Urban metabolism and dynamic modeling: pioneering approaches for resilient planning in the Greater Cairo Region

Abstract

In Egypt, planning practice is physical and rooted in design principles, resulting in plans that seldom consider the impact of land use and land cover changes on the environment. Most used planning models are static. The paper offers urban metabolism and dynamic modeling as an alternative mode for decision making. It models population growth and expanded economic activities that characterize rapid urbanization and induce changes in land use affecting various urban economic sectors using the Greater Cairo Region (GCR) as a case study. Urban transportation contributes to climate change. The authors used secondary data and satellite images to detect land use and cover changes since 2005. After building a stock-flow diagram to describe the system’s structure, they used dynamic modeling and GIS to assess the impact of transportation on air quality. Results indicate that the population of GCR will range from 33.348 to 40.334 million in 2050. The emissions from transportation will be around 52,521.2 Gg, which is beyond the ability of the region’s ecosystems to store carbon. These findings shed doubt about the ability of GCR to reach carbon neutrality and, therefore, call for strict measures to control emitting GHGs and change in planning practices and education.

Graphical abstract

1 Introduction

Egyptians’ daily lives will become increasingly difficult as the decades pass. According to World Bank data, the average annual temperature in Egypt has increased by 1.98 °C since 1901. By 2100, temperatures could be as much as 8 °C higher than the 1971–2000 average (Rechid, 2015). The minimum temperatures will increase, making nights more intolerable, and that heat waves will last up to 100 consecutive days (Lombrana et al., 2022).

Greater Cairo Region (GCR)¹ will suffer the most. Since the 1950s, waves of migrants from distant provinces have settled in the Egyptian capital, while wealthy residents have fled the densely populated central districts for more secluded suburbs. The metropolis has expanded by following conventional urban planning methods not sensitive to environmental needs. Between 2000 and 2020, green spaces shrunk by three percent, and hard surfaces increased from 23 to 35% of the city’s total area, with overpasses built approximately feet from apartment windows, overlapping layers of concrete and traffic. Older sections of GCR have merged with vast satellite cities and seemingly endless stretches of informal housing to form the smog-choked² metropolis of the present day. Under a very high-emissions scenario assuming a global temperature increase of between 3.2 and 5.4 °C by 2100, the excess heat mortality rate in GCR would increase to 80 deaths per 100 thousand inhabitants.³ Researchers predict that the heat-related death rate in GCR will exceed the global average and be significantly higher than the four heat-related deaths per 100 thousand people the city experienced in 2020 (Lombrana et al., 2022).

The metropolis is the country’s largest city. It is near the Nile Delta, with a history that dates to 969 CE. In 1882, the population of the region was 347.9 thousand. In 1947, the population surpassed 2.09 million individuals. Rapid population growth results from the gap between the birth rate (30 births/1000 people) and the death rate (7 deaths/1000 people). In 2016, the city’s population was about 12 million, with a metropolitan population of 20.5 million (World Population Review, 2022).

The Arcadis⁴ Sustainable Cities Index⁵ shows that Cairo’s social infrastructures and the quality of its economy rank 79th and 91st, respectively. Cairo ranked 86th among 100 cities worldwide (ARCADIS, 2022). In 2023, Cairo ranks 226th out of 242 cities worldwide on the quality-of-life index, which Table 1 exhibits. The pollution index indicates an unhealthy living environment. The climate index also doubts the city’s ability to cut down emissions of GHGs (NUMBEO, 2023).

Table 1 Cairene’s quality of life, 2023

The above indices suggest that GCR’s ability to attract investors is limited. Businesspeople depend on internationally believed reports in search of an investment opportunity. Prosperity and quality-of-life are among the reasons to move a business to a metropolitan area, which explains GCR’s poor economic performance (Li et al., 2022).

2 Literature review

2.1 Impact of urbanization on the environment

The rapid urban growth in the GCR negatively impacts the environment. It led to severe problems that require interventions, including food security, air pollution, and scarcity of green spaces. The government has various plans to expand transportation networks and modes to limit traffic congestion and the use of public transportation means (GOPP, 2012). It enlarged the streets by removing tram lines and green median strips and built flyovers to relieve traffic congestion. This action increases the emission of GHGs due, in part, to increasing the traffic capacity by removing the green areas. However, each individual has a limited share of green areas and open spaces in GCR (El-Kholei, 2020; GOPP, 2012).

