Identification of phosphorus emission hotspots in agricultural catchments

Abstract

An enhanced transport-based management approach is presented, which is able to support cost-effective water quality management with respect to diffuse phosphorus pollution. Suspended solids and particulate phosphorus emissions and their transport were modeled in two hilly agricultural watersheds (Wulka River in Austria and Zala River in Hungary) with an improved version of the catchment-scale PhosFate model. Source and transmission areas were ranked by an optimization method in order to provide a priority list of the areas of economically efficient (optimal) management alternatives. The model was calibrated and validated at different gauges and for various years. The spatial distribution of the emissions shows that approximately one third of the catchment area is responsible for the majority of the emissions. However, only a few percent of the source areas can transport fluxes to the catchment outlet. These effective source areas, together with the main transmission areas are potential candidates for improved management practices. In accordance with the critical area concept, it was shown that intervention with better management practices on a properly selected small proportion of the total area (1–3%) is sufficient to reach a remarkable improvement in water quality. If soil nutrient management is also considered in addition to water quality, intervention on 4–12% of the catchment areas can fulfill both aspects.

Comparative assessment of predictions in ungauged basins – Part 1: Runoff-hydrograph studies

“…Finally, there is considerable interest in assessing the effects of environmental change (e.g. land use, hydraulic structures, climate) on the runoff hydrographs and water quality for which accurate runoff predictions are needed (Sachs and McArthur, 2005;Kovacs et al, 2012;Blöschl and Montanari, 2010). Clearly, predictions J. Parajka et al: Part 1: Runoff-hydrograph studies of runoff hydrographs are important for many purposes of societal relevance.…”

Dominant mechanisms for the delivery of fine sediment and phosphorus to fluvial networks draining grassland dominated headwater catchments

“…The delivery of these materials to hydrological networks is augmented by the relatively low filter resistance and restricted potential for temporary storage in these small catchments. Resultantly, the catchment export of sediment and P may be closely related to the magnitude of erosion and land degradation (Kovacs et al, 2012), with adverse impacts on the aquatic habitats ensuing (Collins and Walling, 2004;Haygarth et al, 2005a;Haygarth et al, 2005b;Holden et al, 2007;Valle Junior et al, 2015).…”

“…To moderate the number of watercourses failing to produce ecologically sustainable habitats as a result of enhanced erosion and delivery of pollutants to sensitive headwater fluvial networks, identification of the fine sediment and nutrient sources, and the pathways of delivery is firstly required , with management efforts subsequently focussing on restoring natural attenuation within catchments and disconnecting the identified Critical Source Areas (CSAs), or hot-spots from the fluvial networks (Heathwaite et al, 2005;Kovacs et al, 2012;Newson, 2010;Pionke et al, 1996). Many well established factors act to define the CSAs of fine sediment and P, however, our understanding of how and when these areas are connected to the fluvial networks is limited by the heterogeneity of factors governing process rates (Dean et al, 2009).…”

Upstream to downstream: a multiple-assessment-point approach for targeting non-point-source priority management areas at large watershed scale

“…Unlike point-source pollution, non-point-source (NPS) pollution varies greatly at multiple spatial and temporal scales, making it difficult and costly to identify and alleviate (Kovacs et al, 2012;Squillace and Thurman, 1992). As widely accepted concepts, priority management areas (PMAs) are defined as those areas where the risk potential of certain pollutants exceeds local loss tolerance or contributes more pollutant to the nearby water body (Carpenter et al, 1998;Ghebremichael et al, 2013).…”

“…As widely accepted concepts, priority management areas (PMAs) are defined as those areas where the risk potential of certain pollutants exceeds local loss tolerance or contributes more pollutant to the nearby water body (Carpenter et al, 1998;Ghebremichael et al, 2013). Many successes of the NPS control efforts have been reported based on PMAs (Ghebremichael et al, 2010;Kovacs et al, 2012;Setegn et al, 2006;Strauss et al, 2007;Tripathi et al, 2003;White et al, 2009;Whitehead et al, 2007;Yeghiazarian et al, 2006;Zhou and Gao, 2011). Today, the targeting of watershed PMAs has been integrated as an inherent part of largescale watershed management programs, such as the Total Maximum Daily Load (TMDL) (Savage and Ribaudo, 2013;Sahoo et al, 2013;White et al, 2009).…”