scholarly journals Toward the understanding of saline water intrusion and nutrient flushing in Lake Nokoué

2021 ◽  
Author(s):  
Metogbe Djihouessi ◽  
Rita Houngue ◽  
Firmin Adandedji ◽  
Luc Sintondji
Keyword(s):  
Water Quality ◽  
Atlantic Ocean ◽  
Water Level ◽  
Water Flow ◽  
River Flow ◽  
Saline Water ◽  
High Water ◽  
The North ◽  
High Water Period ◽  
Mike 21

To understand the salinity dynamic at the outlet of Lake Nokoué and to simulate the nutrient flushing from this lake into the Atlantic Ocean, a 2D hydrodynamic model was designed with Mike 21. The choice of the Mike 21 was motivated by the long practice that decision-makers in Benin have with this software. The Hydrodynamics (HD) module simulated water level variations and flows in response, while the ECO-Lab module has been used for water quality modelling. The data used covered the hydrological period of 2013. The results from the HD simulation indicated that for a flow of 725 m3/s at Bonou on the Ouémé River, a tributary of Lake Nokoué. 70% of the land in the delta of Ouémé, between the Ouémé River and the So River (also a tributary of Lake Nokoué), are flooded against 90% for a river flow of 1100 m3/s. The water level in the delta showed a water increase of 0.6 m, in seven days, for a water flow of 725 m3/s at Bonou and a water increase of 1.3 m, in seven days, for a water flow of 1100 m3/s at Bonou. Water quality simulations indicated that the seawater intrusion from the Atlantic Ocean into Lake Nokoué occurred from the bottom to the surface towards the surface of the lake. During flooding, despite the large inflow of fresh water, more than 60% of the water at the bottom of the lake had concentrations greater than 8. Simulation of the dispersion of nutrient point source pollution indicated that there was an accumulation of pollution at the bottom of the lake during low water periods. This accumulation increases in amplitude as one moves away from the Atlantic Ocean towards the north of the lake. In this period tidal flushing evacuated about 20% of the pollution ejected. In the high water period, about 70% of the pollution ejected in the lake was automatically flushed out in the lake the Atlantic Ocean.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

scholarly journals A New Method for Tracking Meddies by Satellite Altimetry

2014 ◽  
Vol 31 (6) ◽  
pp. 1434-1445 ◽  
Author(s):  
Federico Ienna ◽  
Young-Heon Jo ◽  
Xiao-Hai Yan
Keyword(s):  
Remote Sensing ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Saline Water ◽  
Ensemble Empirical Mode Decomposition ◽  
Altimeter Data ◽  
In Situ Techniques ◽  
The North ◽  
The North Atlantic

Abstract Subsurface coherent vortices in the North Atlantic, whose saline water originates from the Mediterranean Sea and which are known as Mediterranean eddies (meddies), have been of particular interest to physical oceanographers since their discovery, especially for their salt and heat transport properties into the North Atlantic Ocean. Many studies in the past have been successful in observing and studying the typical properties of meddies by probing them with in situ techniques. The use of remote sensing techniques would offer a much cheaper and easier alternative for studying these phenomena, but only a few past studies have been able to study meddies by remote sensing, and a reliable method for observing them remotely remains elusive. This research presents a new way of locating and tracking meddies in the North Atlantic Ocean using satellite altimeter data. The method presented in this research makes use of ensemble empirical mode decomposition (EEMD) as a means to isolate the surface expressions of meddies on the ocean surface and separates them from any other surface constituents, allowing robust meddies to be consistently tracked by satellite. One such meddy is successfully tracked over a 6-month time period (2 November 2005 to 17 May 2006). Results of the satellite tracking method are verified using expendable bathythermographs (XBT).

scholarly journals Extreme Hydro/chemical Phenomena in a River System during the Snowmelt Period

2013 ◽  
pp. 20-31
Author(s):  
Keyword(s):  
Water Quality ◽  
Water Flow ◽  
River System ◽  
High Water ◽  
Snowmelt Period ◽  
River Bed ◽  
Extreme Behavior ◽  
Successive Period ◽  
Permanganate Oxidability ◽  
Moskva River

