Diffuse hydrological mass transport through catchments: scenario analysis of coupled physical and biogeochemical uncertainty effects

Abstract

Abstract. This paper quantifies and maps the effects of coupled physical and biogeochemical variability on diffuse hydrological mass transport through and from catchments. It further develops a scenario analysis approach and investigates its applicability for handling uncertainties about both physical and biogeochemical variability and their different possible cross-correlation. The approach enables identification of conservative assumptions, uncertainty ranges, as well as pollutant/nutrient release locations and situations for which further investigations are most needed in order to reduce the most important uncertainty effects. The present scenario results provide different statistical and geographic distributions of advective travel times for diffuse hydrological mass transport. The geographic mapping can be used to identify potential hotspot areas with large mass loading to downstream surface and coastal waters, as well as their opposite, potential lowest-impact areas within the catchment. Results for alternative travel time distributions show that neglect or underestimation of the physical advection variability, and in particular of those transport pathways with much shorter than average advective solute travel times, can lead to substantial underestimation of pollutant and nutrient loads to downstream surface and coastal waters. This is particularly true for relatively high catchment-characteristic product of average attenuation rate and average advective travel time, for which mass delivery would be near zero under assumed transport homogeneity but can be orders of magnitude higher for variable transport conditions. A scenario of high advection variability, with a significant fraction of relatively short travel times, combined with a relevant average Correspondence to: K. Persson (klas.persson@natgeo.su.se) biogeochemical mass attenuation rate, emerges consistently from the present results as a generally reasonable, conservative assumption for estimating maximum diffuse mass loading, when the prevailing physical and biogeochemical variability and cross-correlation are uncertain.

Climate-driven change of nitrogen retention–attenuation near irrigated fields: multi-model projections for Central Asia

“…1), which is a value that is consistent with historical observations of N attenuation in Amu Darya River Basin (Törnqvist et al 2015). Independent assessments additionally show that this attenuation product value agrees with observed attenuation of nitrogen at the field scale (Darracq et al 2010a, b;Persson et al 2011). Specifically, Fig.…”

Subsurface release and transport of dissolved carbon in a discontinuous permafrost region

“…(5) Equations (3)- (5) provide a generic framework for solute release and transport through a catchment, which can be used to quantify different cases of subsurface DOC and DIC release and subsequent transport into streams. Different types and forms of the pdf g(τ ) are possible and relevant for different catchment conditions (Lindgren et al, 2004;Cvetkovic, 2011;Persson et al, 2011). In the following section, we test and illustrate results of the catchment-average solution Eq.…”

Saving the Baltic Sea, the Inland Waters of Its Drainage Basin, or Both? Spatial Perspectives on Reducing P-Loads in Eastern Sweden

“…Due to inherent complexities of coupled subsurface-surface water systems (Jarsjö et al 2008;Destouni et al 2010;Persson et al 2011), effective remediation measures need to be underpinned by a relatively detailed understanding of nutrient transport processes, and not least Fig. 4 Anthropogenic P-load contributions from catchments of the NBS-RBD to their outlets (x-axis) and to the Baltic Sea (y-axis).…”

“…A failure to fully meet these goals will occur for three main reasons: (i) Relatively radical measures are needed, such as extensive land use change (e.g., Wulff et al 2007), which are not feasible from a socio-economic perspective (Volk et al 2009). For example, in the most populated river basin district (RBD) of Sweden, the Northern Baltic Sea (NBS) RBD, the reduction demand of P from the RBD authority (RBDA) of 100 tons per year is larger than the estimated anthropogenic load contribution from agriculture within the RBD to the Baltic Sea (Larsson and Pettersson 2009). (ii) Retention processes and slow transport through the subsurface water systems (Darracq et al , 2010Destouni et al 2010;Persson et al 2011) can delay targeted effects of mitigation measures considerably. Furthermore, ecosystems need to respond to measures taken, which may considerably prolong the time it takes to reach WFD targets (Hering et al 2010).…”