Urban sprawl escalates demands for land and other natural resources besides energy needed for the production and consumption processes, raising metabolic problems and the need for conserving natural resources (Hussain et al., 2019, 2021; Shah et al., 2023; Zhang et al., 2018). The intensive use of raw materials depletes the natural resource base and causes the irreversible loss of ecosystem services. The unmanaged urban expansion increases the costs of service provision, deepens spatial and social inequities, and imposes high economic and environmental costs (Mahendra & Seto, 2019).

Dinarès (2014) and Broto et al. (2012) associated the concept of urban metabolism (UM) with quantity and analyzed material and energy flow within a city. Scholars use UM techniques to quantify material and energy flow in an urban system (Dinarès, 2014). The rationale is to record all physical flows into and from an urban area, thus describing the city and its environmental nexus. Flows have supported accounts in physical units⁷ (Bringezu & Moriguchi, 2019). Raw materials, water, and air are extracted from the natural system as inputs, remodeled for products and producing goods and services, then returned to the ecosystem as solid and liquid wastes and emissions (Balsalobre-Lorente et al., 2023; Hinterberger et al., 2003; Iorember et al., 2022).

El-Kholei (2020) questioned why GCR plans to ease urban ills failed to deliver on their promises and achieve social and environmental justice. He investigated the weaknesses, limitations, and outcomes of planning processes by reviewing official reports, which the Egyptian government and donor agencies published besides unpublished research. He interviewed officials who participated in formulating and implementing urban plans and policies. Sadly, plans that the government elaborated were rarely executed and did not achieve social, spatial, or environmental justice. He argued that the institutional structure is responsible for failed urban planning and complicated urban issues.

2.2 Ability to meet SDGs

Egypt faces significant challenges in meeting SDG 11, where its score is improving slowly. The proportion of people living in slums fell slightly in 2018. 98.8% of the population had access to piped, upgraded water by 2020. Meanwhile, the annual mean concentration of particulate matter with a diameter of fewer than 2.5 microns (PM2.5) fell in 2019. Satisfaction with public transportation was lower in 2020 (Sachs et al., 2022). These two indicators show that Egypt’s ability to achieve these targets by 2030 is questionable.

There are 25 targets of SDGs connected to disaster risk reduction (PreventionWeb, 2018). SDG 11 requires cities to reduce their per capita environmental impact by addressing air quality and municipal and other types of solid wastes. In addition, it aims to revitalize and plan cities so everyone can access essential social services and physical infrastructures (UNEP, 2022).

3 Research problem

Contemporary urban planning aims to facilitate sustainable urban development, requiring different planning techniques, such as UM. As mentioned earlier, GCR grew and developed following traditional approaches that deal with physical dimensions and neglect economic, social, and environmental aspects. Unfortunately, most Egyptian planners seldom consider the environmental impact while preparing urban plans. They do not use the concept of UM to assess the environmental impact of transportation network expansion through energy flow analysis. GCR’s air quality will continue to deteriorate, and the metropolis will not be able to reduce GHGs emissions, hence compounding social and economic costs.

The research aims to sustain urban areas and integrate urban indicators with their environmental impact. In addition, the research will describe how transportation network expansion can harm the environment. The empirical inquiry uses concepts of urban environmental management, particularly UM and energy flow analysis. What is done? What are the needed interventions?

The paper attempts to respond to the following research questions to test this research hypothesis:

• 1. What is happening to the air quality of GCR due, in part, to rapid urban growth, changing land uses, and expanding the transportation sector in terms of networks and modes of transportation?

• 2. What are the consequences for the environment and the residents of the GCR?

• 3. Where is the GCR heading?

• 4. What are the actions for a more sustainable future?

