The Kouilou-Niari River —also spelled Kwilu , Kwila , or Kwil —is the most important river flowing to the Atlantic Ocean of the Republic of the Congo coast. Moreover, its entire drainage area is completely in the Republic of the Congo. The river is called the Kouilou River while flowing in the coastal region of the Kouilou till the Sounda gorges. Upstream from the gorges, its name is the Niari River and it flows through the Niari Valley . The river combines with the Louessé , the Loudima and the Bouenza River and eventually flows into the Atlantic Ocean . It covers about 560 km from its origin in the Batéké Plateau of the Congo to its mouth at the coast.
32-476: The river has numerous waterfalls and is impassable from its mouth, which is of difficult access by multiple sandbars , formed primarily by the action of the Benguela current . The river is usable and boats are coming up to Kakamoéka . From Kakamoéka to Sounda , rapids and rocks are blocking access especially during dry season. Very limited traffic upstream Sounda as they are rapids and a few bridges. Bridges on
64-445: A beach , the term shoal can be applied to larger geological units that form off a coastline as part of the process of coastal erosion, such as spits and baymouth bars that form across the front of embayments and rias . A tombolo is a bar that forms an isthmus between an island or offshore rock and a mainland shore. In places of reentrance along a coastline (such as inlets , coves , rias, and bays), sediments carried by
96-401: A harbor entrance or river mouth by the deposition of freshwater sediment or by the action of waves on the sea floor or on up-current beaches. Where beaches are suitably mobile, or the river's suspended or bed loads are large enough, deposition can build up a sandbar that completely blocks a river mouth and dams the river. It can be a seasonally natural process of aquatic ecology , causing
128-433: A longshore current will fall out where the current dissipates, forming a spit. An area of water isolated behind a large bar is called a lagoon. Over time, lagoons may silt up, becoming salt marshes . In some cases, shoals may be precursors to beach expansion and dunes formation, providing a source of windblown sediment to augment such beach or dunes landforms. Since prehistoric times, humans have chosen some shoals as
160-447: A considerable range in size, from a length of a few meters in a small stream to marine depositions stretching for hundreds of kilometers along a coastline, often called barrier islands . They are typically composed of sand , although they could be of any granular matter that the moving water has access to and is capable of shifting around (for example, soil , silt , gravel , cobble , shingle , or even boulders ). The grain size of
192-418: A deep lake, that occurs at any depth, or is used as a verb for the process of proceeding from a greater to a lesser depth of water. Shoals are characteristically long and narrow (linear) ridges. They can develop where a stream , river , or ocean current promotes deposition of sediment and granular material , resulting in localized shallowing (shoaling) of the water. Marine shoals also develop either by
224-460: A network of shallow channels called distributaries that make up a distributary network that branches off from the mainstream of the river. These networks can be the blueprint for a future progradational deltaic lobe when the initial deltaic lobe is abandoned. As the deltaic lobe progresses, heavier and coarser sediments settle first. As heavier sediments are deposited at the top of the deltaic lobe, smaller and finer sediments get deposited out, creating
256-546: A site of habitation. In some early cases, the locations provided easy access to exploit marine resources. In modern times, these sites are sometimes chosen for the water amenity or view, but many such locations are prone to storm damage. An area in Northwest Alabama is commonly referred to as “ The Shoals ” by local inhabitants, and one of the cities, Muscle Shoals , is named for such landform and its abundance of Mussels . Deltaic lobe A deltaic lobe
288-427: A sloping bank which is shallower at one end than the other, then the shoaling effect will result in the waves slowing more at the shallow end. Thus, the wave fronts will refract, changing direction like light passing through a prism. Refraction also occurs as waves move towards a beach if the waves come in at an angle to the beach, or if the beach slopes more gradually at one end than the other. Sandbars, also known as
320-430: A trough bars, form where the waves are breaking, because the breaking waves set up a shoreward current with a compensating counter-current along the bottom. Sometimes this occurs seaward of a trough (marine landform). Sand carried by the offshore moving bottom current is deposited where the current reaches the wave break. Other longshore bars may lie further offshore, representing the break point of even larger waves, or
