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Tropical Montane Forest Conversion Is a Critical Driver for Sediment Supply in East African Catchments

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Title Tropical Montane Forest Conversion Is a Critical Driver for Sediment Supply in East African Catchments
 
Creator Stenfert Kroese, J.
Jacobs, S.R.
Tych, W.
Breuer, Lutz
Quinton, J.N.
Rufino, Mariana C.
 
Subject catchment hydrology
watershed management
tropical forests
agriculture
 
Description Land use change is known to affect suspended sediment fluxes in headwater catchments. There is however limited empirical evidence of the magnitude of these effects for montane catchments in East Africa. We collected a unique 4-year high-frequency data set and assessed seasonal sediment variation, water pathways, and sediment response to hydrology in three catchments under contrasting land use in the Mau Forest Complex, Kenya's largest tropical montane forest. Annual suspended sediment yield was significantly higher in a smallholder agriculture-dominated catchment (131.5 ± 90.6 t km−2 yr−1) than in a tea-tree plantation catchment (42.0 ± 21.0 t km−2 yr−1) and a natural forest catchment (21.5 ± 11.1 t km−2 yr−1) (p < 0.05). Transfer function models showed that in the natural forest and the tea-tree plantations subsurface flow pathways delivered water to the stream, while in the smallholder agriculture shallow subsurface and surface runoff were dominant. There was a delayed sediment response to rainfall for the smallholder agriculture and the tea-tree plantations. A slow depletion in sediment supply suggests that the wider catchment area supplies sediment, especially in the catchment dominated by smallholder farming. In contrast, a fast sediment response and depletion in sediment supply in the natural forest suggests a dominance of temporarily stored and nearby sediment sources. This study shows that the vegetation cover of a forest ecosystem is very effective in conserving soil, whereas catchments with more bare soil and poor soil conservation practices generated six times more suspended sediment yield. Catchment connectivity through unpaved tracks is thought to be the main explanation for the difference in sediment yield.
 
Date 2020-10
2021-01-21T01:20:56Z
2021-01-21T01:20:56Z
 
Type Journal Article
 
Identifier Stenfert Kroese, J., Jacobs, S.R., Tych, W., Breuer, L., Quinton, J.N., & Rufino, M.C. 2020. Tropical montane forest conversion is a critical driver for sediment supply in East African catchments. Water Resources Research, 56: e2020WR027495. https://doi.org/10.1029/2020WR027495
1944-7973
https://hdl.handle.net/10568/114018
https://www.cifor.org/library/8034
https://doi.org/10.1029/2020WR027495
 
Language en
 
Rights CC-BY-4.0
Open Access
 
Format e2020WR027495
 
Publisher American Geophysical Union (AGU)
 
Source Water Resources Research