In accordance with the latest territorial organization of the country, Algeria counts 58 wilayas. The wilaya is a territorial collectivity enjoying economic and political freedom governed by an elected body, the Assemblée Populaire de Wilaya (APW), and directed by the Wali, an appointed governor. Each wilaya is divided into daïras, themselves subdivided into communes, the smallest administrative territorial and population census unit.
3.1. Wilaya of Tlemcen
The wilaya of Tlemcen is located in the extreme northwest of Algeria, with about 120 km of coast along the Mediterranean Sea and an active population growth. The capital of the wilaya is also named Tlemcen (from here out for administrative units that have the same name, when a name is italicized, it refers to the actual commune’s name). The wilaya currently includes 53 communes, most of which are rural, with less than 40,000 inhabitants in 2018. Among the fastest-growing communes are five that passed the threshold of 60,000 inhabitants in 2018 (Figure 3
). These are the communes of Remchi, Chetouane, Maghnia, Mansourah, and Tlemcen, which account for 42.62% of the total population of the wilaya. Except for Maghnia and Tlemcen, which had 138,596 and 157,751 inhabitants, respectively, the other three largest communes were less populated, with fewer than 66,000 persons. The commune of Sebdou increased by 25% during the decade under consideration and almost made it among the top five communes, with a 2018 population of 49,653 inhabitants. The two smallest communes of Souk Thlata and Beni Bahdel recorded a population of 3130 and 3223 and a growth rate of 14% and 19%, respectively.
The change in built-up area as well as its growth rate for the wilaya of Tlemcen is illustrated in Figure 4
. The change in urban land consumption clearly shows a non-linear relationship between population growth and ISA growth. Indeed, in terms of population, the largest cities have recorded a significant growth of between 10% and 40%. However, in the four communes of Remchi, Maghnia, Chetouane, and Sebdou, the population grew much faster than the urban land consumption, whereas in the communes of Tlemcen
and Mansourah, the population grew by 13% and 34%, respectively, while the impervious surface area (ISA) grew at a rate of 18.7% and 40.4%. In terms of land use, the relationship between the population growth and the urban land consumption is at the basis of the definition of sustainability and implies that as long as the population growth is smaller than consumption of land for urban use in a given period, the urban development gears towards sustainability. Therefore, an area characterized by urban land use growing faster than its population will consume the available land and face several constraints: reduction of lands for housing, parks and recreation, schools, business, roads and parking lots, and green spaces. In sum, the ISA per capita must be reduced.
The ISA per capita represents the total urban land footprint, for urban purposes, per person. This includes land for housing, schools, business, roads, parking lots, highways, driveways, sidewalks, playgrounds, and any other artificial surfaces needed in an urban setting. While this list of urban land uses is not exhaustive, the most flexible and amenable to regulation is land for housing. Indeed, if the ratio of population to available urban land is small, the price of land decreases and leads to housing units with larger land footprints. As population grows, however, and the demand for land follows, land price will go up, and accessibility will decrease. Although other land-use types can also be regulated, the first category of urban land use that is affected is that for housing, which may negatively affect the overall sustainability. An example of this evolution is illustrated in Figure 5
for the largest communes of the Tlemcen wilaya and shows how, in the communes of Tlemcen and Mansourah, land use is increasing much faster than population growth.
The SDG 11.3.1 indicator measures the sustainability of urban development as the ratio of the rate of expansion of urban space to the rate of population growth during the same period and is computed using Equation (3). As defined, an indicator value less than 1 implies that urban land is consumed at a slower rate than population growth, and thus, the urban area is expanding in a sustainable way. To the contrary, a value greater than 1 indicates that the urban area is growing faster than the population and suggests a development away from sustainability. Finally, a value equal to 1 would theoretically indicate that the land consumption rate is commensurate to the population growth rate, and the urban area is maintaining its original sustainability level.
