Riverine suspended sediment is a major transport medium for chemicals, contaminants, and nutrients (1). Downstream impacts of suspended sediment transport on water quality and biota can be very significant (2). The most effective way to control sediment is to mitigate the entry of it into the river, which necessitates knowing the locations where it originates.
Sediment fingerprinting, which utilizes natural tracer technologies, is one technique to determine geographic sources of sediment input into waterways (3). By relying on the distinct physical and biogeochemical properties of sediment sources, laboratory analysis and multivariate statistics can be utilized to determine the proportion of suspended sediment in a waterway from a specific source within the watershed.
I will take an innovative approach to the traditional sediment fingerprinting technique by using it to quantify the influences of a range of wildlife and human activities within the protected area of a semi-arid watershed, an ecosystem type that is historically understudied (4). The Mara River Basin (Kenya and Tanzania) is particularly well suited for this study for several reasons. Increased sediment loads in the river have been blamed for increased pollutant loads (5)and for a 387% increase in the size of the Mara Wetland near the mouth of the river (6). Previous studies have found excessive levels of suspended sediment contributing to an overall decline in aquatic ecosystem health (7-10). The annual wildebeest (Connochaetes taurinus) migration of approximately 1.2 million herbivores, coupled with a growing hippopotamus (Hippopotamus amphibious)population (Kanga, pers. comm.) and increasing tourism (11)also presents a unique opportunity to quantify the sediment fluxes from previously unstudied sources and to improve on the growing body of knowledge concerning sediment and nutrient transport in semi-arid watersheds.
1. M. C. Slattery, T. P. Burt, Earth Surf. Process. Landf. 22, 705 (1997).
2. J. A. Ludwig, B. P. Wilcox, D. D. Breshears, D. J. Tongway, A. C. Imeson, Ecology 86, 288 (Feb, 2005).
3. C. M. Davis, J. F. Fox, J. Environ. Eng.-ASCE 135, 490 (Jul, 2009).
4. S. M. Jacobset al., Ecosystems 10, 1231 (Dec, 2007).
5. H. Singler, M. E. McClain. (Florida International University, 2006), pp. 66.
6. B. M. Mati, S. Mutie, H. Gadain, P. Home, F. Mtalo, Lakes & Reservoirs: Research & Management 13, 169 (2008).
7. G. M. Kiragu, Jomo Kenyatta University of Agriculture and Technology (2009).
8. J. K. Terer, Moi University (2005).
9. LVBC, WWF-ESARPO, “Assessing Reserve Flows for the Mara River, Kenya and Tanzania” (Lake Victoria Basin Commission of the East African Community, Kisumu, 2010).
10. B. McCartney, Florida International University (2010).
11. GoK, “Report on the Inventory of Tourism Facilities in the Greater Mara Ecosystem” (Government of Kenya, Nairobi, 2010).