Effectiveness Of Buffer Strips Research Articles

Riparian buffer strips promote biomass, species richness and abundance of flying insects in agricultural landscapes

Agricultural intensification is debated as one of the major drivers for the decline of insect biodiversity. Agri-environmental schemes (AES) are a common measure to promote biodiversity in agriculture by granting compensational payments to farmers for environmentally friendly practices. In this study we examined the effect of buffer strips of at least 5 m width, adjacent to small watercourses and drainage ditches, on insect biomass and insect species richness in agricultural landscapes. We selected ten arable fields in each of four regions in lower and upper Bavaria, Southern Germany. 25 out of 40 sites had a buffer strip between arable crops and watercourse. Insects were sampled at three time periods (May/June, June/July and August/September) for two weeks each. In each period two samples were collected (one per week). On each site Malaise traps were set up in 5 and 80 m distance to the embankment of the watercourse. Half of the samples was then subjected to metabarcoding and the other half was classified into different insect groups by morphological identification and the number of the individuals for each group was counted. For hoverflies (Syrphidae), individuals were identified at species-level. Data on vegetation structure (cover of grasses and herbs) in the studied riparian buffer strips was collected and correlated with number of species, abundances and biomass of flying insects. The five taxonomic orders with the highest species richness and individual numbers were: Diptera, Hymenoptera, Coleoptera, Lepidoptera and Hemiptera. Diptera dominated hereby with 34% of all species and 81% of all individuals. On average, mixed models indicated 31% higher insect biomass, 15% higher species richness and 29% higher individual numbers of flying insects in buffer strips at 5 m distance to the watercourse compared to sites with no buffer strip. The effect was even stronger for butterflies (32% higher species species richness, 70% more individuals) and hoverflies (24% higher species richness, 51% more individuals). In the presence of a buffer strip significantly higher numbers were found for total individuals, Diptera, Hymenoptera and Coleoptera. In 80 m distance to the watercourse, the samples of flying insects were not significantly influenced by a riparian buffer strip. This study highlights the importance of buffer strips in agricultural regions and their multifunctional potential in fostering biodiversity additionally to their acknowledged use for water protection. Ideally, buffer strips are rich in herbs and inflorescences and are therefore beneficial for the insect fauna by serving as valuable habitat with high potential connectivity at landscape level.

Effect of buffer strips on pesticide risks in freshwaters

Freshwaters and particularly small water bodies are constantly threatened by the use of pesticides in agriculture. These risks have to be mitigated and reduced according to the European Sustainable Use Directive. The creation of vegetated buffer strips is one measure to effectively mitigate the pesticide risk to freshwaters in agricultural landscapes. This study quantifies the buffer strip effects on pesticide risk posed by arable crop farming for German freshwaters using the pesticide risk indicator model SYNOPS. A constant but only slight turnover towards pesticides with lower water body distance requirements over time was observed when no buffer strips were present. However, the presence of buffer strips contributed to a much higher extent to pesticide risk reduction to freshwaters. The chronic risk to freshwaters was reduced by 29% (simulating 5 m buffer strips) and by 47% (simulating 10 m buffer strips). The effect of risk mitigation by buffer strips varied between crop type and pesticide type. Highest effects of buffer strips were achieved for herbicides and in oilseed rape. Overall, the results show that the creation of buffer strips is a crucial step to effectively mitigate pesticide risk to freshwaters in agricultural landscapes.

