape flow losses and the effect of stopping the irrigation during night got a big attention from MWRI in the last decades. Based on (EPIQ Water Policy Team, 1998), canal tail losses in Egypt are estimated to account for 25-50% of the total water losses in irrigation (Tanji and Kielen 2002). The current study investigates the magnitude of escape flow then it investigates its fluctuation between day and night hours. To check the magnitude of the escape flow, figure (14) presents half-monthly ratios of escape flows time with the maximum head recorded during each half of month from the beginning of

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May 2005 to the end of September 2006 for four different branch canals in El-Behira and Kafr El-Sheikh governorates. All presented canals are complete or partial improved canals but because of the un-functionality of the automatic gates, escape flow still exist in all of them.

Figure 14: Half-monthly ratios of escape flow time and associated maximum head above the tail escape of Dakalt canal from May 2005 to September 2006

The highest escape flow was found in Dakalt canal. However, high escaping time ratios and high maximum head above the tail escape were always found during low consumption periods when water supply is very low. During high water supply periods, escape ratio is almost zero as the water is barely reaching the end. Figure (15) presents water supply volume, escape flow volume, and the escape flow as a ratio of the water supply for Dakalt canal. From the figure, half-monthly escape flow ratios reached 18% of the water supply in the second half of September 2005 but water supply at this period is very low compared to other periods. Average escape flow ratios during the three consecutive seasons are 1.1%, 2.16% and 0.07% respectively. The average of the three seasons is 0.98%. In general, it could be concluded that escape flow is not important as might be considered at least in monitoring areas, which includes El-Behira and Kafr El-Sheikh irrigation directorates.

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Figure 15: Half-monthly water supply volume, escape flow volume, and escape flow ratio at the tail escape of Dakalt canal from May 2005 to September 2006

To check the relation between escape flow and irrigation distribution through the day, figure (17) presents the escape flow discharges from Dakalt canals for seven days of four different months calculated each half an hour.

Figure 16: Half-monthly water supply volume, escape flow volume, and escape flow ratio at the tail escape of Dakalt canal from May 2005 to September 2006

During the first half of May, which is a low consumption period, escape flow continued for the most of the time with a low value. There is a difference between day and night escape flow values. The maximum values were at 5:00 to 5:30 AM then it begins to decrease. That is because water levels are close to tail escape

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level and the small change between day and night water levels could cause a difference in escape flow values. During high consumption period (July), escape flow looks as a sudden event that is a result of high water supply. Escape flow increased at the early hours of the day and afternoon hours. During other months, the change in escape flow happen for period of days instead of being changed between day and night. Consistent with the previous section, the change in the water level at the tail end, which leads to escape flow, is more obvious over the days than between day and night.

8. Reason for irrigating during night It is obvious that farmers tend to irrigate during day hours unless there are

reasons that force them to irrigate during night. However, most of the farmers practice night irrigation even for seldom number of irrigations. Figure (17) presents the percentage of farmers who practiced night irrigation in Dakalt and Besentway canals during summer 2006 and winter 2006-07 and the magnitude of different reasons that force them to irrigate at night. The data was collected through the questionnaires.

Figure 17: percentage of farmers who practiced night irrigation and the magnitude of different reasons that force them to irrigate at night

In Dakalt canal and during summer season, 100% of the selected farmers at the head and the tail practiced night irrigation. At the middle, 92% of the selected farmers practiced night irrigation. During winter season, the values were between 33% at the head and the middle and 60% at the tail. In Besentway canal and during summer season, the farmers who practiced night irrigation were between 38% at the middle and 70% at the tail. Regarding the reasons that force the farmers to irrigate during night, and based on farmers’ opinions, the internal rotation in the canal “Motarefa” is the most important reason at the head and the

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middle of Dakalt canal. At the tail, the rotation system, which could be observed at the tail and Motarefa are the main reasons. In Besentway canal, the suitability of the weather and Motarefa are the main reasons. This could explain the reduction of irrigation densities values at afternoon hours during summer season, when the temperature is very high.

9. Conclusion Considering the previous sections, it could be concluded that:

Farmers tend to irrigate during day hours and especially during forenoon hours. Unless there is a reason to force them, farmers stop the irrigation during night.

Statistically, there is no significant difference between irrigation distribution through the day in different improved and unimproved canals. This includes irrigation distribution at different locations of the canals and during summer and winter seasons. However, irrigation distribution is slightly spread more through the day during summer seasons than during winter seasons and in improved canals than in unimproved canals.

The relationship between irrigation distribution and the operation of the branch canals could be concluded in two points; the high consumption at the head could affect the tail farmers, and the farmers tend to irrigate at the late hours in the critical conditions when the water were missed for few days. However, water levels at the tail end changed over days in a rotational trend more than being changed between day and night. Average difference between day and night water levels, at the tail end of investigated canals, was between 10 and 15 cm.

