scholarly journals Dispersion and Transport of Cryptosporidium Oocysts from Fecal Pats under Simulated Rainfall Events

2004 ◽  
Vol 70 (2) ◽  
pp. 1151-1159 ◽  
Author(s):  
Cheryl M. Davies ◽  
Christobel M. Ferguson ◽  
Christine Kaucner ◽  
Martin Krogh ◽  
Nanda Altavilla ◽  
...  
Keyword(s):  
Surface Soil ◽  
Bare Soil ◽  
Vegetation Coverage ◽  
Rainfall Runoff ◽  
Rainfall Events ◽  
Runoff Volume ◽  
Artificial Rainfall ◽  
Cryptosporidium Oocysts ◽  
Loam Soil ◽  
Intact Soil

ABSTRACT The dispersion and initial transport of Cryptosporidium oocysts from fecal pats were investigated during artificial rainfall events on intact soil blocks (1,500 by 900 by 300 mm). Rainfall events of 55 mm h−1 for 30 min and 25 mm h−1 for 180 min were applied to soil plots with artificial fecal pats seeded with approximately 107 oocysts. The soil plots were divided in two, with one side devoid of vegetation and the other left with natural vegetation cover. Each combination of event intensity and duration, vegetation status, and degree of slope (5° and 10°) was evaluated twice. Generally, a fivefold increase (P < 0.05) in runoff volume was generated on bare soil compared to vegetated soil, and significantly more infiltration, although highly variable, occurred through the vegetated soil blocks (P < 0.05). Runoff volume, event conditions (intensity and duration), vegetation status, degree of slope, and their interactions significantly affected the load of oocysts in the runoff. Surface runoff transported from 100.2 oocysts from vegetated loam soil (25-mm h−1, 180-min event on 10° slope) to up to 104.5 oocysts from unvegetated soil (55-mm h−1, 30-min event on 10° slope) over a 1-m distance. Surface soil samples downhill of the fecal pat contained significantly higher concentrations of oocysts on devegetated blocks than on vegetated blocks. Based on these results, there is a need to account for surface soil vegetation coverage as well as slope and rainfall runoff in future assessments of Cryptosporidium transport and when managing pathogen loads from stock grazing near streams within drinking water watersheds.

scholarly journals Field scale quantification of microbial transport from bovine faeces under simulated rainfall events

2006 ◽  
Vol 5 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Christobel M. Ferguson ◽  
Cheryl M. Davies ◽  
Christine Kaucner ◽  
Nicholas J. Ashbolt ◽  
Martin Krogh ◽  
...  
Keyword(s):  
Cryptosporidium Oocyst ◽  
Experimental Treatment ◽  
Bare Soil ◽  
Simulated Rainfall ◽  
Rainfall Events ◽  
E Coli ◽  
Artificial Rainfall ◽  
Cryptosporidium Oocysts ◽  
Cryptosporidium Parvum Oocysts ◽  
Experimental Soil

The dispersion and transport of Cryptosporidium parvum oocysts, Escherichia coli and PRD1 bacteriophage seeded into artificial bovine faecal pats was studied during simulated rainfall events. Experimental soil plots were divided in two, one sub-plot with bare soil and the other with natural vegetation. Simulated rainfall events of 55 mm.h-1 for 30 min were then applied to the soil plots. Each experimental treatment was performed in duplicate and consisted of three sequential artificial rainfall events (‘Runs’): a control run (no faecal pats); a fresh faecal pat run (fresh faecal pats); and an aged faecal pat run (one week aged faecal pats). Transportation efficiency increased with decreasing size of the microorganism studied; Cryptosporidium oocysts were the least mobile followed by E. coli and then PRD1 phage. Rainfall events mobilised 0.5 to 0.9% of the Cryptosporidium oocysts, 1.3‒1.4% of E. coli bacteria, and 0.03‒0.6% of PRD1 bacteriophages from the fresh faecal pats and transported them a distance of 10 m across the bare soil sub-plots. Subsequent rainfall events applied to aged faecal pats only mobilised 0.01‒0.06% of the original Cryptosporidium oocyst load, between 0.04 and 15% of the E. coli load and 0.0006‒0.06% of PRD1 bacteriophages, respectively.