Indicator values for the communes of Tlemcen are shown in Figure 6
and are sorted for easy inter-commune comparison. Out of the total 53 communes, only 21 display an indicator greater than 1.0. We use the theoretical threshold of 1.0 to separate the development sustainability and account for an uncertainty of 0.01 in the indicator, for an error of about 0.3% of the area or population estimates [31
]. Only two of the most populous communes in Figure 5
have an indicator larger than 1.0 and therefore are considered developing away from a sustainable line since their urban land consumption rate is greater than the population growth rate. These are the communes of Tlemcen, with an indicator value of 1.45, and the commune of Mansourah, with a value of 1.16, slightly over the threshold. Tlemcen is the capital of the wilaya and is rapidly expanding. It hosts administrative buildings and other government structures that make it appear to use more urban space compared to its population growth. Therefore, we argue that when estimating the SDG.11.3.1 for capital cities, one needs to account for the space allocated to government buildings as an overhead to the space consumed by the urban population. At any rate, however, the indicator trend needs to be curbed for Tlemcen
to return to sustainability. The results show that the smallest unit, in terms of population growth rate, is the commune of Ouled Mimoun, with an ISA growth rate of 15.5% during the decade and an impervious surface area per capita of 391.45 (m2
/person), resulting in the highest SDG indicator of 4.91, a clearly non-sustainable situation. The large majority of the communes of Tlemcen are rural in nature, with relatively small population counts, and although their urban land use is not strictly regulated, the communes are developing under sustainable conditions.
Since we detailed population and urban area at the commune level, we asked whether the sum of the indicators of several communes is equivalent to the indicator of the total area constituted by the same communes. To that end, we selected an urban zone of interest (UZI) comprised of the three conterminous communes of Chetouane, Tlemcen, and Mansourah, which are densely urbanized in the center of the wilaya, and calculated its SDG indicator as one entity. We found that the sustainability indicator value of the UZI is 1.19, whereas the sum of the individual indicators for the three communes is 3.15, with an average of 1.05, confirming the nonlinearity of this indicator. In line with this idea, we found the SDG of the entire wilaya to be 0.95, indicating that the urban development of the wilaya as a whole follows a sustainable path. It goes without saying that the SDG indicator is nonlinear, and the assessment of the sustainability of a region is best represented over the smallest territorial and census unit. While the wilaya of Tlemcen as a whole appears to be on the sustainable path, 21 of its communes are not (Figure 6
For comparison, we utilized a state variable, the ISA per capita, defined as the impervious surface area (ISA) divided by the total population of the same area at a given time. The ISA per capita provides a precise urban land consumption per person [6
]. The ISA per capita and its variation were then used as a metric to parallel the urban SDG indicator. Results for the wilaya of Tlemcen show that all the communes with an indicator value of less than 1 recorded a decrease in their ISA per capita (Figure 7
). Among these, five communes had a large decrease in ISA per capita, namely El Aricha, Ouled Riah, Remchi, Zenata, and Marsa Ben M’hidi, ranging from 82 m2
/person for Al Aricha to 12 m2
/person in Marsa Ben M’hidi, while all others had a decrease of between 0 and 10 over the considered decade. Similarly, all communes with an SDG indicator value greater than 1 recorded an increase in ISA per capita. This increase is less than 15 m2
/person except for the communes of Honaine, Souk Thlata, El Gor, Djebala, Ain Nehala, and the commune of Bouhlou, which has culminated with an increase of 96 m2
/person over the 10-year period. It is important to note that the ISA per capita decrease between 2008 and 2018 is mainly due to an increase in the 2018 population rather than a decrease in ISA, whereas the ISA per capita increase is mainly driven by an ISA increasing faster than the corresponding population. Overall, as far as the urban development is concerned, the wilaya of Tlemcen seems to be on a sustainable track, with a constant ISA per capita of 116 m2
/person for both 2008 and 2018.
