Home About us Contact
|
Home About us Contact | ||
|
|
||
Runoff Samples (runoff + sample)
Selected AbstractsRUNOFF NUTRIENT AND FECAL COLIFORM CONTENT FROM CATTLE MANURE APPLICATION TO FESCUE PLOTS,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2000D. R. Edwards ABSTRACT: Grazed pastures represent a potential source of non-point pollution. In comparison to other nonpoint sources (e.g., row-cropped lands), relatively little information exists regarding possible magnitudes of pollution from grazed pasture; how that pollution is affected by weather, soil, management and other variables; and how the pollution can be minimized. The objective of this study was to assess how the quality of runoff from fescue plots is influenced by duration of cattle manure application (4,12 weeks) and manure application strategy (none, weekly application of 1.4 kg/plot, and monthly application at 5.6 kg/plot). Additional analyses were performed to relate runoff quality to the timing of sample collection. The study was conducted at the University of Kentucky Maine Chance Agricultural Experiment Station north of Lexington. Plots (2.4 m wide by 6.1 m long) were constructed and established in Kentucky 31 fescue (Festuca arundinacea Schreb.) to represent pasture. Grazing was simulated by application of beef cattle manure to the plots. Runoff was generated by applying simulated rainfall approximately 4, S and 12 weeks following initiation of manure application. Runoff samples were collected and analyzed according to standard methods for nitrogen (N), phosphorus (P) and fecal coliforms (FC). Runoff concentrations of N and P from manure-treated plots were low and generally not consistently different from control plot concentrations or related to manure application strategy. Runoff FC concentrations from manure-treated plots were higher than from control plot concentrations. Runoff concentrations of ammonia N, total Kjeldahl N, ortho-P and FC decreased approximately exponentially in response to increasing time of sample collection. These findings suggest that manure deposition on well-managed pasture at the rates used in this study might have a negligible impact on nutrient content of runoff. [source] Effects of field reorganisation on the spatial variability of runoff and erosion rates in vineyards of Northeastern SpainLAND DEGRADATION AND DEVELOPMENT, Issue 1 2010M. C. Ramos Abstract This study analyses the spatial variability of runoff and erosion rates in vineyards due to mechanisation works. Runoff samples were collected at three positions in two plots after 33 erosive events in three years (2001, 2003, 2004) with different rainfall patterns. Three replications were considered at each position. Soil properties were evaluated in order to analyse its relationship with runoff and erosion rates. Runoff and erosion rates were, on average, higher in the levelled plot (HD), ranging between 8·4 and 34·3 per cent, than in the non-levelled plot (LD) ranging between 8·2 and 24·1 per cent. Mean sediment concentration in runoff ranged between 6 and 8,g,L,1 in the HD plot and about 4·6,g,L,1 in the LD plot, but with high differences within the plot. In the HD plot, runoff-rainfall rates were significantly higher (at 95 per cent level) in the upper part of the slope and decreased along the slope, while in the LD plot, differences in runoff rates were not significant and similar to those observed in the less disturbed areas of the HD plot. The higher susceptibility to soil sealing in areas where the original topsoil was removed conditioned runoff rates. In the lower part of the HD plot runoff rates were, on average, 20 per cent lower than in the upper part of the slope. In those positions runoff rates up to 79 per cent were recorded. Organic matter content and water retention capacity at different potentials are the soil characteristics related to the differences on runoff and erosion rates in the resulting soils. Copyright © 2009 John Wiley & Sons, Ltd. [source] Wind effects on sediment transport by raindrop-impacted shallow flow: a wind-tunnel studyEARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2004G. Erpul Abstract In wind-driven rains, wind velocity and direction are expected to affect not only energy input of rains but also shallow ,ow hydraulics by changing roughness induced by raindrop impacts with an angle on ,ow and the unidirectional splashes in the wind direction. A wind-tunnel study under wind-driven rains was conducted to determine the effects of horizontal wind velocity and direction on sediment transport by the raindrop-impacted shallow ,ow. Windless rains and the rains driven by horizontal wind velocities of 6 m s,1, 10 m s,1, and 14 m s,1 were applied to three agricultural soils packed into a 20 by 55 cm soil pan placed on both windward and leeward slopes