Abstract
Computer-based systems that aid users in judgment and evaluation the navigation efficiency were developed. The effect of the dredging processes for many activities on the river stability at the second reach, which extends from Esna to Naga Hamady barrage in the river Nile, was analyzed. Rating curves downstream Esna Barrage using statistical model Minitab 16 for before and after dredging the navigational path were estimated. The significant changes in water levels just after dredging was occurred and with time the motion of bed particles towards the pools that were created from dredging which mentioned the river became more dynamics. The morphological changes at the location of navigation bottlenecks from 1982 to 2015 were studied to conclude the factors might affect frequent sedimentation. The integrated management of the dredging process was concluded to avoid and mitigate the direct river disturbance consequently keep navigational path efficiency and the results were presented using GIS.
1. Introduction
Natural rivers are normally utilized for navigation since it presents a good opportunity for fuel saving, enhancing the environment, and improving road safety. The constant demand on cargo transportation by River Nile decreases the stress on the road network of Egypt. Therefore, river navigation development was under the consideration of the Egypt Government. Recently, second reach of the river Nile which extends from downstream Esna Barrage at km 760.34 to upstream Naga Hamady Barrage at km 567.5 from Roda gauge station was rehabilitated to become navigable throughout the water year (first August to the end of July). In order to renewal the reach for navigation, it was necessary to modify a navigational channel design within the river course and maintain a navigational depth according to international design with taken into consideration the stability of the Nile river. The experts still believe that safe navigation through the river can be available during such a period by dredging the navigation bottlenecks to provide sufficient depths. It was foreseen that dredging might lead to serious problems if not studied comprehensively. This is attributed to the fact that the river disturbance due to bed dredging will alter the hydraulic characteristics and sediment transport inside the reach. Operational decision – making about maintenance dredging in an engineered river like River Nile is complex; future discharges, water levels, and morphological changes remain uncertain. In this paper, computer-based system was developed to aid users in judgment and evaluation the navigation efficiency using a large scale of data analysis, including the effect of dredging on the navigation management, the navigation bottlenecks, and some impacts of hydraulic structures as Ports, Berths, and Pump Stations. In this study three sets of discharge and water level data were utilized to study and analyze the impact of continually dredging on river morphology consequently navigation efficiency. The first set is the period before dredging from 1995 to 2000; the second set is during and just after dredging from 2003 to 2006 and finally the set which is within maintaining the navigational path from 2009 to 2013. Also, the advantages of this program are introducing the decision question answers for dredging effect on the river stability by analyzing a profile dredging, and calculating the minimum water level which can be abled to determine the navigational bottlenecks locations. Geographic Information System (GIS) was used to present the analysis of results. These results could support decision-makers to plan for navigation management.
2. Literature review
There is a rapidly growing tourism industry based on Nile cruises that travel along the river to visit a number of pharaonic temples along the route. Therefore, the inland waterway transport is considered an important element in the economic development of Egypt. In order to accommodate navigating vessels, several studies were carried out on the local and international levels based on field investigations. Some of these researches can be used as the data base for navigation system as Sadek et al. [1] which examined the effect of bank erosion and bend types on the efficiency for Damietta branch. They estimated that the relations between different bend parameters which may be used to predict the length of navigational path and the bank erosion to mitigate occurrence navigation bottlenecks. Also, Raslan et al. [5] showed the effect of dredging on river aggradation and degradation. Sadek et al. [11] stated that the encroachment on the floodplain during the last three decades reduced the river capacity, which can help appearing new navigation bottlenecks. RTA [12] has observed 71 potential locations as navigational bottlenecks along the River Nile, 6 navigational bottlenecks in the second reach (from Esna to Nag Hammadi Barrage). Sadek et al. [6], studied the morphological changes impact on water surface profile predicted for the Nile River by using mathematical model to analyze different hydraulic parameters. By comparing cross sections at year 1982 and year 1997, they found that sedimentation was more frequent than erosion; also, they found that the difference between the predicted water surface profile for 1982 and 1997 lied within the range of 0.6 m in case of future discharge 350 M m3/day and that was considered relatively small. Valipour et al. [3], forecasted the inflow of Dez dam reservoir by using Auto Regressive Moving Average (ARMA) and Auto Regressive Integrated Moving Average (ARIMA) models. They approved that the accuracy of forecast accuracy increase using both models ARMA and ARIMA when the number of autoregressive and moving average parameters reach to four in these models. RNPD produced a study to the impact of projects on the Nile River, RNPD [8] which included an investigation of water levels, thalweg line levels and known navigation bottlenecks.