Performance of Urban Rainwater Retention by Green Roof: A Case Study of Jinan

2012 ◽  
Vol 178-181 ◽  
pp. 295-299 ◽  
Author(s):  
Liang Ma ◽  
Bing Qin ◽  
Chang Qing Zuo
Keyword(s):  
Green Roof ◽  
Environmental Benefits ◽  
Rainfall Runoff ◽  
Retention Performance ◽  
Retention Efficiency ◽  
Drainage Systems ◽  
Urban Green ◽  
Runoff Volume ◽  
Artificial Rainfall

Green roof can significantly reduce runoff volume and delay the duration of rainwater compared to a conventional roof; however there is insufficient research in China regarding rainwater retention performance. In this research, a comparison of a green roof with a conventional roof on rainwater retention is quantified. Results suggest that the specified sedum green roof delays the start and end time of runoff for 3 –13 and 4 –8 minutes. Artificial rainfall runoff retention ranged from 52.86% to 71% for the green roof. On the retention efficiency, potential 3141.77 ×104m3rainwater could be retained by urban green roof in Jinan. The green roof is demonstrated an optional measure to reduce the quantity of rainwater entering already overburdened city drainage systems with great huge economic and environmental benefits.

scholarly journals The dominant runoff processes on grassland versus bare soil hillslopes in a temperate environment - An experimental study

2019 ◽  
Vol 67 (4) ◽  
pp. 297-304 ◽  
Author(s):  
Gabriel Minea ◽  
Gabriela Ioana-Toroimac ◽  
Gabriela Moroşanu
Keyword(s):  
Overland Flow ◽  
Bare Soil ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Rainfall Events ◽  
Natural Rainfall ◽  
Antecedent Precipitation ◽  
Temperate Environment ◽  
The Relationship

Abstract This paper aimed to investigate the dominant runoff processes (DRP’s) at plot-scale in the Curvature Subcarpathians under natural rainfall conditions characteristic for Romania’s temperate environment. The study was based on 32 selected rainfall-runoff events produced during the interval April–September (2014–2017). By comparing water balance on the analyzed Luvisol plots for two types of land use (grassland vs. bare soil), we showed that DRP’s are mostly formed by Hortonian Overland Flow (HOF), 47% vs. 59% respectively. On grassland, HOF is followed by Deep Percolation (DP, 31%) and Fast Subsurface Flow (SSF, 22%), whereas, on bare soil, DP shows a higher percentage (38%) and SSF a lower one (3%), which suggests that the soil-root interface controls the runoff generation. Concerning the relationship between antecedent precipitation and runoff, the study indicated the nonlinearity of the two processes, more obvious on grassland and in drought conditions than on bare soil and in wet conditions (as demonstrated by the higher runoff coefficients). Moreover, the HOF appeared to respond differently to rainfall events on the two plots - slightly longer lag-time, lower discharge and lower volume on grassland - which suggests the hydrologic key role of vegetation in runoff generation processes.

Morphologic and Engineering Characteristics of East Wasit Watersheds Feeding the Al-Shewicha Trough in Iraq

2020 ◽  
Vol 55 (1) ◽  
Author(s):  
Mohammed S. Shamkhi ◽  
Jasim Mohammed Ridha Azee ◽  
Ali A. Abdul-Sahib
Keyword(s):  
Peak Flow ◽  
Flood Hazard ◽  
Bare Soil ◽  
Elongation Ratio ◽  
High Concentration ◽  
Large Area ◽  
Coarse Texture ◽  
Loam Soil ◽  
High Runoff ◽  
Group B

The Al-Shewicha Trough represents a serious flood hazard to Kut City (the capital of Wasit Province, Iraq) and to the other cities along the Tigris River downstream Kut Barrage, especially in heavy monsoon years. In this study, The Geographic Information System software ArcGIS was used in the morphologic analysis of six river basins that represent the main feeding sources for the Al-Shewicha Trough. The results revealed that the high values for the greatest length of Basins 1, 5, and 6 meant that these watersheds had high concentration time (tc) values, which delay peak flow. All basins consisted of very coarse and permeable subsurface strata that were of coarse texture. Circularity ratio form factor and elongation ratio suggested an elongated shape for all basins with lower peak flow and long duration. Analyses of soil data demonstrated that the soil type that covered a large area was loam soil (classified as hydrologic soil group B), which indicates that all basins had low permeability and high runoff. The predominant land use was bare soil, and all basins had a covering of poor vegetation, which highlighted the fact that basins were highly susceptible to erosion, thus resulting in the generation of higher sedimentation.

scholarly journals Effect of tillage, slope, and rainfall on soil surface microtopography quantified by geostatistical and fractal indices during sheet erosion

2020 ◽  
Vol 12 (1) ◽  
pp. 232-241
Author(s):  
Na Ta ◽  
Chutian Zhang ◽  
Hongru Ding ◽  
Qingfeng Zhang
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Soil Surface ◽  
Rainfall Events ◽  
Tillage Practices ◽  
Surface Microtopography ◽  
Artificial Rainfall ◽  
Soil Surface Roughness ◽  
The Difference ◽  
Sheet Erosion

