Regulation of the abundance and turnover of copepod species by temperature, turbidity and habitat type in a large river basin

2015 ◽  
Vol 40 (6) ◽  
pp. 718-725 ◽  
Author(s):  
Gilmar Perbiche-Neves ◽  
Geoffrey Allan Boxshall ◽  
Daniel Previattelli ◽  
Danilo Augusto Oliveira Naliato ◽  
Marcio Roberto Pie ◽  
...  
Keyword(s):  
River Basin ◽  
Habitat Type ◽  
Large River ◽  
Copepod Species

Trends in planktonic copepod diversity in reservoirs and lotic stretches in a large river basin in South America

2014 ◽  
Vol 65 (8) ◽  
pp. 727 ◽  
Author(s):  
Gilmar Perbiche-Neves ◽  
Geoffrey A. Boxshall ◽  
Marcos G. Nogueira ◽  
Carlos E. F. da Rocha
Keyword(s):  
Species Richness ◽  
South America ◽  
River Basin ◽  
Retention Time ◽  
Water Retention ◽  
Negative Impact ◽  
High Water ◽  
Large River ◽  
Copepod Species ◽  
Water Retention Time

Copepod assemblages were analysed across La Plata River basin, the second largest in South America. High values of species richness and Shannon–Wiener diversity were found in the lower Paraná River, the main and largest river of the basin, and in eutrophic reservoirs located in the upper basin. The species richness was negatively correlated with turbidity, probably because of the negative impact on filtration rates in calanoids. There was a trend of decreasing richness correlated with high water flow in reservoirs with short water-retention time (<40 days) and simple morphometric shape, and also in deeper oligo-mesotrophic reservoirs with very long water-retention time and dendritic shape (variables that occurred in combination in the present study). The number of copepod species (46) found in our study is only about half of the gamma diversity estimated using Jack1 non-parametric analysis for the basin (86 species). There are groups of copepod species typical of reservoirs and rivers, and others that can occur in both of these habitat types. Reservoir and lentic species are favoured by a deeper water column, higher temperatures and higher transparency, whereas the opposite is the case of typical riverine species. There is also a group of species that occur in both sets of conditions.

scholarly journals Capturing transformation of flood hazard over a large River Basin under changing climate using a top-down approach

2020 ◽  
Vol 726 ◽  
pp. 138600 ◽  
Author(s):  
A. Gusain ◽  
M.P. Mohanty ◽  
S. Ghosh ◽  
C. Chatterjee ◽  
S. Karmakar
Keyword(s):  
River Basin ◽  
Flood Hazard ◽  
Large River ◽  
Top Down ◽  
Changing Climate

scholarly journals Distributed model of hydrological and sediment transport processes in large river basins in Southeast Asia

2015 ◽  
Vol 12 (7) ◽  
pp. 6755-6797 ◽  
Author(s):  
S. Zuliziana ◽  
K. Tanuma ◽  
C. Yoshimura ◽  
O. C. Saavedra
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
River Basin ◽  
River Basins ◽  
Large River ◽  
Mekong River ◽  
Distributed Model ◽  
Mekong River Basin ◽  
Chao Phraya River ◽  
Large River Basins

Abstract. Soil erosion and sediment transport have been modeled at several spatial and temporal scales, yet few models have been reported for large river basins (e.g., drainage areas > 100 000 km2). In this study, we propose a process-based distributed model for assessment of sediment transport at a large basin scale. A distributed hydrological model was coupled with a process-based distributed sediment transport model describing soil erosion and sedimentary processes at hillslope units and channels. The model was tested on two large river basins: the Chao Phraya River Basin (drainage area: 160 000 km2) and the Mekong River Basin (795 000 km2). The simulation over 10 years showed good agreement with the observed suspended sediment load in both basins. The average Nash–Sutcliffe efficiency (NSE) and average correlation coefficient (r) between the simulated and observed suspended sediment loads were 0.62 and 0.61, respectively, in the Chao Phraya River Basin except the lowland section. In the Mekong River Basin, the overall average NSE and r were 0.60 and 0.78, respectively. Sensitivity analysis indicated that suspended sediment load is sensitive to detachability by raindrop (k) in the Chao Phraya River Basin and to soil detachability over land (Kf) in the Mekong River Basin. Overall, the results suggest that the present model can be used to understand and simulate erosion and sediment transport in large river basins.