Effect of grass buffer strips on nitrate export from a tile-drained field site

Vegetated buffer strips may reduce nutrient inputs from agricultural land into surface waters. Their effectiveness at tile-drained fields, though, remains unclear. The objective of this study was to quantify nitrate reduction in the groundwater underneath a buffer strip, to evaluate the effect of buffer strip width, and to assess their impact on nitrate loading in a drainage ditch. The study site was a tile-drained lowland field on glacial till in north-eastern Germany. The investigated grass buffer strips were 7, 3 and 1 m wide. Water levels and nitrate concentrations in 29 monitoring wells and in the adjacent ditch were measured during three winter half-years. Groundwater nitrate loads were calculated based on a simple Darcy approach.Initial nitrate concentrations in the shallow groundwater entering the buffer strip were up to 98 mg L−1, with median values ranging between 2 and 36 mg L−1. Within the buffer strip, these concentrations decreased by 56–98 %. We assume that this reduction was caused by denitrification processes in two study years and dilution after snowmelt in the third year. The width of the buffer strip did not have any influence on the nitrate reduction. Presumably, site characteristics and the hydraulic conductivity are of greater importance. The groundwater nitrate load was reduced by the buffer strip, but the contribution of the groundwater to total ditch nitrate load was minor. We conclude that possible positive effects of buffer strips on groundwater quality do not ameliorate surface water quality at tile-drained field sites.

Effects of Grazing Management and Buffer Strips on Metal Runoff from Pastures Fertilized with Poultry Litter.

Metal runoff from fields fertilized with poultry litter may pose a threat to aquatic systems. Buffer strips located adjacent to fields may reduce nutrients and solids in runoff. However, scant information exists on the long-term effects of buffer strips combined with grazing management on metal runoff from pastures. The objective of this study was to assess the 12-yr impact of grazing management and buffer strips on metal runoff from pastures receiving poultry litter. The research was conducted using 15 watersheds (25 m wide and 57 m long) with five treatments: hayed (H), continuously grazed (CG), rotationally grazed (R), rotationally grazed with a buffer strip (RB), and rotationally grazed with a fenced riparian buffer strip (RBR). Poultry litter was applied annually in spring at 5.6 Mg ha. Runoff samples were collected after every rainfall event. Aluminum (Al) and iron (Fe) concentrations were strongly and positively correlated with total suspended solids, indicating soil erosion was the primary source. Soluble Al and Fe were not related to total Al and Fe. However, there was a strong positive correlation between soluble and total copper (Cu) concentrations. The majority of total Cu and zinc was in water-soluble form. The CG treatment had the highest metal concentrations and loads of all treatments. The RBR and H treatments resulted in lower concentrations of total Al, Cu, Fe, potassium, manganese, and total organic carbon in the runoff. Rotational grazing with a fenced riparian buffer and converting pastures to hayfields appear to be effective management systems for decreasing concentrations and loads of metals in surface runoff from pastures fertilized with poultry litter.

Sediment and nutrient removal by integrated tree-grass riparian buffers in Taihu Lake watershed, eastern China

Loss of nitrogen (N) and phosphorus (P) from agricultural runoff is a leading cause of eutrophication in Taihu Lake, China. Riparian buffer strips can effectively remove sediment and nutrients from surface runoff. A field-scale study was conducted to assess the effectiveness of the integrated poplar (<i>Populus</i>)-grass buffer strips with different tree planting density in reducing sediment, N, and P from agricultural runoff during natural rainfall events in Taihu Lake watershed, eastern China. The experimental site consisted of four treatments, including a control plot with no buffer strip (T₀) and three poplar-grass buffer strips with different planting densities of 1,346 trees ha⁻¹ (T₁), 769 trees ha⁻¹ (T₂), and 577 trees ha⁻¹ (T₃) with planting spacing of 2 × 5 m (6.5 × 16.4 ft), 4 × 5 m (13.1 × 16.4 ft), and 6 × 5 m (19.7 × 16.4 ft), respectively. The integrated poplar-grass buffer strips significantly reduced runoff volume, sediment, total N, and total P masses by 49.3% to 61.6%, 78.7% to 90.2%, 57.2% to 71.5%, and 65.4% to 81.4%, respectively. With increasing poplar planting density in buffer strips, the canopy interception and maximum water storage capacity of litter layer increased, while the loss of sediments and nutrients from runoff decreased. There was significantly higher removal efficiency in buffer T₁ than that in buffers T₂ and T₃ for sediment, particle-bound N (PN), and particle-bound P (PP). There was no significant difference in removal efficiency for ammonium as N (NH₄-N), nitrate as N (NO₃-N), and phosphate P (PO₄-P) between buffers T₁ and T₂. According to different rainfall regimes, we found that the reduction in runoff volume, sediment, and nutrients load for buffers were higher under mild-long duration events (rainfall intensity class 2 to 4 mm h⁻¹ [0.078 to 0.15 in hr⁻¹]) and lower under intense-short duration events (rainfall intensity class 6 to 8 mm h⁻¹ [0.23 to 0.31 in hr⁻¹]). The removal efficiency of the buffers was negatively correlated with both precipitation and rainfall intensity, and the rainfall intensity had more effect on the removal efficiency than the precipitation. The results indicated that the impact of tree planting density on the effectiveness of buffer strips depended on the measured parameter. That is, the impact on sediment, PN, and PP was greater than that on the soluble N and P. The effect of tree planting density on the performance of buffer strips is mainly due to the interception of canopy and litter layer.

