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Lake Chad
Lake Chad (Arabic: بحيرة تشاد, Kanuri: Sádǝ, French: Lac Tchad) is an endorheic freshwater lake located at the junction of four countries: Nigeria, Niger, Chad, and Cameroon, in western and central Africa respectively, with a catchment area in excess of 1,000,000 km2 (390,000 sq mi). It is an important wetland ecosystem in West-Central Africa. The lakeside is rich in reeds and swamps, and the plain along the lake is fertile, making it an important irrigated agricultural area. The lake is rich in aquatic resources and is one of the important freshwater fish producing areas in Africa.
Lake Chad is divided into deeper southern parts and shallower northern parts. The water source of the lake mainly comes from rivers such as the Chari River that enter the lake. The water level varies greatly seasonally, and the area of the lake also changes dramatically. During the African humid period, the lake's area reached 400,000 km2 (150,000 sq mi). Due to the increasingly arid climate, the lake surface gradually shrank. In the 19th century, it still had an area of 28,000 km2 (11,000 sq mi). However, due to climate change and human water diversion, it has shrunk significantly since the mid-1970s, and its area has fluctuated between 2,000 and 5,000 km2 (770 and 1,930 sq mi).
The Chad Basin was formed by the depression of the African Shield. The floor of the basin is made of Precambrian bedrock covered by more than 3,600 m (11,800 ft) of sedimentary deposits. For most of the Quaternary, the basin had abundant water sources. Towards the end of this period the climate became drier. Around 20,000–40,000 years ago, eolianite sand dunes began to form in the north of the basin. The area of Lake Chad experienced four heydays between 39,000 BC and 300 BC, leaving thick diatomaceous earth and lacustrine deposits in the strata. This has been called Mega-Chad. The maximum depth of Mega-Chad exceeded 180 m (590 ft) and it covered an area of approximately 400,000 km2 (150,000 sq mi), it flowed into Benue River through the Mayo Kébbi, which drains into the Atlantic Ocean through the Niger River.
The vast waters formed during the African humid period provided conditions for the emergence of lakeside fishermen's settlements, and the Nilo-Saharan ethnic group also migrated to Lake Chad during this period. Agriculture also emerged in the Sahel region at this time. By 1800 BC, a pottery culture known as Gajiganna had emerged, initially as pastoralists, but, starting around 1500 BC, living in settled hamlets at the side of the lake. The archaeological discovery revealed wild grasses, mostly of the tribe Paniceae, and wild rice together with the earliest domesticated Pearl millet in the Lake Chad region, dating to 1200–1000 cal BC. One of the oldest domesticated Pearl millet in West Africa was found in the Chad Basin, charred together with wild grasses, and their era can be traced back to 800–1000 cal BC.
Permanent villages were established to the south of the lake by 500 BC, and major archaeological discoveries include the Sao civilization. According to the records of Claudius Ptolemy in the mid-2nd century AD, the Romans of the 1st century AD had already come into contact with Lake Chad through their connections with Tunisia, Tripolitania, and Fezzan. By the 5th century AD camels were being used for trans-Saharan trade via the Fezzan, or to the east via Darfur. After the Arabs conquered North Africa during the 7th and 8th centuries, the Chad Basin became increasingly linked to the Muslim countries.
Trade and improved agricultural techniques enabled more sophisticated societies. Around 900 AD, the Kanem people who spoke the Kanuri language unified numerous nomadic tribes and established the Kanem Empire in the northeast of Lake Chad. At the beginning of the founding of the country, the Kanem people continued to live a nomadic life until the 11th century, when they were Islamized and settled in Njimi. Through trans-Saharan trade, the power of the Kanem Empire reached its peak in the 13th century, but as the empire declined in the 14th century, its southwestern vassal state of Bornu began to rise, causing the power center of the empire to shift to Bornu around 1400. In the second half of the 16th century, the Bornu Empire began importing firearms from North Africa, consolidating its military hegemony. The Bornu Empire declined in the 18th century, and later lost its western region to the Sokoto Caliphate during the early 19th century. It was later colonised by European powers in the 20th century.
