The Water Networks Modelling training in EPANet was conducted in Pune on 15th and 16th of December 2012. The training was conducted at the Hotel Studio Estique in City Centre and consisted two 6hr sessions of hands on experience in modelling water supply schemes. Trainees were from varied brackgrounds from consultancies and academics to NGO. We had attendees from Infosys, Ramky Infrastructure Ltd, CEPT University, Aga Khan Foundation and JMC Project Ltd. The trainees were provided with softwares, step by step guide to modelling and various resources to help with water networks modelling.
The training focused on hands on experience in using EPAnet to model various water supply elements, importing and exporting networks, integration with AutoCAD and Excel and analysing the network to get optimised result. The training session also included modelling practical situations in water supply where borewells, BPTs, pumping stations, pumping mains, storage tanks etc are involved.
All our trainees gave a very good feedback about the content, instructor and the overall training. The trainees were also provided with certificates in water networks modelling using EPANet.
The Community Engineer announces its next scheduled training on water networks modelling in Pune. The training will be conducted on 15th and 16th of December 2012. The training will consist a two day 12 hr session with hands on training in using EPAnet for analysis and design of water networks. The training will include presentations, step by step tutorials and will dedicate on practical modelling situations.
By the end of the training the aprticipants will:
Please see our training brief here.
Check out our training page for all the trainings we offer.
Participants shall be provided with tea and lunch during the session.
Accomodation has to be arranged by the participants themselves.
Participants are expected to bring their own laptop to work on tutorials and problem sets.
Can I model drip irrigation/sprinklers in EPANET?
Use the emitter option in EPANET. Use a default coefficient of 0.5. For accurate results this can be calculated based on the manufacturers specifications.
see Drip Irrigation Design Guidelines by Jess Stryker for more details
Can I model a borewell source in EPAnet?
All sources can be represented by a reservoir in EPAnet. A head pattern can be utilised to model the draw down curve if data is available. Headloss through the screens and piping can be modelled by using pipes and loss coefficients.
Can I model pumping main in EPANET?
EPAnet is not the ideal software for modelling a pumping main. Modelling a pumping main requires transient analysis, for which specialised software is available and more important an expert in surge analysis.
How do I model a Variable Speed Pump?
Use the control statements to define the relative speed of the pump with respect to the flow. EPAnet applies the pump affinity law to calculate the corresponding head - discharge relationship.
How do I calculate the balancing storage?
Balancing storage can be calculated using the mass curve method.
A mass diagram is the plot of accumulated inflow (i.e. supply) or outflow (i.e. demand) versus time. The mass curve of supply (i.e. supply line) is, therefore, first drawn and is superimposed by the demand curve. The procedure to construct such diagram is as follows:
From the past records, determine the hourly demand for all 24 hours for typical days (maximum, average and minimum).
Calculate and plot the cumulative demand against time, and thus plot the mass curve of demand.
Read the storage required as the sum of the two maximum ordinates between demand and supply line.
Repeat the procedure for all the typical days (maximum, average and minimum), and determine the maximum storage required for the worst day.
How do I fix the storage capacity of tanks?
The total storage capacity of a distribution reservoir will depend on the following.
Balancing Storage: The quantity of water required to be stored in the reservoir for equalising or balancing fluctuating demand against constant supply is known as the balancing storage.
Breakdown Storage: The breakdown storage or often called emergency storage is the storage preserved in order to tide over the emergencies posed by the failure of pumps, electricity, or any othe mechanism driving the pumps. A value of about 25% of the total storage capacity of reservoirs, or 1.5 to 2 times of the average hourly supply, may be considered as enough provision for accounting this storage.
Fire Storage: The third component of the total reservoir storage is the fire storage. This provision takes care of the requirements of water for extinguishing fires. A provision of 1 to 4 per person per day is sufficient to meet the requirement.
How do I model a Check Valve in EPANET?
Insert a link where a check valve needs to be modelled and then change the status to CV. This converts the link to a check valve (check reverse flow).
How do I model a Break Pressure Tank (BPT) ?
