Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, March 2015

Transcription

1 AQUATIC WEEDS MANAGEMENT UPSTREAM NEW NAGA HAMMADY BARRAGES Hosam Ibrahim 1, Emam A. Osman 2, T.A. El -Samman 3, and Mahmoud Zayed 4 1 Prof., Deputy director of Channel Maintenance Research Institute (CMRI), National Water Research Center (NWRC), Kanater El-Khairiea, Kalubeia, 13621, Egypt, Hosamm333@yahoo.com. 2 Researcher, CMRI, NWRC 3 Prof., CMRI, NWRC. 4 Assistant Researcher, CMRI, NWRC. ABSTRACT In order to control high floods through the main Nile River stream, High Aswan Dam "HAD" was constructed in This led to reduce the maximum annual flow discharge downstream of Old Aswan Dam "OAD" from 911 million m 3 /day in 1964 to 275 million m 3 /day in Accordingly, enormous high aquatic weed infestation spots have been generating which caused many problems along the river and various irrigation channels. Therefore, many human activity fields and economic interests have been affected such as water losses, retardation of flow, obstruction of gates and intakes, interference with navigation, health hazards and alteration of water physical-chemical characteristics. Consequently, the present research was planed to investigate the aquatic weed problems upstream the new Naga Hammady barrages which is located on the Nile River at km downstream "OAD". The intake structure of the installed hydropower plant suffers from severe infestation of submerged aquatic weeds upstream the barrage which breakdowns the power plant operation for several hours daily. To overcome such difficulty, specific barriers and trash rack upstream the old and new Naga Hammady barrages were designed and constructed to control the floating and submerged aquatic weeds. Several field measurements that cover a study reach of 38 km upstream the new barrages were conducted. Apply remote sensing and GIS technologies, each of the intensity, percent of infestation, and the moving trend of submerged aquatic weeds were identified over the study reach. Therefore, detailed design criterion for weed control device was established. Using the collected data and based on the analysis of field and laboratory studies, appropriate solutions were designed and constructed to prevent submerged aquatic weeds from reaching the hydropower plant intake structure which consequently led to enhance the generated hydroelectric power by 26% in July Moreover, to remove the deposited aquatic weeds on the trash rack, the appropriate maintenance program for the proposed barriers was recommended. Keywords: Aquatic weeds, Management program, Remote sensing and GIS, Barrier design 1- INTRODUCTION Infestation of aquatic weeds can be considered as major negative effect of "HAD" and its mitigation by means of research, testing and introduction of various control methods, management and maintenance are enormously recommended. The annual high flood discharges - before "HAD" construction tend to flush aquatic weeds from the main Nile River stream and the branched irrigation channels. As most of the sediment is trapped in Nasser Lake after "HAD" construction, water releases have become clear and free of suspended solids. This in turn encouraged weed growth due to water surface fluctuations and deeper penetration of sunlight in water. Consequently, numerous problems were emerged such as water losses by transpiration, changes in water quality, health hazards, interference with navigation waterway and the concern problems with the accumulation of aquatic weeds in the intakes of hydro powers and pumps. The latter influence can be considered as the most important inconvenience problem along the Nile River main stream. An example for that is the loss in the generated electric power which was reduced in 2011 by 38% 264

