scholarly journals Role of Concentrated Flow Pathways on the Movement of Pesticides through Agricultural Fields and Riparian Buffer Zones

2021 ◽  
Vol 64 (3) ◽  
pp. 975-986
Author(s):  
Joseph W. Chandler ◽  
Heather E. Preisendanz ◽  
Tamie L. Veith ◽  
Kyle R. Elkin ◽  
Herschel A. Elliott ◽  
...  
Keyword(s):  
Land Management ◽  
Overland Flow ◽  
Riparian Buffers ◽  
Riparian Zones ◽  
Agricultural Fields ◽  
Hydrologic Connectivity ◽  
Pesticide Transport ◽  
Concentrated Flow ◽  
Corn Fields ◽  
Flow Pathways

HighlightsLand management and hydrologic connectivity cause concentrated flow pathways (CFPs) to serve various functions.Pesticide concentrations diminished along flow pathways from row-cropped fields through functional riparian zones.CFPs facilitated pesticide transport into pasture/hay fields from upgradient corn fields.Subsurface transport was likely a more important transport pathway relative to surface runoff for imidacloprid.Abstract. Riparian buffers, which are an important component of watershed management strategies, can effectively mitigate nutrients and pesticides in agricultural runoff. However, concentrated flow pathways (CFPs) can undermine the performance of buffers by allowing contaminant-laden runoff to bypass the mitigation potential offered by the buffer soils and vegetation. To determine the extent to which CFPs increase pesticide transport from agricultural fields to nearby streams, soil samples (0-2 cm depth) were collected along both CFPs and overland flow (OLF) pathways from the field to the stream for nine fields in a Long-Term Agroecosystem Research (LTAR) site in the ridge and valley physiographic region of Pennsylvania. Soil samples were analyzed for atrazine, metolachlor, and imidacloprid, with two dominant patterns emerging. In corn fields, pesticide concentrations were higher in OLF than CFP samples, suggesting that pesticides were mitigated during transport through each corn field. In contrast, hay and pasture fields, which had not been treated with any of the three pesticides of interest, had lower pesticide concentrations in the OLF samples than the CFP samples. Because the CFPs from these fields originated in upgradient unsampled corn fields, these results suggest that the CFPs were a conduit for pesticides applied in the corn fields and were simply flowing through the hay and pasture fields. Similarly, CFPs in riparian buffers and grass pathways located between the row-cropped fields and the stream tended to have lower concentrations than the upland field (OLF-F) but higher concentrations than the buffer OLF, suggesting a potential for increasing overland flow effectiveness in riparian zones by interrupting CFPs leading to the stream. This study highlights the importance of the land management factors and hydrologic connectivity that cause CFPs to serve different functions (mitigation or enhancement) as runoff is conveyed from agricultural fields to a riparian buffer, and ultimately to an adjacent stream. Further, the results highlight the need for design and maintenance solutions addressing the erosion and sediment control issues that commonly undermine agricultural buffer effectiveness. Keywords: Buffers, Concentrated flow, Contaminant fate and transport, Hydrology, Land management, Pesticides, Overland flow, Water quality.

scholarly journals The Beast from the East: impact of an atypical cold weather event on hydrology and nutrient dynamics in two Irish catchments

2020 ◽  
Author(s):  
S.E. Vero ◽  
N.T. McDonald ◽  
G. McGrath ◽  
P.-E. Mellander
Keyword(s):  
Land Management ◽  
Nutrient Dynamics ◽  
Overland Flow ◽  
Time Lag ◽  
Management Strategies ◽  
Cold Weather ◽  
Catchment Scale ◽  
Continuous Stream ◽  
Baseline Information ◽  
Flow Pathways

