Estimation of annual pollutant loadings in two small catchments and examination of their differences caused by regional properties

2006 ◽  
Vol 53 (2) ◽  
pp. 33-44 ◽  
Author(s):  
S. Fujii ◽  
M. Moriya ◽  
P. Songprasert ◽  
H. Ihara
Keyword(s):  
River Basin ◽  
High Frequency ◽  
Storm Event ◽  
Precipitation Pattern ◽  
Storm Events ◽  
Rainfall Events ◽  
Survey Results ◽  
One Year ◽  
Small Catchments

A series of runoff surveys was conducted for more than one year in two small catchments of the Kamo River basin (75.4 km2) and the Takano River basin (66.8 km2) in Kyoto, Japan, which adjoin each other, and may have the same precipitation pattern. The investigation consisted of a high-frequency periodic survey, a long-term regular survey and a storm event survey. The survey results were compared with the regional properties of the basins, and the following results were obtained. (1) Pollutant loadings were successfully estimated as two portions of base discharge and storm events discharge from the survey results. (2) Estimated annual loading of the sites was 2.9–4.5, 1.3–1.8, 17–27, 1.3–2.2, 0.076–0.97 t/km2/y, respectively for CODMn, DOC, SS, TN and TP. (3) 52–53% of the whole flow, which was caused by rainfall events, conveyed 81–87, 68–73, 92–95, 64–67, 76–81% of the whole loading, respectively for CODMn, DOC, SS, TN and TP. (4) Differences of regional properties in two basins cause different runoff patterns, but the differences in runoff patterns also depend on the rainfall patterns. In general, a more urbanized basin receives early and strong influence of precipitation on the storm event runoff.

Assessing characteristic time and space scales of in-sewer processes by analysis of one year of continuous in-sewer monitoring data

2012 ◽  
Vol 66 (8) ◽  
pp. 1614-1620 ◽  
Author(s):  
R. P. S. Schilperoort ◽  
J. Dirksen ◽  
J. G. Langeveld ◽  
F. H. L. R. Clemens
Keyword(s):  
High Frequency ◽  
Peak Load ◽  
Storm Events ◽  
Pollutant Concentrations ◽  
Load Factors ◽  
Wet Weather ◽  
Using Data ◽  
One Year ◽  
Dry Weather Flow

Long-term and high-frequency in-sewer monitoring opens up a broad range of possibilities to study (influences on) water quantity and quality variations. Using data from the Eindhoven wastewater system in The Netherlands both dry weather flow and wet weather flow situations have been studied. For approximately 160 dry weather days mean diurnal variations of flow and pollutant concentrations have been derived. For wet weather situations (≈ 40 storm events) peak load factors have been studied. Generally, peak load factors for all considered pollutant parameters are larger than one. Peak load factors for particulate matter are larger than for dissolved constituents. Also, the smallest catchment area consistently shows the largest mean peak factors and vice versa.

scholarly journals Contemporary Sediment Delivery Ratios for Small Catchments Subject to Shallow Rainfall Triggered Earthflows in the Waipaoa Catchment, North Island, New Zealand

2021 ◽  
Author(s):  
◽  
Katie Elizabeth Jones
Keyword(s):  
River Mouth ◽  
Storm Event ◽  
Delivery Ratio ◽  
Storm Events ◽  
Spatial And Temporal Patterns ◽  
Channel Coupling ◽  
Sediment Delivery ◽  
Catchment Size ◽  
Fluvial Network ◽  
Small Catchments

<p>The Waipaoa catchment is generally considered to have high hill slope channel coupling due to the large volumes of sediment output at the river mouth. Yet the percentage of sediment that is transported within the fluvial system is low when considered in terms of the total volume of sediment mobilised during episodic failure events. Clearly, there is a discrepancy between generation of sediment and its delivery to the fluvial network. Previous research has suggested there is a strong decrease in catchment connectivity as catchment size increases. However, little research has been undertaken to understand the changes in hillslope-channel coupling over time. This study focuses on the connectivity of shallow rainfall triggered earthflows located in small catchments located within three different land systems in the Waipaoa Catchment. A multiple regression model was developed to predict the sediment delivery ratio for individual earthflows based on an empirical dataset of earthflows which occurred during a storm event in 2002. The results from this modelling were applied to five larger sub-catchments where sequential aerial photograph analysis (1940s to 2004) was used to determine connectivity. From this, spatial and temporal patterns in the catchment sediment delivery ratios were identified. The expected decrease in sediment delivery ratios was observed as catchment size increased. However, the temporal pattern to sediment delivery is not so clear. It appears that catchment evolution, referring specially to the Terrain Event Resistance Model developed by Crozier and Preston (1999), does not have a significant influence on sediment delivery ratios within the six decades examined in this thesis. Furthermore, while earthflows are considered the ultimate source of sediment during storm events, they are not always the mechanism by which this sediment enters the fluvial network. It is also vital to consider rates of gullying, sheet erosion and riparian erosion.</p>

