A NEW PROCEDURE ALLOWING REPLICATED MINIATURE LARVICIDE TESTS IN A LARGE RIVER

1969 ◽  
Vol 101 (7) ◽  
pp. 713-725 ◽  
Author(s):  
F. J. H. Fredeen
Keyword(s):  
Fresh Water ◽  
River Discharge ◽  
Aquatic Invertebrates ◽  
River Pollution ◽  
Large River ◽  
Special Equipment ◽  
Recovery Rates ◽  
Combining Data ◽  
Concentrated Milk ◽  
St Lawrence River

AbstractDDT and DDD emulsifiable formulations were tested against aquatic invertebrates in small plots in rapids in the St. Lawrence River. Pollution was minimal; less than 0.0044% of the river discharge was treated in each rest.The weakest dosage of DDD, 0.8 p.p.m.-minutes, disabled many Trichoptera and Diptera; the strongest, 12.0 p.p.m.-minutes, did not eliminate any one Order of insects except perhaps Plecoptera. A dosage of 6.0 p.p.m.-minutes was selected for tests on a larger scale against shadfly larvae (mainly Trichoptera). Net-spinning Trichoptera were more sensitive than case-bearers. Of the non-insect organisms, amphipods were relatively sensitive but their populations were rapidly restored by immigration. Oligochaetes and molluscs were least affected.The use of small plots in a large river required special equipment and techniques: a larvicide dispenser (to be described separately), the use of concentrated milk as a dye to aid in the survey of plot boundaries, the transfer of disabled organisms to fresh water to compare recovery rates, and a formula combining data from samples of both disabled and surviving organisms to estimate per cent kill.

scholarly journals An Alternative Statistical Model for Predicting Salinity Variations in Estuaries

2020 ◽  
Vol 12 (24) ◽  
pp. 10677
Author(s):  
Ronghui Ye ◽  
Jun Kong ◽  
Chengji Shen ◽  
Jinming Zhang ◽  
Weisheng Zhang
Keyword(s):  
Statistical Model ◽  
River Discharge ◽  
Numerical Models ◽  
Low Cost ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Large River ◽  
Physical Models ◽  
Long Term Effects ◽  
Salinity Variations

Accurate salinity prediction can support the decision-making of water resources management to mitigate the threat of insufficient freshwater supply in densely populated estuaries. Statistical methods are low-cost and less time-consuming compared with numerical models and physical models for predicting estuarine salinity variations. This study proposes an alternative statistical model that can more accurately predict the salinity series in estuaries. The model incorporates an autoregressive model to characterize the memory effect of salinity and includes the changes in salinity driven by river discharge and tides. Furthermore, the Gamma distribution function was introduced to correct the hysteresis effects of river discharge, tides and salinity. Based on fixed corrections of long-term effects, dynamic corrections of short-term effects were added to weaken the hysteresis effects. Real-world model application to the Pearl River Estuary obtained satisfactory agreement between predicted and measured salinity peaks, indicating the accuracy of salinity forecasting. Cross-validation and weekly salinity prediction under small, medium and large river discharges were also conducted to further test the reliability of the model. The statistical model provides a good reference for predicting salinity variations in estuaries.

scholarly journals Analytical approach for determining the mean water level profile in an estuary with substantial fresh water discharge

2016 ◽  
Vol 20 (3) ◽  
pp. 1177-1195 ◽  
Author(s):  
Huayang Cai ◽  
Hubert H. G. Savenije ◽  
Chenjuan Jiang ◽  
Lili Zhao ◽  
Qingshu Yang
Keyword(s):  
Water Level ◽  
Fresh Water ◽  
River Discharge ◽  
River Flow ◽  
Water Discharge ◽  
Value Theory ◽  
Velocity Amplitude ◽  
Mean Water Level ◽  
The Mean ◽  
Fresh Water Discharge