2 due to blocking the frontal inlet of the hydropower plant by aquatic weeds. For this reason, mitigating the aquatic weed problems upstream the new Naga Hammady barrages would be considered during the present paper. A detailed study for solving aquatic weeds problems upstream the new Isna barrages was conducted by the Channel Maintenance Research Institute "CMRI" by Hosam Ibrahim et al (2004) [4]. In this study, the aquatic weeds infestation was monitored along enough river reach for one year, and then the required barriers for mitigating the aquatic weed problems was designed and implemented. Additional study was carried out by "CMRI" (2011) [2] to monitor the submerged aquatic weeds infestation along 38 km of the Nile River upstream the new Naga Hammady barrages which is the subject of the present paper. In this study, the produced hydraulic characteristics by Chow, V.T. (1959) [3] were applied for several cross sections allover the study reach. The recent developments in computer hardware and software allow for integrating remote sensing "RS" and geographic information systems "GIS" to assist sustainable development and management of water resources in easy, flexible and accurate way. With this in mind, the submerged aquatic weed infestation was identified within the study reach which extends for 38 km upstream the new Naga Hammady barrages. The aquatic weed monitoring method was applied and the percentage of infestation was evaluated in the study reach. This revealed that Ceratophyllum demersum weed is the dominant species with the highest infestation at the shoreline of the main stream, and the shoreline bed material was characterized by clay loamy soil. This type of weed constrained water flow by blocking the frontal inlet of the hydropower plant and consequently caused serious problems. Remote sensing and GIS technologies were applied to distinguish and map the distribution of aquatic weeds within the studied reach. Several experimental investigations were carried out concerning the parameters that affect the magnitude of the drag forces exerted by moving fluid on floating circular cylinder placed across a channel. Change of drag coefficient with the Froude number and the relative depth of the approaching flow was examined by Hsieh, T. (1966) [5], Khalil, M.B. (1969) [6], and Ko, S. C. et al, (1972) [7]. These concluded that drag coefficient C D depended mainly upon Froude number irrespective of Reynolds number. F D = ½ C D ρ V 2 L s b.. (1) Where: F D is the drag force: C D is the drag coefficient (dimensionless); L s is the submerged length, b is the unit breadth; V is the maximum measured water velocity at cross section; ρ is the mass density of water. On the other hand, there is acting pressure on the barriers due the floating aquatic weeds which is mainly consists of "Water Hyacinth". This impact was estimated as shearing force due to the accumulated weeds in front of barrier which was evaluated by Ali, R.M. (2000) [1] as follows: F τw = (V* w ) 2. ρ /g.(2) Where: F τw is shear force; V* w is shear velocity; ρ is mass density of water; g is the acceleration due to gravity; 265

3 The above mentioned 2 equations were used for design weed control barriers upstream new Naga Hammady barrages. Hence, the aim of this study is to investigate, design, and construct specific weed control system of barriers and trash rack upstream the old and new Naga Hammady barrages respectively. 2- DESCRIPTION OF THE STUDY AREA The new Naga Hammady barrage was constructed on the main Nile River stream at Km downstream of "OAD" and at 3.2 km downstream the existed one. Its total length is 325 m and consists of a first class navigation lock, low head hydropower plant provided with 4 bulb-turbines and sluiceway which is equipped with 7 radial gates of 17 m width and 13.5 m height each. At normal operation - except for high flood discharge the water surface level upstream the new barrage is maintained at (65.90) m. The Hydropower plant structure is adjacent to the spillway on left bank of Nile river. It consists of four bulb turbines each bulb turbine designed to generate 16 Mega watt, design head 5.7 m, design discharge 320 m3/sec/unit, and started to be connected to the Egyptian electricity network in Feb The average generated power for each bulb turbine in July 2011 was 9.88 Mega Watt, there was a reduction in the generated power 38% from blocking the frontal inlet of the hydroelectric power plant by aquatic weeds. The impending aquatic weeds from the upstream urges to close the hydropower plant for several hours daily and consequently release the total discharge from the spillway only without electric generation. The selected study reach is located along 38 km upstream the new barrages which comprises several islands located in the studied reach which determinate two sub courses water as shown in Figure (1). To facilitate the planed field works, the main studied reach was divided to five smaller sub-reaches as shown in Table (1) and Figure (2) while the located islands within the Study reach are listed in Table (2). Figure (1): The Selected Study Reach 266

4 Table (1): Sub-Reaches Boundaries Reach Distance (km) Area Length No. From (km) To (km) (m 2 ) (km) First Second Third Fourth Fifth Total monitored length (km) Fifth reach Fourth reach Seond reach First reach Third reach Figure (2): Location of the Five Sub-Reaches Table (2): Located Islands within the Study Reach No Island name Island location Distance (km) Island length From To (m 2 ) (km) (km) 1 El Akool island First reach El Hamodia island First reach El Shawaria island Second reach El Kanawia island Third reach El Sahel island Fourth reach El Kalh island Fourth reach El Wasta island Fourth reach Total islands length (km) METHODOLOGY To achieve the objective of the present study for controlling the accumulated aquatic weeds upstream the hydropower trash rack, extensive field measurements were carried out to detect the hydraulic characteristics of the study reach which can be summarized as follows: 267

