Analysis of Drinking Water Distribution System of Ahmedabad City
Analysis of Drinking Water Distribution System of Ahmedabad City, Using EPANET 2.0 –A Case Study
Sejal D Desai*, Dr. Gargi Rajpara**
*Research Scholar, KSV University, Gandhinagar, Gujarat
**Principal, LDRPE, KSV University, Gandhinagar, Gujarat.
Daily increase in water demand has lead to water crisis. The day will come when there will be water war. Municipalities in India are adapting new water policies and there by satisfying the water requirements of city. This paper describes about the detailed analysis of water distribution system of Jodhpur area, Ahmedabad. As the continuous water distribution system would be implemented in this area the system is assessed and analysed for continuous water supply and the demand. The whole area of Jodhpur is divided in to 5 District Metered Area (DMA) of which one area is used for the pilot project study. Various input data of population, elevation, length of pipe, demand of water in the area etc were collected from Ahmedabad Municipal Corporation. The software EPANET 2.0 was adapted for the hydraulic simulation of the network. The output results of pressure, discharge and velocity of water at various junctions and links of the pipes were obtained. The study concluded that as the elevation of the pipe increases pressure reduces that can be observed with the contour plot and graphical representation. Hence it was analysed that water distribution system is efficient enough to carry the continuous water supply to meet the rising demand of the area.
Key Words: EPANET 2.0, Water Distribution System, Pressure , Elevation, Contour plot.
Water is the essential element for the sustainability of living being. The ever increasing demand of water can be fulfilled on modern hydraulic modeling and designing software. Urban water distribution systems hold a critical and strategic position in preserving public health and industrial growth. One of the main goals of continuous water supply systems is to provide safe and protected drinking water to the consumers at sufficient pressures and quality. Urban water systems in Asia and Africa mostly provided intermittent water distribution system. In 2008, an upgrade to continuous water services was provided for 10% of the twin cities of Hubli-Dharwar in Karnataka state as per Karnataka Urban water Supply and Drainage Board Bangalore7.Surat City in Gujarat state 6, The Pimpri-Chinchwad1, Maharashtra’s Badlapur city2 and Nagpur, Maharashtra8 has also opted for continuous water distribution system. EPANET tracks the flow of water in each pipe, the pressure at each node, the height of water in each tank, and the concentration of a chemical species throughout the network. EPANET is designed to be a research tool for improving our understanding of the movement and fate of drinking water constituents within distribution systems. It can be used for many different kinds of applications in distribution systems for the analysis purpose 9. The design and analysis of water distribution system using EPANET appropriate water distribution network and provide minimum head loss, maximum pressure with efficient diameter of the pipe. This study would help the water supply engineers in saving time as this process is fast, less tedious, easy to incorporate the changes etc under one parasol 10.
Objective of the present study is to prepare the elaborate hydraulic model using Epanet 2.0, for an accurate result analysis. Data of Pipe material, Pipe diameter, Headloss detection, Reduce Level, demand of water, supply of water are collected from the wards under study area.
Unless a proper hydraulic model is prepared, it is not possible to convert old intermittent system into a 24×7 system. The approach adopted is of the category Part to Whole. In this approach, small District Metering Areas DMAs are prepared. These DMAs are then converted to 24×7 with various measures. Such DMAs are clubbed to create an operational zone.24 meter elevated tank is constructed to which water is supplied through pumping and then supplied to the designated water distribution system under gravity flow.During operation two conditions can occur (i) System is self sufficient and does not require further division into DMA; (ii) System is sufficient with respect to storage but operation wise certain pockets are still to attain 24×7 in totality. In such case, DMA will be demarcated with respect to the problems reported through water audit. Each DMA is hydraulically discrete (isolable) from adjoining area. It is fed with water from single point, the flow and pressures at key locations are continuously metered and measured which then give indication of the extent of leakages as well as high flow rates.