Subglottic haemangioma in the infant: contribution by CO2 laser

1989 ◽  
Vol 103 (10) ◽  
pp. 930-934 ◽  
Author(s):  
M. Remacle ◽  
X. Declaye ◽  
A. Mayne
Keyword(s):  
High Frequency ◽  
Considerable Improvement ◽  
Jet Ventilation ◽  
Prolonged Intubation ◽  
High Frequency Jet Ventilation ◽  
Low Intensity ◽  
One Year ◽  
Subglottic Haemangioma ◽  
Spontaneous Evolution

AbstractThe availability of the low intensity CO2 laser beam, and the possibility of defocalization that is associated with control of subglottic high frequency jet ventilation, requires a more interventionist attitude regarding dyspnoea caused by a subglottic haemangioma in the infant. It is indeed possible reliably to reduce the size of the subglottic haemangioma, and thus to avoid a lengthy period of intensive care, as well as the problems of prolonged intubation or tracheostomy for drainage, while also avoiding long term steroid therapy. This approach in no way affects the spontaneous evolution of subglottic haemangioma in the infant; there is a tendency for the haemangioma to regress after the age of one year. The treatment does, however, permit a considerable improvement in the comfort of the infant's life during this difficult period between 3 and 12 months.We illustrate this new attitude by presenting a report on four cases.

scholarly journals Contemporary Sediment Delivery Ratios for Small Catchments Subject to Shallow Rainfall Triggered Earthflows in the Waipaoa Catchment, North Island, New Zealand

2021 ◽  
Author(s):  
◽  
Katie Elizabeth Jones
Keyword(s):  
River Mouth ◽  
Storm Event ◽  
Delivery Ratio ◽  
Storm Events ◽  
Spatial And Temporal Patterns ◽  
Channel Coupling ◽  
Sediment Delivery ◽  
Catchment Size ◽  
Fluvial Network ◽  
Small Catchments

<p>The Waipaoa catchment is generally considered to have high hill slope channel coupling due to the large volumes of sediment output at the river mouth. Yet the percentage of sediment that is transported within the fluvial system is low when considered in terms of the total volume of sediment mobilised during episodic failure events. Clearly, there is a discrepancy between generation of sediment and its delivery to the fluvial network. Previous research has suggested there is a strong decrease in catchment connectivity as catchment size increases. However, little research has been undertaken to understand the changes in hillslope-channel coupling over time. This study focuses on the connectivity of shallow rainfall triggered earthflows located in small catchments located within three different land systems in the Waipaoa Catchment. A multiple regression model was developed to predict the sediment delivery ratio for individual earthflows based on an empirical dataset of earthflows which occurred during a storm event in 2002. The results from this modelling were applied to five larger sub-catchments where sequential aerial photograph analysis (1940s to 2004) was used to determine connectivity. From this, spatial and temporal patterns in the catchment sediment delivery ratios were identified. The expected decrease in sediment delivery ratios was observed as catchment size increased. However, the temporal pattern to sediment delivery is not so clear. It appears that catchment evolution, referring specially to the Terrain Event Resistance Model developed by Crozier and Preston (1999), does not have a significant influence on sediment delivery ratios within the six decades examined in this thesis. Furthermore, while earthflows are considered the ultimate source of sediment during storm events, they are not always the mechanism by which this sediment enters the fluvial network. It is also vital to consider rates of gullying, sheet erosion and riparian erosion.</p>

scholarly journals LONGSHORE TRANSPORT AND SEDIMENTATION IN A NAVIGATION CHANNEL AT BLANKENBERGE (BELGIUM)

2012 ◽  
Vol 1 (33) ◽  
pp. 111 ◽  
Author(s):  
Nicolas Zimmermann ◽  
Koen Trouw ◽  
Li Wang ◽  
Mieke Mathys ◽  
Rosalia Delgado ◽  
...  
Keyword(s):  
Wave Climate ◽  
Storm Events ◽  
Climate History ◽  
Longshore Transport ◽  
Navigation Channel ◽  
Morphological Modelling ◽  
One Year ◽  
Modelling Methods ◽  
Total Sediment