5 Survey and monitor aquatic weeds infestation allover the entire reach of 38 km length upstream the new Naga Hammady barrages. Measuring longitudinal velocity profiles along ten cross sections located upstream the new and old Naga Hammady barrage by using electro magnetic current meter. Velocity measurements for each cross section were carried out at 1.0 and 2.0 m depths from water surface. Locations of the velocity measuring cross sections are shown in Figures (3 and 4). The plotted locations in those Figures are the distances (km) upstream El-Roda gauge station which is located at km downstream "OAD". Figure (3): Locations of Measured Velocities and Submerged Weeds Infestation between the New and Old Barrages 268

6 Figure (4): Locations of Measured velocities and submerged Weeds Infestation Upstream Old Naga Hammady Barrages Using Echo Sounder, seventy cross sections were surveyed to detect the percentage of the submerged weeds infestation along the study reach. Using weed sampling device, intensity of moving submerged aquatic weeds along the upper flow layer up to 4.0 m under water surface level were measured in the study sub-reaches. Using floating wood pieces, the moving trend of submerged aquatic weeds were identified in the studied reaches. 4- RESULTS AND DISCUSSIONS 4-1 Field Measurements Results The attainable results from the conducted measurements can be summarised as follows: Velocity distribution The measured velocity profiles and aquatic weeds infestations showed that the maximum stirred submerged weeds are within the main flow stream through about 4.0 m depth under water surface. More over, water velocity distributions along cross section (2) at km downstream "OAD" - which is located at km upstream the new Naga Hammady barrages are shown in Figure (5). This showed that the measured velocity at 1.0 m depth (V 1 ) is higher than that at 2.0 m depth (V 2 ). While Table (3) lists the main variations between the measured flow velocities at 1.0 and 2.0 m respectively for the measured 10 cross sections allover the study reach. This revealed that the measured velocity at 1.0 m is much higher than that at 2.0 m depth which obviously is due to the existence of the submerged aquatic weeds. Moreover, Table (3) also listed that the overall average of the measured flow velocity at 1.0 m depth is about m/s which is about 2.1 times that at 2.0 m depth which is about m/s as listed in Table (3). 269

7 R. Bank Figure (5): Measured Velocity Profiles at km Upstream the New Barrages Sec. No Distance Downstream "OAD" (km) Aquatic weeds survey Table (3): Variations in the Measured Velocities Reach No. Distance Upstream the new barrages (km) Mean velocity variation (m/s) At 1.0 m flow depth At 2.0 m flow depth Fourth Fourth Fourth Fourth Fourth Fourth Fourth Fourth Fifth Fifth Main Average flow velocity (m/s) The attainable results for the monitored aquatic weeds through the entire five study sub-reaches along seventy cross sections by using the Echo Sounder are listed in Table (4). In this Table, the total infested area by submerged aquatic weeds on the right and left shoreline along each sub-reach was determined. This revealed that the total infested area by submerged aquatic weeds on the right and left shoreline of the studied reaches is m 2 as shown in Table (4). 270

8 No Reach Distance (km) Mea From To n River (km) (km) width (m) Table (4): Infested Areas on Both Shorelines Infested area on right shoreline (m 2 ) Infestation Percent Infested area on left shoreline (m 2 ) Infestation Percent First % % % Second % % % % % % % % 8 Third % % % % % % % % % % % % % % % % % % % % % % 19 Fourth % % % Fifth % % Sub-Total Infested Areas Total Infested Area (%) Moreover, the total infested areas by submerged aquatic weeds on the shoreline of the seven located islands within the five sub-reaches were monitored as listed in Table (5). Table (5): Monitored Infested Area on the islands Shoreline No Island name Distance (km) Infested Island area location From To (km) (km) (m 2 ) 1 El Akool island First reach El Hamodia island First reach El Shawaria island Second reach El Kanawia island Third reach El Sahel island Fourth reach El Kalh island Fourth reach El Wasta island Fourth reach Total infested area on the islands shoreline This showed that the total infested area by submerged aquatic weeds on the shorelines of the seven islands is m 2 as shown in Table (5). The mean percentage of infestation was 0.29 % by ditch bank weeds while no floating weeds were detected along the entire reaches. It can be concluded from the monitoring investigation that the studied reaches has been suffering from a remarkable amount of the aquatic weeds infestation. 271