3. Objectives
The main objectives of the present research can be summarized as the following:•
Develop a computer-based system which supports the optimization of the river Nile navigation system using a large scale of data analysis.•
Evaluate and analyze morphological changes at the locations of navigation bottlenecks along second reach.•
Investigate the impact of the implemented dredging activities on the study reach stability.•
Evaluate the effect of maintaining the intakes of water plant and power stations by dredging on the navigation efficiency.
4. Methodology
The continuous dredging has negative impacts on channel characteristics on the long run. Furthermore, the dredging might alter on water surface profile. In this paper, it will be developed a computer-based program including different parameters for navigation management. This research thus proceeded through different study phases. These phases are displayed under the following headlines as shown in Fig. 1:•
Data accumulation and study area description.•
Develop a computer-based system to evaluate and analyze the navigation efficiency for the river Nile.•
Statistical analysis by Minitab16 for water level predictions, using the regression between discharge and water level during the study period.•
Morphological changes analysis and evaluation the results of dredging and their impacts on navigational bottlenecks.•
Present, interface, and analyze using GIS.•
Assessment and evaluate of navigational bottlenecks.•
Conclusions and recommendations.
5. Study area description, and data acquisition
This paper is focused on the second reach as shown in Fig. 2. This reach extends from downstream Esna Barrage to upstream Nag Hammadi Barrage with a total length of about 192 km. It is characterized by having many bends at Qena government that affect river stability. It has also many historic temples and tourist sites on both sides, which gives the importance of river transport. On the other hand, it is usually exposed to many of human interventions that increase the impacts of different low and high flows on morphological characteristics. Moreover, the drinking water intakes, electricity stations, and river navigation route along the second reach may affect its stability.
One of the main advantages of this research is the study reach has recently surveyed maps at year 2015 and the authors were extracted many cross-sections which represent critical locations for river navigation efficiency. In addition, it has recent data for water levels and discharges at the gauging stations. Therefore, the recent geometrical and hydrological data will use in this research to possess results more accurate. Worth noting, GIS will use to present all of these data.
Three data sets were compiled to describe the hydraulic conditions before the channel rehabilitation, just after the development (dredging) and after several years. This was achieved in order to evaluate the effect of the rehabilitation on the river morphology and navigation efficiency. The compiled data sets encompassed the discharge and water level at the years 1995, 1998 and 2000 representing the period before dredging, while the period from 2003 and 2006 during and just after dredging, and finally the period from 2009 till to 2013 which describes navigational path maintaining.
6. Development of a computer-based system
A computer program has been developed by the authors with the intention to evaluate and analyze the navigation in the River Nile, to combine of bathymetric monitoring data, measured water levels, and morphological changes. The program facilitates decision-making on dredging activities during critical low-water periods and after the release of peak flows. This developed program contain five main components modules: (i) data base (ii) data management, (iii) calculations and analysis, (iv) presentation and interface, and (v) assessment and evaluation as shown in Fig. 1.
The program was developed by means of the Visual Basic language representing a flexible interface in Fig. 3; it operates with three-way operation and linking between them as shown in Flow chart in Fig. 4. The first one is a database developed to store and analyze all data of water levels and discharges measurement from gauge stations, and discharges stations, where they are stored. Then linked with the second operation which analyzed these data by using statistical model Minitab 16, to analyze the relationship of the discharge with the corresponding water level at these stations during the period before dredging from 1995 to 2000, and after dredging from 2003 to 2006 and finally within maintaining the navigational path period from 2009 to 2013. The third is Geographic Information System (GIS), which is used to present and analyze the results.