Development of extreme hydro/chemical phenomena during the snowmelt periods in the Moskva River (Rublyovo) and their interrelations with the water flow in the river have been investigated. The analysis was based on the rows of water quality daily average values including turbidity, color, permanganate oxidability, alkalinity, pH, chlorides, ammonia ion, iron, as well as the data on the river water flow. A two-month rated period March 15 – May 15 has been identified out of the data rows over 15 years of observations (1997–2011). It has covered the high water peak, preceding waves of thaw and successive period of relaxation. Special features of the indicators extreme behavior during the said period have been described. Variability of indicators during the snowmelt period was illustrated by the 1998 and 1999 data when washing of the river bed was carried out. During these measures performing links between water quality indicators and water consumption were the most obvious. Определен суммарный сток ингредиентов за половодье в зависимости от стока воды. It has been demonstrated that this dependency obeys the linear law.

scholarly journals Analisis Stabilitas Tubuh Bendungan Raknamo (Hal. 95-104)

2018 ◽  
Vol 4 (3) ◽  
pp. 95
Author(s):  
Dwi Nanda Putra ◽  
Sri Hetty Susantin
Keyword(s):  
Water Level ◽  
Water Flow ◽  
Safety Factor ◽  
High Water ◽  
The Finite Element Method ◽  
Embankment Dam ◽  
High Water Level ◽  
Earthquake Load ◽  
Normal Water ◽  
Dam Stability

ABSTRAKBendungan Raknamo merupakan bendungan tipe urugan dengan inti tegak pada tubuh bendungan. Bendungan urugan berpotensi mengalami keruntuhan akibat berubahnya tegangan dalam tanah akibat aliran air. Untuk menghindari keruntuhan, maka diperlukan analisis stabilitas yang dihitung secara bersamaan antara aliran air dan deformasi menggunakan metode elemen hingga dan model 2D pada program PLAXIS 2D 2016. Kondisi yang dianalisis yaitu saat selesai konstruksi, muka air normal, muka air maksimum dan muka air minimum, yang akan dikombinasikan dengan beban gempa. Untuk kondisi surut cepat, faktor beban gempa diabaikan. Analisis dengan gempa menggunakan metode gempa pseudostatik. Hasil analisis berupa faktor keamanan (FK) terkritis di hilir terjadi pada kondisi muka air maksimum 1,890 sebelum ada gempa. Faktor keamanan yang dianalisis memenuhi kriteria yang mengacu pada RSNI M-03-2002, dimana nilai faktor keamanan yang diperoleh lebih besar dari kriteria minimum yang disyaratkan.Kata kunci: bendungan Raknamo, analisis stabilitas, faktor keamanan ABSTRACTThe Raknamo dam is an embankment with a center of core rock fill dam. Embankment dam is risky to collapse due to changes of stress while ground water flow. To avoid collapse, it is necessary to do stability analyzes which were calculated simultaneously between water flow and deformation using the finite element method and 2D models in PLAXIS 2D 2016 program. The conditions to be analyzed are after construction, normal water level, high water level, minimum water level, which will be combined with the earthquake load. For rapid drawdown conditions, earthquake loads are ignored. Analysis with earthquake use the pseudostatic earthquake method. The result of analysis in the form of critical safety factor (SF) in the downstream occurred on high water level condition is 1,890. The safety factors analyzed meet the criteria referring to the RSNI M-03-2002, where the value of the safety factor obtained is more than the required minimum criteria.Keywords: the Raknamo dam, stability analysis, safety factor

scholarly journals Fluvial lakes affect on phosphorus and potassium concentrations in the Samica Stęszewska River

2010 ◽  
Vol 10 (1) ◽  
pp. 29-36
Author(s):  
Agnieszka Ławniczak ◽  
Janina Zbierska ◽  
Sylwia Machula ◽  
Adam Choiński
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Total Phosphorus ◽  
Water Retention ◽  
Water Discharge ◽  
High Water ◽  
Water Level Fluctuations ◽  
Nutrient Concentrations ◽  
Lake Ecosystem ◽  
Phosphorus And Potassium