How effective are on-farm mitigation measures for delivering an improved water environment? A systematic map

Abstract Background Agricultural activities are estimated to contribute 70% of nitrates, 28% of phosphates and 76% of sediments measured in UK rivers. Catchments dominated by agriculture also have elevated levels of pesticides and bacterial pathogens. European member states have a policy commitment to tackle this pollution through the water framework directive. Here we report on the results of a systematic map to investigate and describe the nature and coverage of research pertaining to the effectiveness of 6 on-farm mitigation measures, slurry storage, cover/catch crops, woodland creation; controlled trafficking, subsoiling and vegetated buffer strips for delivering an improved water environment in terms of a reduction in nitrogen (N), phosphorus (P), sediment, pesticides and faecal indicator organisms (FIOs) or pathogens from faecal material. Methods Research evidence for the effectiveness of the 6 on-farm mitigation measures for delivering an improved water environment (as detailed above) was collated using English language search terms for temperate farming systems in Europe, Canada, New Zealand and northern states of the United States of America. Searches for literature were made from online publication databases, search engines, specialist websites and bibliographies of topic specific reviews. Recognised experts, authors and practitioners were also contacted to identify unpublished literature. Articles were screened for relevance at title, abstract and full text using predefined inclusion criteria set out in an a priori published protocol. All relevant articles were mapped in a searchable database using pre-defined coding and critically appraised for relevance and reliability. Articles reporting the same study were removed. All full text studies without confounding factors were identified and coded for in a separate searchable database. Results A total of 718 articles were included in the database. Buffer strips were the most commonly studied intervention followed by cover crops and slurry storage. Little evidence was found for woodland creation and sub-soiling. No studies were found for controlled trafficking on grassland. Nitrogen was most frequently measured, followed by P, sediment, pesticides and FIOs or pathogens from faecal material. Conclusions The majority of the evidence collated in this map investigated the effectiveness of buffer strips and cover crops for improving water quality. This evidence was predominantly focussed on reducing N pollution. An evidence gap exists for the impact of cover/catch crops in reducing leaching of pesticides, FIOs and pathogens, and for organic forms of N and P. There was limited research investigating the effectiveness of buffer strips for reducing leaching of organic forms of N or P, or for pesticides that are currently authorised for use/commonly used in UK agriculture. Further, long term studies across different seasons with controls, pre and post water quality measurements and multiple sampling points from both field and rivers would improve the evidence base. Evidence gaps exist for woodland creation, subsoiling and controlled trafficking on grassland.