Following the growing interest in Africa among European academic and business communities, the Lake Chad area was extensively described by Europeans in the 19th century. Three scientific expeditions were conducted between 1898 and 1909. During the Berlin Conference in 1884–1885, Africa was divided between the European colonial powers. By the second decade of the 20th century, Lake Chad had been colonized and occupied by Britain, France, and Germany, defining boundaries that are largely intact with the present post-colonial states. At the beginning of independence, the countries surrounding Lake Chad not only had a poor economic foundation, but also had more complex ethnic, religious, and political conflicts. Nigeria and Niger, which had just gained independence, experienced continuous coups, while Chad also experienced ongoing civil war. The inability of countries along the lake to consider the protection of Lake Chad has led to a series of environmental problems.
The Chad Basin includes Chad, Nigeria, Cameroon, Niger, Sudan, and the Central African Republic. It is an extensional fault depression type rift basin, which can be divided into four secondary structural units: southern depression, northern depression, central uplift, and eastern slope. The southern depression of the basin is characterized by an asymmetric fault depression composite rift with steep slopes in the east and gentle slopes in the west on the profile, and is distributed in an NNW direction on the plane. There are two large basin‐bounding normal faults developed on both sides of the basin, with a graben style fault and depression in the middle. The east and west sides are outward dipping low angle gentle slope areas. The eastern boundary fault is steep with a dip angle of about 55°, while the western fault has a dip angle of about 45°. The overall thickness of the inner layer in the slope area is relatively thin. In the central area of the basin, the thickness of the sedimentary strata is large, and the thickness of the sedimentary center zone reaches over 10,000 m (33,000 ft). The northern part of the basin appears steep in the west and gentle in the east on the profile. Five fault structural zones parallel to the basin‐bounding faults have developed from west to east.
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Lake Chad
Lake Chad (Arabic: بحيرة تشاد, Kanuri: Sádǝ, French: Lac Tchad) is an endorheic freshwater lake located at the junction of four countries: Nigeria, Niger, Chad, and Cameroon, in western and central Africa respectively, with a catchment area in excess of 1,000,000 km2 (390,000 sq mi). It is an important wetland ecosystem in West-Central Africa. The lakeside is rich in reeds and swamps, and the plain along the lake is fertile, making it an important irrigated agricultural area. The lake is rich in aquatic resources and is one of the important freshwater fish producing areas in Africa.
Lake Chad is divided into deeper southern parts and shallower northern parts. The water source of the lake mainly comes from rivers such as the Chari River that enter the lake. The water level varies greatly seasonally, and the area of the lake also changes dramatically. During the African humid period, the lake's area reached 400,000 km2 (150,000 sq mi). Due to the increasingly arid climate, the lake surface gradually shrank. In the 19th century, it still had an area of 28,000 km2 (11,000 sq mi). However, due to climate change and human water diversion, it has shrunk significantly since the mid-1970s, and its area has fluctuated between 2,000 and 5,000 km2 (770 and 1,930 sq mi).
The Chad Basin was formed by the depression of the African Shield. The floor of the basin is made of Precambrian bedrock covered by more than 3,600 m (11,800 ft) of sedimentary deposits. For most of the Quaternary, the basin had abundant water sources. Towards the end of this period the climate became drier. Around 20,000–40,000 years ago, eolianite sand dunes began to form in the north of the basin. The area of Lake Chad experienced four heydays between 39,000 BC and 300 BC, leaving thick diatomaceous earth and lacustrine deposits in the strata. This has been called Mega-Chad. The maximum depth of Mega-Chad exceeded 180 m (590 ft) and it covered an area of approximately 400,000 km2 (150,000 sq mi), it flowed into Benue River through the Mayo Kébbi, which drains into the Atlantic Ocean through the Niger River.
