Project Description

What This Release Covers

X-WHAT is an open-source Excel and WebGUI workflow for steady-state analysis and preliminary design optimization of looped water distribution networks. The browser tools prepare inputs and inspect outputs. The workbook carries the hydraulic and cost calculations with visible formulas and Excel's native GRG Nonlinear solver.

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Overview

The current release combines one Excel workbook, one browser-based network builder, one browser-based results viewer, a user manual, and the reference preprint. The project is designed for transparent workflows in which the user can inspect the inputs, equations, constraints, and outputs at each stage.

Problems Solved

  • Water Flow Problem (WFP/HSP): solve steady-state pipe discharges and flow directions under mass and energy conservation.
  • Design Optimization Modeling (DOM): adjust tank water depth and tower elevation while enforcing nodal pressure limits.

Inputs Required

  • Node elevations, demands, and fixed-head boundary data.
  • Pipe lengths, diameters, and friction data.
  • Loop definitions and incidence matrices.
  • Tank and pump parameters for design runs.

Outputs Produced

  • Pipe flows and flow directions.
  • Node heads and pressures.
  • Component-wise cost breakdowns for DOM runs.
  • Transfer files for the WebGUI and Excel workflow.

Workflow

The intended workflow is short and explicit. Draw the network, export the package, solve the workbook, then inspect the solved file.

1

Build the network

Use the Network Builder to place junctions, tanks, pipes, and loops, or load a tutorial case.

2

Export the package

Create a versioned .xwhat.xml package with geometry, parameters, and matrix definitions.

3

Solve in Excel

Import the package into X-WHAT_Model_V1.5.xlsm, run the GRG Nonlinear solver, and save the solved workbook.

4

Inspect the results

Upload the solved workbook to the Results page for pressures, flows, and cost summaries.

What the WebGUI does: it prepares and interprets project data. The hydraulic and cost calculations themselves remain in the Excel workbook.

Validation and Evidence

The public materials report validation against EPANET and published reference cases for three networks of increasing complexity.

Case (A)

Two-loop tutorial network used as a step-by-step reference and checked against EPANET.

Case (B)

Intermediate looped network used to compare friction-model results with published values.

Case (C)

Larger tutorial network with eight loops and 21 links. In the reported DOM case study, the optimized configuration reduced total cost by 151,790 USD, about 9.8% relative to the standard design used in the paper.

Intended Use and Current Limits

Intended Use

  • Teaching looped water-distribution-network concepts.
  • Reproducible screening and worked examples.
  • Preliminary design comparison for small to medium systems.
  • Inspection of the governing equations in a visible workbook.

Current Limits

  • The present formulation is steady-state only. It does not model transients, water age, leakage, or extended-period storage dynamics.
  • Pumps and control valves inside loops are outside the current Excel implementation.
  • Pipe diameters are user-selected inputs, not optimization variables in the shipped workbook.
  • Excel's GRG solver is local and gradient-based, so convergence depends on initialization, scaling, and constraint conditioning.
  • Cost coefficients are suitable for preliminary comparison and should be recalibrated before project-specific professional use.

Project Resources

User Manual

Step-by-step workflow guidance, worked examples, and troubleshooting.

PDF Manual

Printable manual for offline use and classroom distribution.

Theoretical Framework

Equations, cost model, validation summary, and preprint links.

Authors and Citation

Affiliations, contributor roles, and BibTeX information.

GitHub Repository

Workbook, website source, manual source, and repository metadata.

Preprint

Complete formulation, case studies, and comparison results.