The simplest form of modelling a BPT is to model it as a tank with relevant elevation and storage. However since the tanks in EPAnet are modelled as connected from tank bottom, it is preferable to model the tank with a PSV in the upstream with a pressure setting = 0 (atmospheric pressure) and a check valve at the downstream to check reverse flow.
EPANET solver sometimes experiences difficulty with convergence to solution or the solution might differ from the expected. In such cases simulation parameters can be modified to solve the instability.
This sets the number of solution trials that pass during hydraulic balancing before the status of pumps, check valves, flow control valves and pipes connected to tanks are once again updated. The default value is 2, meaning that status checks are made every other trial. A value equal to the maximum number of trials would mean that status checks are made only after a system has converged. (Whenever a status change occurs the trials must continue since the current solution may not be balanced.) The frequency of status checks on pressure reducing and pressure sustaining valves (PRVs and PSVs) is determined by the DAMPLIMIT option (see below).
This is the number of solution trials after which periodic status checks on pumps, check valves flow control valves and pipes connected to tanks are discontinued. Instead, a status check is made only after convergence is achieved. The default value is 10, meaning that after 10 trials, instead of checking status every CHECKFREQ trials, status is checked only at convergence.
This is the accuracy value at which solution damping and status checks on PRVs and PSVs should begin. Damping limits all flow changes to 60% of what they would otherwise be as future trials unfold. The default is 0 which indicates that no damping should be used and that status checks on control valves are made at every iteration. Damping might be needed on networks that have trouble converging, in which case a limit of 0.01 is suggested.
Here are a list of Manuals available from the Urban Dvelopments Ministry.
There have been many questions raised in many forums regarding borewell performance, monitoring and maintenance/rehabilitation.
This post shall be dedicated to discussions on these aspects. Here I have discussed the performance aspect of borewells.
Processes Affecting Performance
1 Physical Process
drilling fluid invasion damage at the time of construction
inter-mixing of aquifer horizons as a result of wash-out and caving during drilling
inter-mixing of aquifer and gravel pack material due to poor installation procedure or
migration of fines from the formation into the gravel pack material due to high flows
migration of aquifer material and infilling of the borehole and pumping system
high velocity particle laden water
2 Chemical Process
coupling of dissimilar metals
impurities in the composition of metals
degree of surface protection
exposure to different conditions
differrence in metal treatment
3 Microbial Process
Microbially induced corrosion
sulphate reducing bacteria
4 Operational Factors
Inappropriate operating schedules
high pumping rate
Aquifer over abstraction
5 Structural and Mechanical Factors
Poor design and construction
poor installation of screen and casing
inappropriate use and placement of grouting materials
poor selection and installation of gravel pack
poor drilling technique
Inappropriate selection of borehole component materials
use of mild steel materials
sand pumping due to enlarged screen
pump failure due to corrosion
clogging by increased iron concentration and hence iron fouling
Water quality parameters and indicators
corrosion and iron incrustation potential
calcium carbonate incrustation
corrosion and iron incrustation potential (used in conjunction with pH)
- saline intrusion
- waste leachate
calcium carbonate incrustation
corrosion resistance (in conjunction with chloride)
aquifer contamination and potability
iron sulphide formation"
calcium carbonate incrustation
Turbidity and colour
iron and manganese content
dissolved carbon dioxide
clay/colloidal matter in suspension
Iron and manganese
incrustation and biofouling
iron incrustation and biofouling
Total organic carbon
microbial activity (see nutrients)
biofouling (eg Gallionella)
biocorrosion (eg Desulphovibrians)
treatment requirement (total coliforms, E coli)
Borewell Diagnosing has been methodically arranged in this spreadsheet. It also lists maintenance actions and methods.Borehole.xls
Hydraulic design is very important for sustainable borewell performance. It decides the screen enterance velocity and the vertical velocity inside the borewell. Commonly recommended value for enterance velocity is 0.03 m/s.
The velocity can be calculated using the following formula.
Ve - Enterance velocity
Q - Discharge in m/s
D - Diameter of screen in m.