The advantages of the presented developed computer based system as shown in Fig. 1 are mainly introducing an evaluation and analysis to the navigation efficiency for the river Nile, by developing database, which introduces optimum answers for decision making questions for different scenarios (before, just after dredging, and maintaining period the navigational path). These questions represent in (where: by determining the bottlenecks locations on the study reach, analyzing and deducing the water levels, when: by defining the priorities of dredging locations depending on the Public services areas (water and power stations) which is determined in this research by using geo-database, how much: according to dredging volumes consequently the cost can be determined, and what: the measurements & traffic control depending on the morphological characteristics (straight – meander- braided) of the reach study.
6.1. Data base for water levels and discharges
The data management component performs the function of storing and maintaining the information that it can be used to support decision makers. In addition, the data management component consists of database management system [4].
The need to create database for water level, and discharges measurements is important to support decision making process on river Nile navigation. Decisions are routinely made by organizations based on the information collected and stored in databases. In addition to database management systems, which effectively apply and implement databases in real systems, a good graphic user interface. (GUI) is needed to allow users to access and manipulate their measurement records or data in databases. Visual Basic is an ideal candidate to be selected to provide this GUI functionality. In this application the database specifications are allow to: connect to the data source locations, browse through the workspaces, examine or explore the data, manage data, data tables and draw graphs, analyze and search for data as shown in Fig. 5. In addition, the database application helps in the preparation the data to MINTAB16 statistical model.
6.2. Data analysis by statistical model Minitab16
The developed program linked between the database and statistical model Minitab 16, to analyze the relationship for the discharge with the corresponding water level at the gauge stations during the study period. The water level regressions were estimated with an extended version of regression model, based on statistical relations between several upstream water levels gauges and discharge station.
6.2.1. Water levels estimation by statistical model
The historical measured data of the major gauging stations were used to analyze and evaluate the relationship of the discharge passing D.S. Esna barrage with the corresponding water level at this station during the period 1995–2013 using simple regression model. These data represent the situation before dredging from 1995 to 2000 and the case during the dredging process from year 2003 to 2006 while the situation after dredging and navigational path maintaining continually during the period from 2009 to 2015. These historical data were analyzed using statistical model Minitab 16. The analysis of the data represents the descriptive statistics of the water level and discharge characteristics for each year. They were the arithmetic mean, median (center value), standard error (the dispersion in the distribution of samples means) standard deviation (The most common measure of dispersion STDV) and minimum and maximum values, first and third Quartiles and finally skewness and kurtosis as shown in Tables 1 and 2. From these tables it is clear that the negative values of kurtosis that indicate a distribution that is flatter than normal. In addition, the mean discharge value at year 1998 increased than at year 1995 due to the flood was very high in this year. In order to manage it, the Ministry of Water Resources and Irrigation (MWRI) released more discharge downstream the high dam. Fig. 6 describe discharge frequency D.S. Esna Barrage before and after dredging at 1995 and 2013, and Fig. 7 describes discharge density D.S. Esna Barrage before, during, and just after dredging, and maintaining navigation path at 1995, 2003, 2006, and 2013. From Figs. 6, 7 and Table 2, it can observe that before dredging the discharge values were ranged between minimum 35 mm3/day and maximum 226 mm3/day at 1995. While after dredging, the discharge value was ranged between minimum 60 and maximum 230 mm3/day at 2013. In addition, the change of standard deviation value during the study period was occurred. From the data results it can be concluded that the dredging has an effect on water levels, causes water level to drop. This means that it needs to pass little more discharges to satisfy demand. This change of water levels and discharges causes these little changes on mean standard deviation of the tabulated values from year to another.