Design of riparian buffer strips affects soil quality parameters

Vegetated buffer strips alongside watercourses are commonly used to counteract diffuse pollution from agricultural activities. If properly designed, they can provide multiple environmental benefits by increasing wildlife habitats and biodiversity. Little attention has been paid to the effects of buffer strips on soil quality. This study was conducted to determine the impact of different buffer designs on soil biochemical parameters and to define relevant quality parameters for soil monitoring. We compared four buffer arrangements: 3m wide grass buffer; 3m grass with one tree row; 6m grass with one tree row; 6m grass with two tree rows; plus two controls: an adjacent maize crop field and a plot without buffer. Buffers were established 13 years ago at the Padua University Experimental Farm in the Po Valley, north-east Italy. Studied parameters included soil organic matter composition and soil microbial and enzymatic assays. As expected, control plots showed the lowest values for all the studied parameters. Among buffer designs, 3m grass and 3m grass with 1 tree row buffers gave the highest values. Multivariate analysis demonstrated that the increase of soil organic carbon content distinguished buffers from controls, whereas soil humic carbon quality parameters such as humic compounds apparent molecular weight, together with acetyl esterase (fluorescein test) enzyme activity, were discriminatory in separating buffer designs. These results are an important contribution to the knowledge base and can help to improve the management of these systems.

Effect of buffer strips and soil texture on runoff losses of flufenacet and isoxaflutole from maize fields

The influence of buffer strips and soil texture on runoff of flufenacet and isoxaflutole was studied for two years in Northern Italy. The efficacy of buffer strips was evaluated on six plots characterized by different soil textures; two plots had Riva soil (18.6% sand, 63.1% silt, 18.3% clay) while the remaining four plots had Tetto Frati (TF) soil (37.1% sand, 57% silt, 5.9% clay). Additionally, the width of the buffer strips, constituted of spontaneous vegetation grown after crop sowing, was also compared for their ability to abate runoff waters. Chemical residues in water following runoff events were investigated, as well as their dissipation in the soil. After the first runoff events, concentrations of herbicides in water samples collected from Riva plots were as much as four times lower in waters from TF plots. On average of two growing seasons, the field half-life of flufenacet in the upper soil layer (5 cm) ranged between 8.1 and 12.8 days in Riva soil, 8.5 and 9.3 days in TF soil. Isoxaflutole field half-life was less than 1 day. The buffer strip was very affective by the uniformity of the vegetative cover, particularly, at the beginning of the season. In TF plots, concentration differences were generally due to the presence or absence of the buffer strip, regardless of its width.

Quantifying the effect of buffer strips for pathogen removal

Buffer strips are effective at minimizing waterway pollution. Their ability to trap human infectious pathogens, however, is largely unknown and is of utmost interest in a drinking water catchment. The aim of this research was to determine a modeling approach to quantify the reduction in pathogens attributable to the implementation of buffer strips in an agricultural catchment. To model reduction in pathogens through buffer strips, a model developed specifically for pathogens was essential. In this research, a simple lumped conceptual model known as EG was used; the model simulates pathogen fate and transport in a catchment on a continuous basis and has a hydrologic flow‐partitioning component. An understanding of pathogen movement at a catchment scale was necessary to enable buffer strip effectiveness to be incorporated into the model. A case study demonstrates the practical application and benefits of the model for drinking water quality managers.

Effectiveness of buffer strips without added fertilizer to reduce phosphorus loads from flat fields to surface waters

AbstractBuffer strips with no added fertilizers are a mitigation measure to reduce P loads from agricultural land to surface water. However, the experimental evidence on their effectiveness (BSE) has been from sloping locations with shallow flow and surface runoff. The aim of this experimental study was to quantify BSE for P on flat agricultural lowland, predominantly with deep flow. We selected sites characteristic of five major hydrogeological classes in the Netherlands and in each experimental field installed paired 5‐m‐wide unfertilized grass (BS) and reference treatments (REF) that abutted the ditch. The REF treatments were managed similar to the adjacent grass or maize field, but BS treatments were only harvested. Each treatment had a reservoir in the ditch to collect and measure discharge and flow‐proportional P concentration for 3 or 4 yr. We also measured net P withdrawal, the P status of the soil and P concentration in upper groundwater. We found a significant BSE for P of 61% on the site with the shallowest flow and steepest slope (2%). At the other sites, BSE was low and statistically insignificant. We conclude that harvested unfertilized buffer strips reduce P loads from flat fields only in specific areas with high surface runoff and/or shallow flow, especially in combination with a high original soil P status.