3. Case Study
Ahmedabad is located at 23o2’1″N and 72o35’6″E Gujarat, India. Ahmedabad Municipal Corporation (AMC) was established in the year 1950, it grew from an area of 52.49 Sq.Km. (in 1950) to 190.84 Sq.Km. (in 1991) over 43 wards. The area of the city is 466.00 sq.km. with population of 56 lacs souls. The city is divided in 6 zones, having 64 wards (Source:AMC).The two pilot projects were taken for the study project. That was ward covering areas of Naranpura, Junavadaj and Sardar Patel Stadium. Second ward was Jodhpur. District Metering Areas (DMA) of Anandnagar is taken for the study purpose.Out of this total area, the developed area of Jodhpur is 777.35 hectares. Area of Anandnagaris 185.9 hectares. Anandnagar is latitude and longitudes as 22? 59″ 19. 20″ N, 72? 29″ 52.00″ E.
Fig:-1 Location Of Anandnagar in Google Earth
Mean Sea level of Ahmedabad Junction is 52.500m.This is same as Reduced Level obtained from Google earth for Ahmedabad junction.
3.1 Water distribution system Network of Jodhpur Area
Treated Water from 30 lacs liter capacity ESR at Jaspur headwork transmit through 350 mm to 800 mm dia. gravity main to four water distribution system in the underground sump,from there water will be transmitted to proposed ESR through pumping main. The total length of proposed pumping main is 2.83 km. The size of pipeline is diameter 600mm of length 2.41km and diameter 450mm of length 370m and diameter 350mm of 50m length. From the ESR, water will be transmitted to consumer through existing distribution network. Pipes are laid with diameters ranging from 100 mm to 600 mm from the ESR to distribution system. Total length of distribution network is 90.0 Km for Jodhpur area. Anandnagar is having total length of water distribution line as 26.31km. House service connection will be given with AMR water meter to each consumer.
Water distribution is done by the grid system. From water treatment plant at Jaspur to Prahaladnagar diameter of trunk main pipe is 2100mm, material is mildsteel pipe line.Water treatment is carried out at Jaspur water treatment plant with chlorination treatment.Jodhpur ward is ward no. 50 and area is 23.34 sq. kms of total area of Ahmedabad of 466 sq kms.Population of the Jodhpur area is 95444. (Reference:Census Department-ward wise population data 2011)Height of over head tank is 24 m. ESR at Anandnagar of capacity 15 lakh liter with diameter 20m. Anandnagar underground water storage tank has a capacity of storage capacity is 27 lac liter.Metropolitan and mega cities provided with piped water supply where sewerage system is existing (As per CPHEEO Manual) for domestic uses 150 lpcd. Add for unaccounted for water (UFW) 15% (Minimum) as 22.5 lpcd.totaling up to 172.5 lpcd. Add for Water for commercial, institutional and civic amenities (minimum) 7.5 lpcd. Therefore total amount of water is 180 lpcd.
4.0 Population Projection:
The population forecast of proposed project area has been estimated by the following
mathematical methods as per CPHEEO Manual on “Water Supply and Treatment” (3rd edition).
(1) Arithmetical Increase Method
(2) Geometrical Increase Method
(3) Incremental Increase Method
The detailed calculations for projected population for all these method for the years 2017, 2021 and 2031, 2041 AD are worked out as below:-
4.1Arithmetic Increase Method
This method is based upon the assumption that the population increases at a constant
rate;ie. The rate of change of population with time (ie. dp/dt) is constant.
Pn=Prospective or forcasted population after n decades from present
(ie. Last known census)
PO= Population at present(last know population)
n= No. of decades between now and future
Xavg=Average(arithmetic mean) of population increase in the known decades.
Table:-1 Arithmetic increase method
3.2 Geometric increase method
In this method, the per decade percentage increase or percentage growth rate (r) is assumed to be constant, and the increase is compounded over the existing population every decade. This method is also known as uniform increase method.