Table 1. The Statistical Analysis of the changes in water level for D.S. Esna barrage (1995–2013).
| Water level | Mean | SEMean | StDev | CVariation | Wl1 | Median | wl3 | Minimum | Maximum | Skewness | Kurtosis |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1995 | 73.00 | 0.06 | 1.10 | 1.51 | 72.34 | 72.88 | 73.90 | 70.90 | 74.96 | 0.18 | −0.85 |
| 1998 | 73.58 | 0.05 | 1.04 | 1.42 | 72.78 | 73.73 | 74.50 | 70.94 | 74.93 | −0.43 | −0.98 |
| 2003 | 73.13 | 0.06 | 1.14 | 1.56 | 72.40 | 72.82 | 74.36 | 71.09 | 75.13 | 0.30 | −1.08 |
| 2006 | 73.32 | 0.06 | 1.18 | 1.60 | 72.52 | 73.16 | 74.44 | 71.24 | 75.21 | 0.03 | −1.22 |
| 2009 | 73.00 | 0.06 | 1.07 | 1.47 | 72.20 | 72.84 | 73.52 | 71.20 | 74.88 | 0.37 | −0.90 |
| 2013 | 73.06 | 0.06 | 1.09 | 1.49 | 72.36 | 72.99 | 74.10 | 71.00 | 74.91 | 0.12 | −1.04 |
Table 2. The statistical analysis of the changes in discharge for D.S. Esna barrage (1995–2013).
| Discharge | Mean | SEMean | StDev | CVariation | Q1 | Median | Q3 | Minimum | Maximum | Skewness | Kurtosis |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1995 | 133.91 | 2.82 | 52.52 | 38.87 | 101.25 | 129.30 | 179.12 | 35.30 | 226.12 | 0.17 | −0.87 |
| 1998 | 161.72 | 2.56 | 48.94 | 30.26 | 124.06 | 169.62 | 205.13 | 37.18 | 225.34 | −0.43 | −0.96 |
| 2003 | 145.63 | 2.75 | 51.55 | 35.40 | 112.99 | 130.75 | 200.68 | 59.03 | 233.85 | 0.35 | −1.08 |
| 2006 | 151.52 | 2.78 | 53.05 | 35.01 | 114.07 | 143.16 | 204.32 | 62.79 | 240.24 | 0.20 | −1.18 |
| 2009 | 146.77 | 2.51 | 47.88 | 32.62 | 108.20 | 147.96 | 183.31 | 60.99 | 223.24 | 0.01 | −1.14 |
| 2013 | 149.63 | 2.65 | 50.66 | 33.86 | 118.82 | 143.44 | 197.14 | 62.33 | 232.83 | 0.11 | −1.08 |
Also in this paper, the rating curves for water levels and discharge downstream Esna barrage during the period 1995–2013 were deduced by using the daily water levels and discharges for each year using the same statistical model Minitab 16 and fitted as shown in Fig. 8, Fig. 9. These equations were derived by the least square method with a correlation factor ranges between 98% and 99%. From the results it can be cleared that the linear model (p-value = 0.000) appears to provide a good fit to the data. A visual inspection of the plot reveals that the data are evenly spread about the regression line implying no systematic lack of fit. The lines labeled c1 are the 95% confidence limit for the downstream Esna barrage discharge. The line label P1 are the 95% prediction limit for new observation. Fig. 10 describes the confidence intervals for water levels and discharge downstream Esna barrage during the period 1995 before dredging and 2013 after dredging as the example to show the major changes for the rating curves over the dredging years. In addition the relations which estimated at year 1995, 1998, 2000, 2003, 2009 and 2013 which shown in Fig. 8 can be read as follows:
(1)1995Wl=70.16+0.02143∗Q-0.000001∗Q2R2=99.5%(2)1998wl=70.15+0.02123∗Q-0.0000001∗Q2R2=99.5%(3)2000Wl=70.135+0.0213∗Q-7E-08∗Q2R2=99.0%(4)2003Wl=69.90+0.0203∗Q+0.00002∗Q2R2=99.1%(5)2006Wl=69.72+0.02514∗Q-0.000011∗Q2R2=99.0%(6)2009Wl=70.01+0.02111∗Q+0.00003∗Q2R2=99.3%(7)2013wl=69.94+0.02032∗Q+0.000003∗Q2R2=98.9%
These relations are used to study and analyze the impact of recently navigational development on the water level consequently on the river morphology as the following section.