Using palm‐mat geotextiles on an arable soil for water erosion control in the UK

AbstractTo date, most studies of the effectiveness of geotextiles on soil erosion rates and processes have been conducted in laboratory experiments for less than 1 h. Hence, at Hilton (52°33′ N, 2°19′ W), UK, the effectiveness of employing palm‐mat geotextiles for soil erosion control under field conditions on arable loamy sands was investigated. Geotextile‐mats constructed from Borassus aethiopum (Borassus palm of West Africa) and Mauritia flexuosa (Buriti palm of South America) leaves are termed Borassus mats and Buriti mats, respectively. Duplicate runoff plots (10 m × 1 m on a 15° slope) had five treatments (bare, permanent grass, Borassus total plot cover, Borassus buffer strip and Buriti buffer strip). Borassus covered plots had about 72% ground cover and to differentiate between this treatment and Borassus buffer strips, the former treatment is termed Borassus completely‐covered. Runoff and eroded soil were collected from each bounded plot in a concrete gutter, leading to a receptacle. Results from 08/01/2007–23/01/2009 (total precipitation = 1776·5 mm; n = 53 time intervals) show that using Borassus buffer strips (area coverage ∼10%) on bare soil decreased runoff volume by about 71% (P &gt; 0·05) and soil erosion by 92% (P &lt; 0·001). Bare plots had nearly 29·1 L m−2 runoff and 2·36 kg m−2 soil erosion during that period. Borassus buffer strip, Buriti buffer strip and Borassus completely‐covered plots had similar effects in decreasing runoff volume and soil erosion. Runoff volumes largely explain the variability in soil erosion rates. Although buffer strips of Borassus mats were as effective as whole plot cover of the same mats, the longevity of Borassus mats was nearly twice that of Buriti mats. Thus, use of Borassus mats as buffer strips on bare plots is highly effective for soil erosion control. The mechanisms explaining the effectiveness of buffer strips require further studies under varied pedo‐climatic conditions. Copyright © 2011 John Wiley &amp; Sons, Ltd.

The effects of buffer strips and bioretention facilities on agricultural productivity and environmental quality in Central Africa

Land degradation is a growing concern in Central Africa as poor management practices continue to cause erosion and increase water runoff in agricultural fields. The implementation of best management practices (BMPs) is needed; however, productivity is often indirectly related to the environmental benefits of such practices and resource constraints often exist. The purpose of this study was to determine the effects of bioretention facilities and buffer strips on environmental quality with productivity and resources as constraints. A water quantity and quality model for an agricultural field in Central Africa was developed. Analyses were conducted to assess the marginal benefits of each BMP, the effect of different BMP combinations on environmental quality and productivity, and the effect of data uncertainty and location uncertainty on model predictions. The results showed that bioretention pits were more effective than buffer strips in increasing environmental quality. Productivity was shown to be directly related to bioretention pits, thus environmental quality can be attained without sacrificing productivity. Data uncertainties resulted in changes in the environmental quality values, but trends remained the same. Guidelines were provided to assist design engineers in developing BMP scenarios that provide the greatest productivity and environmental quality for the constraints involved. The results of this study will bring awareness to the ability of attaining environmental quality without sacrificing productivity as well as the need for accurate data in Central Africa.