352-439: Is a navigation or grounding hazard, with a depth of water of 6 fathoms (11 meters) or less. It therefore applies to a silt accumulation that shallows the entrance to or course of a river, or creek. A bar can form a dangerous obstacle to shipping, preventing access to the river or harbor in poor weather conditions or at some states of the tide . In addition to longshore bars discussed above that are relatively small features of
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#1732780196341384-408: Is a wetland formation that forms as a river empties water and sediment into other bodies of water . As the sediment builds up from this delta , the river will break away from its single channel and the mouth will be pushed outwards, forming a deltaic lobe. When the rate of water discharge and lobe progradation are sufficiently high, a river can form a deltaic lobe. A single deltaic lobe includes
416-400: Is also used in a number of ways that can be either similar to, or quite different from, how it is used in geologic, geomorphic, and oceanographic literature. Sometimes, the term refers to either any relatively shallow place in a stream , lake , sea , or other body of water; a rocky area on the seafloor within an area mapped for navigation purposes; or, a growth of vegetation on the bottom of
448-427: Is called shoaling , and the waves are said to shoal. The waves may or may not build to the point where they break , depending on how large they were to begin with, and how steep the slope of the beach is. In particular, waves shoal as they pass over submerged sandbanks or reefs. This can be treacherous for boats and ships. Shoaling can also refract waves, so the waves change direction. For example, if waves pass over
480-436: Is covered by, sand or other unconsolidated material, and rises from the bed of a body of water close to the surface or above it, which poses a danger to navigation. Shoals are also known as sandbanks , sandbars , or gravelbars . Two or more shoals that are either separated by shared troughs or interconnected by past or present sedimentary and hydrographic processes are referred to as a shoal complex . The term shoal
512-474: Is derived from the Greek letter delta , which, like arcuate deltas, is roughly triangular. Tide dominated deltaic lobes are defined by high levels of sediment transfer, low numbers of distributaries, and the possible creation of tidal dominated fluvial structures such as sandbars. This high level of sediment transfer can be attributed to the tidally generated water movements that control the levels of water flux on
544-415: Is managing the efforts in the country to drive the project on the local scale. Nicolas Tourot, Les Projets de développement hydroélectrique en Afrique noire, mémoire de maîtrise, Paris I, 2003 EDF, études préliminaires du site hydroélectrique de Sounda, 1954. Shoal In oceanography , geomorphology , and geoscience , a shoal is a natural submerged ridge , bank , or bar that consists of, or
576-423: Is shaped by its tidal changes in the summer and winter as well as its shallow and steep basins. The Mississippi River delta (see lede image) is made up of six subdeltas, which in turn are made up of 16 individual lobes. Individual lobes in multilobe deltas can be vastly different from one another. Lobes are sequentially abandoned; the overly-extended seaward lobe silts up, and the river finds another outlet that
608-427: Is shorter and more direct. This sequential channel abandonment causes the deltaic plain to grow, creating a bird's foot delta composed of many deltaic lobes. Each major deltaic lobe is composed of complex non-detrital sediments indigenous to the basin of deposition. A change in sediment supply is responsible not only for the abandonment of a deltaic lobe, but also the coastal retreat and reaccumulation of sediments over
640-427: The beginning of a deltaic fan. When the alluvium, the smallest sediment carried by the deltaic lobe, is deposited and new land is formed, the resulting formation is considered a delta. Lobes are important in forming river deltas over time by amalgamation of channel avulsions. When a lobe is prograded the frequency of avulsion decreases, and the avulsion length increases relative to a non-progradational deltaic lobe. As
672-400: The break point at low tide. In Russian tradition of geomorphology , a peresyp is a sandbar that rises above the water level (like a spit ) and separates a liman or a lagoon from the sea. Unlike tombolo bars, a peresyp seldom forms a contiguous strip and usually has one or several channels that connect the liman and the sea. A harbor or river bar is a sedimentary deposit formed at
