Cahora Bassa retrospective, 1974–1997: effects of flow regulation on the Lower Zambezi River

Davies, B. R.; Beilfuss, Richard D.; Thoms, Martín

doi:10.1080/03680770.1998.11901620

Cited by 18 publications

(32 citation statements)

References 8 publications

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“…In other words, lower flows were simulated with sections narrowing, which agree with the observations of vegetation density increase and abandoned secondary channels. This behaviour was also reported by Davies et al (2000) and .…”

Section: Evolution Of the Zambezi River During The 20th Centurysupporting

confidence: 87%

“…of these reservoirs (Bowmaker, 1960;Attwell, 1970;Hall et al, 1977;Du Toit, 1984;Dunham, 1989;Beilfuss and Davies, 1999;Beilfuss et al, 2001;Scodanibbio and Mañez, 2005;Tilmant et al, 2012;McCartney et al, 2013). Fewer works addressed morphological changes correlated to the dams' impacts on sediment and water discharges (Guy 1981;Suschka and Napica, 1986;Beilfuss and Davies, 1999;Davies et al, 2000;Basson, 2004;Ronco et al, 2010;Brown and King, 2012;. These two major dams have noticeably changed the hydrological cycle of the lower Zambezi River.…”

Section: Case Studiesmentioning

confidence: 99%

“…Data collected at the gauging station of Tete (Mozambique, about 135 km downstream of Cahora Bassa) show a modified pattern of monthly runoff characterized by the increase of minimum and decrease of maximum values (Ronco, 2008;Ronco et al, 2010). As far as the effects on river morphology are concerned, some authors have evaluated changes of the lower part of the Zambezi after the dams' construction (Suschka and Napica, 1986;Beilfuss and Davies, 1999;Davies et al, 2000;Ronco et al, 2010). The removal of sediments from gorge sections, the stabilization of braids and bars in some sections and of an individual channel in others, the delta erosion and the concurrent increase of salt-water intrusion have all been attributed to these impoundments (Chenje, 2000).…”

Section: Case Studiesmentioning

confidence: 99%

“…The Victoria Falls represent the boundary between the upper and middle reaches. About 240 km downstream of the Victoria Falls, the river flows into the Kariba Lake, created in 1959 by the Kariba Dam, which has a storage capacity of 180.6 × 10 9 m 3 (Reeve, 1960;Davies et al, 2000). The middle Zambezi flows into the Cahora Bassa Lake (Mozambique), which has a storage capacity is about 650 km long, reaching from the Cahora Bassa Lake to the Indian Ocean.…”

Section: The Zambezi Rivermentioning

confidence: 99%

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Opportunities from low-resolution modelling of river morphology in remote parts of the world

2014

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Abstract. River morphodynamics are the result of a variety of processes, ranging from the typical small-scale of fluid mechanics (e.g. flow turbulence dissipation) to the large-scale of landscape evolution (e.g. fan deposition). However, problems inherent in the long-term modelling of large rivers derive from limited computational resources and the high level of process detail (i.e. spatial and temporal resolution). These modelling results depend on processes parameterization and calibrations based on detailed field data (e.g. initial morphology). Thus, for these cases, simplified tools are attractive. In this paper, a simplified 1-D approach is presented that is suited for modelling very large rivers. A synthetic description of the variations of cross-sections shapes is implemented on the basis of satellite images, typically also available for remote parts of the world. The model's flexibility is highlighted here by presenting two applications. In the first case, the model is used for analysing the long-term evolution of the lower Zambezi River (Africa) as it relates to the construction of two reservoirs for hydropower exploitation. In the second case, the same model is applied to study the evolution of the middle and lower Paraná River (Argentina), particularly in the context of climate variability. In both cases, having only basic data for boundary and initial conditions, the 1-D model provides results that are in agreement with past studies and therefore shows potential to be used to assist sediment management at the watershed scale or at boundaries of more detailed models.