Effectiveness of buffer strips in removing pollutants in runoff from a cultivated field in North-East Italy

Abstract Buffer strips are an efficient and economical way to reduce agricultural nonpoint source pollution. Local researches are necessary to gain information on buffer performance, with particular emphasis on narrow buffers. The effect of a 6 m buffer strip (BS) in reducing runoff, suspended solids and nutrients from a field growing maize, winter wheat and soybean was assessed in a field experiment conducted in North-East Italy during 1998–2001. The BS was composed of two rows of regularly alternating trees (Platanus hybrida Brot.) and shrubs (Viburnum opulus L.), with grass (Festuca arundinacea L.) in the inter-rows. The BS reduced total runoff by 78% compared to no-BS, in which cumulative runoff depth was 231 mm over 4 years. With no-BS runoff appeared to be influenced mostly by total rainfall, while with BS maximum rainfall intensity was more important. The filtering effect of the BS reduced total suspended solids (TSS), particularly after the second year, when the median yearly concentrations ranged from 0.28 to 0.99 mg L−1 and were smaller than 0.14 mg L−1, with no-BS and with BS respectively. The combination of lower concentrations and runoff volumes significantly reduced TSS losses from 6.9 to 0.4 t ha−1 over the entire period. A tendency to increased concentrations of all forms of N (total, nitrate and ammonium) while passing through the BS was observed, but total N losses were reduced from 17.3 to 4.5 kg ha−1 in terms of mass balance. On the contrary, P concentrations were unmodified (soluble P), or lowered (total P) by the BS, reducing total losses by about 80%. The effect on total P, composed mainly of sediment-bound forms, was related to particulate settling when passing through the BS. A numerical index (Eutrophic Load Index), integrating water quality and runoff volumes, was created to evaluate the eutrophication risk of runoff with or without the BS. It showed that the BS effect was mostly due to a reduction of runoff volumes rather than improving the overall water quality.

Response to clear-cut logging by northern waterthrushes

We examined the distribution and foraging behaviour of northern waterthrushes (Seiurus noveboracensis) in recently harvested and intact landscapes of Newfoundland. Data were collected along six 1-km segments of stream and adjoining upland habitat resulting in four treatments (harvested or intact, upland or stream) with three replicates each. Although known as a riparian specialist, we found waterthrush territories equally distributed across intact upland and riparian habitats. However, few waterthrushes occupied harvested uplands, while large numbers packed into riparian buffer strips adjacent to these 5- to 10-year-old postharvest clearcuts. Arthropod abundance and biomass were highly variable between years and across the four treatments, generating significant year × treatment interaction effects. Riparian habitat (in both intact and harvested areas) had consistently greater numbers of arthropod prey and more biomass than either upland habitat type. Northern waterthrushes foraging in riparian habitat adjacent to harvested uplands had lower attack rates and more frequent long flights than waterthrushes foraging in the intact treatment types. Prolonged packing of individuals into riparian buffer strips, and apparent adverse affects on waterthrush foraging efficiency, raise concerns about the effectiveness of buffer strips for sustaining viable populations of terrestrial riparian habitat specialists.

Measures of the EU Agri-Environmental Protection Scheme (GAEPS) and their impacts on the visual acceptability of Finnish agricultural landscapes

As a member of the European Union, Finland has committed itself to creating an environmental policy for agriculture. The aims of this study were to evaluate visual impacts of the General Agri-Environmental Protection Scheme (GAEPS) and Supplementary Protection Scheme (SPS) and general attitudes towards some activities in those policies and furthermore to examine the suitability of the method of Alho et al. (2001) for the scenic beauty assessment. The study areas consisted of three original, untreated, and 15 modified rural landscapes representing a variety of different activities. The scenic beauty of the landscapes was evaluated through pairwise comparisons of the responses of 68 people. Furthermore, attitudes towards environmental values, water protection, buffer strips and subsidies to agriculture were obtained. The respondents found the maintained buffer strips more pleasing than unmaintained strips and considered that the quality of watercourses was increased by buffer strips along them. A suitable width for the buffer strip along main ditches, brooks and waterways was regarded, on average, to be wider than the current recommendations. Although the opinions of farmers were basically in line with the existing recommendations, farmers' opininons on the second and third most important effects of buffer strips, an increase in weeds and a decrease in cultivated land, clearly differed from those of the other respondents. Afforestation, lack of building maintenance and abandoned fields were considered to be the most important factors impacting rural landscapes. This study indicates that the Finnish Agri-Environmental Protection Schemes have had positive impacts on the visual quality of landscapes. Attitudes towards other impacts are contradictory. This study also showed the improvement of the Alho et al. (2001) method in these kinds of studies relative to other methods of pairwise comparisons.