3.2. The Wilaya of Oran
The wilaya of Oran is located in the north-west of Algeria; it is comprised of 26 communes including its capital, Oran. Because of its population size, commercial and industrial activities, and its cultural importance, Oran is a major coastal metropolis and the second most important in Algeria after the country’s capital, Algiers. The total population of the commune was 600,000 in 2008, while the wilaya had a total population of approximately 1,500,000, making it the second largest in Algeria. The population distribution in the wilaya of Oran is not uniform among its communes. Out of the 26 communes, only 3, namely the wilaya seat Oran
and its adjacent communes Bir El Djir and Sidi Chami, counted more than 100,000 inhabitants in 2008 (Figure 8
). The wilaya contains the three intermediate-sized communes of Arzew, Es Senia, and Hassi Bounif, with more than 60,000 inhabitants, while all other communes had a population count of less than 38,000 inhabitants in 2008. The population dynamic in the wilaya shows that the largest growth rate between 2008 and 2018 was recorded in Bir El Djir, a commune to the east and adjacent to Oran
, which saw its population growing from 152,151 in 2008 to 361,409 in 2018, a formidable growth rate of 137.53%. The different administrative redistricting of the communes in the wilaya created apparent movements of the local population, resulting, for example, in a population decrease in Oran between 2008 and 2018 of about 5.27%, mostly due to the spilling of its population over into Bir El Djir and other neighboring communes in search for affordable housing while still residing within comfortable commuting distance. Similarly, the commune of Oued Tlelat, with a small population count in 2008 of 18,397 persons, has grown to 40,717 in 2018, an unhealthy 121.32% increase. Most of the communes showed significant growth, with many over 40%. The smallest population growth (29.3%) was recorded in the commune of Arzew.
shows the areal expansion of the communes in the wilaya of Oran. It is clear that the largest commune is Oran
, with an ISA of 34.66 km2
in 2008, increasing to 37.82 km2
in 2018. Oran
is the core of the wilaya, with a dense built-up area dating back to the colonial period. The population increase has forced the expansion of buildup to the east, as the commune is limited by the Murdjadjo Mountain to its west and the Great Sebkha Lake to its south [32
]. Large industrial zones have been constructed, and a significant extension has emerged to its east, closing the gap with the adjacent commune of Bir El Djir, which has become the second largest commune of the wilaya, with 21.48 km2
in 2018. While the largest communes recorded a moderate increase in urban land consumption, smaller-sized communes experienced an explosive growth of more than 20%, with the entire wilaya growing at an average 27.9% over the 10-year period.
The population growth and the urban land consumption are not independent, and the UN SDG 11.3.1 as described in (3) defines this dependence. The implementation of new administrative divisions has led to an apparent decrease in population in some communes such as Oran, which recorded a decrease in population between 2008 and 2018. Since the formulation of the indicator does not allow for the population or the built-up area to recede during the measurement period [15
], Oran is not included in the analysis of the SDG 11.3.1 shown in Figure 10
. The wilaya of Oran has a high demand for future growth potential, and only six of its communes, the smallest in size and population, have an indicator value greater than 1 and are therefore developing in a non-sustainable way. These communes are Marsat El Hadjadj, Boutlelis, El Braya, Ain Biya, Ain El Kerma, and Arzew. This is characteristic of small urban areas, which usually populate rapidly due either to a migratory inflow or just an increase in the land consumption per capita during the early phase of the urban settlement. All other communes have an indicator value of less than 1, signifying that land consumption for urban purposes is growing much slower than population and, therefore, is evolving in a sustainable direction. The ISA per capita distribution for the communes of Oran is in line with the SDG 11.3.1 indicator (Figure 11
) and shows that in all the communes indicating unsustainability, the ISA per capita increased. Although not too large for a decadal increase of 14 to 21 m2
per person, the tendency is towards consuming more urban land per person. For all other communes, the ISA per capita decreased, and the land appropriated for urban use grew much slower than the population. For the commune of Oran, for which the SDG 11.3.1 is not defined, the ISA per capita value appears to be a better proxy and gives a direct measurement of the urban land use in relation to the population dynamic. The ISA per capita for Oran
increased by 8.63 m2
/person over the 10 years. Overall, for most of its communes, the wilaya of Oran seems to have an urban land use commensurable to its population increase except for some communes where land tenure regulation and land-use policy need to be revisited to maintain sustainable development within the limits of land availability.