9 4-1-3 Submerged weeds intensity The intensity of moving submerged aquatic weeds was measured along the upper 4.0 m layer depth under water surface in the study reach by using weed sampling device. The device consists of 4.0 m rode length which is fixed on floating cylinder hollow to control the device balance and float on the river flow surface. There are two movable light rods 1.0 m length each which are installed on the long rod, each light rod was supplied with several bolts 0.1 m length for capturing the moving submerged weeds at different water depths. Submerged weeds intensity was identified by using the device at four different water depths from water surface of 0.5 m, 1.0 m, 2.5 m, and 4.0 m in turn for thirty minutes time at each water depth. The device was examined in different locations along cross sections (1 and 2) as shown in Figure (3) directly upstream the new barrages, and cross section (5) directly upstream the old barrages. The captured submerged weeds around the bolts were collected and weighted for each water depth. The collected weight of weeds in thirty minutes directly upstream the new barrage was 1450 gram at water depth 0.5 m and 650 gram at 1.0 m water depth while no weeds were detected at 2.5 m and 4.0 m. While the collected weight of weeds in thirty minutes directly upstream the old barrages was 1400 gram at 0.5 m flow depth and 475 gram at 1.0 m water depth while no weeds were detected at 2.5 m and 4.0 m depth. The huge amount of moving submerged weeds with river flow was estimated by 25 tons per day directly upstream the new barrages, and 23 tons per day directly upstream the old barrages which are accumulated at the hydropower plant intake structure and trash rack. It can be concluded that, the submerged weeds in the studied reach moved with river flow along the upper layer of water surface (2.0 m depth) Submerged weeds moving trends The moving trend of submerged aquatic weeds was identified in different locations of the study area by using pieces of floating woods. Movement of six floating pieces were monitored from upstream El-Wasta island at km downstream of "OAD" to the old barrages by using surveying device as shown in Figure (6). The floating pieces were placed at equal distances between right bank and left bank of the river stream. The first, second and third floating pieces tracks (1), (2) and (3) directly moved toward the old barrages between the right bank and El-Wasta island. The fourth floating piece track (4) moved directly toward the old barrages between the left bank and El-Wasta island. While the fifth and sixth floating pieces track (5) and (6) directly moved toward the old barrage navigation lock between the left bank and El-Wasta island. This concluded that, 67 % of the floating weeds moved toward the old barrage, and 33 % moved toward the old barrages navigation lock. Movement of the five floating pieces were then monitored in the third sub-reach from upstream El-kalh island at km downstream of "OAD" to the end of the island at km by using surveying device as shown in Figure (7). The floating pieces were placed at equal distances between left bank and Elkalh Island. The first and second floating pieces tracks (1) and (2) directly moved toward the shoreline of El- Kalh island. The third, fourth and fifth floating piece tracks (3), (4) and (5) directly followed the stream flow. It can be concluded that, 60 % of floating aquatic weeds in the study reach moved directly with the stream flow, and 40 % of floating aquatic weeds in the study reach moved toward the shoreline of El-Kalh Island. 272

10 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, March 2015 Old Naga Hamade Barrage Track Track 1 2 Track 3 Track 4 Track 6 Figure (6): Aquatic Weeds Track Lines within the Second Sub-Reach Directly Upstream the Old Barrages Track1 Track 2 Track 3 Track 4 Track 5 Figure (7): Tracks of Aquatic Weeds at El-Kalh island. 4-2 Monitoring by Using "RS" and "GIS" Monitoring and classifying aquatic weeds were additionally carried out through the entire length of the study reaches by using Remote Sensing "RS" and "GIS". Submerged and ditch bank aquatic weeds infestations were identified in the reaches. The evaluation showed that the floating aquatic weeds have not 273