L - Net length of screen in m.
p - Proportion of open area in screen
b - blocking factor (take a value of 0.5)
It is recommended to take a design value of 0.02 m/s for borewells with problems of incrustation and biofouling. In fissured aquifers the velocity need to be calculated emperically. (compare with existing borewells in same formation; carry out a trial and error to reduce sand ingress)
Reducing enterance velocity / design discharge have many benefits.
Sand ingress is reduced
Erosion of screen slots are reduced
Supply of nutrients are reduced
Loss of kinetic energy is reduced
What should be the factors that need to be considered while selecting a type of retaining wall? What data are required for design of a retaining structure?
Selection of an earth retaining structure should be carried out taking the following factors in to consideration.
1. Ground conditions.
2. Height of the retaining wall.
3. Ground water / tidal condition
4. Location of the wall and the overall space available.
5. External live loading
6. Life and maintenance
7. Materials available
8. Acceptable ground movement and its effects.
An economic comparison should be carried out in case more than one is suitable for a location. Carbon footprint may be calculated if the client requires a carbon minimizing design.
Design of a retaining structure shall require a load of information on site characteristics, soil properties and load conditions. It is essentially required to conduct a site investigation to gather information on site topography, ground water conditions, and physical conditions in the vicinity. Boreholes should be made to ascertain the soil condition and variability along the length of the wall. Safe depth for borehole would be three times the height of wall. In-situ test such as Standard Penetration Test or Stiffness test should be carried out to gather information on soil properties. Details of foundations of adjacent structures should also be collected. Existence of geological faults, joints and tendency of site to creep or settle should be established.
Design will require details of ground water conditions including seepage pressures and existence of any hydrostatic uplift pressures. Install piezometers where necessary to gather ground water conditions. Possibility of flooding should also be ascertained. Presence of corrosive chemicals in soil or ground water should be examined, so that corrosion prevention measures can be taken. In case of waterfront structure, maximum tidal range, possible surge waves and flooding conditions should be established.
Climatic variation such as temperature changes and rainfall variations along with its effect on earth pressures should be examined. During site investigation presence of trees or shrubs in the vicinity or at site should be noted. This may need to be removed if at close proximity. Soil samples for lab tests (Shear Box test, Tri-axial test etc) should be collected as per the requirements. See the relevant IS codes for details.
All necessary details regarding externally applied loads whether static or dynamic should also be collected.
Design should take in to consideration the different design situations. To list some of them
1. Worst case scenario of loads and its combinations
2. Geometry of structure required in worst condition
3. Material characteristics
4. Unplanned excavation or surcharge
5. Water pressure regime
7. Chemical corrosion
11. Tolerance to deformation
12. Change in ground water levels and seepage
13. Water pressure in tension cracks
14. Effect of time on strength
15. Long term effect of fault, cavities and joints
16. Effect of new structure or service of existing structure in future.
Provide expansion and contraction joints 10mm to 20mm thick at joints and suitable locations.
Hydrostatic uplift should be taken in to account at horizontal joints.
Where bearing quality is poor and soil likely to be saturated Gabions can be used as retaining structure. In such cases the density of fill material can be safely taken as 60% of the fill material.
Seismic design of earth retaining structures and foundations
Retaining and Flood Walls Design - USACE
Geotechnical Software Directory
Site Investigation Manual – US NHI
Selection of a particular technique should be after giving due consideration to the social and cultural aspects prevailing in that area since they are very important for the success of the technique implemented. It should also fulfill a number of basic technical criteria.
1. Soil - soils should have mainly properties of soil suitable for cultivation. It should not be salty or sodic. The infiltration rate should be less than the rainfall intensity so that it induces runoff. Avoid soils with sandy texture.
2. Slope - For area with slope greater than 5%, it is not recommended to have water harvesting structures since this will involve uneconomical earth work and shall affect from uneven distribution of runoff.
3. Cost - Will depend on the earth work or stone work involved. This shall be discussed separately in each systems with detailed quantities.
