The use of visible and near-infrared reflectance measurements for identifying the source of suspended sediment in rivers and comparison with geochemical fingerprinting

Abstract

Purpose -Visible and near-infrared (Vis-NIR) reflectance measurements may be an alternative technique to identify suspended sediment sources in streams of headwater catchments. In this study, we examined if Vis-NIR reflectance measurements are capable of estimating sediment source contribution to sediment yield and compared this technique with the chemical technique.Materials and methods -Two headwater catchments in Ethiopia, Unta (2052 ha) and Desera (1657 ha), were both analyzed with the same techniques in order to find differences and agreements. The first technique used (Vis-NIR) spectral analysis as a fingerprint, using a partial least squares regression model. A second technique was a quantitative composite fingerprinting technique using chemical analysis of soil and suspended sediment samples. As a comparison, the partial least squares model was also used on the chemical data. In the period of August until September 2009, 30 soil samples of 3 different land uses (landslides, cropland and grazing land) and 21 suspended sediment samples at the catchment outlet were collected. Soil samples were all sieved to <63 µm. Chemical analyses consisted of total element concentration, percentage carbon, percentage nitrogen, atom percentage 15 N and δ 13 C. Reflectance measurements were taken on dried soil samples with a spectrometer.Results and discussion -Both techniques were not able to predict the contributions of the three land use types. They could only distinguish between landslide and top soil material. The agreements between the results of both techniques were significant for the Unta catchment (R 2 =0.80) but not for the Desera catchment (R 2 =0.39). The uncertainty of the technique using Vis-NIR reflectance measurements was slightly higher than with the chemical technique. Both techniques revealed that top soil erosion played an important role during storm runoff discharges. Using the partial least squares model for the chemical data revealed that uncertainty can differ a lot when using other statistical techniques.Conclusions -The quantitative composite fingerprinting technique using spectral signatures from both soil and suspended sediment samples was able to quantify the contribution of two source materials (landslides and top soil). It provided a faster and more cost effective alternative to the classical procedure.

Combining visible-based-color parameters and geochemical tracers to improve sediment source discrimination and apportionment

“…However, it can make the fingerprinting exercise highly laborintensive and costly, constraining the adoption of the procedure as a management tool to estimate sediment origin. In this regard, several studies have been carried out in the last years suggesting the use of visible reflectance and color parameters as a rapid and cheap means for investigating sediment sources (Martínez-Carreras et al, 2010a, 2010b, 2010cLegout et al, 2013;Verheyen et al 2014). A UV-VIS spectrometer is a very affordable equipment used in a wide range of science fields (e.g., chemistry, pharmacology, plant physiology, food science, soil science, etc.…”

“…More recently, MIR (Poulenard et al, 2009(Poulenard et al, , 2012Evrard et al, 2013) and VIS-NIR (Martínez-Carreras et al, 2010a,b;Legout et al, 2013;Brosinsky et al, 2014a,b;Verheyen et al 2014;Tiecher et al, 2015) spectroscopy has also been applied to trace suspended sediment origin. The prerequisites for use of tracer properties in sediment fingerprinting studies are the conservativeness and the linear additive behavior.…”

Tracing Sediment Sources Using Mid‐infrared Spectroscopy in Arvorezinha Catchment, Southern Brazil

“…Visible (VIS) and near‐infrared (NIR) reflectance was tested in the French Alps (Legout et al , ), Luxemburg (Martínez‐Carreras et al , , , ), Spain (Brosinsky et al , , ), Ethiopia (Verheyen et al , ), the Eastern Cape of South Africa (Pulley and Rowntree, ), United Kingdom (Collins et al , ) and Southern Brazil (Tiecher et al , , ). Besides, some of these studies showed a good agreement between the results obtained with the spectroscopic method and those provided by the conventional fingerprinting approach based on geochemical properties (Martínez‐Carreras et al , ; Legout et al , ; Verheyen et al , ; Tiecher et al , , ). Near‐infrared spectroscopy have proved to be a valuable tool to trace sediment originating from different land uses [e.g., badland and forest/grassland – Brosinsky et al .…”

“…(, ); landslide, cropland, adnd grazing land –Verheyen et al . (); cropland, unpaved road and stream channels – Tiecher et al . ()], parent material [black marls, limestones and molasses – Legout et al .…”

Coupling spectroscopic and chromatographic techniques for evaluation of the depositional history of hydrocarbons in a subtropical estuary

“…However, bands near 4500 cm À1 can also be characteristic of AlOeH bending and OeH stretching of clay minerals such as kaolinite and gibbsite (Verheyen et al, 2014).…”