The harbour of Blankenberge in Belgium experiences strong sedimentation in its entrance channel requiring frequent dredging. In order to investigate under which conditions this sedimentation is the most pronounced, the instationary coastal model XBeach is used. This paper presents results of long-term morphology modelling of channel sedimentation after applying a specific methodology for input reduction. A reduced time series representative of the annual wind-wave climate is run in combination with a representative tide and a constant morphological acceleration factor (morfac) to cover one year of erosion-sedimentation. While this approach does come with side effects, it has the important advantage to be easy to implement and to preserve part of the climate history compared to other approaches such as MorMerge and a time-varying morfac approach (described in the paper). With this approach and default settings, XBeach is shown to reproduce both qualitatively and quantitatively well the measured sedimentation. Results show that tide, wind and waves all contribute significantly to the total sediment transport, and that both continuous transport and individual storm events cause strong sedimentation. Some aspects of morphological modelling methodologies are discussed, relative to the calibration, input reduction and long-term modelling methods.

scholarly journals Storm pulses of particulate and dissolved organic carbon in a forested headwater stream and their environmental implications – importance of extreme rainfall events

2014 ◽  
Vol 11 (5) ◽  
pp. 6877-6908 ◽  
Author(s):  
B.-J. Jung ◽  
J.-K. Lee ◽  
H. Kim ◽  
J.-H. Park
Keyword(s):  
Organic Carbon ◽  
Extreme Rainfall ◽  
Headwater Stream ◽  
Storm Event ◽  
Extreme Rainfall Event ◽  
Storm Events ◽  
Environmental Implications ◽  
Extreme Rainfall Events ◽  
Organic C ◽  
Rainfall Events

Abstract. Despite recent debates on erosion-enhanced sinks of CO2 and contrasting findings on the biodegradation of recalcitrant organic materials in large rivers, little attention has been paid to the export and transformations of particulate organic carbon (POC) and dissolved organic C (DOC) in mountainous headwater watersheds under monsoon climates. To comparatively evaluate the significance of heavy monsoon rainfalls for the magnitude and environmental implications of storm-enhanced export of POC and DOC, the relationships between storm magnitude and C export were examined in a mountainous, forested headwater stream in the Haean Basin, South Korea, during 50 storm events over the 4 year monitoring period. We also compared biodegradation and disinfection byproduct (DBP) formation potentials of the DOC and POC exported during an extreme rainfall event. Event mean concentrations and export of POC increased nonlinearly above thresholds of precipitation and discharge, significantly exceeding the increases of DOC. The export of POC during a few storm events with a total rainfall above 200 mm per event exceeded the annual organic C export during dry years. During the large storm event (209 mm), concentrations of total trihalomethanes formed by POC-derived dissolved components changed synchronously with POC concentrations, exhibiting lower levels than those formed by DOC. During a 30 day incubation at 25 °C, both DOC and POC exported during peak flow initially exhibited rapid biodegradation of labile components, whereas POC-derived materials increased continuously not only DOC concentrations, but also fulvic- and humic-like fluorescent components. These results highlight the significance of extreme rainfall events as "hot moments" for POC export and also suggest that storm pulses of POC can provide potential sources of labile DOC components that can rapidly biodegrade and form DBPs in headwater streams, contrasting with other studies assuming mountainous rivers as a passive conduit of organic C.

scholarly journals A Landslide Probability Model Based on a Long-Term Landslide Inventory and Rainfall Factors

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 937 ◽  
Author(s):  
Chun-Yi Wu ◽  
Yen-Chu Yeh
Keyword(s):  
Large Scale ◽  
Probability Model ◽  
Threshold Value ◽  
Rain Gauge ◽  
Landslide Inventory ◽  
Exceedance Probability ◽  
Probability Models ◽  
Rainfall Events ◽  
One Year

