Hydraulic Simulation of Existing Water Distribution System using EPANET at Dire Dawa City, Ethiopia

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1 Indian Journal of Science and Technology, Vol 9(S(1)), DOI: /ijst/2016/v9iS1/106859, December 2016 ISSN (Print) : ISSN (Online) : Hydraulic Simulation of Existing Water Distribution System using EPANET at Dire Dawa City, Ethiopia G. Venkata Ramana 1, V. S. S. Sudheer 2 and L.V. N. Prasad 3 1 Department of Civil Engineering, Institute of Aeronautical Engineering (IARE), Jawaharlal Nehru Outer Ring Road, Dundigal, Hyderabad , Telangana, India; ramanagedela@gmail.com 2 Department of Hydraulics and Water Resources Engineering, Debre Tabor University, Debre Tabor, Ethiopia; royal.sudheer@gmail.com 3 Department of Computer Science and Engineering, Institute of Aeronautical Engineering (IARE), Jawaharlal Nehru Outer Ring Road, Dundigal, Hyderabad , Telangana, India; lvnprasad@yahoo.com Abstract The objective of this work is to simulate distribution network and to enhance the efficiency of existing water distribution network to supplying potable water to end users round the clock. Network of the study area is simulated in EPANET by using latest imagery of the study area is collected using Google satellite imagery as per the known latitudes, longitudes for the study area. The scheme design is prepared so that required output is obtained by using available input parameters like population of the study area, rate of growth in population and elevation at required point to install service reservoir. Therefore with all the available input parameters, now the network is run through EPANET tool and the results are thoroughly checked with standards. At the final step, the output results that are obtained after successful RUN from EPANET tool, they are cross checked thoroughly with standard required values. If any of the corresponding values are not within permissible limits, then the network is adjusted accordingly to the required input parameters and again the network will be examined in EPANET tool. This process is repeated until the parameters like velocity, friction factor, water head, pressure head, diameter and friction factor values are in the specific range. Pressure head at all nodes in the study area are having sufficient pressure to extract water. Flow in all pipes or links are adequate enough to withstand the pressures at nodes. Roughness coefficients of pipes are all quite sufficient as the head loss due to friction is little. It is also proposed to install air valves at high elevations and sluice valves at low elevations. The practical applications like, plan and improve a system s hydraulic performance, maintain & improve the quality of water delivered to consumers and study the disinfectant loss and by-product formation. Keywords: EPANET, Hydraulic Simulation, Links, Nodes, Water Distribution Network (WDN) 1. Introduction Modeling rural networks and irregular water supply systems is a challenging task because these systems are not fully pressurized pipeline networks but networks with very low pressures, with restricted water supply hours per day. Hence, Hydraulic simulation of Water Distribution Networks (WDN) becomes a major and challenging task for the present hydrologists as it involves complex and more skill during the process of analysis and simulation. As WDNs are mainly focused on to convey potable water from the water treatment plant to the end users. Simulation of WDNs using various softwares provides and improves the ability to mathematically replicate the nonlinear dynamics of a water distribution network by solving the governing set of virtual steady state hydraulic equations that include conservation of mass and conservation of energy elements 1. In recent days, many numbers of numerical methods have been used like Newton Raphson method and Monte Carlo Method etc, of which former is quite common and in wide use now a day. In addition to above two methods mentioned, a number *Author for correspondence

