Waterwork Management Model :

EPANET

Jinrui Ding

Department of Chemical Engineering 학번 : 200916158

OUTLINE

ArcGIS Exercises

Introduction

Numerical Method

Hydraulic and Water Quality Theory

Input Data

Output Data

Example Network

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The modeled network can consist of: Nodes:

• Pipe junctions• Storage tanks• Reservoirs

Links:• Pipes • Pumps • Valves

EPANET is a computer program that performs extended period simulation of hydraulic and water quality behavior within pressurized pipe networks.

What is EPANET ?

EPANET models:• Flow of water in pipes• Pressure at junctions• Height of water in tanks

• Concentration of a chemical• Water age• Source tracing

EPANET is designed to be a research tool for improving our understanding of the movement and fate of drinking water constituents within distribution systems.

Sampling program design Hydraulic model calibration

Chlorine residual analysis Consumer exposure assessment …

It can be used for many different kinds of applications in distribution systems analysis, such as:

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ArcGIS Exercises

Introduction

Numerical Method

Hydraulic and Water Quality Theory

Input Data

Output Data

Example Network

OUTLINE

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A water supply distribution system consists of a complex network of interconnected pipes, service reservoirs and pumps that deliver water from the treatment plant to a consumer. The distribution of water through the network is governed by complex, non-linear, non-convex and discontinuous hydraulic equations.

Two equations, which are used to determine if a network is hydraulically balanced, are the continuity and energy equations (Eqs. (1) and (2) respectively).

The continuity equation is applied to each node with qi the flow rate (in and out of

the node) and n the number of pipes joined at the node.

The energy equation is applied to each loop in the network with hi the head loss in

each pipe and m the number of pipes in the loop. The head loss is the sum of the local head losses and the friction head losses.

Hydraulic Model

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Water Quality

The governing equations for EPANET’s water quality solver are based on the principles of conservation of mass coupled with reaction kinetics.

Models reactions- bulk flow and at the pipe wall

n-th order kinetics 0 / 1 order

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(1)

(2)

(3)

ArcGIS Exercises

Introduction

Numerical Method

Hydraulic and Water Quality Theory

Input Data

Output Data

Example Network

OUTLINE

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The method used in EPANET to solve the flow continuity and headloss equations that characterize the hydraulic state of the pipe network at a given point in time can be termed a hybrid node-loop approach —— The "Gradient Solution Method".

Assume there is a pipe network with N junction nodes and NF fixed grade nodes (tanks and reservoirs). Let the flow-headloss relation in a pipe between nodes i and j be given as ：

The second set of equations that must be satisfied is flow continuity around all nodes:

Analysis Algorithms

(1)

(2)

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The Gradient solution method begins with an initial estimate of flows in each pipe that may not necessarily satisfy flow continuity. At each iteration of the method, new nodal heads are found by solving the matrix equation:

(3)

(4)

After new heads are computed by solving Eq. (3), new flows are found from:

If the sum of absolute flow changes relative to the total flow in all links is larger thansome tolerance (e.g., 0.001), then Eqs. (D.3) and (D.4) are solved once again.

EPANET’s water quality simulator uses a Lagrangian time-based approach to track the fate of discrete parcels of water as they move along pipes and mix together at junctions between fixed-length time steps.—— “Langrangian Transport Algorithm”

As time progresses, the size of the most upstream segment in a pipe increases as water enters the pipe while an equal loss in size of the most downstream segment occurs as water leaves the link. The size of the segments in between these remains unchanged.

ArcGIS Exercises

Introduction

Numerical Method

Hydraulic and Water Quality Theory

Input Data

Output Data

Example Network

OUTLINE

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Junctions / Reservoir • Coordinates ( can import from GIS )• Elevation / Total head• Demand (gallons per minute)• Initial quality

Pipes• Length • Diameter• Roughness coefficient ( Hazen-Willliams C factor)

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Pumps data• Start node• End node • Pump curve• Initial statue (open, close)

Valves data

Tanks data• Coordinates ( can import from GIS)• Elevation• Levels

• Initial• Minimum• Maximum

• Diameter• volume

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ArcGIS Exercises

Introduction

Numerical Method

Hydraulic and Water Quality Theory

Input Data

Output Data

Example Network

OUTLINE

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Junctions ( nodes )• Pressure• Quality (e.g., residual chlorine concentration )

Pipes ( links )• Flow (gallons per minute)• Velocity (ft per second) • Head loss (ft)

Tanks: inflow, level, quality Pump: flow rate

Tabular resultsGraphical results

Animated map results

Click on this video

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ArcGIS Exercises

Introduction

Numerical Method

Hydraulic and Water Quality Theory

Input Data

Output Data

Example Network

OUTLINE

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Click on this video first

Then click on this video

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ArcGIS Exercises

Introduction

Numerical Method

Hydraulic and Water Quality Theory

Input Data

Output Data

Example Network

OUTLINE

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1. Working with geographic features 2. Working with tables3. Editing features 4. Working with map elements

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