4 Materials and methods

The conceptual model is the Drivers and Pressures, State, Impact, and Response (DPSIR).⁸ Drivers⁹ lead to more specific pressures on the environment,¹⁰ which start changes in the state of the environment. These environmental changes include loss of biodiversity and polluting air, water, and soil, thus affecting the delivery of ecosystem services upon which humankind depends. Ecosystem services include providing freshwater, food, and protection from ultraviolet radiation. Because of changes in services mediated by demographic, social, and material factors impact human well-being (Allmendinger & Tewdwr-Jones, 2002; Aman et al., 2022).¹¹ Responses include formal and informal attempts to either adapt to changes in ecosystem services or reduce environmental pressures (Jäger et al., 2008), Fig. 1.

Fig. 1

(Source: El-Kholei and Abido (2022)

DPSIR conceptual model

We collected data from various governmental agencies, including, but not limited to, the Central Agency for Public Mobilization And Statistics, the Egyptian Electricity Holding Company, the General Organization for Physical Planning, the Egyptian Survey Agency, and the Ministry of Environment.

Empirically, the article applies the Material Flow Approach method to measure energy flow in GCR. Using dynamic modeling to build future scenarios, we adopted UM to examine linkages between urban growth and environmental changes. We built three scenarios for the future based on projected population growth to be the basis for predicting changes in urban land use/cover and transportation to estimate generated CO₂ emissions and the capacity to store carbon. To conclude the analysis, we reviewed government policies and plans for the GCR.

The basis for the first scenario is the curve fitting technique, also known as the extrapolation technique. We used a linear regression model, Eq. 1, by computing the trend for population growth between 1966 and 2017 to project the population in the years 2030 and 2050.

$$y = a + bx$$

(1)

where: y Projected population in the years 2030 and 2050. a Intercept, i.e., when x equals zero, y equals a. b Slope of the trend line, which is the annual population growth. x Observed population in the years 1966 till 2017

The second scenario is the output of the simple linear population growth model using the base year (n) and the rate of growth (g) to project population in the year (t + n), where (t) is the increment of years, Eq. 2.

$$\begin{aligned} P_{t + n} & = P_{t} + g\left( n \right) \\ \forall g & = \left( {P_{t} - P_{0} } \right)*n^{ - 1} \\ \end{aligned}$$

(2)

where: P_t+n Population in the year (t + n). P_t Population projected from the year (t). P₀ Population in the base year, i.e., year (0). g Population growth rate per unit of time (n). n number of years.

We then used a modified exponential model where “the prediction” formula states that the population in time t + n is found by taking the maximum limit, a capacity (K), and subtracting from it some portion (v)ⁿ, of the unused capacity, (K—P_t)” (Krueckeberg & Silvers, 1974, p. 264) Eq. 3 is the formula applied in the third scenario.

$$P_{t + n} = K - \left[ {\left( {K - P_{t} } \right)\left( v \right)^{n} } \right]$$

(3)

where: K = upper limit of capacity and $v = \frac{1}{m}\sum\nolimits_{t = 2}^{d} {\frac{{K - P_{t} }}{{K - P_{t - 1} }}}$.

After calculating the projected population, we used the following quantitative inquiry tools to answer the research questions:

• 1. We used Artificial Neural Network¹² and Cellular Automata¹³ models in the Methods Of Land Use Change Evaluation (MOLUSCE) plug-in of QGIS 2.8.4¹⁴ to project future urban expansion spatially (Schmidt et al., 2022).

• 2. In analyzing transportation, we depended on the Cairo Regional Transport Study (GOPP & JICA, 2008) models to estimate transportation demand and the modal split. It is another component of the dynamic model besides the three scenarios of population projections.

• 3. The stock-flow diagram depicts the structure of a system. Stocks (Level) are crucial to a system’s ability to generate behavior; flows (Rates) cause stocks to fluctuate. Stock-flow diagrams serve as a link between system dynamics modeling and simulation. Stock-flow (or Level and Rate) diagrams describe a system structure in greater depth than a causal loop diagram (Transentis Consulting, 2014).

• 4. Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) is a collection of models that map and value the nature-derived products and services that maintain and enrich human life. It aids in investigating how ecosystem changes can affect the flow of several human benefits (Stanford University (no date)).