11 found allover the entire studied area. For the submerged aquatic weeds the Moriophyllum spicatum and Ceratophyllum demersum were the dominant species. While for the ditch-bank aquatic weeds, the Hycoscyamus muticus and Rumex dentatus were the dominant species. The current study focuses on the acquisition of satellite images (LANDSAT Thematic Mapper) of the studied area. Landsate satellite image with global positioning system "GPS" and geographic information system "GIS" technologies were used to distinguish and map the distribution of submerged and ditch bank aquatic weeds in the study reaches in the following sequences: Spot 5 imagery was used with medium accuracy from 1 to 5 m for detecting and classifying the aquatic weeds. Arc Gis 8.1, ERADS imagine and AutoCAD were used to prepare, digitize and analyze the images for layout the maps. Three methods for detecting and classifying the images were used as follows: A- Supervised and unsupervised classifying method. B- Band ratio by Band calculation. C- NDVI (Normalized different vegetation index). The process of these images and the implementation and application of "RS" were carried out to estimate the aquatic weeds infestation. Table (6) shows the water surface area for the five studied reaches, the infested area by submerged and ditch bank weeds, and the percentage of infestation for each reach. The total infested area by submerged and ditch-bank weeds was estimated by m 2, the submerged weeds m 2, and the ditch bank weeds m 2. The total water area for the studied area was m 2, the total infested area by submerged and ditch-bank weeds was m 2, and the results revealed that the percentage of submerged and ditch-bank weeds infestation was 20.0% in August Also Figure (8) show the satellite images for the study area from new Naga- Hammady barrages to 38.0 kilometer upstream the barrages in August Reach No. Table (6): Monitored Infested Areas Distance (km) From (km) To (km) Area (m 2 ) Infested area (m 2 ) Infeststion intensity First % Second % Third % Fourth % Fifth % Total infested area % 274

12 4-3 Weed Control Utilities Figure (8): Infested Area by Submerged and Ditch Bank Weeds in August 2011 To overcome the current problem, which has an environmental impact, some assured utilities have to be introduced. Using the available knowledge in this field, the basic technical data were used, and the famous approaches and special techniques had been applied to analyze, suggest, and design such works. With this in mind, the breakdown problem of the new Naga Hammady barrages hydropower plant for several hours daily can be considered due to the following causes: The infested weeds are extended along the river far upstream the new barrages, and every where along the shallow depths and island sides within the study reach. The traveling aquatic weeds are moving with the stream, crossing old Naga Hammady barrages and its navigation lock then directed towards the intake structure of the hydropower plant with water current. The problem is mainly due to the moving aquatic weed peaces within the upper 2.0 m under water surface. Breakdown of the hydropower plant is gradually occurred cumulatively in accelerating trend, which requires complete protection upstream the new barrages. Therefore, successive weed traps and weed control lines might be necessarily arranged along the upstream reach to increase the hydroelectric power plant operation efficiency. To control the aquatic weeds in the studied reach in an efficient manner, a compound system of barriers and racks have been designed and constructed, which consists of the following units: 1. Upstream reach barriers; which consist of simple floating buoys with submerged trash racks as shown in Figure (9). Buoys would be fixed to the river bed by using concrete blocks and attached to river banks by stiff cables. The first barrier would be located at km downstream "OAD" on the left river bank with total length of 100 m between the new and old barrage as shown in Figure (10). The second barrier would be installed at km downstream of "OAD" between the river right bank and El-Wasta island with 230 m total length upstream the old barrages as shown in Figure (11). The third barrier would be located at km on the west bank of El-Kalh island with 100 m total length. The barrier should fulfill its purpose if sufficient maintenance and attention have been taken place. 2. The old Naga Hammady barrages sliding trash racks; would be installed in the frontal maintenance groves of the old barrage piers to a certain depth to prevent weeds peaces from passing the opening 275

13 vents of the barrages. The racks have been designed in an efficient angle to collect weeds, and rigid enough to resist the working pressure as shown in Figure (12). Moreover, the possible rack side effects had been studied and minimized (such as the generated upstream heading up and the resulted flow velocity distribution). A K N E B W.L. L W.L. D C Figure (9): Detailed Design of the Upstream Reach Barriers at km , km and km Downstream of "OAD" 276

14 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, March 2015 Figure (10): Proposed Barrier Location at km Upstream the New Barrage Figure (11): Proposed Barrier at km Upstream the Old Barrages 277

