Estimating Catchment Vulnerability to Diffuse Herbicide Losses from Hydrograph Statistics

Leu, Christian; Schneider, Manuel K.; Stamm, Christian

doi:10.2134/jeq2009.0323

Cited by 20 publications

(19 citation statements)

References 41 publications

(63 reference statements)

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“…The observation that findings from small catchments can be extrapolated to larger areas in a meaningful manner may be considered a contradiction to earlier work where important spatial differences between herbicide loss rates within catchments were demonstrated (Doppler et al, 2014;Leu et al, 2010). However, the data suggest that spatial heterogeneity at small scales is averaged out at larger ones such that it does not dominate the large scale patterns.…”

Section: Model Performancecontrasting

confidence: 65%

“…The concept to describe the transfer of the applied herbicides from the fields to the river is based on the empirical observation that herbicide concentrations increase with flow during discharge events during the application period (Leu et al, 2010). Mechanistically this can be explained by the occurrence of fast transport processes (with high herbicide concentrations) such as surface runoff and fast subsurface flow through drainage systems or macropores (Leu et al, 2004a) during discharge events.…”

Section: Outputmentioning

confidence: 99%

See 1 more Smart Citation

Modelling biocide and herbicide concentrations in catchments of the Rhine basin

Möser

Wemyss

Scheidegger

et al. 2018

Hydrol. Earth Syst. Sci.

Self Cite

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Abstract. Impairment of water quality by organic micropollutants such as pesticides, pharmaceuticals or household chemicals is a problem in many catchments worldwide. These chemicals originate from different urban and agricultural usages and are transferred to surface waters from point or diffuse sources by a number of transport pathways. The quantification of this form of pollution in streams is challenging and especially demanding for diffuse pollution due to the high spatio-temporal concentration dynamics, which require large sampling and analytical efforts to obtain representative data on the actual water quality.Models can also be used to predict to what degree streams are affected by these pollutants. However, spatially distributed modelling of water quality is challenging for a number of reasons. Key issues are the lack of such models that incorporate both urban and agricultural sources of organic micropollutants, the large number of parameters to be estimated for many available water quality models, and the difficulty to transfer parameter estimates from calibration sites to areas where predictions are needed.To overcome these difficulties, we used the parsimonious iWaQa model that simulates herbicide transport from agricultural fields and diffuse biocide losses from urban areas (mainly façades and roof materials) and tested its predictive capabilities in the Rhine River basin. The model only requires between one and eight global model parameters per compound that need to be calibrated. Most of the data requirements relate to spatially distributed land use and comprehensive time series of precipitation, air temperature and spatial data on discharge. For larger catchments, routing was explicitly considered by coupling the iWaQa to the AQUASIM model.The model was calibrated with datasets from three different small catchments (0.5-24.6 km 2 ) for three agricultural herbicides (isoproturon, S-metolachlor, terbuthylazine) and two urban biocides (carbendazim, diuron). Subsequently, it was validated for herbicides and biocides in Switzerland for different years on 12 catchments of much larger size (31-35 899 km 2 ) and for herbicides for the entire Rhine basin upstream of the Dutch-German border (160 000 km 2 ) without any modification. For most compound-catchment combinations, the model predictions revealed a satisfactory correlation (median r 2 : 0.5) with the observations. The peak concentrations were mostly predicted within a factor of 2 to 4 (median: 2.1 fold difference for herbicides and 3.2 for biocides respectively). The seasonality of the peak concentration was also well simulated; the predictions of the actual timing of peak concentrations, however, was generally poor.Limited spatio-temporal data, first on the use of the selected pesticides and second on their concentrations in the river network, restrict the possibilities to scrutinize model performance. Nevertheless, the results strongly suggest that input data and model structure are major sources of predictive uncertainty. The latter is for exampl...

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Section: Model Performancecontrasting

confidence: 65%

Section: Outputmentioning

confidence: 99%

Modelling biocide and herbicide concentrations in catchments of the Rhine basin

Möser

Wemyss

Scheidegger

et al. 2018

Hydrol. Earth Syst. Sci.

Self Cite

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show abstract

“…This shows that a different runoff regime was active during event E13. Our observation that infiltration excess overland flow is the main transport process for herbicides is in contrast to previous studies in the Swiss Plateau (Leu et al, 2004a(Leu et al, , 2010Gomides Freitas et al, 2008), which indicated that saturation excess overland flow was the dominant process controlling diffuse herbicide pollution.…”

Section: Transport Processes and Csascontrasting

confidence: 99%

“…Pesticides can enter the water system, where they can harm aquatic organisms even in low concentrations. Small streams in catchments with intensive crop production are especially at risk (Liess and Schulz, 1999), as diffuse pollution from agricultural fields causes major inputs to the stream in these areas (Leu et al, 2010). Pesticides mainly enter surface waters during rain events, when they are mobilised and transported with fast runoff (Thurman et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Spatial variability of herbicide mobilisation and transport at catchment scale: insights from a field experiment