6.2.2. The effect of dredging on water level and river navigation
The variation of water levels, along the River Nile from downstream Esna barrage was estimated during the study period to investigate the dredging effect on the river navigation using the derived rating curves downstream Esna barrage as shown in Table 3. From this table, it is clear that no significant changes in water levels during the period 1995–2000 before dredging. On the other hand, there is a noteworthy drop in the water level just after dredging by about 21 cm at year 2003. From these results, it can conclude that it need passing more discharge during the minimum water requirements to avoid navigation problems but this is considered contrary to the policy of the Ministry of rationalizing consumption. From these results, it can conclude that the erosion and sedimentation processes increased as a result of river disturbance during the dredging while the river tends to stability during the navigation maintain.
Table 3. The changes in water level at D.S. Esna barrage before and after dredging.
| Discharge (million m3/day) | Drop in W.L. ΔWL (m) | |||||
|---|---|---|---|---|---|---|
| ΔWL before dredging (1995–2000) | ΔWL during and just after dredging (2003–2006) | ΔWL after several years situation (maintaining period) (2009–2013) | ||||
| 2000–1995 | 2000–1998 | 2003–2000 | 2006–2003 | 2009–2006 | 2013–2009 | |
| 35 | −0.03 | −0.01 | −0.21 | −0.08 | 0.16 | −0.09 |
| 50 | −0.03 | −0.01 | −0.20 | −0.05 | 0.12 | −0.10 |
| 75 | −0.03 | −0.01 | −0.18 | −0.01 | 0.05 | −0.11 |
| 100 | −0.03 | −0.01 | −0.16 | 0.02 | 0.00 | −0.12 |
| 150 | −0.02 | 0.00 | −0.13 | 0.04 | −0.07 | −0.12 |
| 200 | −0.01 | 0.00 | −0.09 | 0.00 | −0.08 | −0.11 |
| 226 | 0.00 | 0.00 | −0.07 | −0.04 | −0.06 | −0.10 |
6.3. Presentation, and analysis by using GIS
6.3.1. Presentation
The presentation is the most important part of developed computer system for supporting decision making, which give a master plan for operational decision – making about maintenance dredging with a large scale of data analysis on river Nile for navigation management.
6.3.2. GIS analysis
GIS is a computer system capable of assembling, storing, manipulating, and displaying geographically referenced information. The way maps and other data have been stored or filled as layers of information in a GIS makes it possible to perform complex analyses, information retrieval, topological modeling, networks, overlay, and data output [2].
– GIS database: GIS database schema is established for structures along the second reach of Nile River as a global mode. As a first step, the base map of Nile River has been established. The data base schema from personal geo-data base type which includes different modules and layers were implemented in different functions for the developed the Nile River system in Geographic information system, every layer represented unique structure: “bridges, Ports, Hydropower stations, Berths, drinking water intakes, water quality monitoring sites” as shown in Figs. 11 and 12. These structures along the river affect the erosion and sedimentation process consequently impact on the navigation path efficiency, also on the water quality. GIS in this paper is an essential for supporting decision makers and river managers by providing valuable information within a river study reach. Such information can be used to develop management plans and planning dredging process in order to preserve river environments. This requires investigations into a wide range of datasets, which can be collected as field and desk-based. GIS has been demonstrated repeatedly as managing and analyzing this wide range of spatial and tabular data. Indeed, this aids decision makers and provides a full picture about what is happening in the river and therefore allows the most appropriate decision regarding prioritization of where and when to restore the most vulnerable areas of the river [7].
