Storage, properties and seasonal variations in fine‐grained bed sediment within the main channel and headwaters of the River Sanginjoki, Finland

Abstract

Lowland catchments in Finland are intensively managed, promoting erosion and sedimentation that negatively affects aquatic environments. This study quantified fine‐grained bed sediment in the main channel and upstream headwaters of the River Sanginjoki (399.93 km2) catchment, Northern Finland, using remobilization sediment sampling during the ice‐free period (May 2010–December 2011). Average bed sediment storage in river was 1332 g m−2. Storage and seasonal variations were greater in small headwater areas (total bed sediment storage mean 1527 g m−2, range 122–6700 g m−2 at individual sites; storage of organic sediment: mean 414 g m−2, range 27–3159 g m−2) than in the main channel (total bed sediment storage: mean 1137 g m−2, range 61–4945 g m−2); storage of organic sediment: mean 329 g m−2, range 13–1938 g m−2). Average reach‐specific bed sediment storage increased from downstream to upstream tributaries. In main channel reaches, mean specific storage was 8.73 t km−1, and mean specific storage of organic sediment 2.45 t km−1, whereas in tributaries, it was 126.94 and 34.05 t km−1, respectively. Total fine‐grained bed sediment storage averaged 563 t in the main channel and 6831 t in the catchment. The proportion of mean organic matter at individual sites was 15–47% and organic carbon 4–455 g C m−2, with both being highest in small headwater tributaries. Main channel bed sediment storage comprised 52% of mean annual suspended sediment flux and stored organic carbon comprised 7% of mean annual total organic carbon load. This indicates the importance of small headwater brooks for temporary within‐catchment storage of bed sediment and organic carbon and the significance of fine‐grained sediment stored in channels for the suspended sediment budget of boreal lowland rivers. Copyright © 2013 John Wiley & Sons, Ltd.

Asynchronicity of fine sediment supply and its effects on transport and storage in a regulated river

“…Heppell et al 2009), although the median particle size (D 50 = 164 μm) is greater than other studies (e.g. Marttila and Kløve 2014;7-60 μm). The major flow events of NovemberDecember 2015 influenced the relative proportions of sand and silt across the upper reach, with the proportion of silt being reduced to 14.5% and the proportion of sand increasing to 81.3% (clay~unchanged, 4.2%).…”

“…Walling et al 2003;Collins and Walling 2007a, b). Others have observed mixed patterns, arguing for the importance of cycles of vegetation growth and senescence (Heppell et al 2009) or the greater influence of flow conditions and local channel characteristics (Marttila and Kløve 2014). The latter authors also found that, in a catchment exploited for peat and wood in central Finland, the high volumes of sediment delivered by headwater tributaries were quickly conveyed downstream; similar dynamics have been reported in Mediterranean streams (Francke et al 2014;Piqué et al 2014).…”

Understanding the controls on deposited fine sediment in the streams of agricultural catchments

“…The organic component of deposited fine sediment is a critical, yet with notable exceptions (e.g. Marttila and Kløve, 2014; often overlooked, determinant of biological response to fine sediment pressure (Collins et al, 2009c;Murphy et al, 2015).…”

Spatial and temporal variation in particle size and particulate organic matter content in suspended particulate matter from peatland‐dominated catchments in Finland

“…Sediment problems resulting from land uses and management have frequently been reported globally (Vörösmarty et al ., : Walling, ). In boreal regions, intensive peatland use cause problems with organic sediments (Laine and Heikkinen, ; Finer et al ., ; Marttila and Kløve, , ). Suspended particulate matter (SPM) containing a high organic fraction has been shown to have a number of negative environmental effects on river hydraulics and stream biota.…”