These are diamond shaped basins surrounded by small earth bunds. It will have an infiltration pit at the lowest corner of each. Runoff collected from the basin is collected in the infiltration pit. This method is suitable for small scale tree planting in area which is moisture deficit. These micro-catchments does soil conservation also apart from water harvesting.
Israel has the most widespread and best developed Negarim catchments.These are suitable for even areas with rainfall as low as 100mm to 150mm per annum.
The shape of each unit is normally square.
The soil should be at least 1.5m deep but 2m is preferred for better root development and storage of water. Negarim is suitable for slopes from flat to 5%.
Size of micro catchments vary from 10m2 to 100m2 depending on the plantation. More than one tree can also be planted in a unit. The area may be decided based on the water requirement of the tree.
Maximum size of the bund (at the pit) see table below
The least height of the bund should be maintained at 25cm. The width of the bund should be 25cm with a 1:1 slope on sides, with grass cover to avoid soil erosion.
The pit size can be decided as in table below.
Design variation of allowing overflow from each unit by constructing V shaped bund is also common. However the storage capacity will be less than closed system. These types can be done for broken terrains.
1. Find the contour line. Use a water level tube to establish the contour line. Even out the contour to get a smooth line. If the topography is very uneven, consider smaller units.
2. Use a tape to measure the tip of the bunds (1,2,3 etc) on the contour line. see the image below.
The distance between the points (1 and 2) corresponding to the unit size is shown below.
3. With a string of length equal to the length of unit, intersect the point 11 from points 1 and 2 (3m for a 3m x 3m catchment). Now the length 1-11 and 2-11 are equal to the length of the bund wall. Repeat this until the first row alignments have been marked.
4. Repeat the step 3 with points 11, 12 etc to make the second row. Continue this to make all the rows.
5. Stake out and dig the infiltration pits at the lower corner as per the dimension in the above table. Leave a small step towards the back of the pit to plant seedlings.
See the image below.
6. Clear all the vegetation before building the bund. Use the excavated material from the pit to form the bund. Build the bund in two layers, compacting each layer after wetting it. Use a string to keep the bund height uniform.
Contour bund is a simplified form of micro-catchments. Bund follows close contour and are separated in to micro-catchments through earth ties. These are more economical and suits particularly large scale implementation. It is more economical and efficient and their is suitability for cultivation of fodder or crops along with trees.
Contour bund is suitable for arid to semi arid areas where rainfall is 200mm - 750mm. 2m deep soil is preferred with smooth topography.Generally a spacing of 5m to 10m is adopted between the contours. An infiltration pit is dug between ties and bund wall. Diversion ditches are provided where necessary for protection. Common sizes of micro-catchments are 10m2 to 50m2.
Bund heights vary from 25cm to 40cm depending on the slope. Bund should not be less than 25cm height, and the base width must be at least 75cm. Cross ties should be at least 2m long at a spacing of 2m to 10m. Infiltration pit size is commonly 80cm x 80 cm and 40 cm deep. The excavated soil can be used to build ties.
1. Determine the contour using water levels. Make a uniform contour line.
2. Mark the alignment of the bund on the ground. Keep a spacing of 10m to 5m between the bunds depending on slope.
3. Determine the spacing between the cross ties depending on the area required for trees. Make an infiltration pit in the furrow above the bund. The pit should be at least 30cm away from the tie wall to enable planting seedling. Make ties at least 2m long with 25cm height and 75cm base width.
4. Build a lateral bund at the end to prevent loss of runoff. Connect the lateral bund to the contour bund.
5. Make a diversion ditch at the top of the block to divert any additional runoff from outside the block. Make it to 50cm deep with 1m to 1.5 width and a 0.25% slope.
Jalanidhi is acclaimed as the most effective of all rural water supply schemes ever implemented in India. More than 3500 water supply schemes have been completed under Jalanidhi in Kerala. Following the Olavanna model of participatory approach, Jalanidhi has attained an efficiency of more than 90% on the fund spent on the project.
To understand the success of the project, it is necessary to understand the philosophy behind this.