2 Hydraulic Simulation of Existing Water Distribution System using EPANET at Dire Dawa City, Ethiopia of packages are made available that allow fit simulation models to be constructed for WDNs. Among the all, most popular packages include EPANET (US Environmental Protection Agency Network), AQUIS (7T), Info works (Wallingford software), and Syner GEE (Advantica). The design of distribution networks using these software packages has developed from trial and error to, more recently, the use of various forms of optimization, including genetic algorithms. This paper highlights the main importance and procedure of hydraulic simulation of WDN at Dire Dawa city, Ethiopia. Also, it was mainly concentrated on the network analysis using EPANET software as it was having a wide range of applications and mostly accepted tool by many of Government Organizations. Detailed procedure and applications of EPANET tool are briefly described in the following sections. Finally, it evaluates flow of water in each link, pressure of water at all nodes and height of water in tanks in terms of pressure head etc irrespective of size of network. Provides easy user interface atmosphere during analysis process. Generates graphs and contours for various parameters with different time periods as shown in Figure 1. It also can duplicate demands which vary over time. It also has a capability to add backdrop for the network, which illustrates real or existing prominent features on the ground which can be seen in Figure Applications of EPANET In addition to above considerations for considering EPANET, in this section, some supplementary applica- 2. Role of EPANET in Network Analysis The history of water distribution network analysis from primitive period to recent periods has been briefly recognized with many challenges from day to day and involving many complications. American Water Works Association (AWWA) has recognized the development of water distribution systems and analysis methods from wood pipes to the modern piping materials that are existing today is from crude rule of thumb analysis to lengthy long-hand iterative Hardy Cross method to modern computer aided design 2. Of all the various available computer tools, EPANET is considered to be mainly advantageous because of following considerations. Can model systems of any size Computes friction head loss using one of the following equations such as Hazen Williams s method, Darcy Weisbach method, Chezy Manning s method. Allows minor head losses for bends, bends fittings, etc. Computes pumping energy and cost. Models storage tanks of any shape irrespective of its diameter and height. Allows multiple demand categories at nodes, each with its own pattern of time variation. Traces contamination in the source, provided with sufficient input parameters. Estimates the age of water and concentration of chemicals in the flowing water. Figure 1. periods. Figure 2. Multiple demand patterns for different time Background map showing with links / pipes. 2 Vol 9 (S(1)) December Indian Journal of Science and Technology

3 G. Venkata Ramana, V. S. S. Sudheer and L.V. N. Prasad tions can also strongly recommend usage of EPANET. They are as follows: Plan and improve a system's hydraulic performance Pipe, pump and valve placement and sizing Fire flow analysis Maintain and improve the quality of water delivered to consumers Study disinfectant loss and by-product formation Evaluate alternative strategies for improving water quality such as: i. Altering source utilization within multi-source systems, ii. Modifying pumping and tank filling/emptying schedules to reduce water age, iii. Utilizing booster disinfection stations at key locations to maintain target residuals Hence by considering all the above points, we can conclude that EPANET tool can be extensively used for Water distribution Networks 3. In this paper, EPANET tool is used for simulation of network and analysis. Figure 3. Map of Ethiopia with neighbouring countries. 3. Objectives The main objective of this paper is to simulate distribution network by using various softwares like AUTO CAD, GIS and EPANET tools etc. Also, it was mainly emphasised to improve the efficiency of the existing water distribution network in study area in terms of supplying portable water to end user round the clock. Besides the quality of water, we mainly underlined key parameters like required pressure heads at all nodes, diameter of pipes with sufficient flow using EPANET tool by the process of iteration. 4. Study Area Ethiopia, also known as The Federal Democratic Republic of Ethiopia, lies in Eastern Africa having several diversities with nine zones. The neighbouring or border countries that share with Ethiopia are Eritrea, Djibouti, Somalia, Sudan and Kenya. Study area, Dire Dawa, lie in the eastern part of Ethiopia country as shown in Figure 3 and Figure 4 represents the network map of Dire Dawa city. It covers about 1, 33, 262 hectares which is second largest populist city of the country. The geographical coordinates of Dire Dawa city are 41 o 38 E and 42 o 19 E longitude and 9 o 27 N 9 o 49 N latitudes. Altitudes of the country Figure 4. Map showing kebeles of Dire Dawa with boundaries, Ethiopia. vary widely which ranges from 1130 to 1335 meters above sea level. Study area is situated in the Awash River Basin, having Hills and steep slopes are found in the South, moderate and gentle slopes span to the north. The distribution system of the town is divided in to three pressure zones namely P-I, P-II, P-III. Of all these regions, study area of this paper, Sabiyan region belongs to P-II region ranging from 1195 to 1240 MSL (Above Mean Sea Level). The current sources of the water supply system for this study area are mainly from Sabian boreholes and Legedol Spring is known to have providing uninterrupted service for the last 100 years is expected to provide in the range of l/sec. In conjunction to this, Sabian Pumping stations are supplementing the gab by in water demand. Each of the regions in study area is consisting of its own service reservoir and proper distribution network based on population during the past years. The water distribution system for the present study area is of direct pumping to end users with storage during minimum consumption hours; stored in existing reservoirs and distributed by gravity systems during high consumption period of the day. The water distribution system for the Vol 9 (S(1)) December Indian Journal of Science and Technology 3