Measures of the EU Agri-Environmental Protection Scheme (GAEPS) and their impacts on the visual acceptability of Finnish agricultural landscapes

As a member of the European Union, Finland has committed itself to creating an environmental policy for agriculture. The aims of this study were to evaluate visual impacts of the General Agri-Environmental Protection Scheme (GAEPS) and Supplementary Protection Scheme (SPS) and general attitudes towards some activities in those policies and furthermore to examine the suitability of the method of Alho et al. (2001) for the scenic beauty assessment. The study areas consisted of three original, untreated, and 15 modified rural landscapes representing a variety of different activities. The scenic beauty of the landscapes was evaluated through pairwise comparisons of the responses of 68 people. Furthermore, attitudes towards environmental values, water protection, buffer strips and subsidies to agriculture were obtained. The respondents found the maintained buffer strips more pleasing than unmaintained strips and considered that the quality of watercourses was increased by buffer strips along them. A suitable width for the buffer strip along main ditches, brooks and waterways was regarded, on average, to be wider than the current recommendations. Although the opinions of farmers were basically in line with the existing recommendations, farmers' opininons on the second and third most important effects of buffer strips, an increase in weeds and a decrease in cultivated land, clearly differed from those of the other respondents. Afforestation, lack of building maintenance and abandoned fields were considered to be the most important factors impacting rural landscapes. This study indicates that the Finnish Agri-Environmental Protection Schemes have had positive impacts on the visual quality of landscapes. Attitudes towards other impacts are contradictory. This study also showed the improvement of the Alho et al. (2001) method in these kinds of studies relative to other methods of pairwise comparisons.

THE INFLUENCE OF GRASS AND POROUS BARRIER STRIPS ON RUNOFF HYDROLOGY AND SEDIMENT TRANSPORT

A series of experiments was conducted in a large tilting flume to investigate the effects of buffer strips on flowhydrology and sediment transport/deposition in and around the strips. Changes in flow depth caused by buffer strips of eithernails or grass were recorded, photographed, and measured with a high degree of accuracy. Flow retardation took place atsome distance ahead of the strips, causing the water level to rise. This distance is dependent upon flume slope and strip densityfor any given flow rate. With any increase in flume slope, the point at which water depth increased moved closer to the strip,entering it at around 6% slope. An exponential relationship exists between flume slope and backwater length. Backwaterlength is also dependent on strip density, and the relationship between these two factors is linear. Under our experimentalconditions, sediment deposition did not take place within the strips, but before and after it. The lack of deposition inside thestrips appears to be contrary to the common expectation from this technique. The bulk of sediment load in the sedimentladenflow approaching the strips was deposited ahead of the strips, commencing at the point where flow depth started to rise. Thefiner fraction of sediment load that entered the strip with the flow emerged from the other end unchanged. Some depositiontook place as fans downstream of the strips, an indication of resistive flow velocity being slower before and after the stripsthan within them. When the soil or sand were not consolidated, significant erosion took place inside the strips, creating a headfall at the exit end of the strips, which moved upslope within the strips as experiments continued. For the range of slopes andstrip widths studied, the efficiency of the grass or nail strips in slowing down the flow and unloading its sediment in thebackwater region was independent of the width of strips in the flow direction. Grass strips thus appear to behave more likegrass barriers or grass buffers than filter strips, as they are referred to in some literature. The process interpretationof these results is discussed in this article.