Suspended Sediment and Particulate Phosphorus Transport and Delivery Pathways in an Arable Catchment, Gelbæk Stream, Denmark

Abstract

Reliable quanti®cation of suspended sediment (SS) and particulate phosphorus (PP) transport, and identi®cation of the various delivery pathways at the catchment level, is an important and necessary aid to appropriate catchment management. In this study we measured storm event, seasonal and annual losses of SS and PP from a Danish arable catchment, Gelbñk Stream, using a multisampling strategy. SS losses for the study years May 1993±April 1994 and May 1994± April 1995 ranged from 71 to 88 kg ha À1 , while PP losses ranged from 0 . 32 to 0 . 36 kg P ha À1 . In both cases losses mainly occurred during infrequent storm events. In comparison with intensive storm sampling, infrequent (fortnightly) sampling underestimated annual transport during the two study years by À24 and À3317, respectively, for SS, and by À8Á6 and À1517, respectively, for PP. Reliable estimation of the transport of sediment and sediment-associated nutrients and other substances thus necessitates the use of an intensive monitoring approach. Turbidimeters proved to be a good substitute for direct measurement of SS, especially during storm events, although careful calibration is needed at the seasonal and storm event levels.Experience shows that in arti®cially drained and geologically complex catchments such as Gelbñk, simultaneous comparative monitoring of dierent sources (e.g. subsurface drainage water) is an important means of reliably discriminating between the various diuse sources of sediment and phosphorus. Subsurface drainage water was found to account for 11±15% of the annual SS export from the catchment; the corresponding ®gure for PP being 11±18%. Surface runo was only a source of SS and PP during the ®rst study year, when it accounted for 19% of SS and 7% of PP catchment export. Stream bank/bed erosion must therefore have been the major diuse source of SS and PP in both study years. The study also revealed that analysis of the trace element content (e.g. 137 Cs, 210 Pb) of the SS transported in subsurface drainage water and stream water during storm events is a useful means of discriminating between diuse losses of SS delivered from topsoil and subsoil compartments.

A review of phosphorus and sediment release from Irish tillage soils, the methods used to quantify losses and the current state of mitigation practice

“…Very few studies in Ireland have looked at soil erosion rates on tillage soils, despite international research by Kronvang et al (1997), , Deasy et al (2009), Stevens et al (2009) and Van Oost et al (2009) concentrating specifically on such soils due to their erosion propensity. The loss of fertile topsoil due to soil erosion on agricultural land is a growing problem in Western Europe, and has been identified as a threat to soil quality and the ability of soils to provide environmental services (Boardman et al 2009).…”

“…Increasing eutrophication of many surface water bodies in arable regions of the UK has been linked with increasing rates of soil erosion causing sediment and P loss from fields cropped with winter cereals and with an accumulation of soil P through continuous application of fertiliser and manures (Catt et al 1998). Research to establish the circumstances leading to sediment and P losses from arable land and to quantify these losses has been carried out in the UK (Speirs and Frost 1987;Chambers et al 1992;Catt et al 1998; and throughout Europe (Kronvang et al 1997;Verstraeten and Poesen 2001;Miller and Quinton 2009) at multiple scales. Reported sediment and P losses from arable sites in these and other similar studies were significantly higher than losses from grassland, and were high enough to cause concern over the eutrophication of surface water bodies in arable areas.…”

SEPAL – a simple GIS-based tool to estimate sediment pathways in lowland catchments

“…Collins and Walling (2004) point out that, though it is difficult to acquire information about sediment entry pathways, it is important to understand sediment sources for deriving management plans and to prevent environmental problems. The main sediment entry pathways in lowlands are the input from agricultural drains, bank erosion and field erosion (Russel et al, 2001;Kronvang et al, 1997;Walling et al, 2002). Different criteria influence sediment input from these three sources: The sediment contribution from drains is highly variable and rarely researched.…”

“…It seems to be governed by factors like soil type, groundwater levels, soil moisture, drainage depth and age, land use, irrigation (Walling et al, 2002;Stone and Krishnappan, 2002) as well as the size of the drained area (Smith et al, 2005). While Kronvang et al (1997) and Stone and Krishnappan (2002) found sediment losses from drains of 20 to 130 kg ha −1 yr −1 , Ulèn and Persson (1999) and Chapman et al (2005) investigated drains under loamy and clayey soils with a high susceptibility to form macropores and measured extremely high values of up to 230 and up to 1000 kg ha −1 yr −1 , respectively. River bank erosion depends on water flow characteristics like depth and velocity, freezing and thawing processes, the soil type, soil density and moisture, vessel traffic, cattle treading, as well as stream properties like curvature, cross-sectional shape and plant cover (Hooke, 1979;Saynor et al, 2003;Laubel et al, 1999;Bradbury et al, 1995;Wynn et al, 2004).…”

The Potential of P Loss from Livestock Farms to Watercourses in Wensleydale; A Risk Mapping Approach

“…Nevertheless, the risk pose by rainfall events can be improve in the implemented risk model as long as rainfall intensity data are available. It should be stressed that large amounts of nutrients are flushed out from lands during a few heavy rainfall events [76]. This is particularly relevant when manure is applied and left exposed on the surface (splash-plate method).…”