AbstractTillage and slope will influence soil surface roughness that changes during rainfall events. This study tests this effect under controlled conditions quantified by geostatistical and fractal indices. When four commonly adopted tillage practices, namely, artificial backhoe (AB), artificial digging (AD), contour tillage (CT), and linear slope (CK), were prepared on soil surfaces at 2 × 1 × 0.5 m soil pans at 5°, 10°, or 20° slope gradients, artificial rainfall with an intensity of 60 or 90 mm h−1 was applied to it. Measurements of the difference in elevation points of the surface profiles were taken before rainfall and after rainfall events for sheet erosion. Tillage practices had a relationship with fractal indices that the surface treated with CT exhibited the biggest fractal dimension D value, followed by the surfaces AD, AB, and CK. Surfaces under a stronger rainfall tended to have a greater D value. Tillage treatments affected anisotropy differently and the surface CT had the strongest effect on anisotropy, followed by the surfaces AD, AB, and CK. A steeper surface would have less effect on anisotropy. Since the surface CT had the strongest effect on spatial variability or the weakest spatial autocorrelation, it had the smallest effect on runoff and sediment yield. Therefore, tillage CT could make a better tillage practice of conserving water and soil. Simultaneously, changes in semivariogram and fractal parameters for surface roughness were examined and evaluated. Fractal parameter – crossover length l – is more sensitive than fractal dimension D to rainfall action to describe vertical differences in soil surface roughness evolution.

scholarly journals Hillslope Contribution to the Clark Instantaneous Unit Hydrograph: Application to the Seolmacheon Basin, Korea

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1707
Author(s):  
Chulsang Yoo ◽  
Huy Phuong Doan ◽  
Changhyun Jun ◽  
Wooyoung Na
Keyword(s):  
Peak Flow ◽  
Peak Time ◽  
Rainfall Runoff ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Storage Coefficient ◽  
Channel Velocity ◽  
Linear Reservoir ◽  
Mountainous Basin

In this study, the time–area curve of an ellipse is analytically derived by considering flow velocities within both channel and hillslope. The Clark IUH is also derived analytically by solving the continuity equation with the input of the derived time–area curve to the linear reservoir. The derived Clark IUH is then evaluated by application to the Seolmacheon basin, a small mountainous basin in Korea. The findings in this study are summarized as follows. (1) The time–area curve of a basin can more realistically be derived by considering both the channel and hillslope velocities. The role of the hillslope velocity can also be easily confirmed by analyzing the derived time–area curve. (2) The analytically derived Clark IUH shows the relative roles of the hillslope velocity and the storage coefficient. Under the condition that the channel velocity remains unchanged, the hillslope velocity controls the runoff peak flow and the concentration time. On the other hand, the effect of the storage coefficient can be found in the runoff peak flow and peak time, as well as in the falling limb of the runoff hydrograph. These findings are also confirmed in the analysis of rainfall–runoff events of the Seolmacheon basin. (3) The effect of the hillslope velocity varies considerably depending on the rainfall events, which is also found to be mostly dependent upon the maximum rainfall intensity.

COMPUTER ASSISTED MAPPING OF SOIL EROSION POTENTIAL

1985 ◽  
Vol 65 (3) ◽  
pp. 411-418 ◽  
Author(s):  
T. VOLD ◽  
M. W. SONDHEIM ◽  
N. K. NAGPAL
Keyword(s):  
Soil Erosion ◽  
Soil Loss ◽  
Surface Soil ◽  
Mineral Soil ◽  
Weighted Average ◽  
Bare Soil ◽  
Computer Assisted ◽  
Additional Information ◽  
Potential Map ◽  
Fraser Valley

Soil erosion potential maps and summary statistics can be produced from existing information with relative ease with the aid of computers. Soil maps are digitized and survey information is stored as attributes for each soil. Algorithms are then prepared which evaluate the appropriate data base attributes (e.g. texture, slope) for each interpretation. Forty surface soil erosion potential maps were produced for the Lower Fraser Valley which identify the most erosion-prone areas and indicate average potential soil losses to be expected under assumed conditions. The algorithm developed follows the universal soil loss equation. Differences across the landscape in the R, K, and S factors are taken into account whereas the L factor is considered as a constant equal to 1.0. Worst conditions of bare soil (no crop cover, i.e. C = 1.0) and no erosion control practices (i.e. P = 1.0) are assumed. The five surface soil erosion potential classes are determined by a weighted average annual soil loss value based both on the upper 20 cm of mineral soil and on the proportion of the various soils in the polygon. A unique polygon number shown on the erosion potential map provides a link to computer tables which give additional information for each individual soil within that polygon. Key words: Erosion, computer mapping, USLE

Herbicide loss in runoff: effects of herbicide properties, slope, and rainfall intensity