Doppler¹,

Camenzuli²,

Hirzel³

et al. 2012

Preprint

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During rain events, herbicides can be transported from their point of application to surface waters where they may harm aquatic organisms. Since the spatial pattern of mobilisation and transport is heterogeneous, the contributions of different fields to the herbicide load in the stream may differ considerably within one catchment. Therefore, the prediction of contributing areas could help to target mitigation measures efficiently to those locations where they reduce herbicide pollution the most. Such spatial predictions require sufficient insight into the underlying transport processes. To improve the understanding of the process chain of herbicide mobilisation on the field and the subsequent transport through the catchment to the stream, we performed a controlled herbicide application on corn fields in a small agricultural catchment (ca. 1 km2) with intensive crop production in the Swiss Plateau. For two months after application in 2009, water samples were taken at different locations in the catchment (overland flow, tile drains and open channel) with a high temporal resolution during rain events. We also analysed soil samples from the experimental fields and measured discharge, groundwater level, soil moisture and the occurrence of overland flow at several locations. Several rain events with varying intensities and magnitudes occurred during the study period. Overland flow and erosion were frequently observed in the entire catchment. Infiltration excess and saturation excess overland flow were both observed. However, the main herbicide loss event was dominated by infiltration excess. This is in contrast to earlier studies in the Swiss Plateau, demonstrating that saturation excess overland flow was the dominant process. Despite the frequent and wide-spread occurrence of overland flow, most of this water did not directly reach the channel. It mostly got retained in small sinks in the catchment. From there, it reached the stream via macropores and tile drains. Manholes of the drainage system and catch basins for road and farmyard runoff acted as additional shortcuts to the stream. Although fast flow processes like overland and macropore flow reduce the influence of herbicide properties due to short travel times, sorption properties influenced the herbicide transfer from ponding overland flow to tile drains (macropore flow). However, no influence of sorption was observed during the mobilisation of the herbicides from soil to overland flow. These two observations on the role of herbicide properties contradict, to some degrees, previous findings. They demonstrate that valuable insight can be gained by spatially detailed observations along the flow paths

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“…Pesticides can enter the water system, where they can harm aquatic organisms even in low concentrations. Small streams in catchments with intensive crop production are especially at risk (Liess and Schulz, 1999), as diffuse pollution from T. Doppler et al: Spatial variability of herbicide mobilisation and transport agricultural fields causes major inputs to the stream in these areas (Leu et al, 2010). Pesticides mainly enter surface waters during rain events, when they are mobilised and transported with fast runoff (Thurman et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Spatial variability of herbicide mobilisation and transport at catchment scale: insights from a field experiment

Doppler

Camenzuli

Hirzel

et al. 2012

Hydrol. Earth Syst. Sci.

105

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During rain events, herbicides can be transported from their point of application to surface waters, where they may harm aquatic organisms. Since the spatial pattern of mobilisation and transport is heterogeneous, the contributions of different fields to the herbicide load in the stream may vary considerably within one catchment. Therefore, the prediction of contributing areas could help to target mitigation measures efficiently to those locations where they reduce herbicide pollution the most. Such spatial predictions require sufficient insight into the underlying transport processes. To improve the understanding of the process chain of herbicide mobilisation on the field and the subsequent transport through the catchment to the stream, we performed a controlled herbicide application on corn fields in a small agricultural catchment (ca. 1 km2) with intensive crop production in the Swiss Plateau. Water samples were collected at different locations in the catchment (overland flow, tile drains and open channel) for two months after application in 2009, with a high temporal resolution during rain events. We also analysed soil samples from the experimental fields and measured discharge, groundwater level, soil moisture and the occurrence of overland flow at several locations. Several rain events with varying intensities and magnitudes occurred during the study period. Overland flow and erosion were frequently observed in the entire catchment. Infiltration excess and saturation excess overland flow were both observed. However, the main herbicide loss event was dominated by infiltration excess. Despite the frequent and wide-spread occurrence of overland flow, most of this water did not reach the channel directly, but was retained in small depressions in the catchment. From there, it reached the stream via macropores and tile drains. Manholes of the drainage system and storm drains for road and farmyard runoff acted as additional shortcuts to the stream. Although fast flow processes such as overland and macropore flow reduce the influence of the herbicide's chemical properties on transport due to short travel times, sorption properties influenced the herbicide transfer from ponding overland flow to tile drains (macropore flow). However, no influence of sorption was observed during the mobilisation of the herbicides from soil to overland flow. These observations on the role of herbicide properties contradict previous findings to some degree. Furthermore, they demonstrate that valuable insight can be gained by making spatially detailed observations along the flow paths

show abstract

Estimating Catchment Vulnerability to Diffuse Herbicide Losses from Hydrograph Statistics

Cited by 20 publications

References 41 publications

Modelling biocide and herbicide concentrations in catchments of the Rhine basin

Modelling biocide and herbicide concentrations in catchments of the Rhine basin

Spatial variability of herbicide mobilisation and transport at catchment scale: insights from a field experiment

Spatial variability of herbicide mobilisation and transport at catchment scale: insights from a field experiment

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