4 Hydraulic Simulation of Existing Water Distribution System using EPANET at Dire Dawa City, Ethiopia present study area is of direct pumping to end users with storage during minimum consumption hours; stored in existing reservoirs and distributed by gravity systems during high consumption period of the day. Figure 3 represents the entire network of Dire Dawa city which was divided into three zones namely P I, P II and P III which was already mentioned earlier. The corresponding network map of Dire Dawa along with boundaries of kebels is shown in Figure 4. But, in this paper, mainly Sabian region is considered for hydraulic simulation and network analysis by using EPANET tool. The concerned detailed road network for Sabian region is also shown in the Figure Methodology Following methodology is adopted during the network analysis for the study area and mentioned here below. Network of the study area is simulated in EPANET by using the latest imagery of the study area is collected using Google satellite imagery as per the known latitudes, longitudes for the study area 4. From the known latitudes and longitudes, Contours were generated with an interval of 5 m by using Global mapper software as shown in Figure 5 Contours play a key and vital role in any network analysis. Here prominent care should be taken while generating contours in view of latitudes and longitudes units. Figure 5 signifies that contours of study area with an interval of 5 m which is generated by using Global mapper software. Use of Auto CAD tool, road network map is generated which is shown in Figure 6. By knowing the demographics of the study area, population is forecasted for the required years say twenty or thirty years 4. The rate of demand per capita in litres is estimated from the previous records and total volume of water required is estimated. Thus, scheme design is prepared so that the required output is obtained by using various available input parameters like population of the study area, rate of growth in population and elevation at required point to install service reservoir etc as shown in Table 1. Therefore with all the available input parameters, now the network is run through EPANET tool and the results are thoroughly checked with standards. At the final step, the output results that are obtained after successful RUN from EPANET tool, they are cross checked thoroughly with standard required values. If any of the corresponding values are not with in permissible limits, then the network is adjusted accordingly to the required input parameters and again the network will be examined in EPANET tool 6. Figure 5. Contours of the study area generated using global mapper software. Figure 6. Network map of study area. 4 Vol 9 (S(1)) December Indian Journal of Science and Technology

5 G. Venkata Ramana, V. S. S. Sudheer and L.V. N. Prasad Table 1. Scheme design for the network i) Population as per 2008 (G C) census = No s Base Year of the Scheme i.e. completion of the scheme = 2017 No. of House Holds Growth of Population proposed = % By the method of Geometrical incremental method, population for the ultimate year is forecasted as follows: P n = P(1+I g /100) n Base year Population (2017) = No s Prospective population (2027) = No s Ultimate Population (2037) = No s This proposal is designed for a period of 30 years, where the forecasted population for the year 2037, from the base year is estimated to be No s. ii) Per Capita Supply (including losses) = 80 lpcd iii) Pumping hours = 15 hrs iv) Storage capacity (GLSR) = % of Prospective Demand v) Demand for year ( Base year) = lpd = lpm v) Prospective Demand for the year 2027 = lpd Prospective LPM = lpm vi) Ultimate Demand for the year 2037 = lpd Ultimate LPM = lpm vii) Infrastructure Source Bore Well Source = Bore well Storage capacity of OHSR = ltrs Assuming Fire and other emergency services, Therefore assume 10 % excess of the total capacity of the total volume of the tank 10 % total capacity = ltrs Therefore total capacity of tank to be provided as = ltrs Rounding off to the nearest value, Provide tank capacity as = liters = 7 Million liters Capacity of existing tank at Bridge café = liters 1.7 Million liters Hence, Finally provide tank capacity as = 5.30 Million liters Therefore, provide two tanks ( GLSR) of capacity each 2.7 Million liters for the Sabiyan region, Diri Dawa For GLSR - I R.L of GL. at GLSR = M Highest GL. in Distribution network = M GL at GLSR = M LWL of GLSR = M MWL of GLSR (LWL+10 M) = M For GLSR - II R.L of GL. at GLSR = M Highest GL. in Distribution network = M GL at GLSR = M LWL of GLSR = M MWL of GLSR (LWL+10 M) = M Vol 9 (S(1)) December Indian Journal of Science and Technology 5