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#1732780196341704-447: The deltaic lobe progrades, the channel bed gradient is lowered, resulting in a sedimentary push upstream. This shifts the location of the avulsion forwards creating a completed deltaic lobe on which overlies a delta. Lobe formation is determined by a relationship between water discharge and lobe progradation. A model must take into account both factors in order to accurately predict avulsion timing and location. In wave-dominated settings
736-489: The detrital lens. A cuspate deltaic lobe involves the creation and subsequent abandonment of deltaic lobe cusps to create unique linear delta formations. The cuspate deltaic lobe is defined by its abrupt rate of discharge from river to body of water, and the creation of multiple cusp systems built up into separate but active distributaries. One such example of a cuspate delta is the Tiber River delta of Italy. The river
768-459: The development of the project. Coming together with the potential users and financial institution to put the project on track for success. Such a project is expected to help develop the country's huge mineral potential. In October 2012, APC increased their presence in the country and name a country representative. Nicolas Rouzé has a great experience in the Congo as he has been in country since 1998. He
800-422: The formation of estuaries and wetlands in the lower course of the river. This situation will persist until the bar is eroded by the sea, or the dammed river develops sufficient head to break through the bar. The formation of harbor bars that prevent access for boats and shipping can be the result of: In a nautical sense, a bar is a shoal, similar to a reef : a shallow formation of (usually) sand that
832-462: The in-place drowning of barrier islands as the result of episodic sea level rise or by the erosion and submergence of inactive delta lobes . Shoals can appear as a coastal landform in the sea , where they are classified as a type of ocean bank , or as fluvial landforms in rivers, streams, and lakes . A shoal–sandbar may seasonally separate a smaller body of water from the sea, such as: The term bar can apply to landform features spanning
864-408: The material comprising a bar is related to the size of the waves or the strength of the currents moving the material, but the availability of material to be worked by waves and currents is also important. Wave shoaling is the process when surface waves move towards shallow water, such as a beach, they slow down, their wave height increases and the distance between waves decreases. This behavior
896-562: The mid 1950s when France was looking at developing the region. Ten years of research have led to a tunnel built in the mountain, a bridge and a camp established on site. In May 2011, a protocole d'accord has been signed with a South African Company IDG and the Republic of Congo for the development of the Sounda dam project. IDG has teamed up with strategic partner African Power Corporation (APC). The two companies have joined forces to lead
928-426: The number of created deltaic lobes is limited by the number of distributaries. Lobes are rarely distinguished from one another in high tide settings as tidal currents favor channel stability and suppress avulsions. The Nile, for example, is considered to be an arcuate delta because of its arc shaping. As it is waves that shape it into an arc , it also falls under the category of a wave-dominated delta. The word delta
960-466: The river are located at Bas-Kouilou , Sounda , Kimbangou , Makabana , Loudima and Bouenza . The Kouilou part is fairly flat with the water level rising only 16 metres above sea level on first 70 km. In the area of Kimbangou, the water level is around 60 metres above sea level and reaches 115 metres at the Loudima junction. In Sounda, a large hydro electrical project has been evaluated since
992-537: The system, and to a lesser extent the increase of river discharge and local precipitation. All created channels are widened by the incoming and outgoing tide but the water depth does not increase significantly so the tidal deltaic lobe progrades further sea-word creating multiple distributaries and a flooding effect. One example of a tide-dominated deltaic lobe system is the Han River delta in Korea. The Han River delta
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1024-585: Was formed first as a deltaic lobe cusp prograded from the river mouth. An abrupt southward migration of the river mouth left the first cusp abandoned and a new deltaic lobe prograded. Finally, the two distributary channels formed one deltaic formation running through the city center. Gilbert deltaic lobes are defined by their movement of coarse-grained materials, relatively large sizes, and steep slopes into basins. This rise in level commonly results in intensified aggradation and eventual decrease in topset slope. The most well documented example of gilbert deltaic lobes
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