A historic lack of continuous stream nutrient monitoring at the catchment scale limits understanding of the effects of snowstorms. The most significant snowstorm since 1985, nicknamed “the Beast from the East”, occurred in February–March 2018. High-frequency stream outlet monitoring in two close but hydrologically and agriculturally contrasting catchments (<1,200 ha) captured phosphorus (total and reactive), total oxygenated nitrogen (TON), temperature and discharge dynamics during and after the event. The grassland catchment consists of poorly drained gley soils and exhibits overland flow pathways, while the arable catchment consists of well-drained brown earths and is dominated by subsurface pathways. Nitrate (NO 3 -N) concentrations were initially elevated (3.50 and 7.89 mg/L for poorly drained grassland and well-drained arable catchments, respectively) before becoming diluted by meltwater. Total reactive phosphorus (TRP) displayed a distal (anti-clockwise) concentration-discharge hysteresis in the poorly drained grassland catchment suggesting low mobilisation from the soil. Conversely, the well-drained arable catchment displayed proximal (clockwise) hysteresis, indicative of the mobilisation from stream and bank sediment. These relatively infrequent snow events behave similarly to heavy rainfall as regards nutrient losses, albeit subject to a time-lag induced by the speed of snowmelt and the soil moisture deficit (SMD) prior to snowfall. Antecedent land management is crucial to mitigate risk. The current absence of records and analyses of catchment response, particularly nutrient dynamics, to atypical cold weather events in Ireland limits understanding of their effects on water quality. The present study provides the first such baseline information from which land management strategies and the implications for attaining environmental targets can be explored.

Towards predicting the initiation of overland flow from relatively flat agricultural fields using surface water coverage

2021 ◽  
pp. 126125
Author(s):  
Chandra Prasad Ghimire ◽  
Willemijn M. Appels ◽  
Laura Grundy ◽  
Willis Ritchie ◽  
Stuart Bradley ◽  
...  
Keyword(s):  
Surface Water ◽  
Overland Flow ◽  
Agricultural Fields

Structural, Hydrologic, and Sediment Connectivity in a Shrub-Encroached and Restored Semiarid Grassland

2021 ◽  
Author(s):  
Justin Johnson ◽  
Jason Williams ◽  
Phillip Guertin ◽  
Steven Archer ◽  
Philip Heilman ◽  
...  
Keyword(s):  
Sediment Yield ◽  
Soil Loss ◽  
Rainfall Intensity ◽  
Overland Flow ◽  
Spatial Scales ◽  
Structural Connectivity ◽  
Post Treatment ◽  
Semiarid Grassland ◽  
Concentrated Flow ◽  
Shrub Canopy

&lt;p&gt;Shrub encroachment of semiarid grasslands is influenced by connected runoff and erosion patterns that preferentially accumulate resources under vegetated patches (canopy microsites) and deplete interspaces. Soil loss from dryland hillslopes results when areas of bare ground become structurally and functionally connected through overland flow. Although these patterns have been well-described, uncertainty remains regarding how these feedbacks respond to restoration practices. This study compared the structure and hydrologic function of a shrub-encroached semiarid grassland treated five years prior with the herbicide, tebuthiuron, to that of an adjacent untreated grassland. Through a series of hydrologic experiments conducted at increasing spatial scales, vegetation and soil structural patterns were related to runoff and erosion responses. At a fine scale (0.5 m&lt;sup&gt;2&lt;/sup&gt;), rainfall simulations (120 mm&amp;#183;h&lt;sup&gt;-1&lt;/sup&gt; rainfall intensity; 45 min) showed herbicided shrub canopy microsites had greater infiltration capacities (105 and 71 mm&amp;#183;h&lt;sup&gt;-1&lt;/sup&gt; terminal infiltration rates) and were less susceptible to splash-sheet erosion (3 and 26 g sediment yield) than untreated shrub canopy microsites, while interspaces were statistically comparable between study sites. Concentrated flow simulations at a coarse scale (~9 m&lt;sup&gt;2&lt;/sup&gt;) revealed that gaps between the bases of vegetation (i.e. basal gaps) &gt; 2 m&lt;sup&gt;&lt;/sup&gt;were positively related to both concentrated flow runoff (r = 0.72, p = 0.008) and sediment yield (r = 0.70, p = 0.012). Modeled hillslope-scale (50 m&lt;sup&gt;2&lt;/sup&gt;) runoff and erosion (120 mm&amp;#183;h&lt;sup&gt;-1&lt;/sup&gt; rainfall intensity; 45 min) indicated less soil loss in the tebuthiuron-treated site (1.78 Mg&amp;#183;ha&lt;sup&gt;-1&lt;/sup&gt; tebuthiuron; 3.19 Mg&amp;#183;ha&lt;sup&gt;-1&lt;/sup&gt; untreated), even though runoff was similar between sites. Our results suggest interspaces in shrub-encroached grasslands continue to be runoff sources following herbicide-induced shrub mortality and may be indicators of runoff responses at larger spatial scales. In contrast, sediment sources are limited post-treatment due to lesser sediment detachment from sheet-splash and concentrated flow processes. Reduced sediment supplies provide evidence that connectivity feedbacks that sustain a shrub-dominant ecological state may have been dampened post-treatment. Our study also highlights the utility of simple measures of structural connectivity, such as basal gaps, as an indicator of hillslope susceptibility to increased runoff and erosion.&lt;/p&gt;