6.3.3. The effect of dredging on river morphology using GIS
GIS was used to evaluate the morphological changes, which occurred at the study region D.S. Esna Barrage affected by dredging. Fig. 13 shows digital terrain model DTM for this region at 2003 representing the period during dredging and DTM for the maintaining period along the navigational path at 2015 using the available data surveyed by Nile Research Institute. While Fig. 14 illustrates the changes, which occurred at the bed level consequently the erosion and sedimentation was analyzed. From these figures, it can conclude that the elevation was decreased around the study region causing the drop in the water level according to the cross section in Fig. 13. These results are considered the same that were performed by rating curve. In addition, it can conclude that the erosion and sedimentation processes were increased during and after dredging indicating the river became more dynamic.
7. Navigation bottlenecks
Navigation bottlenecks appear due to riverbed aggradation and any hydraulic structures, which may be caused river morphology changes. Therefore, this change requires frequently maintenance works to keep the path navigable along the year. However, the major questions is how long the path will be navigable and what affects its operational efficiency searched for quenching answers in this section.
7.1. Effect of dredging around the water and power station intakes on river navigation
One of the problems, may affect the navigation efficiency, is the continually dredging around the water and power station intakes required for keeping their operational efficiency especially when dredging in the opposite side of navigational path. Fig. 15 describes the location of water stations according to navigation bottlenecks from year 1982 up till now using Geographic information System (GIS). According to RTA [12], there are six critical navigation bottlenecks locations along the second reach as shown in Table 4. From the figure and table, it can be noticed that there are one water plant station upstream and three downstream at El Karnak bottlenecks location. Also, El Ashey bottleneck location; there are four water plant upstream and two downstream it. Therefore, it can conclude that these water stations may cause negative impacts on the river morphology resulting from continually dredging around them consequently may effect on navigation bottlenecks. Thus, it can recommend that the intakes locations need studying by numerical model for simulating the motion of sediment with water and then it can be predicted the rate of deposition with time to get the results more accurate.
Table 4. The location of navigation bottlenecks at the study reach (1982) [9].
| No. | Name | km (Roda) | km (Aswan) | Position X | Position Y |
|---|---|---|---|---|---|
| 1 | Dandrah | 636 | 291 | 782024.9 | 386096.4 |
| 2 | Abnod | 654 | 273 | 792057.8 | 372981.2 |
| 3 | El Ashey | 690 | 237 | 788015.9 | 343607.4 |
| 4 | El Karnak | 701.5 | 226.8 | 777135.9 | 323514.2 |
| 5 | El Mallah | 737 | 190 | 776632.2 | 318648.9 |
| 6 | Waborat Armant | 756 | 171 | 772462.1 | 300569.1 |
7.2. Morphological changes at the navigation bottlenecks
The morphological changes analysis for critical navigation bottlenecks cross-sections along the study reach describe at Fig. 16, Fig. 17, Fig. 18, Fig. 19, Fig. 20, Fig. 21, Fig. 22, Fig. 23, Fig. 24, Fig. 25, Fig. 26, Fig. 27. These sections were extracted from hydrographic survey and topographic maps, which produced by Nile Research Institute at year 1982, 2005 and 2015. In addition to using, the Orth-photo, which included the navigational path to evaluate and analyze any changes, occurred as the human interventions, their effects on river characteristics and navigational path during the study period. Fig. 16 shows the cross section of Wabrat Arment bottleneck location at km 171 down stream Aswan dam, the area of attachment island at the west bank increased from 2005 to 2015 and the deposition occurred in the middle channel at the navigational path as shown in Fig. 17a and b.
Fig. 18 shows the cross section at El Mallah bottleneck location at km 190 D/S Aswan, it is clear that the deposition was occurred in the east channel at the navigational path as the result of bank erosion that happened at the eastern side. In addition to a deposition that occurred in the middle of navigational channel, where the reformed island area on the east channel at 2015 increased comparing with 2005 as shown in Fig. 19.
On the other hand, the cross section at El Karnak navigation bottleneck location at km 226.8 D.S. Aswan dam in Fig. 20. It is obvious that there was a deposition happen in the west side of navigational channel, and erosion in the east channel during the period from 1982 to 2005, otherwise from 2005 to 2015 the deposition increased in the east of navigational channel, and the erosion increased on the west side. It is very clear in this section the effect of dredging as maintenance operation of new water station at 2015 as shown in Fig. 21a and b. It can conclude that the modifications that happened in navigation path from east to west channel according to human interventions as the new water station maintenance operations as shown Fig. 21c.