of 7 per cent, 15 per cent, and 20 per cent. During each rainfall application, sediment and runoff samples were collected at 5-min intervals at the bottom edge of the soil pan with wide-mouth bottles and were determined gravimetrically. Based on the interrill erosion mechanics, kinetic energy ,ux (Ern) as a rainfall parameter and product of unit discharge and slope in the form of qbSco as a ,ow parameter were used to explain the interactions between impact and ,ow parameters and sediment transport (qs). The differential sediment transport rates occurred depending on the variation in raindrop trajectory and rain intensity with the wind velocity and direction. Flux of rain energy computed by combining the effects of wind on the velocity, frequency, and angle of raindrop impact reasonably explained the characteristics of wind-driven rains and acceptably accounted for the differences in sediment delivery rates to the shallow ,ow transport (R2 , 0·78). Further analysis of the Pearson correlation coef,cients between Ern and qSo and qs also showed that wind velocity and direction signi,cantly affected the hydraulics of the shallow ,ow. Ern had a smaller correlation coef,cient with the qs in windward slopes where not only reverse splashes but also reverse lateral raindrop stress with respect to the shallow ,ow direction occurred. However, Ern was as much effective as qSo in the sediment transport in the leeward slopes where advance splashes and advance lateral raindrop stress on the ,ow occurred. Copyright © 2004 John Wiley & Sons, Ltd. [source] Organophosphorus pesticides in storm-water runoff from southern California (USA)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2004Kenneth Schiff Abstract Large quantities of the organophosphorus (OP) pesticides diazinon and chlorpyrifos are applied to California (USA) watersheds every year, but few data are available on the sources of OP pesticides in urban watersheds. The goal of this study was to characterize diazinon and chlorpyrifos concentrations from different land uses indicative of source categories in urban southern California watersheds. This characterization included analysis of 128 runoff samples from eight different land uses over five storm events. Diazinon was consistently detected (93% of samples) during this study, whereas chlorpyrifos was not consistently detected (12% of samples). The mixed agricultural land use had the highest flow weighted mean (FWM) concentration of diazinon (4,076 ng/L), which exceeded the next-highest land-use categories (commercial and residential) by one to two orders of magnitude (324,99 ng/L, respectively). Open space had the lowest concentration of diazinon (<20 ng/L). Concentrations of diazinon at replicate land-use sites and during replicate storm events at the same site were highly variable. The difference in diazinon FWM concentrations among replicate sites ranged from 1.5-fold to 45-fold. The difference in diazinon FWM concentrations among storms at the same site ranged from 1.25-fold to 30-fold. Part of this variability is a response to the temporal patterns observed within a storm event. The majority of land-use site-events had peak concentrations before peak flow indicating a first-flush effect, but this was not always a predictable temporal trend. The first-flush effect was rarely evident in terms of mass loadings because flows can range orders of magnitude during a single event in highly impervious urban watersheds. Flow variability thus overwhelms the variability in diazinon concentrations attributable to the first-flush effect. [source] Modified passive capillary samplers for collecting samples of snowmelt infiltration for stable isotope analysis in remote, seasonally inaccessible watersheds 1: laboratory evaluationHYDROLOGICAL PROCESSES, Issue 7 2010Marty D. Frisbee Abstract Snowmelt is the most significant source of runoff generation and recharge in many of the mountainous watersheds worldwide and this is especially true in the southwestern United States. Yet, the isotopic and geochemical composition of the soil,meltwater endmember remains poorly constrained. Using the isotopic compositions of snow and snowmelt runoff samples taken from the landscape surface as proxies for soil,meltwater endmembers is problematic since they are typically not representative of the actual composition of soil meltwater. Furthermore, the applicability of current methodologies to collect the isotopic composition of meltwater is limited because of the remote and often seasonally inaccessible nature of the terrain where snowpacks develop. Therefore, a robust methodology requiring little maintenance or monitoring is desirable. A lab experiment was conducted to determine the suitability of using a modified passive capillary sampler (M-PCAPS) design to collect snowmelt