Chapter 8: Summary, Conclusions and Recommendations
8.1 Summary and Conclusions
The aim of this study was to provide a decision-support mechanism to assist water decision-makers and policymakers in preparing long-term water sustainability plans. The research was divided into five phases to achieve its goals. The first phase involved reviewing the literature of all critical issues that led to the creation of the proposed DSS (Chapter 2). The literature review focused on four areas; water balances models, scenarios analysis in water management, optimization techniques used in capacity expansion and planning, and an overall review of DSSs available in various areas of water management. According to the literature, DSSs are valuable tools for long-term water planning. The study aided in the creation of the SuWaB-AD DSS, and stressed the value of a user-interactive DSS in order to facilitate decision-making.
To accomplish the first objective a dynamic water budget model for Abu Dhabi has been developed. This model satisfies not only mass balance between the various water subsystems of Abu Dhabi but also is capable for forecasting water demands, future availability of water resources, and future water balances (year-wise surplus/deficit) as well with the use of equations incorporated in the model. This formed second phase of the research with a detailed study of Abu Dhabi water system.
The ADWBM developed is a numerical tool for producing precise forecasts of water supply and demand in the EAD until 2050. The model also served as a planning tool in order to accommodate necessary steps to avoid a future shortage. ADWBM was calibrated and validated with the available actual data. The second objective was to build water scenarios for Abu Dhabi and simulate the water conditions using the
ADWBM. Therefore, a series of future water scenarios were simulated in the third phase to represent various future water conditions in Abu Dhabi (Chapter 4). This focused on the factors affecting current and potential water use in the EAD. Analysis of conservations needed to achieve a balanced water budget was identified for all scenarios. The importance of each driver in the model was calculated using a sensitivity analysis. The developed model aimed to recognize needed demand reductions for the different proposed interventions. The second objective of the research was thus fulfilled with simulation of four suites of water scenarios which followed a sensitivity analysis which identified significant demand drivers of each demand sector in Abu Dhabi.
The third objective was based on the need of an optimal planning solutions for long term water planning in arid and semi-arid regions. Thus, in the fourth phase, a multi-period MILP optimization model was developed to determine the needed capacity expansion pathway for the water sector in Abu Dhabi in order to meet future water demands with minimum cost, CO2 emissions, and brine disposal. In addition, the model identifies the optimal capacity of water treatment plants, water transmission systems, and minimal utilization of non-renewable natural water resource (Chapter 5).
The third objective of this research was thus achieved.
Another objective was to demonstrate the developed MILP for a case scenario and interpret its results. Therefore, a case study was undertaken for a planning horizon of 30 years, starting from 2021. The optimization model developed for the case scenario was run using GAMS software and solved using Cplex solver. The optimization framework considered the capacities of existing water infrastructure, decommissioning of retiring assets, construction lead time, environmental cost of CO2
emissions and GW utilization, and other technical, economic and environmental criteria involved in the capacity planning of water sector. The results showed that the potable demand in the EAD, currently satisfied by desalination plants, will require a drastic change of technology from thermal processes like MED and MSF to RO; even if moderate consideration is given to the environmental aspects. It was also concluded that treated sewage plants, covering the non-potable demand, would require capacity increase at different stages of the planning period. In all cases, the best opted technology to treat the wastewater is the conventional-ASP process. The GW usage will continue to be the major supply source for irrigational requirement. It was found that when a limit was set for annual GW abstraction, whereby GW reserve would last for another 150 years, the optimal solution showed constant utilization of allowed GW except for few odd years with peak GW use because of dip in DW capacity due to decommission of DW plants at some locations. It was also seen that assigning high environmental cost for the economic value of GW will affect the DW capacity as more DW will be preferred for irrigation in such condition. The model results show that the capacity of DW transmission lines will have to be increased. Especially to Al Ain region, where all potable demand is satisfied by importation since there is no provision to install DW plants. The model solved for optimal diameter of pipelines and also years in which retrofits are required. The model, therefore, has accommodated all possible options of water allocation and supply feasible in the UAE condition. The model developed in this dissertation, to the best of the author’s knowledge, is the first of its kind to be developed for an arid or semi-arid region considering multi-period integrated water management and planning. This can be used as a decision making tool for developing long-term water strategies for large geographical land area. Thus, the forth objective was accomplished.
For accomplishing the fifth research objective, a graphical interface that incorporates the ADWBM and ADWCPM to assist water planners and decision makers in water planning is developed (Chapter 7). Thus, a DSS for sustainable water planning is developed for the Emirate of Abu Dhabi (EAD), UAE and is named as
“Sustainable Water Budgeter for Abu Dhabi” (SuWaB-AD). With the strong movement toward more sustainable water planning and management, more water decision makers have realized the value of comprehensive models and decision support systems. This is a tool that incorporates economic and environmental criteria into the decision-making process and could help decision makers promote sustainability in water planning.
The final research objective was to demonstrate the use of the developed tool, SuWaB-AD, to: (i) perform scenario-based analysis by building future water scenarios using ADWBM, and (ii) find optimal planning solution for the analyzed scenarios using ADWCPM. SuWaB-AD as an integrated tool for long-term planning of infrastructure (such as water and wastewater treatment plants, and pipeline capacity) was used to simulate a future water scenario for Abu Dhabi and to solve for optimal capacity planning solution. The SuWaB-AD is helpful in sustainable management and planning of natural resources like groundwater. Since it incorporates the cost and environmental aspects into the decision-making process, it can be very useful in promoting sustainability among the decision-makers. Also, the case study showed that SuWaB-AD can be helpful to water decision-makers worldwide. The primary significance of the SuWaB-AD is its usefulness to policy makers in supporting sustainability plans.