River discharge, sediment transport and exchange in the Tana Estuary, Kenya

Kitheka, Johnson U.; Obiero, Maurice; Nthenge, P.

doi:10.1016/j.ecss.2004.11.011

Cited by 84 publications

(56 citation statements)

References 7 publications

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“…For the tropics, data are only available from systems draining the west coast, hence global extrapolations include a large uncertainty (see, e.g., Schlü nz and Schneider 2000). For the Tana River, the total annual sediment flux has recently been estimated at 6.8 3 10 9 kg yr 21 (Kitheka et al 2005), but this estimate is more than twice as high as that used in the global compilation of data presented in Syvitski et al (2005), i.e., 3.0 3 10 9 kg yr 21 . However, the discharge data set used in the calculations of Kitheka et al (2005) covers ,1.5 yr of data and shows several peaks that may not be representative over longer terms, e.g., their average discharge rate of 230 m 3 s 21 is significantly higher than the reported average of 155 m 3 s 21 reported for the Tana at Garissa (University of New Hampshire, Global Runoff Data Centre database for a period of 42 yr).…”

Section: Discussionmentioning

confidence: 99%

“…For the Tana River, the total annual sediment flux has recently been estimated at 6.8 3 10 9 kg yr 21 (Kitheka et al 2005), but this estimate is more than twice as high as that used in the global compilation of data presented in Syvitski et al (2005), i.e., 3.0 3 10 9 kg yr 21 . However, the discharge data set used in the calculations of Kitheka et al (2005) covers ,1.5 yr of data and shows several peaks that may not be representative over longer terms, e.g., their average discharge rate of 230 m 3 s 21 is significantly higher than the reported average of 155 m 3 s 21 reported for the Tana at Garissa (University of New Hampshire, Global Runoff Data Centre database for a period of 42 yr). A rough calculation using our average TSM concentrations for all freshwater stations (802 mg L 21 ) and multiplying this with the total average annual discharge (4 3 10 9 m 3 ) gives an estimate of annual suspended matter transport (3.21 3 10 9 kg yr 21 ) remarkably close to that in the Syvitski et al (2005) data set.…”

Section: Discussionmentioning

confidence: 99%

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Biogeochemistry of the Tana estuary and delta (northern Kenya)

Bouillon

Dehairs

Schiettecatte

et al. 2007

Limnology & Oceanography

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The estuarine mixing zone of the Tana River (northern Kenya) and an extensive deltaic area just south of the estuary were sampled in April 2004 with the aim of identifying the distribution, sources, and processing of particulate and dissolved organic carbon (POC, DOC) and inorganic carbon (DIC). C4 inputs from the catchment contributed ,50% to the POC pool in the Tana River and estuary, and in the mangrove creek water column and intertidal sediments. The d 13 C values of DOC, however, were typically much more negative than that of POC, indicating a substantially higher contribution by C3 and/or mangrove-derived carbon in the DOC pool. The undersaturation of O 2 , high pCO 2 , and the nonconservative nature of DIC and d 13 C DIC suggest a strongly heterotrophic water column, particularly in the freshwater part of the Tana and in the tidal creeks in the delta, where high additional inputs of organic matter were observed. However, some of these sites showed d 18 O DO signatures lower than the atmospheric equilibrium (i.e., +24.2%) indicative of significant O 2 production by photosynthesis. Therefore, the heterotrophic signature in the water column is likely the result of a strong interaction with the large intertidal areas, whereby respiratory activity in sediments and in the overlying water column during tidal inundation leave a marked signature on the water column. This is confirmed by the covariation between salinity-normalized total alkalinity and DIC, whose slope indicates an important role for anaerobic diagenetic processes. If our data are representative for other large river systems in the region, current estimates are likely to underestimate suspended matter and both inorganic and organic C fluxes to the Indian Ocean from tropical east Africa.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Biogeochemistry of the Tana estuary and delta (northern Kenya)

Bouillon

Dehairs

Schiettecatte

et al. 2007

Limnology & Oceanography

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“…1), like most parts of East Africa, receives its rainfall in two seasons during March, April, and May (MAM) and October, November, and December (OND) locally known as the Blong rains^and Bshort rains,^respectively, due to the south-north oscillation of the Intertropical Convergence Zone (ITCZ) (Kitheka et al 2005;Nakaegawa and Wachana 2012;Oludhe et al 2013). The mean annual rainfall ranges between 960 and 1200 mm, while climatologically, the region experiences low annual/monthly mean temperatures of about 17°C or less (Kerandi et al 2016).…”