15 L150X150X15 PL 330 x 330 x10 mm PL 330 x 330 x10 mm [ 280 ب كرة [ 280 L150X150X15 PL 410 x 500 x12 mm L150X150X15 PL 410 x 500 x12 mm [ 280 [ 280 L150X150X15 L150X150X15 Figure (12): Proposed Old Naga Hammady Barrage Trash Rack 278

16 If the proposed barriers system is installed in a complete way (with all components working together in a harmonic manner), and exerting sufficient active maintenance efforts, the system will be capable of controlling the aquatic weeds upstream the hydropower plant with high efficiency. 5- SYSTEM DESIGN To achieve final practical design of the control system components, detailed design have been carried out, and the following concepts have been taken into consideration. 5-1 The Upstream Reach Barriers The barrier units had been designed and constructed in a specified shape as shown in Figure (9) to suite its purpose and all the required calculation and stresses checks have been carried out. The buoyancy of the barrier units was checked with the proposed buoy unit shape. Loads on submerged trash racks according to weeds existence and water current have been considered. Fixation devices have been designed in order to hold the barrier considering all the probable loads, the required fixing anchorage blocks, and mooring utilities (wires, chains, and locks). All related items such as river bed material frictional capacity with anchorage blocks, water current velocity, and shear stress have been sufficiently considered. The developed barrier is a buoy system, each unit provided with labors walk, and a frontal inclined trash rack (for 2.2 m depth). Buoys are built from steel sections and filled with foams to save buoys from sinking. The buoy units are anchored to each other and to anchorage blocks on the river bed, which are responsible for barrier fixation. The barrier units were designed to fulfill all the following requirements:- 1. Preventing weeds > 20 cm from passing to the intake structure of the hydropower plant. 2. Sustaining weeds load and water pressure on it (shear, drag and hydrostatic forces). 3. To be held completely by the anchorage blocks on the river bed considering all loads on the barrier, and the blocks frictional resistance on the bed material. 4. Validating safety for the barrier by using side anchorage between buoys units, and for the labors by using labor walks for maintenance availability. The barrier units have been suggested and designed in a specified shape, which consists of the following:- 1. Floating unit (A). 2. Frontal trash-rack, which prevent weeds and defend the intake from aquatic weeds & debris (B). 3. Anchorage block (C). 4. Chain for connecting floating unit with anchorage blocks (D). 5. Pocket in the floating unit can be filled with sand for adjusting the barrier unit balance (E). 6. Top maintenance walk path for maintenance workers (k). 7. Hand - rail, 8. Safety utilities likewise; extra side anchorage, safety handrails, and buoy s inner foam filling (L). 5-2 Old Naga Hammady Barrages Trash Racks Trash racks are normally selected to prevent some debris from passing through the old barrage vent, and the rack type varies according to the design target. The used racks were designed and constructed specially to prevent the weeds of big size from reaching the hydropower plant, and meet new Naga Hammady barrage requirements. The tight steel trash racks were installed in the frontal maintenance groves of the old Barrage piers, to a certain depth to prevent weeds from passing the barrages opening vents. The racks are firm removable and vertically adjustable (with changeable water levels) with an efficient angel to easy collect weeds, and made rigid enough to resist the working pressure. Designation process had considered the working loads existed on the racks resulting from hydrodynamic forces (shear with weeds and rack bars), and hydrostatic forces resulting from the small expected head difference. Rack was adapted to lie in a certain angel of inclination, and allow for easy weed collection. The rack dimensions are 3 m height and 6 m width for each vent as shown in Figure (12). Finally probable hazard had been studied to ensure safety of 279

