Journal cover Journal topic
SOIL An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 3.343 IF 3.343
  • IF 5-year value: 4.963 IF 5-year
    4.963
  • CiteScore value: 9.6 CiteScore
    9.6
  • SNIP value: 1.637 SNIP 1.637
  • IPP value: 4.28 IPP 4.28
  • SJR value: 1.403 SJR 1.403
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 25 Scimago H
    index 25
Volume 2, issue 3
SOIL, 2, 337–349, 2016
https://doi.org/10.5194/soil-2-337-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
SOIL, 2, 337–349, 2016
https://doi.org/10.5194/soil-2-337-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Original research article 21 Jul 2016

Original research article | 21 Jul 2016

Sediment concentration rating curves for a monsoonal climate: upper Blue Nile

Mamaru A. Moges1,2, Fasikaw A. Zemale1,2, Muluken L. Alemu1, Getaneh K. Ayele1, Dessalegn C. Dagnew1, Seifu A. Tilahun2, and Tammo S. Steenhuis2,3 Mamaru A. Moges et al.
  • 1PhD Program in Integrated Water Management, Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar, Ethiopia
  • 2Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar, Ethiopia
  • 3Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853 USA

Abstract. Information on sediment concentration in rivers is important for design of reservoirs and for environmental applications. Because of the scarcity of continuous sediment data, methods have been developed to predict sediment loads based on few discontinuous measurements. Traditionally, loads are being predicted using rating curves that relate sediment load to discharge. The relationship assumes inherently a unique relationship between concentration and discharge and therefore although performing satisfactorily in predicting loads, it may be less suitable for predicting concentration. This is especially true in the Blue Nile Basin of Ethiopia where concentrations decrease for a given discharge with the progression of the rainy monsoon phase. The objective of this paper is to improve the sediment concentration predictions throughout the monsoon period for the Ethiopian highlands with a modified rating type equation. To capture the observed sediment concentration pattern, we assume that the sediment concentration was at the transport limit early in the rainy season and then decreases linearly with effective rainfall towards source-limited concentration. The modified concentration rating curve was calibrated for the four main rivers in the Lake Tana basin where sediment concentrations affect fish production and tourism. Then the scalability of the rating type equation was checked in three 100 ha watersheds for which historic data were available. The results show that for predicting sediment concentrations, the (modified) concentration rating curve was more accurate than the (standard) load rating curve as expected. In addition loads were predicted more accurately for three of the four rivers. We expect that after more extensive testing over a wider geographical area, the proposed concentration rating curve will offer improved predictions of sediment concentrations in monsoonal climates.

Publications Copernicus
Download
Short summary
In tropical monsoonal Africa, sediment concentration data in rivers are lacking. Using occasional historically observed sediment loads, we developed a simple method for prediction sediment concentrations. Unlike previous methods, our techniques take into account that sediment concentrations decrease with the progression of the monsoon rains. With more testing, the developed method could improve sediment predictions in monsoonal climates.
In tropical monsoonal Africa, sediment concentration data in rivers are lacking. Using...
Citation