scholarly journals Sediment yield of the lower Tana River, Kenya, is insensitive to dam construction: sediment mobilization processes in a semi-arid tropical river system

2015 ◽  
Vol 40 (13) ◽  
pp. 1827-1838 ◽  
Author(s):  
Naomi Geeraert ◽  
Fred Ochieng Omengo ◽  
Fredrick Tamooh ◽  
Paolo Paron ◽  
Steven Bouillon ◽  
...  
Keyword(s):  
Sediment Yield ◽  
River System ◽  
Dam Construction ◽  
Tropical River ◽  
Tana River ◽  
Semi Arid ◽  
Sediment Mobilization

scholarly journals Seasonal and inter-annual variations in carbon fluxes in a tropical river system (Tana River, Kenya)

2018 ◽  
Vol 80 (2) ◽  
Author(s):  
Naomi Geeraert ◽  
Fred O. Omengo ◽  
Fredrick Tamooh ◽  
Trent R. Marwick ◽  
Alberto V. Borges ◽  
...  
Keyword(s):  
River System ◽  
Carbon Fluxes ◽  
Tropical River ◽  
Annual Variations ◽  
Tana River

Event loading drives distribution of the organochlorine pesticide metabolite DDE in a sub-tropical river system, Brisbane River, Australia

2021 ◽  
Vol 170 ◽  
pp. 112671
Author(s):  
Alistair Grinham ◽  
Nathaniel Deering ◽  
Ryan Beecroft ◽  
Jessica Rudd ◽  
Craig Heatherington ◽  
...  
Keyword(s):  
Organochlorine Pesticide ◽  
River System ◽  
Tropical River

Modern sediment yield compared to geologic rates of sediment production in a semi-arid basin, New Mexico: assessing the human impact

2004 ◽  
Vol 29 (11) ◽  
pp. 1359-1372 ◽  
Author(s):  
Allen C. Gellis ◽  
Milan J. Pavich ◽  
Paul R. Bierman ◽  
Eric M. Clapp ◽  
Amy Ellevein ◽  
...  
Keyword(s):  
New Mexico ◽  
Human Impact ◽  
Sediment Yield ◽  
Modern Sediment ◽  
Sediment Production ◽  
Semi Arid

scholarly journals Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system

2015 ◽  
Vol 12 (15) ◽  
pp. 12761-12782
Author(s):  
N. Geeraert ◽  
F. O. Omengo ◽  
G. Govers ◽  
S. Bouillon
Keyword(s):  
Stable Isotope ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Isotope Composition ◽  
River System ◽  
Photochemical Oxidation ◽  
Microbial Decomposition ◽  
Tana River ◽  
Incubation Experiments ◽  
Microbial Consumption

Abstract. A significant amount of carbon is transported to the ocean as dissolved organic carbon (DOC) in rivers. During transport, it can be transformed through microbial consumption and photochemical oxidation. In dark incubation experiments with water from the Tana River, Kenya, we examined the consumption of DOC through microbial decomposition and the associated change in its carbon stable isotope composition (δ13C). In 15 of the 18 incubations, DOC concentrations decreased significantly by 10 to 60 %, with most of the decomposition taking place within the first 24–48 h. After 8 days, the remaining DOC was up to 3 ‰ more depleted in 13C compared with the initial pool, and the change in δ13C correlated strongly with the fraction of DOC remaining. We propose that the shift in δ13C is consistent with greater microbial lability of DOC originating from herbaceous C4 vegetation than DOC derived from woody C3 vegetation in the semi-arid lower Tana. The findings complement earlier data that riverine C sources do not necessarily reflect their proportion in the catchment: besides spatial distribution, also processing within the river can further influence the riverine δ13C.

Development of a Non-Linear Integrated Drought Index (NDI) for Managing Drought and Water Resources Forecasting in the Upper Tana River Basin-Kenya

2020 ◽  
Vol 11 (1) ◽  
pp. 15-33
Author(s):  
Raphael Muli Wambua
Keyword(s):  
Water Resources ◽  
River Basin ◽  
Lead Time ◽  
Drought Index ◽  
Meteorological Data ◽  
Principal Component ◽  
Drought Forecasting ◽  
Tropical River ◽  
Tana River ◽  
Non Linear

This article uses the non-linear integrated drought index (NDI) for managing drought and water resources forecasting in a tropical river basin. The NDI was formulated using principal component analysis (PCA). The NDI used hydro-meteorological data and forecasted using recursive multi-step neural networks. In this article, drought forecasting and projection is adopted for planning ahead for mitigation and for the adaptation of adverse effects of droughts and food insecurity in the river basin. Results that forecasting ability of NDI model using ANNs decreased with increase in lead time. The formulated NDI as a tool for projecting into the future.

scholarly journals Livestock redistribute runoff and sediments in semi-arid rangeland areas

Solid Earth ◽  
2015 ◽  
Vol 6 (2) ◽  
pp. 433-443 ◽  
Author(s):  
P. Sarah ◽  
M. Zonana
Keyword(s):  
Sediment Yield ◽  
Overland Flow ◽  
Arid Areas ◽  
Mosaic Pattern ◽  
Two Phase ◽  
Surface Patches ◽  
Sediment Deposits ◽  
Three Phase ◽  
Almost All ◽  
Semi Arid

Abstract. Semi-arid areas where grazing is the main land use exhibit a "three-phase-mosaic" pattern of dominant surface patches: shrubs, trampling routes, and intershrub areas. This pattern differs from the "two-phase mosaic" seen in grazing-free semi-arid areas. The patches might create a positive feedback process in which enhanced infiltration beneath shrubs minimizes overland flow from under their canopies, thereby strengthening the sink–source mechanism by which overland flow generated between shrubs rapidly infiltrates into the soil beneath them, where it deposits soil particles, litter, nutrients and organic matter, thereby enhancing infiltration by changing the local microtopography, and improving soil properties. To analyze sink–source relationships among the patches in grazed areas in rangelands of the semi-arid northern Negev region of Israel, we constructed small runoff plots, 0.25–1.0 m2 in area, of five types: shrub (Sarcopoterium spinosum), intershrub, route, route–shrub combination, and intershrub–shrub combination. The shrubs always occupied the downslope part of the plot. Overland flow and sediment deposits were measured in all plots during 2007/8 and 2008/9. The combined plots yielded much less overland flow and sediments than intershrub, routes and shrub ones, indicating that the shrubs absorbed almost all the yields of the upper part of their plots. The shrubs generated less runoff and sediments than routes and intershrubs; runoff flows from the routes and intershrubs were similar; sediment yield was highest in the intershrubs. Thus, runoff yield exhibited a two-phase mosaic pattern, and sediment yield, i.e., soil erosion, a three-phase mosaic pattern.

scholarly journals Water Flow Behavior and Storage Potential of the Semi-Arid Ephemeral River System in the Mara Basin of Kenya

2020 ◽  
Vol 8 ◽  
Author(s):  
Sospeter Simiyu Wekesa ◽  
Tibor Yvan Stigter ◽  
Luke O. Olang ◽  
Francis Oloo ◽  
Kelly Fouchy ◽  
...  
Keyword(s):  
Water Flow ◽  
Flow Behavior ◽  
River System ◽  
Storage Potential ◽  
And Storage ◽  
Semi Arid
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