Introduction to Water Distribution System Analysis

CE 572 – Urban Water Systems Analysis

Larry A. Roesner, Ph.D., P.E.

Fall 2008

History of Water Distribution System Analysis

• 1936: Hardy Cross – steady state iterative algorithm solvable with slide rule

• 1960’s: Computerized Hardy Cross Models Wood’s KYPIPE (early 1970’s)

• Late 1970’s: Optimization algorithms (Alperovits and Shamir) and large system simulation capability (1,000s of pipes)

• 1990’s: Transient analysis on complex systems (water hammer)

• 1993: EPANet – Lew Rossman• 1996: H20Net – MWH Soft, Inc (EPANet with GUIs

and CAD interface)

Definitions

• water distribution system

• pipes, pumps, valves, and tanks

• junction nodes

• steady state

• extended period simulation (EPS)

• dynamic (unsteady) water quality modeling

• transient analysis

Modeling Philosophy

• System analysis to develop or improve a water distribution system taking into account:– Cost– Time– Safety– Ease of modification– Operation– Aid to communication

• The dilemma: simplicity vs. accuracy

Model Development

• Formulation (conceptual analysis)

• Calibration

• Verification, Validation, Confirmation

• Refinement

Problems of Modeling

• Complexity of the real system

• Calibration and data

• Sensitivity

• Numerical algorithms and methods

• Adaptation of the model to the real system

• Nesting of submodels

Model Formulation

Basic Terms in the Energy Equation

Solution of the Energy Equation

Problem

Solutions

H2ONET Solution

EPANET

http://www.epa.gov/nrmrl/wswrd/dw/epanet.html#toolkit

RD 4 – EPANET Introduction

• Access the EPANET Webpage and read the introductory material about the model

• Download EPANET from the Web or access it from ENS “Engineering Applications”

• Browse the EN2manual• Run the Tutorial• Due by Tuesday Sept 23rd