1. Demand driven approach - The Project will be introduced only in areas where interested groups of people show their willingness to participate in the project and abide by the conditions of cost-sharing. The group then gets a legal entity by registering themselves and only then proceeds with the rest of the planning.
2. Cost sharing - To ensure stake holding of the project, 15% of the capital costs should be borne by the beneficiary community. Grama Panchayath shall bear 10% and 75% is shared by the Govt.
3. Cost Recovery - The Beneficiary Groups themselves meet 100% of the recurring costs of operations and maintenance. This lightens the burden on the state exchequer, thereby helping the Govt. to utilise this money for other priority needs like in the health sector.
4. Integrated Approach - The objective of the projects is sustainability in supply of safe drinking water, source, operation/maintenance and quality of water which are met through well-integrated components. Sustainability of source is ensured through point-source recharge measures. Quality is ascertained through a mix of sanitation & hygiene promotion and provision of infrastructure like latrines, compost pits, drainage etc. Sustainability of system is ensured through community empowerment, capacity building, women empowerment and social mobilization.
5. Pro-Poor Approach - Special efforts have been taken in the project design to include the poor and vulnerable while selecting the user groups. The project has been so designed to incorporate the beneficiary contribution of 15% of capital costs either through cash or in kind, as labor. Intra-group subsidization and even inter- group subsidization is permitted at the behest of and under the total responsibility of the beneficiary groups. Thrift & Credit schemes are promoted in the Beneficiary Groups as "Self Help Groups" which are operated by the women of that group.
6. Women Development Initiatives - Women are the most affected both directly and indirectly, during water shortages. The project makes conscious efforts to mainstream the women users in the planning and decision-making activities. Apart from this, they are also encouraged to form "Thrift & Credit Groups" to help them make the payments towards the recurring expenditures of the water supply system. Income generation activities are also designed in the project where groups of women are given financial assistance and skill development training to start viable micro- enterprises of their choice.
7. Community Empowerment - Capacity building and equipping the community to operate the project is a major thrust area of this project as this is planned, designed, implemented, owned, and operated by the users themselves. This will not only ensure the involvement of the people but will also chart a new path to community- based approach for meeting any local needs.
8. Community Contracting - The users themselves are fully involved in all the activities right from identifying their sources, deciding on the technology to be utilised, community contracting and implementation till the operations and maintenance aspects of the schemes. All contracting of goods, works, and services will be done at the user level itself for which adequate training will be provided and guidelines made available.
9. Utilization of available resources - The Schemes already operational in these project areas, will also be rehabilitated, and handed over to the User groups. This will ensure efficient utilization of investments made.
10. Dovetailing with Decentralised Planning - This project will be operationalised through the Grama Panchayaths and the beneficiary groups, thereby acknowledging and strengthening the efforts of decentralised planning in Kerala.
One of the major driving forces behind this project was the committed people who supported this initiative from KRWSA district project management units and the support organisations. The project was successful even in tribal hamlets of Attapady where contribution to the scheme was collected as labour through trenching activities.
The project has eliminated corruption through community participation and transparency in each steps of the project. The community had opportunity to involve in procurement, material selection, material testing and quality monitoring thereby increasing transparency and accountability of the project. Initial and final estimates are discussed within the community, including the approved rates and specifications.
Community involvement has also accelerated the hygiene and sanitation drive in rural areas. Bulk purchases and supporting organisations negotiation skills have helped cost effective latrine constructions at many places including tribal hamlets. Locally available materials and skill have been effectively utilised to reduce the superstructure cost. Tribes have made use of bamboo and mud which are readily available in these areas.
The project has also executed many rain water harvesting structures where these are suitable enough for sustainable drinking water supply. Ferro-cement structures have enabled cost effective construction of rain water storage tanks. Support organisations like SEUF have been instrumental in popularizing ferro-cement structures and its construction by providing trainings and support.
The project has thus shown that if empowered the community can plan, design, construct and operate water supply schemes sustainably.
I stumbled upon this interesting story, from Baluti Village in Nainital about a middle class farmer, Padmadutta Balutiya.