6 Hydraulic Simulation of Existing Water Distribution System using EPANET at Dire Dawa City, Ethiopia This process is repeated until the parameters like velocity, friction factor, water head, pressure head, diameter and friction factor values are in the specific range. Following are some standard specified values for various hydraulic parameters. Maximum Static water pressure of 70 m and minimum of 3 m in the distribution network. Pipes with greater than 300 mm shall be used based on the corresponding ISO standards. The minimum and maximum velocity of flow should be fixed to 0.6 m/s and 2.0 m/s for distribution respectively. 5.1 Assumptions Following are some of the basic assumptions were made during the process of analysis. There should be a single link between two nodes. All the nodes are well connected with links at all junctions. In this network analysis, it was also assumed that all the pipes follow the existing road network. For the new proposed pipes, it was assumed that all pipes are laid left to the existing roads. Population forecasting is done by the method of geometrical progression method. In the initial run, diameters of pipes are assumed to be constant In this network analysis, material of all pipes are assumed to be same (i.e.,) PVC pipes. Hence, the roughness co-efficient of the pipes are also same. During the network analysis, head loss is estimated by using Hazen Williams Formulae. All the units used during this network analysis are in Metric system. Demands at nodes are distributed equally to all nodes. Distribution is of gravity type of system. Pipes / links used in the network used for distribution system were designed with a pressure of 4 kg/ cm 25. Hence from the above mentioned methodology and assumptions, as seen that the advantages are more when compared to disadvantages. Hence, it is strongly recommended to use EPANET tool for the network analysis. At this stage, as the network is all set with required input parameters, then it has to run in EPANET tool. The inputs that are assigned for the network and the scheme design of the entire distribution system are shown below. Table 1 represents scheme design of the entire network, which shows the population of the base year 2017, as well for both prospective and ultimate years say 2027 and 2037 respectively. This distribution system is mainly focused to design for the prospective year which shows that there is a total demand of lpm for the entire network. It can also be observed that, the total capacity of storage reservoir to be provided is 5.30 MLD including all fire and other emergency services. As the capacity of tank is seems to be high and due to its own constraints, two tanks of 2.7 MLD are proposed for this network. Table 2 represents rate of demand at each node required for the network, which was arrived by assuming there is an equal distribution of total demand corresponding to all nodes. Hence from the available data, inputs were assigned to the network and were shown in the following table. Table 3 indicates that input parameters assigned to network, like length between start and end nodes, assumed internal diameter of pipes with their roughness co-efficient (C) and nodal or base demand at nodes. As it was mentioned earlier, diameter and demand at nodes all are assumed to be constant which can be clearly seen from Table 3. As a final stage of analysis, with all the available input parameters, now the network is set into EPANET tool and it was thoroughly checked for output 5. Thereby, after two iterations, network RUN is successful, which can be seen in Figure 7. Table 2. Demand calculations for study area Assuming that there is equal number of population at each demand and therefore, demand is also equal at each node Perspective population from Scheme design No s Population for this network No s Rate of demand per each person as per scheme design 80 Lpcd Demand for network Lpcd Demand in lpm for network Lpm Number of nodes for the network ( From Epanet) 507 No s Demand at each node Lpm 6 Vol 9 (S(1)) December Indian Journal of Science and Technology

7 G. Venkata Ramana, V. S. S. Sudheer and L.V. N. Prasad On the other hand, output results were presented in the following sections in the form of tables and pictorial formats. Table 4 represents output generated after successful RUN using EPANET tool. From the above table, it can be Table 3. Link No. / Pipe No. Input parameters assigned for the network Start node End node Length (m) Assumed Diameter (mm) Base Demand (LPM) Roughness ( C ) seen that internal diameters of all pipes were fixed based on elevation, pressure head and nodal demands. In addition to above, it can also be observed that, parameter like velocity of water, head loss in pipes all are with in its permissible limits where those limits were mentioned in the earlier sections. Last two columns of Table 4 shows the pressure head and head of water in m at all nodes of the network. On Figure 7. area. Diameter diagram (output for links) of the study Table 4. Link no. / Pipe no Output generated from EPANET tool Start node End node Length (m) Diameter (mm) Flow (lpm) Velocity (m/s) Head loss (m / km) Head (m) Pressure head (m) Vol 9 (S(1)) December Indian Journal of Science and Technology 7

