Evaluating the combined impacts of hydrological change, coastal dynamics and human activity on mangrove cover and health in the Tana River delta, Kenya
Gitau, P.N.; Duvail, S.; Verschuren, D. (2023). Evaluating the combined impacts of hydrological change, coastal dynamics and human activity on mangrove cover and health in the Tana River delta, Kenya. Regional Studies in Marine Science 61: 102898. https://dx.doi.org/10.1016/j.rsma.2023.102898
In: Regional Studies in Marine Science. Elsevier: Amsterdam. ISSN 2352-4855, more
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Mangroves;Landcover change;Precipitation;Hydrology;Tana River delta;Kenya;SEA-LEVEL;CLIMATE-CHANGE;FORESTS;RESTORATION;MANAGEMENT;DEPOSITION;RESPONSES;SYSTEMS;FLOODS;ISLAND |
| Authors | | Top |
- Gitau, P.N.
- Duvail, S.
- Verschuren, D., more
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| Abstract |
The long-term dynamics of tropical mangrove ecosystems, and especially how they have responded to the combined pressures of local human activity, changing river hydrology and climate-change related coastal processes are insufficiently documented. In this study we combined a chronological sequence of remote sensing data spanning the last three decades (1992-2021) with time series of river-flow and precipitation data to discriminate between the respective impacts of hydroclimatic drivers and land-use changes on mangroves of the Tana River delta in Kenya. Our land-cover analysis showed an overall increase in mangrove forest cover of 5.5% over the past 30 years, however this included a 14% increase between 1992 and 2013 followed by a 8% decrease between 2013 and 2021. Normalised Difference Vegetation Index (NDVI) data still indicate an overall positive trend (R2 = 0.58, p< 0.01) in the overall health of Tana River delta mangroves between 1992 and 2021. We also observe positive correlations between mangrove NDVI and precipitation (R=0.41, p = 0.042) and Tana River water level (R=0.82, p< 0.0001), as well as between mangrove NDVI and modelled measures of Tana River discharge (R= 0.79, p< 0.0001) and flooded area (R=0.73, p< 0.001). Overall our results show that recent historical variation in the areal cover and health of Tana River mangroves is mainly associated with changing hydrology in the Tana River delta, but that intensifying local land use and accelerating coastal erosion has also impacted their health. We suggest that management of the Tana River delta mangroves should focus on improving Tana River flows and sediment recharge.(c) 2023 Elsevier B.V. All rights reserved. |
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