According to the elders in the area, in the late 1880s, the water in the Nal Damyanti Tal and its vicinity used to flow in the form of a rivulet across an area two kilometers long and down the hills to Bhabhar and Tarai area. However, the water could not be used, whereas there was tremendous need for irrigation in the neighbouring regions. During that period, Bhabhar area was in the process of being settled and water for irrigation and drinking was necessary for the settlements. Robertson, the British Commissioner at the time, had a dam constructed to retain the water in Bheemtal, so that it would not be wasted and could be used when the need arose, especially during the summer. But the dam broke down during the rainy season. Colonel Ramsay, who succeeded Robertson, was a generous and intelligent officer who, at the request of farmers, decided to do something to solve the problem of water shortage. He thought that if a check dam was made, the water from the natural source that was flowing away could be collected in the valley and could then be transported through canals. Accordingly, he made a proposal and sent it to London through the Viceroy of India. The proposal was accepted and Ramsay decided to construct a check dam.
As soon as Shri Padmadutt Balutiya came to know that Ramsey was going to build a dam, he went to the site and checked the design of the dam. He felt that the design was flawed and told Ramsey that it would not be able to withhold the water pressure. He suggested that instead of the straight wall, if the dam could be constructed with a convex shape it would resist the pressure of water, because the force of water would not concentrate at a particular point but would be distributed evenly over the entire length, thus minimizing the water pressure. Unfortunately, Ramsay did not heed his suggestions and had the dam constructed ‘his way’. The dam was washed off in the first rain. Ramsay tried three more times, but each time he met with the same results. He was, however; still not ready to listen to Padmadutt Balutiya. The next time, Ramsay wrote to London, explaining his case and asking for a specialized engineer. The engineer came and started the work with a new design. Again Padmadutt went to Ramsay and suggested that if this dam could not withhold the water pressure, he should be allowed to build the dam the next year according to his design. Ramsay agreed.
Padmadutt returned to his farm, but he was thinking all the time about the site of the dam 25 kilometers away. Finally he sent one of his farm labourers to the work site and asked him to report within the first week of rain. As he had predicted, the dam was washed away in the first rain and his man reported this to Padmadutt Balutiya before the official message came from Ramsay. Padmadutt immediately set out for Ramsay’s office and waited outside his room. When Ramsay came out, Padmadutt told him that the dam has been washed away. Till then, Ramsay had not received any official message from the work site. Impressed by the interest and initiative taken by Padmadutt Balutiya, he called a meeting and instructed every body to follow Padmadutt’s advice.
The 109-year old check dam in Bheemtal is truly a modern day wonder. The dam, designed by the late Padmadutt Balutiya in 1895 continues to stand strong and has not required any repairs since its construction. The check dam was designed based on the old traditional method i.e. “lehria” method which has been used to make bunds for rice fields since ancient times. The check dam is constructed in the form of a canal shaped like an arc. Water is allowed to enter this canal so that the force of the water inside the canal reduces the force exerted by the water from the outer side. This enables the check dam to withstand the heavy force exerted by the water. The pressure on the second wall of the dam is automatically reduced, as it is not in direct contact with the larger volume of water. Several outlets are made on the second wall of the dam so that water is discharged uniformly. These outlets are at different levels so that water can be discharged in such way that it exerts minimum pressure in the process.
Among many reasons given for this dam to stand the test of time for so many years, one is that the shape of the dam facing the flow of water is convex. Due to the presence of water on both sides of the dam, the pressure on the dam itself is lessened. In addition, instead of only one sluice gate, the check dam has four gates that dissipate the water pressure on the dam structure equally. The building material is unusual. Instead of cement, traditional materials such as lime, flour, powdered pulses, and straw have been used.
It's yet another wonder that too little of us know about him and his contributions.
The community Engineer is not yet another site for knowledge transfer. This has been designed to empower and support engineers at grass root level to work more efficiently in contributing to the growth of the country. This is for the inexperienced, who needs exposure to best practices and tools to help them perform better. Purposefully hence this is not a forum for state of the art technologies, but for a practical approach to our all the more practical problems.
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