3.3. The Wilaya of Algiers
The wilaya of Algiers is the most populated in Algeria. Its seat, Algiers, is also the country’s capital. Located on the shores of the Mediterranean Sea, the wilaya of Algiers is made up of 57 communes (Figure 12
) with approximately 3 million inhabitants in 2008. The wilaya experienced a significant growth rate during the 2008–2018 decade. The modern city in the commune of Algiers is built on the ground level by the seashore, while the ancient city climbs the steep hill and is crowned by the Casbah, a citadel located about 100 m above sea level. Algiers is known for its fast-growing economy, population, and urban expansion. The most populated communes as of 2008 are Bordj El Kifan (151,950), Djisr Ksentina (147,541), Baraki (116,375), Les Eucalyptus (116,107), Kouba (104,708), and Algiers
in the sixth position with only 99,843 inhabitants. Apart from these communes and few others with a population of more than 60,000 inhabitants, most of the communes of Algiers have a population count of between 10,000 and 50,000 inhabitants, with the commune of Rahmania having the smallest population of 7396 inhabitants in 2008. Since population was not available for the communes of Algiers in 2018, we are not able to comment on the growth rate at the communal level.
The distribution of the ISA in the communes of Algiers is shown in Figure 13
and reveals three categories of growth: (1) communes that are originally small in size (<4 km2
) and densely populated, for example, Casbah, Bab El Oued, and Bologhine, where the built-up growth between 2008 and 2018 was relatively small (<10%); (2) communes that were originally small (<4 km2
) but not densely populated, such as Bordj El Bahri, Baba Hassen, and Birtouta, which recorded an explosive growth of more than 40%, with some extreme growth of more than 100% in the communes of Saouala, Ouled Chbel, Souidania, Douera, Tassala, Mahelma, Ouled Fayet, Khraissia, and Rahmania; and (3) the remaining communes that have experienced sizable growth in urban land consumption of 10% to 40%. This uneven correlation between urban land consumption and population growth leads to an urban development dynamic that is not sustainable, as described by the SDG indicator in Figure 14
. Out of 57 communes, only 14 have an SDG 11.3.1 value of less than 1, pointing to a tendency towards sustainable growth. All other communes show an urban land consumption rate higher than the population growth rate, a sign of unsustainability and irrational urban land use. In a wilaya such as Algiers, which hosts the capital buildings, it is difficult to assess the relationship between population and impervious surface area, as the urban area includes government buildings that are uninhabited but are accounted for as land consumed and therefore counterbalance sustainability as defined by the UN SDG indicator and the ISA per capita. It is clear from the ISA distribution that the communes with concentrated government buildings, such as El Madania, El Mouradia, Hydra, and Algiers
, have had minimal growth in terms of area, whereas limitrophe communes at the periphery of the wilaya, where capital city workers seek affordable housing, have experienced an explosive growth of up to 170% in places such as Rahmania (Figure 13
To further assess this tendency, we analyzed the ISA per capita change between 2008 and 2018. The ISA per capita precisely describes the footprint of each individual inhabitant of the urban area and includes all impervious surfaces making up the artificial ground. Figure 15
shows that all the 14 communes with an SDG indicator value of less than 1 had a reduction in ISA per capita. Knowing that the ISA did not decrease in any of these communes (Figure 13
), a decrease in ISA per capita points to an increase in population. While the indicators suggest a tendency towards sustainability, the reality on the ground suggests otherwise. In these urban areas where population growth exceeds urban land growth, there will be overcrowding, with more people than what the urban land can support, an aspect neither the SDG 11.3.1 nor the ISA per capita indicator captures. This result, in addition to the limitations listed in Bounoua et al. [15
], makes SDG 11.3.1 incomplete for the determination of sustainable urbanization.