scholarly journals Land Management Impacts on Soil Water Erosion and Loss of Nutrients

Proceedings ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 35 ◽  
Author(s):  
Telak ◽  
Bogunovic ◽  
Rodrigo-Comino
Keyword(s):  
Organic Matter ◽  
Soil Properties ◽  
Land Management ◽  
Sediment Yield ◽  
Management Practices ◽  
Overland Flow ◽  
Organic Matter Content ◽  
Nutrient Loss ◽  
Plant Residues ◽  
Significant Difference

Humans are the driving factor of soil erosion and degradation. Therefore, sustainable land management practices should be developed and applied. The aim of this study was to determine land management impacts on soil properties, soil loss and nutrient loss in 3 different treatments; grass-covered vineyard (GCV), tilled vineyard (TV), and tilled hazelnut orchard (HO). The study area is located in Orahovica, Croatia (45°31′ N, 17°51′ E; elevation 230 m) on ~7° slope. The soil under the study area was classified as a Stagnosol. 8 rainfall simulations (58 mm h−1, during 30 min, over 0.785 m2 plots) were performed at each treatment where the next data were noted: ponding time, runoff time, and collection of overland flow. Soil samples were taken for determination of mean weight diameter (MWD), water stable aggregates (WSA), P2O5 content, and organic matter content. Analyses of sediment revealed concentrations of P2O5 and N. All three treatments had significantly different values of MWD (GCV 3.30 mm; TV 2.94 mm; HO 2.16 mm), while WSA and organic matter significantly differs between GCV and HO. The infiltration rate showed no significant difference between treatments. Sediment yield was significantly the highest at the TV (21.01 g kg−1 runoff), while no significant difference was noted between GCV (2.91) and HO (6.59). Sediments of GCV treatment showed higher concentrations of P2O5 and N, compared to TV and HO. Nutrients loss was highest in the TV (450.3 g P2O5 ha−1; 1891.7 g N ha−1) as a result of highest sediment yield, despite the fact GCV had the highest nutrients concentrations. Results indicate that land management (and/or tillage) affects soil properties and their stability. Even tough HO was tilled and had the lowest values of organic matter, WSA, and MWD, measurements were performed immediately after tillage where the plant residues reduced potential erodibility of the soil. Such results reveal that tillage should be avoided in vineyard and hazelnut production in order to prevent soil and nutrient losses.

Risk Assessment of Erosion from Concentrated Flow on Rangelands Using Overland Flow Distribution and Shear Stress Partitioning

2013 ◽  
Vol 56 (2) ◽  
pp. 539-548 ◽  
Author(s):  
Osama Z. Al-Hamdan ◽  
Frederick B. Pierson ◽  
Mark A. Nearing ◽  
Christopher Jason Williams ◽  
Jeffry J. Stone ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Shear Stress ◽  
Overland Flow ◽  
Flow Distribution ◽  
Concentrated Flow ◽  
Stress Partitioning ◽  
Shear Stress Partitioning

scholarly journals Identifying Flow Pathways for Phosphorus Transport Using Observed Event Forensics and the CRAFT (Catchment Runoff Attenuation Flux Tool)