infiltration for isotopic analysis. Passive capillary samplers are constructed from fiberglass wicks that can be installed in the soil to sample vadose-zone waters under a wide range of matric potentials and require little maintenance. Results from this lab experiment indicate that the wicking process associated with M-PCAPS does not fractionate water but certain precautions are necessary to prevent exchange between the wick and the atmosphere. In this experiment, M-PCAPS effectively tracked the changing isotopic composition of a soil reservoir undergoing evaporation. Therefore, M-PCAPS provide a robust methodology to sample the isotopic composition of snowmelt infiltration in remote watersheds and similar applications. Copyright © 2009 John Wiley & Sons, Ltd. [source] Simulated rainfall evaluation of revegetation/mulch erosion control in the Lake Tahoe Basin,1: method assessmentLAND DEGRADATION AND DEVELOPMENT, Issue 6 2004M. E. Grismer Abstract Revegetation of road cuts and fills is intended to stabilize those drastically disturbed areas so that sediment is not transported to adjacent waterways. Sediment has resulted in water quality degradation, an extremely critical issue in the Lake Tahoe Basin. Many revegetation efforts in this semiarid, subalpine environment have resulted in low levels of plant cover, thus failing to meet project goals. Further, no adequate physical method of assessing project effectiveness has been developed, relative to runoff or sediment movement. This paper describes the use of a portable rainfall simulator (RS) to conduct a preliminary assessment of the effectiveness of a variety of erosion-control treatments and treatment effects on hydrologic parameters and erosion. The particular goal of this paper is to determine whether the RS method can measure revegetation treatment effects on infiltration and erosion. The RS-plot studies were used to determine slope, cover (mulch and vegetation) and surface roughness effects on infiltration, runoff and erosion rates at several roadcuts across the basin. A rainfall rate of ,60,mm,h,1, approximating the 100-yr, 15-min design storm, was applied over replicated 0·64,m2 plots in each treatment type and over bare-soil plots for comparison. Simulated rainfall had a mean drop size of ,2·1,mm and approximately 70% of ,natural' kinetic energy. Measured parameters included time to runoff, infiltration, runoff/infiltration rate, sediment discharge rate and average sediment concentration as well as analysis of total Kjeldahl nitrogen (TKN) and dissolved phosphorus (TDP) from filtered (0·45,,m) runoff samples. Runoff rates, sediment concentrations and yields were greater from volcanic soils as compared to that from granitic soils for nearly all cover conditions. For example, bare soil sediment yields from volcanic soils ranged from 2,12 as compared to 0·3,3,g,m,2,mm,1 for granitic soils. Pine-needle mulch cover treatments substantially reduced sediment yields from all plots. Plot microtopography or roughness and cross-slope had no effect on sediment concentrations in runoff or sediment yield. RS measurements showed discernible differences in runoff, infiltration, and sediment yields between treatments. Runoff nutrient concentrations were not distinguishable from that in the rainwater used. Copyright © 2004 John Wiley & Sons, Ltd. [source] Runoff transport of faecal coliforms and phosphorus released from manure in grass buffer conditionsLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2005W.L. Stout Abstract Aims:, To test the hypothesis that faecal coliform (FC) and phosphorus (P) are transported similarly in surface runoff through the vegetative filter strip after being released from land-applied manure. Methods and Results:, The Hagerstown soil was packed into boxes that were 10 cm deep, 30 cm wide and 100, 200 or 300 cm long. Grass was grown in boxes prior experiments. Same-length boxes were placed under rainfall simulator and tilted to have with either 2% or 4% slopes. Dairy manure was broadcast on the upper 30-cm section. Rainfall was simulated and runoff samples were collected and analysed for Cl, FC and total phosphorus (TP). Mass recovery, the concentration decrease rate k, and the ratio FC : TP showed that there was a consistent relationship between FC and TP in runoff. Conclusion:, The FC and TP transport through simulated vegetated buffer strips were highly correlated. Significance and Impact of the Study:, As a knowledge base on the effect of the environmental parameters on P transport in vegetated buffer strips is substantially larger than for manure-borne bacteria, the observed similarity may enhance ability to assess the efficiency of the vegetated buffer strips in retention of FC currently used as indicator organisms for manure-borne pathogens. [source] | ||||||||||||||||