Abstract. The mean water level in estuaries rises in the landward direction due to a combination of the density gradient, the tidal asymmetry, and the backwater effect. This phenomenon is more prominent under an increase of the fresh water discharge, which strongly intensifies both the tidal asymmetry and the backwater effect. However, the interactions between tide and river flow and their individual contributions to the rise of the mean water level along the estuary are not yet completely understood. In this study, we adopt an analytical approach to describe the tidal wave propagation under the influence of substantial fresh water discharge, where the analytical solutions are obtained by solving a set of four implicit equations for the tidal damping, the velocity amplitude, the wave celerity, and the phase lag. The analytical model is used to quantify the contributions made by tide, river, and tide–river interaction to the water level slope along the estuary, which sheds new light on the generation of backwater due to tide–river interaction. Subsequently, the method is applied to the Yangtze estuary under a wide range of river discharge conditions where the influence of both tidal amplitude and fresh water discharge on the longitudinal variation of the mean tidal water level is explored. Analytical model results show that in the tide-dominated region the mean water level is mainly controlled by the tide–river interaction, while it is primarily determined by the river flow in the river-dominated region, which is in agreement with previous studies. Interestingly, we demonstrate that the effect of the tide alone is most important in the transitional zone, where the ratio of velocity amplitude to river flow velocity approaches unity. This has to do with the fact that the contribution of tidal flow, river flow, and tide–river interaction to the residual water level slope are all proportional to the square of the velocity scale. Finally, we show that, in combination with extreme-value theory (e.g. generalized extreme-value theory), the method may be used to obtain a first-order estimation of the frequency of extreme water levels relevant for water management and flood control. By presenting these analytical relations, we provide direct insight into the interaction between tide and river flow, which will be useful for the study of other estuaries that experience substantial river discharge in a tidal region.

scholarly journals River Discharge Estimation based on Satellite Water Extent and Topography: An Application over the Amazon

2019 ◽  
Vol 20 (9) ◽  
pp. 1851-1866 ◽  
Author(s):  
Dinh Thi Lan Anh ◽  
Filipe Aires
Keyword(s):  
River Discharge ◽  
Amazon Basin ◽  
Water Cycle ◽  
Large River ◽  
Water Volume ◽  
Discharge Estimation ◽  
Three Rivers ◽  
Storage Change

Abstract River discharge (RD) estimates are necessary for many applications, including water management, flood risk, and water cycle studies. Satellite-derived long-term GIEMS-D3 surface water extent (SWE) maps and HydroSHEDS data, at 90-m resolution, are here used to estimate several hydrological quantities at a monthly time scale over a few selected locations within the Amazon basin. Two methods are first presented to derive the water level (WL): the “hypsometric curve” and the “histogram cutoff” approaches at an 18 km × 18 km resolution. The obtained WL values are interpolated over the whole water mask using a bilinear interpolation. The two methods give similar results and validation with altimetry is satisfactory, with a correlation ranging from 0.72 to 0.89 in the seven considered stations over three rivers (i.e., Wingu, Negro, and Solimoes Rivers). River width (RW) and water volume change (WVC) are also estimated. WVC is evaluated with GRACE total water storage change, and correlations range from 0.77 to 0.88. A neural network (NN) statistical model is then used to estimate the RD based on four predictors (SWE, WL, WVC, and RW) and on in situ RD measurements. Results compare well to in situ measurements with a correlation of about 0.97 for the raw data (and 0.84 for the anomalies). The presented methodologies show the potential of historical satellite data (the combination of SWE with topography) to help estimate RD. Our study focuses here on a large river in the Amazon basin at a monthly scale; additional analyses would be required for other rivers, including smaller ones, in different environments, and at higher temporal scale.

A 50-yr Record of Pollution by Nutrients, Trace Metals, and Organic Chemicals in the St Lawrence River

1994 ◽  
Vol 51 (5) ◽  
pp. 1088-1100 ◽  
Author(s):  
Richard Carignan ◽  
Stéphane Lorrain ◽  
Ken Lum
Keyword(s):  
Trace Metals ◽  
Trace Metal ◽  
Organic Contaminants ◽  
River Discharge ◽  
Organic Chemicals ◽  
Metal Concentrations ◽  
Organic C ◽  
Pcb Congeners ◽  
Anthropogenic Inputs ◽  
St Lawrence River

The deposition chronology of algal pigments, organic C, N, P, trace metals, and organic contaminants (PCB congeners, DDD, DDE, Mirex, hexachlorobenzene) is described for two sites in fluvial lakes (St. Francis and St. Louis) of the St. Lawrence River. Pigment concentrations rapidly decrease in the top 10 cm due to degradation, but show a broad secondary peak consistent with higher primary productivity between 1960 and 1975. In Lake St. Francis, deposition of organic C, N, and P peaked between 1950 and 1975. In both lakes, trace metal concentrations reached maximum values between 1960 and 1970 and decreased considerably between 1970 and 1980. At both sites, surficial trace metal concentrations are approaching (within a factor of 3) those observed in preindustrial sediments except Cd, which is still 5–6 times higher. Concentrations of Cr, Cu, Ni, and Zn are inversely related (p < 0.05) to river discharge whereas those of Pb are positively related to discharge. Concentrations of organic contaminants have declined by a factor of 5–10 between the mid-1960's and the early 1980's, except Mirex, which shows no obvious trend with time. Historic trends in pollution by organic chemicals appear to have been influenced not only by changing anthropogenic inputs, but also by river discharge.