Soil Research ◽  
2004 ◽  
Vol 42 (1) ◽  
pp. 17 ◽  
Author(s):  
K. Müller ◽  
M. Trolove ◽  
T. K. James ◽  
A. Rahman
Keyword(s):  
Rainfall Intensity ◽  
Water Solubility ◽  
Small Scale ◽  
Herbicide Application ◽  
Rainfall Events ◽  
Kd Values ◽  
Loam Soil ◽  
The Impact ◽  
Field Plots ◽  
Dissolved Form

Runoff potential of 5 herbicides (acetochlor, atrazine, hexazinone, pendimethalin, and terbuthylazine) was evaluated in a small-scale study under simulated rainfall on a cultivated Hamilton clay loam soil. At 24 h after herbicide application, rainfall events of different intensities were simulated to 0.5-m2 field plots with 20% (70, 88, and 111 mm/h) and 30% (60, 70, and 80 mm/h) slope, respectively. The objective of this study was to compare the behaviour of pesticides covering a range of properties under identical hydrodynamic conditions. Sediment amounts and herbicide concentrations were determined in the runoff samples. As the transported sediment amounts were not sufficient for chemical analyses, herbicide residues attached to sediment were estimated using Kd values determined locally for the soil. Whereas pendimethalin concentrations followed no noticeable pattern, the concentrations for the other herbicides were highest in the first runoff samples, and decreased exponentially with further rain. Results show that herbicides were primarily transported in their dissolved form with the exception of pendimethalin. Slope affected cumulative runoff, sediment, and herbicide losses significantly (P < 0.05). The impact of increased rainfall intensity on runoff initiation followed a similar trend, but herbicide losses from plots exposed to different intensities were not always significant. Losses dissolved in runoff from plots with 20% slope were ≤1% of the applied herbicide, whereas on plots with 30% slope the maximum recorded loss was 65%. Here, losses for all herbicides ranged between 1 and 7% at 60 mm/h and 8 and 65% at 80 mm/h. Exports of herbicides with moderate solubility were negatively correlated with their Kd values and their water solubility.

scholarly journals Quantitative and qualitative comparison of three wet aggregate stability methods using a long-term tillage system and crop rotation experiment

2018 ◽  
Vol 98 (4) ◽  
pp. 738-742 ◽  
Author(s):  
L.L. Van Eerd ◽  
A.H. DeBruyn ◽  
L. Ouellette ◽  
D.C. Hooker ◽  
D.E. Robinson
Keyword(s):  
Capital Investment ◽  
Surface Soil ◽  
Aggregate Stability ◽  
Clay Loam Soil ◽  
Qualitative Comparison ◽  
No Till ◽  
Tillage System ◽  
Loam Soil ◽  
Wet Aggregate Stability

Automated wet-sieving is preferred for this clay loam soil due to better sensitivity and savings (time and disposables) despite a larger capital investment. Rotations with greater frequency of winter wheat and no-till compared with conventional plow system had greater wet aggregate stability values, indicating better surface soil quality.

scholarly journals Rainfall-runoff relationships at event scale in western Mediterranean ephemeral streams

2021 ◽  
Author(s):  
Roberto Serrano-Notivoli ◽  
Alberto Martínez-Salvador ◽  
Rafael García-Lorenzo ◽  
David Espín-Sánchez ◽  
Carmelo Conesa-García
Keyword(s):  
Western Mediterranean ◽  
Additive Models ◽  
Future Climate Change ◽  
Ephemeral Streams ◽  
Return Periods ◽  
Rainfall Runoff ◽  
Event Scale ◽  
Rainfall Events ◽  
Flow Generation ◽  
Terrain Characteristics

Abstract. Ephemeral streams are highly dependent on rainfall and terrain characteristics and, therefore, very sensitive to minor changes in these environments. Western Mediterranean area exhibits a highly irregular precipitation regime with a great variety of rainfall events driving the flow generation on intermittent watercourses, and future climate change scenarios depict a lower magnitude and higher intensity of precipitation in this area, potentially leading to severe changes in flows. We explored the rainfall-runoff relationships in two semiarid watersheds in southern Spain (Algeciras and Upper Mula) to model the different types of rainfall events required to generate new flow in both intermittent streams. We used a nonlinear approach through Generalized Additive Models at event scale in terms of magnitude, duration, and intensity, contextualizing resulting thresholds in a long-term perspective through the calculation of return periods. Results showed that the average ~ 1.2-day and <1.5 mm event was not enough to create new flows. At least a 4-day event ranging from 4 to 20 mm, depending on the watershed was needed to ensure new flow at a high probability (95 %). While these thresholds represented low return periods (from 4 to 10 years), the great irregularity of annual precipitation and rainfall characteristics, makes prediction highly uncertain. Almost a third part of the rainfall events resulted in similar or lower flow than previous day, emphasizing the importance of lithological and terrain characteristics that lead to differences in flow generation between the watersheds.

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