Date of Award

6-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Environmental Science

First Advisor

Walid Elshorbagy

Second Advisor

Vijay Panchang

Third Advisor

Basim Mohamed Abu-Jdayil

Abstract

The prime objectives of this dissertation are to develop, validate, and use a

state of the art 3D Hydrodynamic Model (HD) to evaluate the long term salinity and

seawater temperature variations in the Gulf subject to climate change and coastal

effluent; and to develop a quantification tool that can assess the impact of projected

ambient conditions upon the cost of desalination. Both objectives were realized.

Evaluating the long-term variability of seawater salinity and temperature due

to climate change and coastal effluent is a growing concern. It may represent an

economic and operational limiting factor in desalination process given the clear trend

for constructing new plants and/or expanding existing ones to meet the growing

demand for fresh water. This is also significant for the research and development of

sustainable desalination technologies in the Gulf and beyond. The hydrodynamic

model (HD) developed here was rigorously validated against short term and long

term field observations. It proved to be reliable in evaluating long term basin-wide

response to climate change and coastal effluent loading in the Gulf.

An Atmospheric Ocean General Circulation Model (AOGCM) data base of

twenty CMIP3/AR4 models re-gridded to 2.5 x 2.5 degrees latitude/longitude, and

globally observed data bases within a common 20-year reference period (1980-1999)

were used to obtain data for air temperature, precipitation and sea level rises in the

Gulf for long term evaluation. Including the contribution of coastal discharge from

desalination plants, refineries and power generation plants, the HD was used to

simulate a total of 17 scenarios, each with a duration of 90 years to appraise the

future condition of the Gulf. These scenarios include realistic, optimistic and extreme

case scenarios for fresh water demand in Gulf countries. The results ascertained the

long term increase in salinity and seawater temperature in every scenario. The

responses were found to vary spatially based on several factors such as season, water

depth, degree of flow restriction, vertical mixing and flushing. Coastal effluent

impact was localized to within 10 to 20 km offshore from the discharge location, but

did not show a serious trend for massive alongshore phenomena. Salinity and

temperature were found to be steadily increasing over time near desalination plants.

Based on a conceptual understanding of the cost of desalination a mathematical

assessment tool was developed to map the projected changes in salinity and seawater

temperature into operational costs, particularly chemical and electrical costs.

Accordingly, desalination technologies were ranked by time for each desalination

plant (a total of 34 plants) to advice on the most appropriate planning approaches at

each location until 2080. The main finding of this study indicated insignificant

impact of future ambient conditions in the Gulf on the operational cost of the

considered desalination technologies and that the Multi Effect Distillation (MED)

technology is expected to be the least affected

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