Chapter 7: A Decision Support System for Sustainable Water Planning in Arid
7.3 Application of SuWaB-AD
7.3.1 Simulation of a Water Scenario using ADWBM Module
The SuWaB-AD DSS was used to simulate a water scenario named the Sustainable Environment Scenario (SES). The scenario was formulated by considering the different strategies required in Abu Dhabi for a sustainable future, such as supply and demand side measures and population growth control. The planning period considered was 2021–2050. In general, based on the ADWBM simulation, the results can be viewed as tables and graphs for variables such as sector-wise water demands;
abstractions of GW; use of treated sewage effluent; production and loss of DW; and water supply/demand balances (potable, non-potable), which are dependent on human actions and governmental policies, strategies, and visons. However, this study discusses only the specific topics that form the core of the scenario building and future capacity planning.
7.3.1.1 Population Growth for the SES
Population is one of key drivers of water demand in Abu Dhabi. This subsection in the ADWBM module permits forecasting the population for nationals and non-nationals, separately, by dividing the planning horizon into more than one
distinguished periods of growth. In this scenario building, two periods were used:
medium term (P1, for years 2021–2030) and long-term (P2, for years 2031–2050). The GUI shown in Figure 23 was used to input the values shown in Table 20 as published in (Mohamed et al., 2020); to forecast the population under the SES. The average annual growth rates for these periods are used based on the assumption that a medium population growth represents a balanced and sustainable environment, and steady economy. The forecasted population by SuWaB-AD using the module included in ADWBM (Kizhisseri et al., 2021) for the SES is shown in the Figure 28. The population forecast forms the basis of water demand calculation of all the population dependent demand sectors.
Table 20: User data inputs for population forecast under SE scenario
Input Field Names Input Values
Planning Horizon (years) 2021-2050 ( P1&P2) Number of distinguished periods within the
planning horizon for setting targets
2 subperiods: (P1&P2):
P1:Years 2021-2030, P2:Years 2031-2050 Start year of each distinguished period P1: 2021, P2:2031 End year of each distinguished period P1:2030, P2:2050 Population growth rate of nationals in each
distinguished period
P1:3, P2:3.5 Population growth rate of non-nationals in
each distinguished period
P1:5.3, P2:3
Figure 28: Population forecast under SE scenario 7.3.1.2 Waters Demands for the SES
The ADWBM allows a targeting demand forecast in the model that sets the reduction targets in demand drivers of the demand sectors based on regulations and policy for every distinguished period (or years). Therefore, to establish targets for consumption rates in the distinguished periods, various published documents by the government and stakeholders were gathered and judgments were made for estimations to forecast the demand under this scenario. For the SES, different factors were considered and can be summarized as follows.
(a) Conservation regulations:
Conservation regulations could decrease water consumption by all population- dependent demand sectors (residential, commercial, and municipal). Therefore, a reasonable possible reduction in the baseline per capita water allocation to these sectors was assumed and implemented in the scenario development. In the SES, a
reduction of 10% per capita consumption by 2030 and another 10% reduction by 2050 is assumed to be achievable in all potable sectors,
(b) Agricultural, Forestry, and Amenities Sectors:
The population-independent demand sectors such as agriculture, forestry, and amenities is assumed to be essential for a balanced food security and green environment. Therefore, working toward optimizing water use intensity and increasing efficiency in the agricultural, forestry, and amenities sectors are the targets to reduce water use by 35% by 2050.
(c) Industry Sector:
For industry sectors, the projected demands are only driven by the governmental policies and visions. However, taking into consideration economic growth in relation to population growth, a 10% increase by 2030 and another 20% by 2050 is considered under the SES. These values were included in development of the SES and were entered into the SuWaB-AD using the GUI pages shown in Figure 24.
The water demand pattern of various sectors until 2050 under the SES as projected by the ADWBM within the SuWaB-AD is shown in Figure 29.
Figure 29: Sector-wise demands forecasted for SE scenario 7.3.1.3 Available Water Supply Sources for the SES
The amount of water from various sources that can be allocated to meet demands of different quality types are subject to the availability, the sustainability policies, capacity of the production facilities, loss during transmission and distribution, usability for specific purposes and other operational aspects. The ADWBM encompasses all these aspects while estimating yearly available water supply from each source. For the SES, based on the assumption that all the treated sewage is usable for non-potable purposes, the GW use for the planning horizon had to be kept under control in line with a feasible target reduction in GW extraction, as pointed out in the Environment Vision 2030 policy agenda (Environment Agency - Abu Dhabi, 2012).
Therefore, under SES a GW reduction of 10% by 2030 is targeted and another 25%
reduction is to be achieved by 2050. The rainfall—which is a natural source of water but very limited in Abu Dhabi—was been included as dependable source in future.
The DS capacity is proposed to deliver uniformly throughout the entire planning period. The option of importing potable water from outside the Emirate by its legal agreement with Fujairah Government is also taken into account. The changes to baseline settings of supply for developing the SES was achieved by entering values using templates shown in Figure 26. The key target values applicable for water supply sources as used in SES are shown in Table 21. These values are in line with sustainability visions of Abu Dhabi government (Abu Dhabi Council for Economic Development, 2009; Environment Agency - Abu Dhabi, 2009a, 2012, 2014).The outputs from the SuWaB-AD are shown in the Figure 30.
Table 21: User data inputs for water supply availability forecast under SE scenario
Input Field Names Input Values
Target reduction in extraction rate of GW for each period P1: 10%
P2: 25%
Recyle-ratio of TS produced P1: 90%
P2: 90%
Production Plant Capacities Base year 2020
Transmission and leakage loss percentage P1: 10%
P2: 10%
Figure 30: Available water supply under SE scenario 7.3.1.4 Yearly Water Balances for the Sustainable Environment Scenario
The SuWaB-AD results allowed users to obtain the yearly data on water balances for the entire planning horizon. Based on these data, the useful results for the capacity planning in the ADWCPM module are yearly water surpluses or deficits for potable, non-potable, and irrigation demands. The growth of water deficits for the SES obtained from the SuWaB-AD are shown in Figure 31.
Figure 31: Growth of water deficit under SE Scenario