El Ashey navigation bottleneck cross section locates at km 237 downstream Aswan Dam as shown in Fig. 22. It shows that the deposition increased in the west and middle of the channel, while the erosion occurred in the east side comparing cross section at 1982 with 2005. From Ortho photo in Fig. 23 it can observe the reformed island area on the west side of the channel decreased and the erosion increased causing continually navigation bottlenecks.
For Abnod bottleneck location at km 273 and Dandara bottleneck location at km 291 D.S. Aswan, there is no available data for 2015. Fig. 24 shows Abnod cross-section, where the area of island in the west side of the channel increased, and the deposition were happened in the west and in the middle of the channel, and that is obvious the bank erosion in the east occurred. From ortho photo in Fig. 25b at 2015 it is clear that the wider area of the island on the west bank, causing narrow the navigation width, which may cause bottleneck in this area.
Fig. 26 Cross section of Dandara bottleneck location at km 291 downstream Aswan, shows that there was an erosion in the west channel, from Fig. 27 there is a bridge at km 292 D/S Aswan, and a human intervention may be occurred in the east bank by filling.
The evaluation of the deposition and erosion processes for the critical navigation bottleneck cross sections was performed. The total amount of them were calculated between 1982 and 2005 and between 2005 and –2015 as shown Table 5, Table 6 according to water surface profile and navigational bed level along second reach as shown in Fig. 28. The area of erosion ranges between 548 and 4171 m2 and the deposition ranges between 110 and 10,856 m2 during the period between 1982 and 2005. While, the erosion area ranges between 1119 and 8135 m2 and the deposition ranges between 81.45 and 3881 m2 within the period 1982–2005. From these results, it can be concluded that the deposition is more frequent than the erosion at the period 1982–2005 and the opposite in the period 2005–2015.
Table 5. Total amount of Erosion and Deposition along the reach (1982–2005).
| No. | Name of navigation bottleneck | Erosion | Deposition |
|---|---|---|---|
| 1 | Dandrah | 4171.73 | 10856.12 |
| 2 | Abnod | 3304.91 | 8143.29 |
| 3 | El Ashey | 548.26 | 2436.37 |
| 4 | El Karnak | 3505.65 | 4970.29 |
| 5 | El Mallah | 2907.67 | 110.45 |
| 6 | Waborat Armant | 1920.03 | 203.65 |
Table 6. Total amount of erosion and deposition along the reach (2005–2015).
| No. | Name of navigation bottleneck | Erosion | Deposition |
|---|---|---|---|
| 1 | Dandrah | Not available | Not available |
| 2 | Abnod | Not available | Not available |
| 3 | El Ashey | 7236.96 | 81.45 |
| 4 | El Karnak | 8015.39 | 3881.32 |
| 5 | El Mallah | 8135.32 | 3001.69 |
| 6 | Waborat Armant | 1119.56 | 956.67 |
7.3. Assessment and evaluation the current significant critical navigational bottlenecks
Fig. 29 and Table 7 show the comparison between the bottlenecks locations in the present situation at year 2016 [10] and in the past at year 1982. From them it can be noticed that the number of locations are increased and changed, but there are two bottlenecks locations in 1982 and 2016 still not changed (Elkarnak and El Ashey). So it was analyzed the two locations by creating a Digital Terrain Model (DTM) in Arc GIS as shown in Fig. 30. From these results it can conclude that their locations which changed because of both natural changes and human intervention as dredging. It was found that significant changes (aggradation-degradation) had been occurred as many of undeforming islands appear consequently affecting free river movement. Also, many of curves found along the study reach which may increase the erosion on the outer concave curve and deposit in the inner convex curve (see Fig. 31).