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Section: Evolution Of the Zambezi River During The 20th Centurysupporting

confidence: 87%

Section: Case Studiesmentioning

confidence: 99%

Section: Case Studiesmentioning

confidence: 99%

Section: The Zambezi Rivermentioning

confidence: 99%

See 2 more Smart Citations

Opportunities from low-resolution modelling of river morphology in remote parts of the world

2014

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“…Along this reach in the second half of the last century, the Kariba and the Cahora Bassa dams were built for hydroelectric energy production. The Kariba dam, along the border between Zambia and Zimbabwe, was completed in 1959 and created an artificial lake with a storage capacity of 180.6 billion m 3 and a surface area of 5364 km 2 [9]. The Cahora Bassa dam, in Mozambique, was completed at the end of 1974; it gives rise to an artificial lake that, according to data provided by the electrical company Hidroeléctrica de Cahora Bassa [10], has a useful capacity of 52 billion m 3 , a length of 270 km, a width of 30 km, and a surface area of 2900 km 2 at maximum water level.…”

Section: Introductionmentioning

confidence: 99%

A Survey near Tambara along the Lower Zambezi River

2016

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Abstract:The paper reports a field investigation on a reach of the lower Zambezi River about 230-240 km downstream of the Cahora Bassa dam in the Republic of Mozambique. In the framework of a wider research program, bathymetric measures of the riverbed were performed on a 10 km stretch of the river using an echo sounder, a GPS receiver, and an integrated navigation-acquisition system. Field observations and measures revealed a general agreement with macro-features of river morphology reported in early literature, dealing with the morphological response of the river to the construction of large dams, in the second half of the 20th century. Results hereby reported are some of the few examples of direct field measures in the lower Zambezi reported in literature, and could be used by researchers and practitioners either as a knowledge base for further surveys or as input data for validation and calibration of mathematical models and remote sensing observations.

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The Sanaga discharge at the Edea Catchment outlet (Cameroon): An example of hydrologic responses of a tropical rain‐fed river system to changes in precipitation and groundwater inputs and to flow regulation

Dzana

Ngoupayou

Tchawa

2011

River Research & Apps

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The Sanaga River is one of Sub-Saharan Africa's largest and greatly regulated rivers. Available flow data for this hydrosystem largely cover the pre-and post-regulation periods. From comparisons between unregulated (hypothetical) and observed scenarios, it has been possible to separate and to quantify hydro-climatic (groundwater þ rainfall) change effects from anthropogenic impacts (especially dam-related alterations). To appreciate shifts in the river regime, discontinuity detection tests and the IHA model were applied to discharge data series reflecting average and extreme flow conditions, respectively. Results obtained principally from the Hubert segmentation method reveal that a major discontinuity occurred in 1970-1971 separating a surplus phase between 1945-1946 and 1969-1970, and a deficient and much contrasted one, from 1971/1972. This implies that the Sanaga catchment is dominantly affected by hydro-climatic changes. However, wide land cover/land use changes experienced here since 1988 have resulted in an increase in surface runoff. Additional quickflows linked to these changes may have partly compensated for the substantial decline in the dry season rainfall and groundwater inputs observed from this date. Although at the monthly scale, dam-related impacts on average flows increase with stage of regulation, the seasonal variability of the river regime remains generally unaffected. A comparison of the IHA statistics, calculated from unregulated and observed streamflow data, show that hydrologic shifts occurring in maximum and minimum discharges are mostly significant from 1971/1972 and are mainly due to the action of dams. Minimum flows appear, however, widely impacted, thus reflecting the prime objective assigned to the existing reservoirs, constructed to supplement flows for hydroelectricity production during the dry season.

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Cahora Bassa retrospective, 1974–1997: effects of flow regulation on the Lower Zambezi River

Cited by 18 publications

References 8 publications

Opportunities from low-resolution modelling of river morphology in remote parts of the world

Opportunities from low-resolution modelling of river morphology in remote parts of the world

A Survey near Tambara along the Lower Zambezi River

The Sanaga discharge at the Edea Catchment outlet (Cameroon): An example of hydrologic responses of a tropical rain‐fed river system to changes in precipitation and groundwater inputs and to flow regulation

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