The prediction and advanced warning of landslide hazards in large-scale areas must deal with a large amount of uncertainty, therefore a growing number of studies are using stochastic models to analyze the probability of landslide occurrences. In this study, we used a modified Thiessen’s polygon method to divide the research area into several rain gauge control areas, and divided the control areas into slope units reflecting the topographic characteristics to enhance the spatial resolution of a landslide probability model. We used a 2000–2015 long-term landslide inventory, daily rainfall, and effective accumulated rainfall to estimate the rainfall threshold that can trigger landslides. We then employed a Poisson probability model and historical rainfall data from 1987 to 2016 to calculate the exceedance probability that rainfall events will exceed the threshold value. We calculated the number of landslides occurring from the events when rainfall exceeds the threshold value in the slope units to estimate the probability that a landslide will occur in this situation. Lastly, we employed the concept of conditional probability by multiplying this probability with the exceedance probability of rainfall events exceeding the threshold value, which yielded the probability that a landslide will occur in each slope unit for one year. The results indicated the slope units with high probability that at least one rainfall event will exceed the threshold value at the same time that one landslide will occur within any one year are largely located in the southwestern part of the Taipei Water Source Domain, and the highest probability is 0.26. These slope units are located in parts of the study area with relatively weak lithology, high elevations, and steep slopes. Compared with probability models based solely on landslide inventories, our proposed landslide probability model, combined with a long-term landslide inventory and rainfall factors, can avoid problems resulting from an incomplete landslide inventory, and can also be used to estimate landslide occurrence probability based on future potential changes in rainfall.

scholarly journals Review on uncertainty of the first-flush phenomenon in diffuse pollution control

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Abdullah Al Mamun ◽  
Shahriar Shams ◽  
Md. Nuruzzaman
Keyword(s):  
Best Management Practices ◽  
Management Practices ◽  
Nonpoint Source ◽  
Diffuse Pollution ◽  
Storm Runoff ◽  
Storm Event ◽  
First Flush ◽  
Storm Events ◽  
Treatment Facility ◽  
Small Catchments

AbstractSeveral definitions and criteria of the first-flush are being used to assess and control the nonpoint source (diffuse) pollution. The common consensus is that the first-flush is generally noticed in the small catchments (e.g. < 10 ha) of regular shapes. It is also considered that 80% of the pollution load can be captured by capturing 30% of the runoff volume, which is assumed to be due to first-flush of the storm event. However, such phenomenon is uncertain in the considerably large catchments, principally due to the dilution and delay in transport of the pollutant. This paper critically examines the ‘first-flush’ phenomenon in controlling diffuse pollution based on various studies conducted by the researchers. Based on the review, it can be inferred that the first-flush may be an effective criterion for sizing on-site treatment facilities for small catchments (with similar dimensions of length and width), from where the runoff is expected to reach the treatment facility (roughly) at the same time. However, for the large and elongated catchments with an area covering more than 10 ha, a huge volume of storm runoff needs to be captured that would make the treatment system large or less effective. As such, for the community and regional facilities; the presence of the first-flush needs to be confirmed based on the sampling and analysis of data collected from several storm events of different durations and intensities. Therefore, the use of the first-flush phenomenon should not be applied for the design of storm runoff treatment facility in large drainage system (say > 10 ha) without on-site monitoring being conducted. However, it is also recommended to come up with a simplistic approach of designing the best management practices (BMPs) to capture and treat certain depth of the initial storm runoff (e.g. first 20 mm), which will help reduce the effect of nonpoint source (NPS) pollution.

Runoff characteristics of highway pollutants based on a long-term survey through a year

2008 ◽  
Vol 57 (11) ◽  
pp. 1769-1776 ◽  
Author(s):  
A. Ichiki ◽  
F. Ido ◽  
T. Minami
Keyword(s):  
Aromatic Hydrocarbons ◽  
Basic Unit ◽  
Water Sampling ◽  
Storm Events ◽  
Chemical Substances ◽  
Polycyclic Aromatic ◽  
One Year ◽  
Pollutant Runoff ◽  
Long Term Survey

Highway pollutants generated mainly from traffics are repeating accumulation, raise, drift and move on the highways. Some of them are removed by road cleanings done regularly, the others are flushed by stormwater into receiving water. The objectives of this study are to survey characteristics of the highway pollutants, and to quantify their behavior on the highways. The study area is a part of Meishin Expressway running through the main island of Japan. Surveys on pollutant runoff from the highway were done for all storm events through one year from December 2004 to November 2005. For the surveys, samples were collected by continuous water sampling during storm events. And chemical substances in each sample such as SS, TOC, TN, TP, heavy metals and polycyclic aromatic hydrocarbons (PAHs) for each class of particle size were measured. Using the results of the survey, characteristics of pollutant runoff during storm events were examined. And it cleared the basic unit loads for the highway pollutants throughout a year. As a result, some significant knowledge for the environmental management of highway pollution has been obtained.

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