Modelling the dry season inundation pattern of Yala Swamp in Kenya
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ORIGINAL ARTICLE
Modelling the dry season inundation pattern of Yala Swamp in Kenya Johanna Anyesi Wanjala1 · Arthur Wafula Sichangi1 · Charles Ndegwa Mundia1 · Godfrey Ouma Makokha2 Received: 4 April 2020 / Accepted: 21 May 2020 © Springer Nature Switzerland AG 2020
Abstract Ecological processes in wetlands rely on the natural variability of inundation cycle guided by different seasons. Humaninduced modifications have, however, influenced the seasonality and the period of inundation, altering its inherent variability. The adjustments have further affected the functioning of many global wetlands by shifting their natural equilibrium. In a quest to understand the wetland’s inundation pattern, cellular automata and Markov chain analysis (CA–MCA) model was used to simulate the 2029 dry season inundation variation of Yala Swamp in Kenya. The model utilised parameters obtained from Tasselled Cap Wetness Index, supervised classification, population growth model and elevation for the years 1986, 2006, 2015 and 2019. The study established that inundation characteristics in the swamp varied as the years progressed from 1986 to 2019. Consistency was found between inundation variation and changes in land-use practices. Consequently, the area covered by the wetland decreased in its spatial extent by approximately 35%. The model projected that the swamp would additionally lose 12% of its inundated area by 2029, should the current practices continue. It is therefore essential to regulate anthropogenic activities to control the variability in the swamps inundation. Keywords Cellular automata · Inundation · Markov chain analysis · Yala Swamp · Tasseled cap wetness index
Introduction Wetland ecological functions such as water purification, flood protection, shoreline stabilisation, groundwater recharge and streamflow maintenance depend on the variability of inundation (Renaud et al. 2016). Variation in inundation pattern occurs naturally as wetland’s landscape develops over time in response to the changing interaction between geomorphology and climate variability (Zhu et al. 2018). Many wetlands become inundated to full capacity during the wet season, and the inundation reduces to the extent of some drying out during the dry season (Huang et al. 2014). Wetland inundation is, however, not explicitly defined by the seasons. Land-use practices, topography and climate variability also affect the way it behaves (Lloréns and Lucas 2016).
* Johanna Anyesi Wanjala [email protected] 1
Institute of Geomatics, GIS and Remote Sensing, Dedan Kimathi University of Technology, P.O Box 657, Nyeri, Kenya
Taita Taveta University, Voi, Kenya
2
In recent years, human-induced modifications have influenced the dynamics of inundation pattern, creating different levels of physiological stress on wetland ecosystems (Zhao et al. 2019). Land management decisions to utilise fertile land and abundance of water resources have led to the conversion of wetlands into majorly large-scale cropland, grazing areas and power generation sites (B
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