• 5. Causal loop diagram (CLD) is a snapshot of all significant links. It visualizes the relationships between essential variables, depicting them as text and their causal relationships as arrows. It defines the variable of the main pillars and their interactions and establishes causal relationships between variables (Azad et al., 2010; Haraldsson, 2004; Jiakui et al., 2023). We used CLD¹⁵ to determine the model structure and interactions, Fig. 2.

Fig. 2

(Source: The Researchers)

CLD for the relationship between the main aspects of the research

5 Results

5.1 Population

The population of GCR is young and will continue to grow to put more pressure on natural resources. Using a linear population projection model to estimate the population of GCR using 2017 as the base year and the stock variable, we constructed three scenarios using the rate of change as the flow. For the first scenario, we used a linear regression model where the slope of the trend line is 310,568 per annum. Thus, the projected population will reach 27.137 in 2030 and 33.348 million in 2050. Between 2006 and 2017, the simple linear population growth model’s growth rate (g) is 501,063 per annum. GCR’s population grew by 29.3%. We projected the population of GCR to be 30.313 and 40.334 million in 2030 and 2050, respectively. For the third scenario, we used a modified exponential model. We estimated the capacity (K)¹⁶of GCR as 132.051 million and projected the population of GCR to be 28.5872 in 2030 and 35.5448 million in 2050; Fig. 3 depicts these three scenarios.

Fig. 3

(Source: The researchers)

Stock-flow diagram of population and its impact 2017–2050

The general trend for population growth in the Cairo metropolitan area and Egypt is declining, as Table 2 implies. First, the decline in population growth seems to result from government policies encouraging birth control. Second, in 2009, the fertility rate in Egypt was 2.85% which dropped to −1.25% (United Nations-World Population Prospects, 2022b). Consequently, we used the estimates from the third scenario, i.e., the modified exponential, because there is the maximum limit, a capacity (K).

Table 2 The population of Egypt and metropolitan Cairo, 2017–2022

5.2 Economic activities

Population and economic growth are intertwined. Between 2006 and 2017, primary, secondary, and tertiary jobs¹⁷ increased by 8.41%. The entire labor force will reach 10.13 million in 2030 and 16.89 million in 2050. The population projection resulting from the modified exponential model and the percentage of the population active economically are the basis for computing these values.

In 2020, Egypt’s labor force distribution among agriculture, industry, and services sectors was 23.286, 28.164, and 48.55%. Figure 4 implies that the service sector is growing, unlike agriculture and industry employment rates. Cairo is Egypt’s capital and the country’s primate city, besides the seat for regional offices of international organizations, such as the Food and Agriculture Organization and the League of Arab States. Service employment, therefore, is the basic economic sector.¹⁸

Fig. 4

Source: The Researchers generated using World Bank data (September 2022)

Distribution of Employment by economic sector in Egypt 2009–2019

Secondary and tertiary jobs increased while primary jobs decreased, Fig. 4. We expect these trends to continue in the future, Fig. 5. By 2030, primary jobs will decline to 0.39 million, then drop to −0.07 million in 2050. Secondary jobs will grow to 2.24 million in 2030 and then to 2.58 million in 2050. Tertiary jobs will increase to 7.50 million in 2030 and 14.38 million in 2050. The tertiary jobs will increase because of the growth of services sectors in GCR, like financial services, communications and information technology, retail trade, and tourism. Thus, the increase in jobs may result from the availability of a competitive service field.

Fig. 5

(Source: The Researchers)

Impacts of employment projection from 2017 to 2050

5.3 Urban areas

Steady population and economic growth have changed the urban area and land cover. The metropolitan areas of GCR reached 211,551.7 feddan¹⁹ in 2017, with 3,094.32 feddan of areas transformed into urban uses, primarily residential. The model projected Land Use Land Cover (LULC) patterns for 2030 and 2050, Fig. 6, based on the 2010 and 2020 land cover maps.

