Rainfall-runoff processes and modelling

O'Loughlin, Geoffrey; Huber, Wayne C.; Chocat, Bernard

doi:10.1080/00221689609498447

Cited by 52 publications

(25 citation statements)

References 10 publications

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“…Further, for njn = 1/40 and C t /C p = 10, the time of concentration of the urbanized plane was only 4% of that of the rural plane. This result is in fact consistent with the generally perceived maximum decrease in lag time due to urbanization (O'Loughlin et al, 1996). …”

Section: Combined Effect Of Manning Resistance Coefficient and Runoffsupporting

confidence: 80%

Assessment of changes in overland time of concentration for two opposing urbanization sequences

Wong

1998

Hydrological Sciences Journal

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By considering the urbanization process on an overland plane whereby a relatively rough permeable surface is replaced by a relatively smooth impermeable surface, the effect of urbanization on the time of concentration is assessed. In the assessment, two opposing urbanization sequences are considered: one from downstream to upstream, and the other from upstream to downstream. The assessment is carried out in terms of the individual effect as well as the combined effect of the Manning resistance coefficient and the runoff coefficient. For both urbanization sequences and for all degrees of urbanization, the assessment shows that surface conversion from rough to smooth or from permeable to impermeable causes the time of concentration to be shorter. Urbanization at the upstream end causes the greatest decrease in the time of concentration, and the reduction in surface roughness causes a greater decrease in time of concentration as compared to the reduction in permeability. Depending on the pre-and post-urbanization land surface conditions, the assessment shows that the time of concentration could decrease to 4-39% of its original value. Moreover, the time of concentration for a plane with urbanization from downstream to upstream could be more than four times longer than that for a plane with urbanization from upstream to downstream. Finally, there is a remarkable resemblance between the results of this study with those obtained from drainage basins in earlier studies, and it appears that the results from earlier studies are only applicable for the upstream to downstream urbanization sequence. Evaluation de la modification du temps de concentration pour deux scénarios d'urbanisationRésumé Nous avons étudié les effets de l'urbanisation sur le temps de concentration d'une étendue plane où une surface imperméable relativement lisse se substitue à une surface perméable relativement rugueuse. Deux scénarios d'urbanisation contrastés ont été considérés : l'un allant de l'aval vers l'amont, l'autre de l'amont vers l'aval. L'évaluation a porté aussi bien sur les processus élémentaires que sur l'effet combiné du coefficient de résistance de Manning et du coefficient de ruissellement. Pour les deux scénarios d'urbanisation et pour tous les niveaux d'urbanisation, l'évaluation montre que la substitution d'une surface lisse à une surface rugueuse ou d'une surface imperméable à une surface perméable entraine une diminution du temps de concentration. L'urbanisation en amont entraine la diminution du temps de concentration la plus importante et la diminution de la rugosité a des effets plus prononcés que la diminution de la perméabilité. En fonction de l'état de surface avant et après l'urbanisation, l'évaluation montre que le temps de concentration peut descendre jusqu'à 39 voire 4% de sa valeur originelle. Dans le cas d'une urbanisation d'aval en amont, le temps de concentration peut être jusqu'à quatre fois plus long que dans le cas d'une urbanisation d'amont en aval. Il y a en définitive une analogie remarquable entre l...

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Section: Combined Effect Of Manning Resistance Coefficient and Runoffsupporting

confidence: 80%

Assessment of changes in overland time of concentration for two opposing urbanization sequences

Wong

1998

Hydrological Sciences Journal

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“…A spreadsheet model based on the rational method (O'Loughlin et al 1996) was used to generate freshwater runoff Q (m 3 d 21 ) and the N loads associated with wetweather events. Modeled storm discharge (Q) was calculated as a function of drainage area (A, km 2 ), mean rainfall intensity (I, mm d 21 ), hydraulic runoff coefficient (C), and conversion constant (k):…”

