Spatial Quantification of Non-Point Source Pollution in a Meso-Scale Catchment for an Assessment of Buffer Zones Efficiency

Abstract

The objective of this paper was to spatially quantify diffuse pollution sources and estimate the potential efficiency of applying riparian buffer zones as a conservation practice for mitigating chemical pollutant losses. This study was conducted using a semi-distributed Soil and Water Assessment Tool (SWAT) model that underwent extensive calibration and validation in the Sulejów Reservoir catchment (SRC), which occupies 4900 km 2 in central Poland. The model was calibrated and validated against daily discharges (10 gauges), NO 3 -N and TP loads (7 gauges). Overall, the model generally performed well during the calibration period but not during the validation period for simulating discharge and loading of NO 3 -N and TP. Diffuse agricultural sources appeared to be the main contributors to the elevated NO 3 -N and TP loads in the streams. The existing, default representation of buffer zones in SWAT uses a VFS sub-model that only affects the contaminants present in surface runoff.Water 2015, 7 1890The results of an extensive monitoring program carried out in 2011-2013 in the SRC suggest that buffer zones are highly efficient for reducing NO 3 -N and TP concentrations in shallow groundwater. On average, reductions of 56% and 76% were observed, respectively. An improved simulation of buffer zones in SWAT was achieved through empirical upscaling of the measurement results. The mean values of the sub-basin level reductions are 0.16 kg NO 3 /ha (5.9%) and 0.03 kg TP/ha (19.4%). The buffer zones simulated using this approach contributed 24% for NO 3 -N and 54% for TP to the total achieved mean reduction at the sub-basin level. This result suggests that additional measures are needed to achieve acceptable water quality status in all water bodies of the SRC, despite the fact that the buffer zones have a high potential for reducing contaminant emissions.

Effect of Climate Change on Hydrology, Sediment and Nutrient Losses in Two Lowland Catchments in Poland

“…Among reasons for poor behavior in some stations, Marcinkowski et al [35] reported: (1) the dominant importance of global over local parameters in calibration; (2) simultaneous calibration of different pools of water quality parameters (with different optimal parameter sets achieved for different pools); and (3) input uncertainty (e.g., differences between defined agricultural management operations and the reality). A previous study applying SWAT in Poland for modeling water quality also showed that [41], frequently, the magnitude of the highest observed loads of nutrients is captured well by the model, but there is a shift in timing by a few days (the flood peak is sometimes advanced or lagged by 1-3 days compared with the timing of the peak identified in the observed data) which has a negative effect on the objective function value.…”

Long-term changes in the fish community structure revealed by gillnet monitoring in a shallow, lowland reservoir

“…Therefore, bream can more successfully coexist with piscivores and increase their foraging efficiency with increasing reservoir trophy, thus benefiting from lower competition for food resources (Lammens 1989). According to the latest findings, external nutrient loading is decreasing due to different conservation practices aimed at mitigating diffuse pollution sources (e.g., establishing riparian buffer zones in agriculture (23) areas) upstream of the reservoir (Piniewski et al 2015). Considering these factors, the reason for the recently reversed trend in bream/roach biomass is unknown, but one potential explanation could be the decrease in the zebra mussel population, a recent phenomenon in Polish lakes due to environmental changes (Stańczykowska et al 2010).…”

Challenges in modelling of water quantity and quality in two contrasting meso-scale catchments in Poland

“…The minimum and maximum values presented in these tables are related to extreme values of parameters across the calibrated gauges and water quality monitoring points for each variable. Selection of the parameters set was made based on previous applications of the SWAT model under Polish conditions [PINIEWSKI et al 2014;PINIEWSKI et al 2015;MAR-CINKOWSKI et al 2013] and on the sensitivity analysis performed in both catchments. An important thing in the context of multi-site calibration is the fact that parameters are either global (i.e.…”

“…One of the most popular models is Soil and Water Assessment Tool (SWAT) which was applied in Europe across a range of spatial scales: from the whole continent , to largest river basins [ČERKASOVA et al 2016;PAGLIERO et al 2014;PI-NIEWSKI et al 2016], meso-scale catchments [OSTOJ-SKI et al 2014;PINIEWSKI et al 2015] and small catchments [BRZOZOWSKI et al 2011;MARCINKOW-SKI et al 2013;MOLINA-NAVARRO et al 2014; SMA-RZYŃSKA, MIATKOWSKI 2016;ŚMIETANKA 2014]. An increasing interest in the model triggers more com-plex and challenging applications, especially concerning implementation of new remote sensing techniques and datasets [AL-DOUSARI et al 2010] or more detailed multi-site and multi-variable calibration approach [WOZNICKI et al 2016].…”