Fluvial lakes affect on phosphorus and potassium concentrations in the Samica Stęszewska River The aim of the study was to evaluate the effect of shallow lakes on reactive, total phosphorus and potassium concentrations in the river water and analyse the effect of changes in water retention in lake on nutrient concentrations in river waters. The study was carried out in the Samica Steszewska River. This is lowland river, which flows through two polymictic lakes. The study site is located in the Wielkopolska Lowland, Central-west Poland. Water samples were collected at depths of 0.5 m below the water surface. Reactive, total phosphorus and potassium were analysed monthly by standard methods. The study was carried out from January to December 1999-2002 (period with high water retention), 2005-2008 (period with low water retention), at four control points. Sites were located at the inflow and outflow of the Samica Stęszewska River into and out of Niepruszewskie and Tomickie Lakes. From 1974 to 2002, Lake Niepruszewskie was regulated at its outlet by a weir. In 2002, the water level was reduced. Changes of water retention in Niepruszewskie Lake influenced water discharge of the Samica Stęszewska River. The results indicate that changes in water retention have significantly influenced water quality in the river, particularly total and reactive phosphorus concentrations; however, this influence was not observed in respect to potassium concentrations. Nutrient concentrations in river strongly depend on water quality of the lake ecosystem and their buffering capacity. Additionally, by improving water quality, increased oxygen concentrations, and decreasing dissolved nutrient concentrations, as well as increased amplitude of water level fluctuations in lakes may increase P-fixation rates in outlet streams.

scholarly journals The turbidity behavior in an Amazon floodplain

2009 ◽  
Vol 6 (3) ◽  
pp. 3947-3992
Author(s):  
E. Alcântara ◽  
E. Novo ◽  
J. Stech ◽  
J. Lorenzzetti ◽  
C. Barbosa ◽  
...  
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Spatial Data ◽  
Automatic Monitoring ◽  
High Water ◽  
Quantitative Information ◽  
Amazon River ◽  
Automatic Monitoring System ◽  
Amazon Floodplain ◽  
Temporal And Spatial

Abstract. The main objective of this study is to understand the turbidity behavior of an Amazon Floodplain Lake. Observations of turbidity provide quantitative information about water quality. However, the number of available in situ measurements for water quality determination is usually limited in time and space. Here, we present an analysis of the temporal and spatial variability using two approaches: (i) the first is based on wavelet analysis of a turbidity time series measured by an automatic monitoring system; (ii) the second is based on turbidity samples measured in different locations and then interpolated by an ordinary kriging algorithm. The space/time turbidity variability is clearly related to the Amazon River flood pulses in the floodplain. When the water level in the floodplain is rising or receding, the exchange between the Amazon River and the floodplain is the major driving force in turbidity variability. At high water level, the turbidity variability is controlled by the lake bathymetry. Finally, when the water level is low, the wind action and lake morphometry are the main causes of turbidity variability. The combined use of temporal and spatial data showed a great potential for understanding the turbidity behavior in a complex aquatic system, like the Amazon floodplain.

scholarly journals Water Quality Changes during High Water Flow in Small Rivers : A Case Study in Ono River, Matsuyama

2002 ◽  
Vol 7 (2) ◽  
pp. 31-38
Author(s):  
Junsheng Gao ◽  
Tadao Fukushima ◽  
Masayuki Fujihara ◽  
Toshiko Kakihara ◽  
Takashi Watanabe
Keyword(s):  
Water Quality ◽  
Water Flow ◽  
High Water ◽  
Small Rivers ◽  
Quality Changes

scholarly journals INCREASED WATER LEVELS DUE TO MORPHODYNAMIC CHANGES; THE LIMFJORD, DENMARK

2012 ◽  
Vol 1 (33) ◽  
pp. 49 ◽  
Author(s):  
Soeren Bjerre Knudsen ◽  
Signe M. Ingvardsen ◽  
Holger Toxvig Madsen ◽  
Carlo Sorensen ◽  
Bo Brahtz Christensen
Keyword(s):  
Water Level ◽  
Cross Section ◽  
North Sea ◽  
High Water ◽  
Water Levels ◽  
Channel Cross Section ◽  
Strongly Correlated ◽  
The North ◽  
Threefold Increase ◽  
The North Sea

The Limfjord is an estuary in Denmark between The North Sea and Kattegat. The Thyboroen Channel connects the fjord with The North Sea. The water levels in the western part of the Limfjord are strongly correlated with the water level in the sea at Thyboroen. Analyses revealed a close to threefold increase in the channel cross section over the last 100 years. This has led to a detailed investigation into the effects of the channel cross section on the extreme high water levels in the Limfjord now and in the future. For Lemvig in the western part of the Limfjord the water level with a return period of 100 years would have been 1.73 m with the 1958 channel bathymetry throughout the whole period and 1.99 m with the 2005 channel bathymetry. With the extrapolated 2060-bathymetry the 100 years water level will be 2.38 m. A number of measures to counteract the consequences of this development have been evaluated.