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1081 ◽  
Author(s):  
Russell Adams ◽  
Paul Quinn ◽  
Nick Barber ◽  
Sean Burke
Keyword(s):  
Overland Flow ◽  
Forensic Analysis ◽  
Frequency Resolution ◽  
Storm Event ◽  
Hydrograph Separation ◽  
Near Surface ◽  
Headwater Catchments ◽  
Additional Tool ◽  
Flow Pathways ◽  
Catchment Runoff

Identifying key flow pathways is critical in order to understand the transport of Phosphorus (P) from agricultural headwater catchments. High frequency/resolution datasets from two such catchments in Northwest England enabled individual events to be examined to identify the flow (Q) and Total P (TP) and Total Reactive P (TRP) dynamics (forensics). Detailed analysis of multiple flow and water quality parameters is referred to here as the event forensics. Are there more flow pathways than just surface runoff (dominated by overland flow) and baseflow (mainly groundwater) contributing at the outlet of these catchments? If so, hydrograph separation alone will not be sufficient. This forensic analysis gives a classification of four storm event response types. Three classes are based on the balance of old and new water giving enrichment and dilution of TRP pattern in the subsurface flow. A fourth type was observed where a plume of nutrient is lost to the channel when there is no observed flow. Modelling is also essential when used in combination with the event forensics as this additional tool can identify distinct flow pathways in a robust form. A case study will apply the Catchment Runoff Attenuation Flux Tool (CRAFT) to two contrasting small headwater catchments in Northwest England, which formed part of the Demonstration Test Catchments (DTC) Programme. The model will use data collected during a series of events observed in the two catchments between the period 2012 and 2014. It has the ability to simulate fast near surface (that can represent flow in the upper soil horizons and field drains) and event subsurface soil flow, plus slower groundwater discharge. The model can capture P enrichment, dilution and the role that displacement of “old” P rich water has during events by mixing these flows. CRAFT captures the dominant flow and P fluxes as seen in the forensic analysis and can create outputs including smart export coefficients (based on flow pathways) that can be conveyed to policy makers to better underpin decision making.

scholarly journals Changes in land-use and their impact on erosion rates and overland flow generation in the Maghreb region

2005 ◽  
Vol 17 (2) ◽  
pp. 163-180 ◽  
Author(s):  
C. O.A. Coelho ◽  
A. J.D. Ferreira ◽  
A. Laouina ◽  
A.-K. Boulet ◽  
M. Chaker ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Erosion ◽  
Land Management ◽  
Overland Flow ◽  
Animal Husbandry ◽  
Rainfall Simulation ◽  
Management Systems ◽  
Simulation Experiments ◽  
Erosion Hazard ◽  
Erosion Rates

The ongoing intensification of grazing as well as the replacement of traditional land management systems in the Maghreb has brought to the forefront the fundamental role of land-use in determining soil erosion hazard. This paper reports on erosion rates and soil hydrological characteristics of a variety of land uses in Morocco and Tunisia. The results were obtained through rainfall simulation experiments carried out in the field using a portable simulator, following the design of CERDÀ et al. (1997). Traditional land management systems - typically involving a combination of agriculture, animal husbandry and forestry - produced the least amounts of overland flow and the lowest soil erosion rates. Over-exploitation of these systems apparently has only minor hydrological and erosional impacts. Heavily grazed, degraded "maquis" shrublands, on the other hand, produced considerable amounts of overland flow. At the plot scale of the rainfall simulation experiments (0.24 m2), the corresponding sediment loads are rather insignificant. Nevertheless, slopes where "maquis" shrublands (which generally have very compacted soils) occur upslope from more erodible soils may present a major erosion hazard.

scholarly journals Delineating wetland catchments and modeling hydrologic connectivity using lidar data and aerial imagery

2017 ◽  
Vol 21 (7) ◽  
pp. 3579-3595 ◽  
Author(s):  
Qiusheng Wu ◽  
Charles R. Lane
Keyword(s):  
High Resolution ◽  
Spatial Data ◽  
Overland Flow ◽  
Flow Simulation ◽  
Hierarchical Structures ◽  
Aerial Imagery ◽  
Lidar Data ◽  
Hydrologic Connectivity ◽  
Least Cost Path ◽  
Elevation Model