Pn + P (1 + IG / 100)n
P = Present population, N = No. of decades
Geometric mean IG = 28556 / 95444 = (0.2999) = 0.2999
IG = 29.9%
Table:-2 Geometric increase
3.3 Incremental increase method
In this method, the per decade growth rate is not assumed to be constant as in the arithmetic or geometric progression methods; but is progressively increasing or decreasing, depending upon whether the average of the incremental increases in the past data is positive or negative.
Pn = Po + n.X (avg) + n (n + 1)/2 xY (avg)
Table:-3 Incremental increase method
Year Population Incremental Increase X Incremental increase Y
2011 95,444 – –
2015 1,24,000 X (Avg)= 28556 Y(Avg)= 28556
X (avg) = Average increase of population of known decades
Y (avg) = Average of incremental increase of the known decades
Table:-4 Comparative Statement Showing Anticipated Population Projections by various methods, suggested by CPHEEO Manual
Arithmetic increase Geometric increase Incremental increase
2017 1,29,711 1,30,660 1,33,137
2021 1,35,421 1,37,678 1,43,418
2031 1,52,556 1,61,076 1,81,112
2041 1,81,112 2,09,237 2,66,780
Name of Zone Population Water Demand
In MLD @ 180 lpcd
2011 2015 2017 2021 2031 2041 2011 2015 2021 2031 2041
133137 143418 181112
25.81 32.6 48.02
Table:-5 Water Demand for various years
4. Hydraulic Simulation of water distribution system Analysis
EPANET can be used to plan and improve a system’s hydraulic performance (Rossman, 2000). In EPANET links represent pipes, pumps and control valves while the nodes represent junctions, tanks and reservoirs. Junctions are points where links join together or where water enters or leaves the network. The model requires elevation, usually the mean above sea level, water demand as input parameters and it outputs hydraulic head, pressure for each node. Junctions can have varying demand, negative demand implying that water is entering the network. Reservoirs are nodes that represent an external source of water to the network (Rossman, 2000).
Tanks are nodes that have storage capacity. The volume stored can vary with time during simulation. The input parameters for tanks are the bottom elevation where the water level is zero, the diameter, the maximum and minimum water level and the initial water quality. The model computes and outputs hydraulic head and water quality over the simulation period.
Flow direction is from the end at higher hydraulic head to the end with lower hydraulic head. The hydraulic input parameters for pipes are start and end nodes, diameter, length, roughness coefficient and status. The model computes and outputs the flow rate, velocity of flow, head loss and the Darcy Weisbach friction factor (Rossman, 2000).
Benefits of EPANET system are 1. Places no limit on the size of the network that can be analyzed 2. Computes friction head-loss using the Hazen-Williams, Darcy-Weisbach, or Chezy-Manning formulas 3. Includes minor head losses for bends, fittings etc 4. Allows storage tanks to have any shape 5. Considers multiple demand categories at nodes, each with its own pattern of time variation.
Fig:-2 Successful run of Anandnagar in EPANET
5. Results and Conclusions
Contour plot of base demand is ploted as shown in fig. 3 and it is observed that demand is more in the areas of densely populated of 1.6lps to sparsely populated area of 0.4lps.Pressure observed in the contour plot as in fig.4 shows that the pressure varies between 20 m to maximum of 39 m. Contour plot of elevation as shown in fig. 5shows that area under the study is varying between reduced level above mean sea level from 40.00m to 60.00m.as shown in fig. 6 it is observed that there is constant increment in the population from year 2011 to projected population year 2041.Among all the three method highest forecasting of population is obtained by calculation in incremental increase method .which is taken for base demand at each junction in EPANET .It is found from the fig.7 that with the increase in the ground elevation pressure in the pipe reduces and vice a versa.
EPANET software used for the analysis of the network at the Anandnagar is showing Successful run. This shows that with this hydraulic performance can be planned and improved wherever lacking .There is an increase in the population of The output results are graphically represented. It is observed that negative direction in the results shows the reverse flow directions.
Figure:3 Contour plot of base demand
Figure:4 Contour Plot of pressure
Figure:5 Contour Plot of elevation
Figure:6 Graphical presentation of population increment
Figure:7 Graph representing Elevation and Pressure
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