scholarly journals Changes in GHG Emissions Based on Irrigation Water Quality in Short-Term Incubated Agricultural Soil of the North China Plain

Agriculture ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1268
Author(s):  
Guangshuai Wang ◽  
Zhenjie Du ◽  
Huifeng Ning ◽  
Hao Liu ◽  
Sunusi Amin Abubakar ◽  
...  
Keyword(s):  
Water Quality ◽  
Irrigation Water ◽  
North China Plain ◽  
Saline Water ◽  
Ghg Emissions ◽  
Water Shortage ◽  
N2o Emissions ◽  
Irrigation Water Quality ◽  
The North ◽  
Ch4 Uptake

A worsening water shortage is threatening the sustainable development of agriculture in the North China Plain (NCP). How to make effective use of inferior water resources and alleviate the impact of insufficient water resources on agricultural environments is one of the urgent problems in agricultural production. Although agriculture plays an important role in greenhouse gas (GHG) emissions, the effects of irrigation water quality on such emissions in the NCP are not clear. In this study, we used a short-term incubation experiment to test the effects of the irrigation water quality (underground water (UW), saline water (SW), and reclaimed water (RW)) and frequency (high (H) and low (L)) on regulating the soil GHG emissions of the NCP. The results indicated that RW treatment increased the CO2 and N2O emissions by 15.00% and 20.81%, respectively, and reduced the CH4 uptake by 12.50% compared with the UW treatment. In addition, SW treatment decreased the CO2 and N2O emissions and CH4 uptake by 35.18%, 40.27%, and 20.09% against UW treatment, respectively. The high-frequency water added to the soil significantly increased the GHG emissions for all water qualities applied. Compared with UW, the global warming potential was significantly increased by RW_H and RW_L with 26.48% and 14.5% and decreased by SW_H and SW_L with 32.13% and 43.9%, respectively. Compared with the increase brought by reclaimed water, changing irrigation water sources from conventional groundwater to saline water (4 g L−1) will moderately reduce GHG emissions under the worsening water shortage conditions occurring in the NCP.

scholarly journals MODERN STATUS OF THE MICROECOSYSTEMS OF THE NORTHERN CASPIAN

2018 ◽  
pp. 30-38
Author(s):  
Svetlana Aleksandrovna Dyakova ◽  
Ecatherina Rafaelevna Galyautdinova ◽  
Elena Glebovna Lardygina
Keyword(s):  
Water Quality ◽  
Antimicrobial Agents ◽  
Vegetation Period ◽  
High Water ◽  
Water Area ◽  
Multi Drug Resistance ◽  
The Caspian Sea ◽  
Volga River ◽  
The North ◽  
Pathogenic Factors

The article highlights the data on the abundance of saprotrophic bacterioplankton and bacteriobenthos in the water area of the Northern Caspian in the period from 2013 to 2017. There has been described the influence of the Volga river runoff during the spring flood on bacterioplankton and bacteriobenthos in the northern part of the Caspian Sea. The number of saprotrophic bacterioplankton in the spring period depended on water content; the minimum of saprotrophs was recorded in 2015 (low water year), maximum - in 2016 (high water year). Studying the vertical distribution of saprotrophs number showed that near the bottom it was somewhat less than on the surface. The most favorable sanitary situation in the Northern Caspian was registered in 2015 (throughout the year, water quality was estimated as clean), unfavorable periods occurred in 2013 and 2016 (during nearly whole vegetation period water quality was estimated as contaminated). In the bottom sediments seasonal changes of saprophytes completely corresponded to bacterioplankton, the abundance of bacteriobenthos exceeding the parameters of bacterioplankton. There has been studied species composition of saprophyte bacteriocenoses of the North Caspian, determined the dynamics of yearly occurrence of different groups and families of microorganisms. In the period from 2013 to 2016 there was observed a decline in the number of species of microorganisms, in 2017, species diversity increased slightly. In summer months and at the beginning of autumn species maximum was observed, in spring and late autumn there was registered species minimum. Most of isolated bacteria belonged to a group of opportunistic pathogens, while true saprophytes were much less common. Among the isolated species there have been determined potentially pathogenic microorganisms, their pathogenic activity and antibiotic resistance have been studied. The presence of one or more pathogenic factors, together with multi-drug resistance of bacteria to antimicrobial agents proved the potential danger of these representatives of bacterioplankton and bacteriobenthos for hydrobionts and humans.

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