The vast waters formed during the African humid period provided conditions for the emergence of lakeside fishermen's settlements, and the Nilo-Saharan ethnic group also migrated to Lake Chad during this period. Agriculture also emerged in the Sahel region at this time. By 1800 BC, a pottery culture known as Gajiganna had emerged, initially as pastoralists, but, starting around 1500 BC, living in settled hamlets at the side of the lake. The archaeological discovery revealed wild grasses, mostly of the tribe Paniceae, and wild rice together with the earliest domesticated Pearl millet in the Lake Chad region, dating to 1200–1000 cal BC. One of the oldest domesticated Pearl millet in West Africa was found in the Chad Basin, charred together with wild grasses, and their era can be traced back to 800–1000 cal BC.
Permanent villages were established to the south of the lake by 500 BC, and major archaeological discoveries include the Sao civilization. According to the records of Claudius Ptolemy in the mid-2nd century AD, the Romans of the 1st century AD had already come into contact with Lake Chad through their connections with Tunisia, Tripolitania, and Fezzan. By the 5th century AD camels were being used for trans-Saharan trade via the Fezzan, or to the east via Darfur. After the Arabs conquered North Africa during the 7th and 8th centuries, the Chad Basin became increasingly linked to the Muslim countries.
Trade and improved agricultural techniques enabled more sophisticated societies. Around 900 AD, the Kanem people who spoke the Kanuri language unified numerous nomadic tribes and established the Kanem Empire in the northeast of Lake Chad. At the beginning of the founding of the country, the Kanem people continued to live a nomadic life until the 11th century, when they were Islamized and settled in Njimi. Through trans-Saharan trade, the power of the Kanem Empire reached its peak in the 13th century, but as the empire declined in the 14th century, its southwestern vassal state of Bornu began to rise, causing the power center of the empire to shift to Bornu around 1400. In the second half of the 16th century, the Bornu Empire began importing firearms from North Africa, consolidating its military hegemony. The Bornu Empire declined in the 18th century, and later lost its western region to the Sokoto Caliphate during the early 19th century. It was later colonised by European powers in the 20th century.
Following the growing interest in Africa among European academic and business communities, the Lake Chad area was extensively described by Europeans in the 19th century. Three scientific expeditions were conducted between 1898 and 1909. During the Berlin Conference in 1884–1885, Africa was divided between the European colonial powers. By the second decade of the 20th century, Lake Chad had been colonized and occupied by Britain, France, and Germany, defining boundaries that are largely intact with the present post-colonial states. At the beginning of independence, the countries surrounding Lake Chad not only had a poor economic foundation, but also had more complex ethnic, religious, and political conflicts. Nigeria and Niger, which had just gained independence, experienced continuous coups, while Chad also experienced ongoing civil war. The inability of countries along the lake to consider the protection of Lake Chad has led to a series of environmental problems.
The Chad Basin includes Chad, Nigeria, Cameroon, Niger, Sudan, and the Central African Republic. It is an extensional fault depression type rift basin, which can be divided into four secondary structural units: southern depression, northern depression, central uplift, and eastern slope. The southern depression of the basin is characterized by an asymmetric fault depression composite rift with steep slopes in the east and gentle slopes in the west on the profile, and is distributed in an NNW direction on the plane. There are two large basin‐bounding normal faults developed on both sides of the basin, with a graben style fault and depression in the middle. The east and west sides are outward dipping low angle gentle slope areas. The eastern boundary fault is steep with a dip angle of about 55°, while the western fault has a dip angle of about 45°. The overall thickness of the inner layer in the slope area is relatively thin. In the central area of the basin, the thickness of the sedimentary strata is large, and the thickness of the sedimentary center zone reaches over 10,000 m (33,000 ft). The northern part of the basin appears steep in the west and gentle in the east on the profile. Five fault structural zones parallel to the basin‐bounding faults have developed from west to east.