scholarly journals River Water Quality of the Selenga-Baikal Basin: Part II—Metal Partitioning under Different Hydroclimatic Conditions

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2392
Author(s):  
Nikolay Kasimov ◽  
Galina Shinkareva ◽  
Mikhail Lychagin ◽  
Sergey Chalov ◽  
Margarita Pashkina ◽  
...  
Keyword(s):  
River Basin ◽  
Large River ◽  
Metal Partitioning ◽  
River Systems ◽  
Catchment Scale ◽  
Selenga River Basin ◽  
Extensive Field ◽  
Basin Scale ◽  
Wide Range ◽  
Dissolved Form

The partitioning of metals and metalloids between their dissolved and suspended forms in river systems largely governs their mobility and bioavailability. However, most of the existing knowledge about catchment-scale metal partitioning in river systems is based on a limited number of observation points, which is not sufficient to characterize the complexity of large river systems. Here we present an extensive field-based dataset, composed of multi-year data from over 100 monitoring locations distributed over the large, transboundary Selenga River basin (of Russia and Mongolia), sampled during different hydrological seasons. The aim is to investigate on the basin scale, the influence of different hydroclimatic conditions on metal partitioning and transport. Our results showed that the investigated metals exhibited a wide range of different behaviors. Some metals were mostly found in the dissolved form (84–96% of Mo, U, B, and Sb on an average), whereas many others predominantly existed in suspension (66–87% of Al, Fe, Mn, Pb, Co, and Bi). Nevertheless, our results also showed a consistently increasing share of metals in dissolved form as the metals were transported to the downstream parts of the basin, closer to the Lake Baikal. Under high discharge conditions (including floods), metal transport by suspended particulate matter was significantly greater (about 2–6 times). However, since high and low water conditions could prevail simultaneously at a given point of time within the large river basin, e.g., as a result of on-going flood propagation, snap-shot observations of metal partitioning demonstrated contrasting patterns with domination of both particulate and dissolved phases in different parts of the basin. Such heterogeneity of metal partitioning is likely to be found in many large river systems. These results point out the importance of looking into different hydroclimatic conditions across space and time, both for management purposes and contaminant modeling efforts at the basin scale.

scholarly journals On how wetlands can provide flood resilience in a large river basin: A case study in Nenjiang river Basin, China

2020 ◽  
Vol 587 ◽  
pp. 125012 ◽  
Author(s):  
Yanfeng Wu ◽  
Guangxin Zhang ◽  
Alain N. Rousseau ◽  
Y. Jun Xu ◽  
Étienne Foulon
Keyword(s):  
River Basin ◽  
Large River ◽  
Nenjiang River Basin

Modelling chloride-discharge relationships in Krishna river basin

2003 ◽  
Vol 48 (7) ◽  
pp. 57-63 ◽  
Author(s):  
M.C. Sekhar ◽  
Ch. Indira
Keyword(s):  
River Basin ◽  
Pollution Control ◽  
South India ◽  
Control Strategies ◽  
Linear Regression Analysis ◽  
Large River ◽  
Model Parameters ◽  
Source Contributions ◽  
Monitoring Stations

Chloride discharge relationships at several monitoring stations on the River Krishna in South India are investigated, both qualitatively and quantitatively, to identify probable source contributions. The chloride behaviour along the waterway is studied in detail to assess the source contributions at various monitoring stations falling within the study area. Seasonal variations in the intensity of rainfall cause wide variations in the quality of the River Krishna. As there is strong seasonal dependence between the flow in the river and chlorides, seasonal models are developed for prediction of concentrations and loads. Linear regression analysis is carried out to determine the model parameters. The predicted concentrations and loads are in agreement with the observed values within the uncertainty of data. As the area is characterized by distinct dry and wet seasons (based on rainfall distribution over the year), mass balances are used to differentiate between point and non-point source contributions to the river. In large river basins, monitoring all individual sources is difficult and/or impossible and expensive; hence the presented approach based on receiving water quality and flow serves as an alternative for modeling chlorides in the river basin. Results of the study can be used to emphasise water pollution control strategies.

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