Table 7. The bottlenecks locations at 1982 [9] and 2016 [10].
| No. | Bottlenecks location | km (from Roda) | 1982 | 2016 |
|---|---|---|---|---|
| 1 | Waborat Arment | 751 | ✓ | |
| 2 | El Mallah | 740.5 | ✓ | |
| 3 | Ben gabaleen | 737.5 | ✓ | |
| 4 | Arment | 721.5 | ✓ | |
| 5 | Karnak | 701.2 | ✓ | ✓ |
| 6 | Marees | 716 | ✓ | |
| 7 | ElZeena | 698.5 | ✓ | |
| 8 | Al Ashey | 688.5 | ✓ | ✓ |
| 9 | Abnod | 654 | ✓ | |
| 10 | Qena Bridge | 650 | ✓ | |
| 11 | Dandara | 636 | ✓ | |
| 12 | AlSamta | 617 | ✓ |
The bold values indicate to the two locations which suffering from the permanent navigation bottlenecks during the study period.
8. Conclusions and recommendations
The developed program through this work represented a valuable tool for evaluating and analyzing navigation efficiency for the River Nile which supporting the decision making process on river navigation by developing a flexible interface that operates with three-way operation to evaluate the navigation efficiency in the River Nile. The program included database for water level, discharges measurements, which it is important to access, and manipulate their records to support decision making process especially by calculating the min water level which can be abled to determine the navigational bottlenecks location. During this study it was deduced the rating curve relations downstream Esna Barrage using the statistical model Minitab 16. It was concluded that no significant changes in water levels during the period 1995–2000 before dredging. On the other hand, there was a noteworthy drop in the water level just after dredging by about 21 cm at year 2003. While at year 2009, it can conclude that the drop in water level is decreased with time, which initiated the motion of bed particles towards the pools that were created from dredging. By analyzing the effect of continual dredging around water pump stations and water intakes to keep their operational efficiency especially when dredging in the opposite side of navigational path had negative significant effect on its efficiency. The comparison between the navigation bottlenecks locations in the present situation at year 2016, and in the past at year 1982 was evaluated and analyzed using GIS. It can be noticed that the number of locations are increased and changed, but there are two bottlenecks locations in 1982 and 2016 are not changed (Elkarnak and El Ashey). So it was analyzed the two locations by creating a Digital Terrain Model (DTM) in Arc GIS and it can be concluded that significant changes (aggradation-degradation) have been occurred due to the sedimentation process is very complicated due to many of undeforming islands affecting free river movement. In addition, many of curves found along the study reach which increase the erosion on the outer concave curve and deposition in the inner convex curve. Moreover, it can be recommended that these locations need to study by numerical model for simulating the motion of sediment with water and then it can be predicted the rate of deposition with time. Therefore, it can conclude that it must build integrated dredging strategic to avoid or mitigate continually dredging on the river behavior, which cause the appearance of navigation bottlenecks by making any maintenance in the Nile should take place on a one-time. The Geographic Information System (GIS) was used in the final stage to present the analysis of results that could support decision-makers to plan for navigation management.Recommended articles
References
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Further reading
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Dr. Noha Kamal is Researcher, in River Engineering department, Nile Research Institute – National Water Research Center, Ministry of Water Resources and Irrigation. She received a Ph.D. and MSc from Benha University, Shoubra Faculty of Engineering, Electrical Engineering Department, Cairo, Egypt. Dr. Noha received international training in Water Management in Netherland and Tunisia in 2014, The author published over 8 scientific papers and Co-author in 11 technical reports.
Dr. Nahla Sadek is Professor, Head of River Engineering department, NileResearch Institute – National Water Research Center, Ministry of Water Resources and Irrigation. She received a PhD and MSc from Ain Shams University, Faculty of Engineering, Civil Engineering Department, Cairo, Egypt. Dr. Nahla was awarded seven Prizes in engineering from Ministry of Water Resources and Irrigation in 2003, 2004 and 2007. She also got the prize of the ideal engineer in 1996. The author published over 35 scientific papers and Co-author in 28 technical reports.Her researches focused on hydrology, hydraulics, Protection and Development Project and water resources management.
Peer review under responsibility of Ain Shams University.