The influence of salinity on Scirpus americanus tidal marshes in the St. Lawrence River estuary, Québec

1985 ◽  
Vol 63 (5) ◽  
pp. 920-927 ◽  
Author(s):  
J. Deschênes ◽  
J.-B. Sérodes
Keyword(s):  
Fresh Water ◽  
Lower Limit ◽  
Brackish Water ◽  
Saline Water ◽  
River Estuary ◽  
Considerable Effect ◽  
Tidal Marshes ◽  
Brackish Waters ◽  
Scirpus Americanus ◽  
St Lawrence River

The amount of sodium in the aboveground part of the stalks of Scirpus americanus taken at the peak of biomass is a good indicator of the amount of salinity in the waters flooding the tidal marshes of an estuary. In fresh water, the Na concentrations remain below 10 000 and then increase sharply up to 20 000 – 30 000 mg/kg in brackish waters. Even though this plant can grow under brackish conditions, salinity has a considerable effect on the percentage of submersion it can withstand. Consequently, in the presence of saline water, the lower limit of the vegetation regresses towards the shore. In the case of fresh water, Scirpus americanus occupies the lower part of marshes up to an average of 75% of submersion, while in brackish water it extends to about 35% and then disappears when waters are more saline.

The role of sewage in a large river food web

2003 ◽  
Vol 60 (11) ◽  
pp. 1332-1344 ◽  
Author(s):  
Adrian M.H deBruyn ◽  
David J Marcogliese ◽  
Joseph B Rasmussen
Keyword(s):  
Food Web ◽  
Secondary Production ◽  
Isotope Analysis ◽  
Large River ◽  
Fish Production ◽  
Daily Discharge ◽  
Primary Consumers ◽  
Secondary Consumers ◽  
St Lawrence River

We evaluated the role of sewage as a resource for the littoral food web of the fluvial St. Lawrence River near Montreal, Quebec. Stable isotope analysis indicated that macroinvertebrate primary consumers were feeding on local epiphytic production at sites outside the sewage plume, but shifts in δ15N of primary and secondary consumers revealed a substantial uptake of sewage-derived resources within the plume, up to 10 km from the outfall. Daily secondary production of macroinvertebrates was 1.8- to 4.1-fold higher at sewage-enriched sites, and the fraction of this production attributable to larval Chironomidae increased from 46% (outside the plume) to 85% (at sewage-enriched sites). Sewage enrichment also stimulated increases in daily fish production based on algivory-detritivory (1.3- to 4.4-fold), invertivory (1.7- to 10-fold), and piscivory (11- to 73-fold). We estimate a daily flux of 13 tonnes of sewage-derived particulate matter, 184 kg of total nitrogen, and 13 kg of total phosphorus into the food web over 1.2 km2 of the littoral zone within 10 km of the outfall. These values represent no more than a few percent of the total daily discharge of sewage-derived resources but were sufficient to support an overall fivefold increase in secondary production relative to sites outside the plume.

scholarly journals Analisis Pengendalian Puncak Banjir Menggunakan Kolam Retensi di DAS Batang Air Dingin Kota Padang

2020 ◽  
Vol 16 (1) ◽  
pp. 1
Author(s):  
Fajri Ramadhan ◽  
Yola Amelia ◽  
Revalin Herdianto ◽  
Elvi Roza Syofyan
Keyword(s):  
Return Period ◽  
Surface Runoff ◽  
River Discharge ◽  
River Flow ◽  
Storage Capacity ◽  
Large River ◽  
Hydraulic Modelling ◽  
Retention Pond ◽  
Flood Discharge ◽  
Local Residents

Batang Air Dingin Watershed is one of the watersheds in Padang City which is located at 00050’12,5” to 00050’22,5” South Latitude and 100023’35,85” to 100022’42,84” East Longitude has changed its function. Land in the area around the river flow results in greater surface runoff, which has the potential to cause erosion. Runoff that occurs in Batang Air Dingin Watershed area causes the river to shrink during the dry season causing the local residents’ wells to be drought, while in the rainy season the river discharge value used is obtained. Through the calculation of the hydrograps discharge using the HSS Nakayasu and HEC-HMS methods whose values are validated by the field flood discharge. Hydraulic modelling using HEC-RAS software with discharge from HSS Nakayasu method. The retention pond plan is based on the amount of runoff that cannot be accommodated by the original storage capacity of Batang Air Dingin Watershed during 100 year return period was 1212, 94 m3/second with large river storage capacity is 1205,317 m3/second. The debit that can be deducted by making a retention pond is 30,5%.