Fig. 6

(Source: The Researchers using MOLUSCE and results from dynamic model)

LULC map of GCR for the years 2020, 2030, and 2050

Table 3 exhibits changes in LULC in 2030 and 2050 compared to 2020. Except for urban areas, all other LULCs will decline. Urban areas will grow by 14 and 37% compared to 2020 in 2030 and 2050, respectively. Other agriculture and bare areas presented a declining trend. The area of bare land will decline by two and five percent in 2030 and 2050, and agricultural land will decrease because of urban sprawl. In addition, the results suggest that urban growth will occur on bare land and agricultural areas.

Table 3 LULC Change between 2020, 2030, and 2050

Based on data on land uses in 2020, we project residential areas to grow from 70,693.4 feddan to 80,964.6 and 101,507 feddan in 2030 and 2050, respectively, thus raising the net density to about 352 persons/feddan. In 2017, the manufacturing plants occupied 23,990 feddan, while the share of commercial uses was 4,357.97 feddan. There will be 28,727.8 and 5,218.63 feddan dedicated to industrial and commercial establishments in 2030. In 2050, industrial and commercial enterprises will occupy 36,016.6 and 6,545.71 feddan, respectively.

5.4 Transportation

The changes in land use and cover generate demand for expanding transportation networks and diverse modes of transport. The stock-flow diagram, Fig. 7, depicts projection of transportation volume and modal split in 2030 and 2050. The first component of the stock and flow diagram projects the demand for trips. In 2030, home-based education trips will increase to 33.62-million-person trips/day. In 2050, it will rise to 41.80-million-person trips/day. Home-based work trips will peak at 17.85 and 37.44 person trips/day in 2030 and 2050, while home-based other and non-home-based will grow to 25.44- and 11.33-million-person trips/day in 2050.

Fig. 7

Transportation generation and modal split stock-flow diagram. (Source: The Researchers)

The second component is the modal split. Public transit passengers will grow to 38.80 million in 2030 and increase to 60.25 million. Cairo Transportation Authority (CTA) and mini- and micro-buses passengers will increase. CTA will pick up about 6.67 and 10.50 million passengers in 2030 and 2050, while mini- and micro-buses passengers will rise to 47.82 million. Using private cars, including taxis, will increase to 13.06 million trips in 2030 and 21.28 in 2050. The truck trip demand will increase to 47.2 thousand in 2030 and reach 54.5 thousand in 2050.

Emissions from the transportation sector result from consuming fossil fuels. According to the modal split, the transportation sector will consume 17,491.8 Ktoe.²⁰ The transportation sector will emit 52,521.2 Gg of CO2e, Fig. 8. The emissions may decline as a response to successfully implementing new interventions, such as the new subway lines and the Light Rail Transit, besides encouraging the use of electric vehicles. Currently, the network is overloaded, and the citizens depend heavily on private cars.

Fig. 8

Total fuel consumption and CO₂e emissions from 2017–2050. (Source: The Researchers)

5.5 Carbon storage

The ability for carbon sequestration and storage are among the outcomes of changing LULC. We estimated carbon storage maps in 2050 compared to 2020, showing an increase from 10.43 million Mg²¹ to 10.71 million Mg. Carbon storage will grow by 0.28 million Mg from 2020 to 2050, Fig. 9. Using the exact cost of $60 per ton and a change rate of 20 percent, the net present value of carbon storage between 2020 and 2050 will be about $3.34 million. The decline in the ability to store carbon, and thus the associated losses in monetary terms, is directly related to transforming agricultural areas, green areas, and barren land into urban uses, as Wang et al. (2016) and Lü et al. (2014) indicated in their papers.

Fig. 9

Carbon sequestration under urban growth from 2020 to 2050. (Source: The Researchers)

5.6 Government responses

In response to the population growth and the need to expand the urban area for economic sectors, the Authority for New Urban Communities (ANUC) has developed the first generation of new towns since the late 1970s to ease congestion in GCR and protect valuable agricultural land. ANUC continued to develop other generations of new towns using the same excuse from 1982 to 1995. The Government founded New Cairo five kilometers east of Nasr City in 2000; approximately two million people live in New Cairo’s 330 residential compounds. ANUC is currently constructing multiple new towns. The New Administrative Capital tops these communities. It will house 6.5 million individuals (Authority for New Urban Communities, no date).

