Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Master of Science in Civil Engineering (MSCE)

Document Type

Master's Thesis




Civil Engineering

First Advisor

Dr. Lindell Ormsbee


The main objective of this research is to study if the hydraulic and water quality models can be used for water quality analysis of chlorine decay and TTHM formation at various locations across a water distribution system. This is particularly important because it is not always easy or economical to take multiple field samples and analyze them in the laboratory. In this study, models of two different water distribution systems (one more urban and efficiently managed system located in a relative flat topography, and other more rural and less efficiently managed system located in a mountainous topography) were developed in a commercial software package. These models were then calibrated and successfully applied to predict water age, and chlorine residual values.

Furthermore, these models are used to incorporate water age and chlorine demand based regression relationship to predict TTHM values throughout the distribution system. Regression models based on water age and chlorine decay approach can simplify the TTHM prediction by lowering the number of parameters involved in the water quality analysis. Both water age and chlorine demand can be useful in prediction of TTHM in water distribution systems, but their accuracy depends on available data and decency the model calibration.

Based on the investigation of possible operational changes using these models, it appeared that both the change in demand and plant chlorination can have significant impact in the chlorine residual and TTHM formation in the system. The reduction in system demand after controlling the water loss can cause significant decrease in the chlorine residuals in the distribution system as the flow velocity decreases and the time to reach the consumers increases allowing enough time for chlorine decay and for TTHM formation.

Digital Object Identifier (DOI)

Funding Information

This study was supported by NIEHS through Grants R01ES032396 and P30ES026529. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS.