The topography of the Algiers coast is characterized
The topography of the Algerian coast is characterized by the succession from the current shore and up to an altitude of more than 300 meters , of a series of steps, arranged one above the other like the steps of a staircase.These steps abruptly interrupt the continuity of the slopes, generally very steep, which border the Algiers coastline.
Hydrography
Geology and relief
Algiers is crossed by several rivers and several watercourses that are indifferently called Oued. All the rivers that cross it flow into the Mediterranean which borders the entire Algerian coast. Its hydrographic system is specific to the Mediterranean environment: the water flow is low but its watercourses experience significant floods in the event of rain. The Bouzaréah massif, known for its rugged relief, has a very dense hydrographic network, drained by eight main watercourses (Baranès, Sidi Medjber, Frais vallon, jaubert, Scotto Nadal, Chemin du Fort, Birtraria and Oued Koriche or Oued Atoun (ex-Oued Mkacel)). Half of its watercourses have been artificialized and channeled by buried collectors. To the west, the Mazafran Wadi forms the border between the wilayas of Algiers and Tipaza, further east, between Chéraga and Aïn Benian, the mouth of the Beni Messous Wadi. To the east, the El Harrach , El Hamiz and Réghaïa Wadis as well as the area known as “Lake Réghaia”, a site of international ecological importance protected by the Ramsar Convention , are particularly affected by pollution due to the many factories located in this area. In recent years, the El Harrach Wadi has benefited from a sanitation and development project.
Overexploitation of groundwater tables in dry seasons would cause a significant drawdown of the piezometric level, a reversal of the direction of underground flow and consequently problems of marine intrusion towards the coastal aquifer 9 . The Douéra reservoir dam (Skalandji) allows the storage of water from the Mazafran (39 hm 3 ) and El Harrach (71 hm 3 ) wadis. The total capacity of this reservoir is 87 hm 3 intended mainly for the irrigation of 17,200 ha of the central Mitidja plain and the replenishment of the water table by infiltration 10 .
Algiers is supplied with drinking water by the Bouroumi 11 , Keddara 12 , Beni Amrane 13 and Taksebt 14 dams and by the El Hamma desalination plant which began operating in March 2008.
The geological study of the Algiers region, which is not very extensive in surface area and forms a rock which juts out into the sea, reveals that behind it it is covered by a strip of dunes beyond which we find the sedimentary terrains 15 of the Tertiary series 16 .
In a geological and topographical sketch of the coastline of Algiers dating from 1911, it appears that this coastline essentially includes the entire low region which borders the foot of the Atlas for more than 100 kilometers , from the Sidi-Fredj massif to the north of Thénia des Béni Aïcha, to Mount Chenoua to the west of Tipaza 17 .
The relief is characterized by three longitudinal zones: the Sahel, the coast and the Mitidja.
Natural hazards
Algiers is a sensitive seismic zone, several faults are detected in its territory (Khaïr al Dine, Zemmouri, Sahel, Chenoua, Blida, Thenia). These faults with different seismic potentials are likely to generate earthquakes 23 . The most violent that has ever been recorded is that ofJanuary 3, 1365, as a result of which Algiers was completely destroyed and partly flooded 24 . The last major earthquake dates back toFebruary 3, 1716and cost the lives of 20,000 people. In addition, several neighborhoods were affected by the Boumerdes earthquake in 2003 (Zemmouri fault).
Due to its geographical location, Algiers is highly exposed to flood risks due to rainwater runoff from the heights of the city to the districts located below. This risk is accentuated by several factors linked to an urban development that takes little account of the risks. Several buildings are built on wadi beds, such as in the Hydra valley.
THENovember 10, 2001, torrential rains fell on Algiers, transforming the wadi beds into torrents of mud. This catastrophe caused the death of more than 750 people , mainly in Bab El Oued , a district where entire buildings were destroyed 25 .
Current period
Prehistory
There is no administrative definition of the city of Algiers intramuros . The wilaya of Algiers comprises 57 communes, almost all of which correspond to districts of Algiers. The wilaya of Algiers therefore corresponds roughly to the city of Algiers, as a continuous urban unit.
According to the ANIREF source [ archive ] the wilaya of Algiers had 3,309,896 inhabitants in 2020.
However, the urban area of Algiers extends beyond the wilaya of Algiers alone, into the three neighboring wilayas of Blida , Boumerdes and Tipaza . These three wilayas had respectively 1,275,568 , 801,068 and 809,311 inhabitants in 2018 or 2020 according to the same source.
Thus, the cumulative population of the wilayas of Algiers, Blida, Boumerdes and Tipaza was 6,195,843 inhabitants in 2018-2020. Excluding the parts furthest from Algiers (west of the wilaya of Tipaza and east of the wilaya of Boumerdes), it seems reasonable to estimate the population of the Algiers urban area at around 5 million inhabitants. The publication of data from the 2022 population census should make it possible to refine this estimate.
Unofficial and foreign sources sometimes put forward a population of up to 8 million inhabitants for the agglomeration or urban area of Algiers, but such a population seems impossible given the official figures provided by the Algerian authorities (population census, ONS and ANIREF). Indeed, such estimates exceed the cumulative population of the four wilayas encompassing the urban area of Algiers, which is objectively impossible.
The age pyramid of the wilaya of Algiers highlights a relatively large young population, almost a third of the population is under 20 years old . However, there has been a decrease in births since 1983 and a recovery in the birth rate over the period 2004/2008.
The only trace of human presence, for the Lower Paleolithic, is summed up in a single biface that was discovered in the vicinity of Mahelma and attributed to a Middle Acheulean , if not more likely Upper Acheulean 51 . The two most important deposits discovered in the Sahel of Algiers date back to the Middle Paleolithic , one of them being the one discovered during the construction, in 1961, of the city of Malki (ex-Allobroges), in Ben Aknoun, and the other, that of the cave of the Grand Rocher, in Aïn Benian, which dates back to the Neolithic 52 . Other deposits have yielded remains attributed to the Iberomaurusian dating back to the Neolithic and Poor Neolithic. Around 1840, Adrien Berbrugger had discovered one of the most important megalithic necropolises on the Algerian coast: the dolmens of Beni Messous. The necropolis extended over both banks of the Oued Beni Messous, that of Beni Messous (right bank) and that of Aïn Kalaa (left bank) 53. The Sahel of Algiers offers a panel of the different prehistoric cultures of the Maghreb with the exception of the heeled axe, from the Bronze Age, discovered in Saint-Eugène (Bologhine) and which represents a unique case in the Maghreb.
Antiquity
Une localité appelée à l’origine par les Puniques Ikosim (nom signifiant « l’île aux mouettes » d’après Victor Bérard ou « l’île aux épines » ou « aux hiboux » d’après Joseph Cantineau et Louis Leschi54), lorsqu’elle acquit le statut de comptoir phénicien d’importance, la fondation d’Ikosim est antérieure au IVe siècle av. J.-C. Des débris de vases campiniens datant du IIIe siècle av. J.-C. y furent découverts dans un puits de vingt mètres de profondeur en 1940.
Déjà au début du Ier millénaire av. J.-C., Ikosim était un important comptoir phénicien. En -202, la ville passa sous influence romaine à la suite de l’alliance scellée entre Massinissa et Scipion l’Africain contre Carthage. Le nom d’Ikosim prend sa forme romanisée, Icosium, sous Juba Ier et Ptolémée.
Les tribus berbères Maghraouas étaient très nombreuses dans les environs d’Icosium et Ptolémée de Maurétanie devait les contenir. Ptolémée de Maurétanie fit transférer une partie des Maghraoua vers le Chlef55 et il combat les résistants berbères soulevés par Tacfarinas56, dans cette même période. Après Tibère, Vespasien envoya une colonie à Icosium pour arrêter les révoltes57.
Après la révolte de Tacfarinas, Firmus (général maure berbère) détruisit Icosium en mettant le feu avec l’aide de toutes les tribus berbères maures (non romanisés) qui vivaient dans les montagnes des environs au IVe siècle58.
C’est vers le Ve siècle que le christianisme s’introduisit à Icosium. En 429, la ville passa sous domination vandale, lors de leur conquête de l’Afrique du Nord. En 442, un traité entre Romains et Vandales permit aux Romains de récupérer Icosium et ce durant les cent ans de présence vandale en Algérie.
Après 533, la ville, à peine contrôlée par les Byzantins, fut attaquée par des tribus berbères.
Siege of Algiers by Emperor Charles V
After the Battle of Tunis in 1535 and with the aim of securing his Mediterranean positions, Charles V decided in 1541 to seize Algiers which had become a real “corsair” base (in the sense of the Mediterranean corso) under the leadership of the brothers Arudj then Khayr ad-Din Barbarossa.
In October 1541, the emperor assembled a war fleet. Algiers was then under the authority of Hassan Agha. Hassan Agha strengthened the city’s fortifications and arsenals. During the siege of the city, a violent storm broke out. The storm continued all evening and even all night. In the early morning, the rain continued to fall, making the powder for the cannons and arquebuses unusable. The imperial troops were then decimated by the troops of Hassan Agha and irregulars from the surrounding countryside. The imperial army then retreated towards Cape Matifou.
The retreat was disastrous for the imperial forces because the road was cut by a flood of the Oued El-Harrach while the Algiers and irregular troops harassed them, causing them great losses. The survivors arrived at Tamentfoust, then Charles V’s troops took refuge in Béjaïa, then still in the hands of the Spanish. After this debacle, the city became the most powerful of the new cities in the Mediterranean. The regency of Algiers, firmly established, lasted three centuries, until 1830.
Colonisation française
In 1830, after 3 years of a blockade which began on June 16, 1827, King Charles , minister of war, so that he could take possession of the city, which fell on July 5, 1830, three weeks after the landing of Sidi-Ferruch located at 30 km west75. General de Bourmont’s troops seized the treasure of Algiers which, according to Pierre Péan, amounted to 500 million francs at the time (or 4 billion euros), a good part of which was misappropriated76,77. Originally presented as a simple punitive military raid, the French occupation continued for more than 130 years, and had a profound impact on the city, which had barely 30,000 inhabitants at that time.
“Moorish (in) interior costume” in Algiers (c. 1880).
The city, built like an amphitheater on a rock whose inclination faces east, then extended, in the part between the current rue Benganif, boulevard Hahkad, the casbah (the citadel) and the port, i.e. 3 200 meters of ramparts with five gates (Bab El Oued, Bab Azzoun, Bab Dzira, Bab El Bhar and Bab Jedid) which enclosed approximately 12 200 houses of varying sizes, all containing a courtyard of greater or lesser extent, 103 mosques, around ten synagogues, 7 large janissary barracks, 150 fountains and 60 Moorish cafes.
The suburbs made up the countryside with beautiful villas buried in a green setting and vast gardens which were the admiration of Europeans. The upper town, the Jebel, constituted the real town with its mosques, its zaouïas and its narrow streets.
Following colonization, the city was maintained as the capital of the new colony of Algeria, where a government commission and a municipal council established by Bourmont, meeting first at the Bacri hotel (today “Dar Khedaouedj palace Amiya”), rue Socgémah, replaced the Turkish administration. This assembly, composed of seven Moors and two Israelites, was chaired by a Moor married to a French woman, Ahmed Bouderbah who, before 1830, had lived as a merchant in Marseille. It was he who, with Hamdan Khodja, negotiated the surrender of the city with Dey Hussein. Mr. Brugière, military deputy intendant, acting as “King’s commissioner near the municipality” assisted him in his task.
French colonization began with the repression of the natives, who were chased from the entire Algiers Sahel, then evolved into their cantonment which forced them to sell their work to the neighboring colonist78.
Seconde Guerre mondiale
Pendant la Seconde Guerre mondiale, l’Afrique du Nord française, dont Alger, resta sous les ordres de la métropole, donc à compter de juin 1940 du gouvernement de Vichy. Le 8 novembre 1942 seulement, Alger vit débarquer les forces alliées, dans le cadre de l’opération Torch. À Alger, le succès du débarquement est lié à une opération de résistance de grande ampleur. Quatre cents combattants, dont de nombreux membres de la communauté juive d’Alger85, occupèrent les principaux points stratégiques de la ville la nuit précédant le débarquement, emmenés par Henri d’Astier de La Vigerie et José Aboulker. Ce putsch permit d’éviter toute résistance du 19e corps d’armée vichyste, stationné dans la ville sous le commandement du général Juin.
Alger devint le siège du commandement allié, chargé de libérer la Tunisie de la tutelle de l’Axe et de préparer le débarquement en Italie sous la direction du général Eisenhower, futur président des États-Unis.
Le succès militaire de l’opération permet à la France libre de transférer sa capitale figurative de Brazzaville à Alger86, lorsque, après un maintien provisoire du régime de Vichy sous l’amiral Darlan et le général Giraud (voir Situation politique en Afrique libérée (1942-1943)), elle accueillit le général De Gaulle qui le 3 juin 1943 y forma, avec Giraud, le Comité français de libération nationale (CFLN), puis convoqua une Assemblée consultative provisoire. Le 3 juin 1944, le CFLN devint le Gouvernement provisoire de la République française (GPRF), qui siégea à Alger jusqu’au 31 août 1944.
Guerre d'indépendance
Alger se constitua en Zone autonome d’Alger, fin de l’année 1956 sous le commandement de Ramdane Abane et ensuite de Yacef Saâdi en 1957, joua aussi un rôle décisif durant la guerre d’Algérie (1954-1962), notamment pendant la bataille d’Alger, durant laquelle la 10e division parachutiste de l’armée française, à partir du 7 janvier 1957, mena la chasse aux indépendantistes algériens, sur ordre du garde des Sceaux François Mitterrand, qui lui donne tout pouvoir pour « éliminer les insurgés ». La ville comptait alors 884 000 habitants. Un an plus tard, les manifestations du 13 mai lors de la crise de mai 1958 y consacrèrent la chute de la Quatrième République en France, ainsi que le retour du général De Gaulle aux affaires.
Alger reste marquée par cet épisode caractérisé par une lutte sans quartier entre les indépendantistes et l’Armée française menant des opérations de police et pratiquant la torture. Des opposants à l’ordre colonial, comme le jeune professeur de mathématiques Maurice Audin ou le leader nationaliste Larbi Ben M’hidi sont maintenant honorés depuis par la municipalité : des artères principales de la ville portent désormais leurs noms. La bataille d’Alger, remportée par le général Massu, reste cependant une réussite mitigée car si sur le plan militaire, en quelques mois, les principaux dirigeants du FLN sont arrêtés, l’action de ces derniers ainsi que les aspirations du peuple algérien apparaissent sous un jour nouveau aux yeux de l’opinion internationale. Le 11 décembre 1960, des cortèges formés d’habitants des bidonvilles envahissent les rues des quartiers européens afin de réclamer la fin de la guerre. Charles de Gaulle autorise l’armée à ouvrir le feu sur les manifestants, tuant au moins 260 personnes