River Pollution: Big Cost of Future (Light on Mumbai Metropolis Rivers)

2019 ◽  
Vol 8 (8) ◽  
pp. 86-90
Author(s):  
Chinmay . M ◽  
Leena Muralidharan ◽  
Sangeeta Gaur
Keyword(s):  
Water Quality ◽  
Environmental Health ◽  
Fresh Water ◽  
Well Being ◽  
River Pollution ◽  
Polar Ice ◽  
Recreational Activities ◽  
Ice Caps ◽  
The Earth ◽  
Health And Well Being

Water is one of necessity of life without which it is not possible for life to sustain. Approximately 71% part of the earth is enclosed with water in which 97% seawater, 2% polar ice caps, and 1% is fresh water. Water quality is an indicator of environmental health and well being of society. The environment nearby river area are very productive, beside this they also have economically values for fisheries, tourism, and recreational activities (Donde and Patil, 2018).  In India, approximately 1000 rivers are present which are source of livelihood for large number of population.

Salt and Freshwater Exchange on Roberts Bank, British Columbia

1988 ◽  
Vol 23 (1) ◽  
pp. 160-178 ◽  
Author(s):  
P.B. Crean ◽  
T.S. Murty ◽  
J.A. Stronach
Keyword(s):  
Fresh Water ◽  
Seasonal Changes ◽  
River Discharge ◽  
Retaining Wall ◽  
Surface Currents ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Shallow Layer ◽  
Layer Flow ◽  
Incoming Tide

Abstract One of the aspects of the seaward movement of fresh water from the Fraser River is its passage tangential to Roberts Bank and subsequent recirculation onto the bank. A synoptic study of the oceanography of the bank is described, part, of a larger study of surface currents in the Strait of Georgia. Seasonal changes in salinity and temperature over Roberts Bank are presented. The freshwater flows and motions of the salt wedges in the river and on the bank are described. Under the restraints of a retaining wall immediately north of the river, and on the incoming tide, a shallow layer of fresh water briefly forms an eddy, varying in size with river discharge and extending over the bank to the south. The influence of the two-layer flow on sedimentation is also discussed.

Salt intrusion in an estuarine network, a study with an exploratory model

2020 ◽  
Author(s):  
Huib E. de Swart ◽  
Inge van Tongeren
Keyword(s):  
River Water ◽  
Fresh Water ◽  
River Discharge ◽  
Yangtze Estuary ◽  
Strong Impact ◽  
The South ◽  
The Yangtze Estuary ◽  
Salt Intrusion ◽  
The North ◽  
Averaged Model

&lt;p&gt;Many estuarine systems experience increased salt intrusion, which is harmful for ecology and agriculture and may cause problems for fresh water supply to cities. Some causes of salt intrusion are extraction of fresh water in the upper reaches of the estuary and climate change. Besides, anthropogenic measures, like deepening of channels, are known to have a strong impact on the salt balance.&lt;/p&gt;&lt;p&gt;This contribution focuses on salt intrusion in estuarine networks, which consist of multiple connected channels. The motivation of the study arose from observations in the Yangtze estuary that reveal frequent overspill of salt between its different channels. To understand the underlying physics of such behaviour, an exploratory, width- and tidally averaged model has been developed and analysed. This model describes the competition between export of salt by river flow and import of salt by density-driven flow and horizontal diffusion. Its key new aspect is that it generalises an earlier model MacCready (2004) from a single channel to estuarine networks. The new model calculates the distribution of salt in, and salt exchange between the channels, as well as the distribution of river water over the different channels.&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;Here, results will be presented for a simplified estuarine network consisting of the South Channel, South Passage and North Passage of the Yangtze Estuary. It will be shown that, for the present-day situation, dry season and spring tide, salt intrusion is larger in the South Passage than in the North Passage. As will be explained, this is mainly due to the different geometry of the two channels. Furthermore, it will be shown that there is slightly more river water transport through the South Passage than through the North Passage, except during high river discharge and neap tide. These results agree with field data and results from numerical studies.&lt;/p&gt;&lt;p&gt;Other results that will be presented are the sensitivity of salinity intrusion length and distribution of river water over the different channels to changes in, respectively, upstream river discharge, tidal currents and human interventions. Specifically, the effects of the creation of a Deepwater Navigation Channel in the North Passage on salt dynamics will be shown and discussed.&lt;/p&gt;&lt;p&gt;Reference:&lt;br&gt;MacCready, P. 2004. Toward a unified theory of tidally-averaged estuarine salinity structure. Estuaries 27, 561-570.&lt;/p&gt;

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