17 old Naga Hammady barrages with the maximum expected Heading-up resulting from entire rack blockage by weeds. 6- MAINTENANCE PROGRAME Removal of the aquatic weed in Nile River is commonly executed by means of mechanical equipments. However, the current maintenance programm can be considered ineffective for controlling the aquatic weeds upstream the old and new Naga Hammadi barrages. Although there are a nubmer of harvesters, more than 4 harvesters, exist upstream the old barrages, but they are out of order for long time and not in use. Those conditions lead weeds to grow and spread of weeds upstream the two barrages and threaten the hydropower plant operation as well as the existing hydraulic structures. For these reasons it is recommend to use floating units loaded with mechanical equipments. Two aquatic weeds harvesters and two floating hydraulic excavators are required for maintaining the studied reach (left, right shorelines and for the shoreline of the existed islands). While barrires and trach rack are recommended to be manually maintained by using hand tools and small boat. Dry weeds are later loaded into truck and transferred to the dumping locations. Labors included are harvester driver and assistant, crane operator, truck driver loader driver and two manual labors. The proposed maintenance program for the body of barriers and trash racks are as follows: Buoy body routine maintenance must be frequently carried out using anti-rust and anti foaling paints. Using the buoy crane, the rack will be tilted in an oblique angle, and drop the stuck weeds on the barrier deck, which could be removed later using some maintenance boats. Trash racks must frequently check for damage, accidents, or destroying safety by submarine check. Trash racks must be left up using the same frontal maintenance crane and cleaned using water jet to remove weeds, debris and stuck bodies. 7- CONCLUSIONS 1. The applied method for solving the aquatic weeds problems upstream the new Naga-Hammady barrages can be considered as a practical example for treating such difficulty. Several field measurements and "RS" as well as "GIS" were carried out to assist development of particular solution for the problem which revealed the following: The infested weeds are extended along the river far upstream the new barrages, and every where along the shallow depths and island sides within the study reach. The traveling aquatic weeds are moving with the stream, crossing old Naga Hammady barrages and its navigation lock then directed towards the intake structure of the hydropower plant with the stream flow. The problem is mainly due to the moving aquatic weed peaces within the upper 2.0 m layer under water surface level. Breakdown of the hydropower plant is gradually occurred cumulatively in accelerating trend, which requires complete protection upstream the new barrages. 2. To control the aquatic weeds in the study reach, a compound system of barriers and racks have been designed and constructed, which consists of the following: The upstream reach barriers; each barrier consists of a compound floating buoy units, provided with submerged trash rack extended to 2.2 m under water surface. The first barrier would be located at km on the left river bank with 100 m length between the new and old barrage. The second barrier would be located at km betwen the right river bank and El-Wasta island with 230 m total length upstream the old barrages. Third barrier located at km on the west bank of El-Kalh island with 100 m total length. Sliding trash racks at old Naga Hammady barrages which would be installed in the frontal maintenance groves of the old barrages piers. 280

18 3. It is also recommend to use loaded floating units with mechanical equipments. Two aquatic weeds harvesters and two floating hydraulic excavators are required for maintaining the study reach (left, right shorelines and for the shoreline of the existed islands). While the proposed barrires and trach rack are recommended to be manually maitained by using hand tools and small boat. 4. Satisfactory and active maintenance program must be followed to maintain all the system elements performance with optimum efficiency. 5. The implemented solution for the aquatic weeds problems upstream each of old and new Naga- Hammady barrages led to enhance the generated hydroelectric power from the new barrages by 26% in July 2014 which recorded an average decline of 38% in year REFERENCES Ali, Reda M.(2000), Hydraulic characteristics of open channels with floating weeds, M. Sc. Thesis, Faculty of Engineering, Ain Shams University, Cairo, Egypt. Channel Maintenance Research Institute (2011), Aquatic weeds management upstream New Nagh Hamady Barrage, Delta Barrage, Cairo, Egypt. Chow, V.T. (1959), Open Channel Hydraulic. McGraw-Hill, New York. Hosam Ibrahim, Mohamed Bakry, and Sherif Saad, (2004), "Designing Barriers For Solving Aquatic Weeds Problems Upstream New Esna Barrage," World Conference on Energy For Sustainable Development: Technology Advances & Environmental Issues, 6-9 December, Cairo, Egypt. Hsieh, T., (1966), Resistance of cylindrical piers on open channel flow, Jour. of Hyd. Div., proc., ASCE., Vol. 90, Hy l, January, pp Khalil, M. B., (1969), Resistance and behaviour of a cylinder placed on bed of an open flow, submitted to the Bulletin of Science and Technology, Assiut University for publication. Ko, S. C., and Graf, W. H., (1972), Drag coefficient of cylinders in turbulent flow, Jour. Of Hyd. Div., proc. ASCE., Vol. 98, No. Hy. 5, May, pp