Many researchers do not view new towns as a success story. These new towns are designed without the environment in mind. The density of these communities is low, and the neighborhood layout is neither compact nor designed for mixed uses. Sixty to seventy percent of the homes in eight satellite cities surrounding Cairo are vacant, housing less than five percent of Cairo’s population (Sims, 2012; Zwangsleitner, 2014). The construction of new towns had no effect on urban sprawl on agricultural land. Egypt lost 586,705 feddan to the expansion of human settlements between 1984 and 2007 and allocated 695,037 feddan to roads, irrigation canals, and drains. Between 1984 and 2007, the gross cultivated land in the Nile Delta decreased to 297,981 feddan, while the area of human settlements increased to 297,761 feddan (El-Kholei, 2020).

The construction of new towns did not halt the development of informal settlements. Expensive housing units, lack of public transportation within the city, connections to GCR, and absence of jobs and social services prevent low-income people from relocating to new communities. In contrast, informal settlements grew to house the poor and provide them with employment opportunities, as approximately 60 percent of the GCR’s population lives in informal settlements (Arandel & El-Batran, 1997; El-Batran & Arandel, 1998; Khalifa, 2011, 2015).

Ineffective urban planning is one of the causes of air pollution. The length of paved roads surrounding gated communities and resorts increases travel time and gasoline consumption, which contributes to GHGs. Satellite cities surrounding Cairo increased the metropolitan area’s Urban Heat Island, causing increased demand for energy to cool buildings. Since the late 1990s, GCR’s congestion, the incineration of solid wastes, and using fossil fuels in manufacturing have been responsible for smog²² episodes.

Air pollution has serious health and economic consequences, contributing to respiratory and cardiovascular diseases that cause morbidity and mortality. In 2017, the damages²³ caused by air pollution accounted for 0.6 percent of the Gross National Product or $3,340 per capita. Meanwhile, the damage caused by carbon dioxide was approximately 2.1 percent of the Gross National Income (World Bank, 2017).

The Prime Minister’s decree No. 1969/1998 designated the Nile’s islands as natural protectorates. However, on April 18, 2018, the Cabinet of Ministers approved the transfer of Al-Warraq Island to ANUC so that it could begin implementing a plan for its development and expansion (Khalil, 2017; Soliman, 2018). The decree and Law 143/1981 stipulate that local administrations manage and develop lands within their authority, including two kilometers of the desert hinterland. The decision violates both. Consequently, al-Warraq is administered by the Governorate of Giza. However, APCK! Studio²⁴ presented its proposal for al-Warraq Island Development, which will evict the current residents and convert agricultural land into a real estate development comprising towers, villas, and a shopping mall (APCK! studio, no date).

Urban sprawl’s devastating effects extend to protectorates. The Petrified Forest Protected Area near New Cairo was once a branch of the Nile River millions of years ago during the Oligocene period. The government sold a portion of the Petrified Forest Protected Area, citing the loss of biodiversity on the parcel. The government violates the law and international treaties to safeguard imperiled environmental resources (Hassan, 2018).

6 Discussion and implications

6.1 Discussion

The drivers and pressures in the form of population growth and economic expansion will continue. The urban sprawl will be at the expense of valuable agricultural land. Neither the state of air quality will improve, nor the emissions of GHGs will decline. The quality of Cairenes’ life will continue to deteriorate, and the sustainability of the metropolitan area is questionable. The policies and plans are ineffective, which affirms the findings of El-Kholei (2020), calling for radical change in the planning process by employing UM and dynamic modeling in the stages of problem definition and dynamic modeling to evaluate alternatives and assess the impacts of decisions.

Degraded air quality affects people’s health, thus raising morbidity and mortality rates, leading to losses in labor productivity and economic and social costs, besides damaging properties and cultural heritage, where emission reacts with building materials, thus deteriorating monuments and leading to revenue losses from the tourism industry. Maintaining higher rates of GHGs suggests that GCR and Egypt at large might not meet Egypt’s Nationally Intended Contributions registered at the United Nations Framework Convention on Climate Change.