Section: Methodsmentioning

confidence: 99%

Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight

Howard

Sutula

Caron

et al. 2014

Limnology & Oceanography

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Anthropogenic nutrients have been shown to provide significant sources of nitrogen (N) that have been linked to increased primary production and harmful algal blooms worldwide. There is a general perception that in upwelling regions, the flux of anthropogenic nutrient inputs is small relative to upwelling flux, and therefore anthropogenic inputs have relatively little effect on the productivity of coastal waters. To test the hypothesis that natural sources (e.g., upwelling) greatly exceed anthropogenic nutrient sources to the Southern California Bight (SCB), this study compared the source contributions of N from four major nutrient sources: (1) upwelling, (2) treated wastewater effluent discharged to ocean outfalls, (3) riverine runoff, and (4) atmospheric deposition. This comparison was made using large regional data sets combined with modeling on both regional and local scales. At the regional bight-wide spatial scale, upwelling was the largest source of N by an order of magnitude to effluent and two orders of magnitude to riverine runoff. However, at smaller spatial scales, more relevant to algal bloom development, natural and anthropogenic contributions were equivalent. In particular, wastewater effluent and upwelling contributed the same quantity of N in several subregions of the SCB. These findings contradict the currently held perception that in upwelling-dominated regions anthropogenic nutrient inputs are negligible, and suggest that anthropogenic nutrients, mainly wastewater effluent, can provide a significant source of nitrogen for nearshore productivity in Southern California coastal waters.

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“…The spatial variability of rainfall is often identified as the major source of error in investigations of rainfall-runoff processes and hydrological modelling (O'Loughlin et al, 1996;Syed et al, 2003). Especially for smaller catchments and for runoff processes that respond directly to precipitation detailed rainfall information is necessary (Woods et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Significance of spatial variability in precipitation for process-oriented modelling: results from two nested catchments using radar and ground station data

Tetzlaff

Uhlenbrook

2005

Hydrol. Earth Syst. Sci.

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Abstract. The importance of considering the spatial distribution of rainfall for process-oriented hydrological modelling is well-known. However, the application of rainfall radar data to provide such detailed spatial resolution is still under debate. In this study the process-oriented TAC D (Tracer Aided Catchment model, Distributed) model had been used to investigate the effects of different spatially distributed rainfall input on simulated discharge and runoff components on an event base. TAC D is fully distributed (50×50 m 2 raster cells) and was applied on an hourly base. As model input rainfall data from up to 7 ground stations and high resolution rainfall radar data from operational C-band radar were used. For seven rainfall events the discharge simulations were investigated in further detail for the mountainous Brugga catchment (40 km 2 ) and the St. Wilhelmer Talbach (15.2 km 2 ) sub-basin, which are located in the Southern Black Forest Mountains, south-west Germany. The significance of spatial variable precipitation data was clearly demonstrated. Dependent on event characteristics, localized rain cells were occasionally poorly captured even by a dense ground station network, and this resulted in inadequate model results. For such events, radar data can provide better input data. However, an extensive data adjustment using ground station data is required. For this purpose a method was developed that considers the temporal variability in rainfall intensity in high temporal resolution in combination with the total rainfall amount of both data sets. The use of the distributed catchment model allowed further insights into spatially variable impacts of different rainfall estimates. Impacts for discharge predictions are the largest in areas that are dominated by the production of fast runoff components. The improvements for distributed Correspondence to: D. Tetzlaff (d.tetzlaff@abdn.ac.uk) runoff simulation using high resolution rainfall radar input data are strongly dependent on the investigated scale, the event characteristics and the existing monitoring network.

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Rainfall-runoff processes and modelling

Cited by 52 publications

References 10 publications

Assessment of changes in overland time of concentration for two opposing urbanization sequences

Assessment of changes in overland time of concentration for two opposing urbanization sequences

Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight

Significance of spatial variability in precipitation for process-oriented modelling: results from two nested catchments using radar and ground station data

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