3.4. The Wilaya of Annaba
The wilaya of Annaba is located in the extreme east of Algeria about 600 km away from its capital of Algiers. It is a coastal province on the Mediterranean Sea and has 12 communes. With a population of about 600,000 inhabitants in 2008, it is considered the fourth most important locality in Algeria. Annaba, the seat and capital of the wilaya, like most other northern Algeria cities, is marked with different models of urban fabrics: the Medina, the colonial sector, the modern post-colonial parts, and the informal slums. This structure makes the commune of Annaba fragmented, with the inner Medina the least integrated [33
]. Annaba has a metropolitan area with a higher population density than the other metropolises on the Algerian coastline, such as Tlemcen, Oran, and Algiers. Between 2008 and 2018, the wilaya population increased by 20.54%, but the ISA increased by 40.13 km2
or 49.5%. The population distribution for the wilaya of Annaba is uneven between its communes, as can be seen in Figure 16
. Its 2018 population of 734,468 is basically concentrated in three large communes of Annaba, which represents 43% of the total population, and El Bouni and Sidi Amer, accounting for 20% and 14%, respectively. For the remaining communes, except for El Hadjar, with little more than 42,000 inhabitants, all have a population count of less than 30,000. All the communes have had a significant growth rate varying between 8.5% and 29%. In contrast to the population, the ISA growth rate in the wilaya of Annaba was important in the smaller communes with smaller population sizes, with the largest growth occurring in the commune of Oued El Aneb, where the ISA increased from 3.12 km2
in 2008 to 8.65 km2
or 17.72% (Figure 17
). The large discrepancies in growth rates between population and urban land consumption is the core issue addressed by the SDG 11.3.1 that, as a whole, should provide a metric to monitor the harmonious growth of population and land consumption for urban purposes. The least one can say is that the evolution of these quantities is not homogenous across communes and not sustainable in mid- to long-term timeframes for the wilaya of Annaba. Figure 18
shows the distribution of the SDG 11.3.1 indicator for the communes of the wilaya, and except for the commune of Ain Berda, where the indicator is less than unity, all other communes have consumed urban lands at a rate faster than population growth. Indeed, while the wilaya of Annaba is expanding its tourism infrastructure mainly in the urban area of the Annaba
commune, other tourism-related projects are expanding in the commune of Seraidi, which appears to have an explosive built-up growth rate. The SDG indicates that, except for Ain Berda, all communes have an urban land use that is much higher than their population growth rate and are, therefore, developing away from sustainability.
While economic development is high in Algeria in general, especially in some prime coastal wilayas encouraging tourism infrastructure, it must consider a rational land-use policy where regulation of land tenure and use is applied. At the pace observed between 2008 and 2018, the land use in the communes of Annaba will reach saturation, and further expansion must be considered, often at the expense of vegetated lands. Verticality is an option to reduce the population footprint, but here, too, caution must be taken to avoid overcrowding and maintain sustainable living. Similar to other wilayas, the ISA per capita has decreased for the commune, where the SDG 11.3.1 indicator was less than unity but has increased significantly elsewhere, with the highest per capita land-use increase of 169.86 and 183.58 m2/person recorded in Oued El Aneb and Seraidi, respectively.
3.5. The Wilaya of Ghardaïa
The wilaya of Ghardaia is located in the northern part of the Sahara Desert. It contains the valley of M’Zab, distinguished by architecture designed for community life with respect to family structures while perfectly adapting to the arid environment. The wilaya is composed of 13 communes and spans an area of 86,560 km2. The unique layout of construction in Ghardaia is constrained by the rocky landscape and the M’Zab River. Houses are often laid in alleyways in the form of labyrinths and are oriented towards sunlight. The fabric of the urban areas consists of housing, mosques, and marketplaces.
The commune of Ghardaia is the capital of the wilaya and represents the most populated commune (Figure 19
). In 2008, it had 93,423 inhabitants, which increased to 101,374 in 2018. On the other hand, the commune of Sebseb is the least populated, with only 2437 inhabitants in 2008. The population growth rates varied between about 25% and 87%, with only two communes having a growth rate of less than ten. The commune of Hassi Lefhal recorded the highest population growth rate in the wilaya at 87.18% between 2008 and 2018. The wilaya of Ghardaia is small in terms of population count, as it had only 363,598 inhabitants in 2008. However, the impact of this population growth on land use is significant, as shown in Figure 20
, especially in smaller communes where the built-up area increased by up to 174.2% in El Mansoura and up to 249.7% in Hassi Lefhal. The SDG 11.3.1 indicator shows that the communes of Ghardaia are not homogeneous in terms of development. While five communes follow a sustainable development path with indictor values much less than unity, others (seven communes) have indicator values ranging from about 1.3 to 2, suggesting a development away from sustainability with varying degrees of severity. The commune of Sebseb, however, which had an increase in urban land use of 52.3% and a population growth rate of only 5.99%, measured an indicator value of 7.24, clearly signifying that the development is not sustainable (Figure 21