8 Hydraulic Simulation of Existing Water Distribution System using EPANET at Dire Dawa City, Ethiopia observing, the pressure head at all nodes is greater than that of assumed value i.e m. Hence, it can be concluded that water flows due to action of gravity to all the nodes without any obstruction. Note: As the numbers of pages are limited, we are unable to present all the input and output results related to nodes and pipes. Results or output for the part of network are shown in above Table 3 and Table 4 respectively. Besides to Table 4, overall values of different diameters of pipes and their corresponding lengths were shown clearly in Table 5. In addition to the above results, EPANET tool has the capability to produce pictorial results and graphs for various combinations between links and nodes. They represent the entire network in the form of pictures which was very helpful for thorough understanding. Some of them are presented below from Figure 7 to Figure 12. Figure 7 is represent s the diameter diagram (output for links) of the study area, Figure 8 is shows the flow diagram (output for links) of the study area. Also Pressure diagram (output for nodes) of the study area is shown in Figure 9 and Head diagram (output for nodes) of the study area is shown in Figure 10, which are all generated in EPANET tool, these are various pictorial outputs for the networks in different combination with nodes and links. They represent an easy way to analyse the net- Table 5. Length statement corresponding to different diameters of pipes Outer diameter (mm) Inner diameter (mm) Length for corresponding diameter Figure 9. area. Pressure diagram (output for nodes) of the study Figure 8. area. Flow diagram (output for links) of the study Figure 10. area. Head diagram (output for nodes) of the study 8 Vol 9 (S(1)) December Indian Journal of Science and Technology

9 G. Venkata Ramana, V. S. S. Sudheer and L.V. N. Prasad Figure 11. Contour plot for elevation of the study area. Pressure head at all nodes in the study area are having sufficient pressure to extract water. Flow in all pipes or links are also adequate enough to withstand the pressures at nodes. Roughness coefficients of pipes are all quite sufficient as the head loss due to friction is little. It is also proposed to install air valves at high elevations and sluice valves at low elevations 7. Acknowledgment At first, Authors are greatly thankful to the publishers and conference organisers for providing the best platform to enlighten the skills of various authors across the globe. The authors of this paper are grateful to the Dire Dawa City Administration, Water Supply and Sewerage Board for providing adequate information and guidance during the process of analysis. Last but not least, authors are also thankful to M.S Consultancy for providing basic information required for the smooth processing of this network. 8. References Figure 12. Contour plot for pressure of the study area. work at the required node or pipes. On the other hand Figure 11 is signifies as Contour plot for elevation of the study area and Figure 12 indicates the contour plot for pressure of the study area for entire Water Distribution Network (WDN). 1. Ayad A, Awad H, Yassin A. Developed hydraulic simulation model for water pipeline networks. Alexandria Engineering Journal Mar; 52(1): Ingeduld P, Svitak.Z. Modelling intermittent water supply systems with EPANET. In the Proceedings of Eighth Annual Water Distribution Systems Analysis Symposium (WDSA); 2006 Aug Machell J, Mounce SR, Boxall JB. Online modeling of water distribution systems: a UK case study. Drinking Water Engineering and Science. 2010; 3: Saminu A, Abubakar, Nasiru, Sagir L. Design of NDA water distribution network using EPANET. International Journal of Emerging Science and Engineering (IJESE) Jul; 1(9): Swamee PK, Sharma AK. Design of water supply pipe networks. A John Wiley and Sons; 2008 Jan. p Pipe networks analysis [Internet] [cited 2015 Oct 14]. Available from: pipe-networks. 6. Conclusion Once successful run is done using EPANET tool after simulation, following results may be drawn from the analysis. Vol 9 (S(1)) December Indian Journal of Science and Technology 9