Escape flow is found in both improved and unimproved canals. Improved canals could not stop escape flow, as all automatic gates are out of order.

In general, escape flow is not a significant source of water losses. On the other hand, stopping the irrigation during night is not the main reason for the increase of the escape flow even it has slight effect. The escape flow has a rotational trend over days more than having a quick change between day and night hours.

The main reasons that bush the farmers to irrigate during night in improved canals, based on their opinions, are the implementation of the internal rotation “Motarefa”, the suitability of the weather and the existence of the rotational system at the end of branch canals.

10. References

1. EPIQ Water Policy Team, “National policy for drainage water.” Report No. 8. Cairo, Ministry of Public Works and Water Resources, 1998

2. K. K. Tanji, and N. C. Kielen, “Agricultural drainage water management in arid and semi-arid areas” FAO irrigation and drainage paper # 61, 2002

3. Water Management Research Institute (WMRI) “Monitoring and Evaluation Program for Irrigation Improvement Project (IIP) - Canals and Drain Monitoring Study”, first extension report, Egypt, August 2006

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4. Water Management Research Institute (WMRI) “Monitoring and Evaluation Program for Irrigation Improvement Project (IIP) - Canals and Drain Monitoring Study”, second extension interim report, Egypt, September 2007

5. Water Management Research Institute (WMRI) “Monitoring and Evaluation Program for Irrigation Improvement Project (IIP) – Farmer Survey Study”, Summer 2006 report, Egypt, April 2007

6. Water Management Research Institute (WMRI) “Monitoring and Evaluation Program for Irrigation Improvement Project (IIP) – Farmer Survey Study”, Winter 2006-07 report, Egypt, November 2007

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جدولة الري على الترع الفرعية وعالقتها بأداء هذه الترع

وتوفير المياه وممارسات المزارعين

**جمال محمد فوزى *طلعت الجمل

ـ -معهد بحوث إدارة المياه وطرق الـرى ** استاذ باحث مساعد * باحث ز القـومى المرك

لبحوث المياه

تهدف الدراسة الحالية إلى بحث الوضع الحالي لجدولة الري على التـرع الفرعيـة،

المطـورة .وتوزيع الري على فترات اليوم المختلفة وتأثير ذلك على أداء الترع الفرعية

كما تم دراسـة . وغير المطورة حيث تم وصف ومقارنة توزيع المياه تحت كالً النظامين

كما تـم التعـرف علـى آراء .أثير توزيع المياه على أداء الترع الفرعية وتوفير المياه ت

.وممارسات المزارعين للري الليلي

أوضحت نتائج الدراسة أن أغلب أعمال الري تتركز خالل ساعات الـضحى بينمـا

يوم فترات محدودة من ال الرى خالل ويؤثر تركز . يتوقف الرى تقريباً خالل فترات الليل

على كمية المياه المتاحة فى نهاية الترع الفرعية خالل تلك الفترة كما أن توقـف الـرى

كما أوضحت . خالل فترات الليل قد يؤدى إلى زيادة كمية المياه المتسربة من نهاية الترع

نتائج الدراسة أن الري الليلي أكثر انتشاراً خالل فصل الصيف عنه فى فصل الشتاء، وفى

ن االختالفات بين الترع المطورة وغير إإال (مطورة عنه فى الترع غير المطورة الترع ال

كذلك ال يوجد فارق بين توزيـع الـرى ،)المطورة كانت ضئيلة ولم يتم إثباتهاً إحصائياً

. خالل فترات اليوم بين المناطق المختلفة سواء على الترع المطورة أو غيـر المطـورة

وبالنسبة لتأثير توزيع الرى على أداء الترع الفرعية فإن التغير فى مناسيب الميـاه فـى

ام المختلفة أوضـح نهايات الترع الفرعية يأخذ شكل المناوبات حيث يكون التغير بين األي

تشير النتائج أن فواقد المياه المتـسربة مـن كم .عن االختالف بين ساعات الليل والنهار

نهايات الترع مازالت مستمرة فى الترع المطورة، إال أن نسبة الفواقد الناتجة عن تـسرب

يـر ومن جهة أخرى فإن التغ . المياه من نهايات الترع ضئيل مقارنة بإجمالي فواقد الرى

فى كميات المياه المتسربة كان أكثر وضوحاً بين األيام المختلفة عنه بين سـاعات الليـل

الدراسة على األسباب التى تدفع المزارعين إلى الرى ليالً على التـرع وتعرفت. والنهار

، "ةرفاالمط" تطبيق نظام المناوبات على الترع الفرعية :األسباب المطورة، وكانت أهم هذه

.الطقس ليالً بالنسبة لبعض المحاصيل، وعدم وجود المياه باستمرار فى النهاياتومالئمة

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