Water Supply System Modelling using WaterGEMS (Ex.3)

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Water Supply System Modelling using WaterGEMS (Ex.3)


Water Supply System Modelling (Tutorial 3)

Mastering water supply system modelling using computer software is essential for engineers these days. TheFluidMechanic would help you with the modelling process through a set of water supply systems tutorials. For this tutorial, Bentley WaterGEMS SELECTseries 5 will be used. You can follow this step by step tutorial (including screenshots) to understand how water supply systems are modeled from scratch. Finally, you can download the WaterGEMS hydraulic model for this tutorial at the end of the post to double check your work and make sure that everything is working all right. Lets start with our tutorial.

Objectives of WaterGEMS Tutorial 3 :

  • Using Pipes & Junctions Flex Tables
  • Performing Extended Period Simulation Analysis EPS
  • Performing Age Analysis
  • Creating Line Series Graphs for different elements in the hydraulic model
  • Defining & Assigning Demand Patterns to Junctions
  • Defining Tank Data (Elevations, Diameter & Inactive Volume)
  • Defining & Assigning Pump Definitions
  • Defining & Assigning Pump Controls

Problem Statement

A local water company is concerned with the water quality in its distribution network. The company wishes to determine the age and chlorine concentration of the water as it exits the system at different junctions. The water surface at the reservoir is 70 m. Chlorine is injected into the system at the source of flow, R-1, as shown in the following figure at a concentration of 1 mg/L. It has been determined through a series of bottle tests that the average bulk reaction rate of the chlorine in the system (including all pipes and tanks) is approximately 30.5 per day.

WaterGEMS Tutorials 3 - Pipe Network Layout

Demand Pattern :

WaterGEMS Tutorials 3 - Demand Pattern

Pipe Data :

WaterGEMS Tutorials 3 - Pipe Data

Junctions Data :

WaterGEMS Tutorials 3 - Junction Data

Pumps Data :

WaterGEMS Tutorials 3 - Pump Data & Controls

The tank is circular with a diameter of 15.0 m. The minimum elevation is 99.0 m. The maximum elevation is 104.0 m, and the initial elevation is 103.4 m. The base elevation is 98.0 m, and the inactive volume is 10.0 m3. The elevation of the pump is 70.0 m and it is initially on.

Part 1 : Perform an age analysis on the system using a duration of 7 days and a time step of 1 h. Determine the youngest and oldest water in the distribution system and the storage tank. Explain why water age varies.

Part 2 : Perform a constituent analysis using the same duration and time step as in part 1. Determine the range of concentrations in the system and the storage tank. Explain the behavior of the system with regard to chlorine.

Part 3 : Are the simulation results consistent with the known behavior of chlorine ?

Part 4 : Why is it necessary to run the model for such a long period of time? Do you feel 7 days is too long or too short a time period to test the model ? Why ?