Abstract. In traditional watershed delineation and topographic modeling, surface depressions are generally treated as spurious features and simply removed from a digital elevation model (DEM) to enforce flow continuity of water across the topographic surface to the watershed outlets. In reality, however, many depressions in the DEM are actual wetland landscape features with seasonal to permanent inundation patterning characterized by nested hierarchical structures and dynamic filling–spilling–merging surface-water hydrological processes. Differentiating and appropriately processing such ecohydrologically meaningful features remains a major technical terrain-processing challenge, particularly as high-resolution spatial data are increasingly used to support modeling and geographic analysis needs. The objectives of this study were to delineate hierarchical wetland catchments and model their hydrologic connectivity using high-resolution lidar data and aerial imagery. The graph-theory-based contour tree method was used to delineate the hierarchical wetland catchments and characterize their geometric and topological properties. Potential hydrologic connectivity between wetlands and streams were simulated using the least-cost-path algorithm. The resulting flow network delineated potential flow paths connecting wetland depressions to each other or to the river network on scales finer than those available through the National Hydrography Dataset. The results demonstrated that our proposed framework is promising for improving overland flow simulation and hydrologic connectivity analysis.

Pragmatic, fast and easy to use Model for Predicting Susceptibility to Concentrated Flow Erosion in a GIS in data-sparse regions

2020 ◽  
Author(s):  
Liberty Lazrus Orapine Mgbanyi ◽  
Matthew Johnson ◽  
Colin Thorne
Keyword(s):  
High Resolution ◽  
Soil Loss ◽  
Overland Flow ◽  
Agricultural Practices ◽  
Alternative Methods ◽  
Management Decision ◽  
Predictive Tool ◽  
High Resolution Data ◽  
Concentrated Flow ◽  
Resolution Data

&lt;p&gt;Less Economically Developed Countries (LEDCs) are at particular risk of gullying due to climate change, land-use change, poor agricultural practices and widespread farming intensification, but in these areas, the data required to apply most predictive models are usually unavailable. Therefore, an urgent need for a practical and rapid predictive tool for assessing gullying potential in data-sparse regions, to inform planning, agricultural practices and environmental management decision-making is required. Given the difficulty in applying existing empirical models to developing areas, where input data is sparse, but the risk of gullying is high, alternative methods need to be developed to identify areas susceptible to gullying. Here it is hypothesised that detailed data is required to apply existing models of soil loss from agricultural areas because they focus on predicting the quantities of sediment lost after agriculture has commenced. The data requirements for successful model application could be less if the focus were instead on identifying areas that are susceptible to gullying.&amp;#160; The decision to avoiding soil loss by either protecting them from agricultural development or at least applying soil conservation measures from the outset, without attempting to predict the extents or the specific metre-scale locations of individual gully channels will come much handy. The Compound Topography Index (CTI) meets the criteria for that candidate predictive model for concentrated flow erosion in the data-sparse regions. The CTI, however, required quality and high-resolution data(&lt;5m LiDAR DEMs) available in data-rich regions to perform, but with weak quality and low-resolution data(30m DEM) found in the data-sparse regions, fuzzy logic data applied to this data before using it as input into the CTI model to at least on identifying areas that are susceptible to gullying. The accuracy of the model was moderately improved when used with high-resolution data, and consistent in prediction for coarse resolution DEMs. A key finding is that the fuzzy CTI reveals that much of the landscape has the potential to suffer gullying &amp;#8211; i.e. there is sufficient planform and profile curvature to concentrate and accelerate overland flow. Soil degradation and loss of soil structure, or removal of natural vegetation and, especially forests, could exacerbate the condition rapidly lead to widespread gullying based on the occurrence of concentrated overland flow driven by the topography, while the incorporation of soil structural stability index in the fuzzy CTI slightly improved it performance as per modelling concentrated flow erosion. The calculation of CTI is easy, repeatable, require less comprehensive, sophisticated data collection and not over extended periods and could widely be an applicable predictor of gullying, for use in sparse data regions.&lt;/p&gt;

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