Journal of Soils and Sediments

, Volume 13, Issue 10, pp 1708–1723

A novel sediment fingerprinting method using filtration: application to the Mara River, East Africa

  • Christopher Dutton
  • Shimon C. Anisfeld
  • Helmut Ernstberger
WATERSHED SEDIMENT SOURCE IDENTIFICATION: TOOLS, APPROACHES, AND CASE STUDIES

DOI: 10.1007/s11368-013-0725-z

Cite this article as:
Dutton, C., Anisfeld, S.C. & Ernstberger, H. J Soils Sediments (2013) 13: 1708. doi:10.1007/s11368-013-0725-z

Abstract

Purpose

Sediment fingerprinting with elemental tracers is widely used to identify sources of sediment to rivers. However, due to the need to isolate large amounts of suspended sediment, this approach can be difficult to implement in remote locations, such as the Mara River in Kenya, where high (and increasing) sediment loads are of concern.

Materials and methods

We report several innovations that allowed us to carry out sediment fingerprinting in a portion (>6,500 km2) of the Mara River Basin. First, we utilized sediment-laden filters (sediment mass ∼0.1 g) for our river samples, rather than the traditional approach of extracting >1 g of sediment from large volumes of water. This allowed us to easily collect flow-weighted samples, and to process and analyze samples without access to centrifugation equipment. We carried out extensive quality control tests to ensure that we could reproducibly measure elemental concentrations of sediment trapped on filters. Second, we modified a readily available Bayesian inference mixing model (Stable Isotope Analysis in R) to create source signatures and to apportion downstream samples to sources. Third, we included hippo feces as a potential source, given the critical role that large wildlife plays in this ecosystem.

Results and discussion

We found that: (1) sediment captured by filtration can be digested and analyzed reproducibly and used in sediment fingerprinting; (2) our four sources (three geographic categories and hippo feces) were reasonably well-separated in their signatures; (3) the three sub-basins all contributed substantially to sediment loading in the Mara; and (4) hippo feces contributed a small, but measurable, proportion of sediment in this system.

Conclusions

Sediment-laden filters can be used successfully in identifying sediment sources through fingerprinting. The modified method of sediment fingerprinting should prove useful in other remote river basins. Our results support the hypothesis that the Upper Mara is important in supplying sediments to the river, while also highlighting the Talek sub-basin as a major contributor.

Keywords

Bayesian mixing model East Africa Filtration Hippopotamus Sediment fingerprinting 

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Christopher Dutton
    • 1
  • Shimon C. Anisfeld
    • 1
  • Helmut Ernstberger
    • 1
  1. 1.Yale School of Forestry and Environmental StudiesNew HavenUSA

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