Section: The Study Areamentioning

confidence: 99%

Joint atmospheric-terrestrial water balances for East Africa: a WRF-Hydro case study for the upper Tana River basin

Kerandi

Arnault

Laux

et al. 2017

Theor Appl Climatol

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For an improved understanding of the hydrometeorological conditions of the Tana River basin of Kenya, East Africa, its joint atmospheric-terrestrial water balances are investigated. This is achieved through the application of the Weather Research and Forecasting (WRF) and the fully coupled WRF-Hydro modeling system over the MathioyaSagana subcatchment (3279 km 2 ) and its surroundings in the upper Tana River basin for 4 years (2011)(2012)(2013)(2014). The model setup consists of an outer domain at 25 km (East Africa) and an inner one at 5-km (Mathioya-Sagana subcatchment) horizontal resolution. The WRF-Hydro inner domain is enhanced with hydrological routing at 500-m horizontal resolution. The results from the fully coupled modeling system are compared to those of the WRF-only model. The coupled WRF-Hydro slightly reduces precipitation, evapotranspiration, and the soil water storage but increases runoff. The total precipitation from March to May and October to December for WRF-only (974 mm/year) and coupled WRF-Hydro (940 mm/year) is closer to that derived from the Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) data (989 mm/year) than from the TRMM (795 mm/year) precipitation product. The coupled WRF-Hydro-accumulated discharge (323 mm/year) is close to that observed (333 mm/ year). However, the coupled WRF-Hydro underestimates the observed peak flows registering low but acceptable NSE (0.02) and RSR (0.99) at daily time step. The precipitation recycling and efficiency measures between WRF-only and coupled WRF-Hydro are very close and small. This suggests that most of precipitation in the region comes from moisture advection from the outside of the analysis domain, indicating a minor impact of potential land-precipitation feedback mechanisms in this case. The coupled WRF-Hydro nonetheless serves as a tool in quantifying the atmospheric-terrestrial water balance in this region.

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“…Knoop et al (2012) reports that within the upper basin there is a direct relationship between stream flows and sediment loads, with low flows of 0.10 m 3 s -1 producing 2-5 mg/l loads and higher flows of 100 m 3 s -1 producing as much as 100 mg/l of sediment. It is estimated that the sediment load in the Tana River varies from 2,796 tonnes per day during dry season to about 24,322 tonnes per day during the rainy season (Kitheka et al 2005). This sediment load translates to between 1 and 8 million tonnes per year.…”

Section: Sedimentationmentioning

confidence: 99%

Baseline review and ecosystem services assessment of the Tana River Basin, Kenya

Baker¹,

Kiptala²,

Olaka³

et al. 2015

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The publications in this series record the work and thinking of IWMI researchers, and knowledge that the Institute's scientific management feels is worthy of documenting. This series will ensure that scientific data and other information gathered or prepared as a part of the research work of the Institute are recorded and referenced. Working Papers could include project reports, case studies, conference or workshop proceedings, discussion papers or reports on progress of research, country-specific research reports, monographs, etc. Working Papers may be copublished, by IWMI and partner organizations.Although most of the reports are published by IWMI staff and their collaborators, we welcome contributions from others. Each report is reviewed internally by IWMI staff. The reports are published and distributed both in hard copy and electronically (www.iwmi.org) and where possible all data and analyses will be available as separate downloadable files. Reports may be copied freely and cited with due acknowledgment. About IWMIIWMI's mission is to provide evidence-based solutions to sustainably manage water and land resources for food security, people's livelihoods and the environment. IWMI works in partnership with governments, civil society and the private sector to develop scalable agricultural water management solutions that have a tangible impact on poverty reduction, food security and ecosystem health.

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River discharge, sediment transport and exchange in the Tana Estuary, Kenya

Cited by 84 publications

References 7 publications

Biogeochemistry of the Tana estuary and delta (northern Kenya)

Biogeochemistry of the Tana estuary and delta (northern Kenya)

Joint atmospheric-terrestrial water balances for East Africa: a WRF-Hydro case study for the upper Tana River basin

Baseline review and ecosystem services assessment of the Tana River Basin, Kenya

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