Air quality is among the measures for urban planning and management effectiveness. Our research findings demonstrate that the current planning practice is among the hurdles that obstruct Egypt’s ability to accomplish the targets of SDG 11, as Sachs et al. (2022) indicated. In 2021, based on the annual average PM2.5 concentration (μg/m³), Cairo ranked 11th among the most polluted capitals (IQAir, 2022).

The implemented plans do not appear to achieve the desired environmental outcomes. The institutional framework within which the plans are developed appears to be the reason. The failure of urban planning and management to control the rapid urban growth in the GCR negatively affected the environment and reduced the region’s capacity to store carbon. Air pollution and a lack of green spaces are among the severe problems that should be addressed because of current planning and management practices. The government expanded road networks to reduce traffic congestion by eliminating tram lines and green median strips, widening streets, and constructing flyovers. This action contributes to a rise in GHGs emissions by increasing traffic capacity and removing green areas.

The applied method is a significant contribution to the theory of planning. We successfully used dynamic modeling and GIS to project the expected future of GCR, assuming the current planning practices continue as usual. The future of GCR does not seem environmentally promising if there is no drastic change in the adopted modus operandi for decision making.

The results call for reconsidering the planning process and practices. Conventionally, planning in Egypt rarely depends on the use of dynamic modeling. Most planning models for population and employment projection linked to land use models are often static, and selected alternatives are usually based on design criteria. Dynamic modeling linked to GIS applications can contribute to impact assessments, which can ensure the implemented plans’ success.

6.2 Implications

It is of utmost importance to address the causes of degraded air quality and emissions of GHGs; otherwise, the GCR, which is the prime metropolis in Egypt, will not reach carbon neutrality. Egypt is highly vulnerable to the risks of climate change, including severe weather episodes, sea level rise, and drought. Following the Business-As-Usual scenario²⁵ is futile, with expected economic and financial losses, social suffering, and environmental damages, calling for a change in planning land uses.

7 Limitations

Quantitative analyses have limitations, such as the potential for biased outcomes and the inability to investigate qualitative phenomena, such as people’s transportation preferences, due, in part, to the intangible nature of human factors. The analysis does not consider the influence of an individual's attitudes, beliefs, and other personal determinants on their preferences failing to consider habitual behaviors, which can influence the decision to accept a recommended course of action. Another research limitation is the quality of the data used. The researchers collected the data from various official sources, which sheds doubt on the accuracy and precision²⁶ of the results. Replicating the inquiry is among the means to certify the results.

8 Conclusion and policy recommendations

GCR is facing significant challenges due to rapid urbanization, which has led to air pollution, a lack of green areas, and increased demand for land and natural resources. Findings show that the population of the GCR is young and will continue to increase, placing a greater strain on natural resources. The total labor force will reach 10,13 million in 2030 and 16,89 million in 2050.

Transportation sector emissions result from the consumption of fossil fuels. The road network is overloaded, and citizens rely heavily on private vehicles. We expect that the transportation sector will consume 17,491.8 Ktoe. Transportation will release 52,521,2 Gg of CO2e. The ability to sequester and store carbon is one outcome of modifying LULC. Carbon storage in 2050 will increase from 10.43 million Mg to 10.71 million between 2020 and 2050. Using an exact cost of $60 per ton and a change rate of 20%, the net present value of carbon storage between 2020 and 2050 is approximately $3.34 million. The decline in the capacity to store carbon and the associated monetary losses result from transforming agricultural lands into urban uses and losing green spaces.

SDG 11 mandates cities to reduce their environmental impact per capita, address solid waste, and revitalize urban areas for access to essential services and infrastructures. Cairo ranked eleventh among the most polluted capitals in 2021, and public transportation satisfaction has decreased.

Egyptians’ daily lives will become increasingly difficult. GCR will be the hardest hit. The future of GCR is not environmentally promising unless the current decision-making process drastically changes. The findings require reevaluating the planning process and practices, as dynamic modeling linked to GIS applications can contribute to impact evaluations and ensure the success of implemented plans. Egyptian urban planners must use techniques like energy flow analysis to evaluate the environmental impact of changes in land uses, requiring major capacity building and training, plus transformations in planning education curricula.