Effects of water transfers projected in the Spanish National Hydrological Plan on the ecology of the lower River Ebro (N.E. Spain) and its delta

1995 ◽  
Vol 31 (8) ◽  
pp. 79-86 ◽  
Author(s):  
Narcís Prat ◽  
Carles Ibañez
Keyword(s):  
River Flow ◽  
Management Strategies ◽  
River Mouth ◽  
Water Transfers ◽  
Salt Wedge ◽  
Water Abstraction ◽  
High Productivity ◽  
The Mean ◽  
Freshwater Inputs ◽  
Annual Discharge

This paper refers to the effects of projected water transfers, envisaged in the Spanish National Hydrological Plan, on the ecology of the lower River Ebro and its delta. Present management strategies, have resulted in highly eutrophic river water and a salt wedge which runs for more than 30 km upstream from the river mouth and its presence has been recorded during most of the year. Some parts of the delta coast are in regression as most of the inorganic sediments carried by the river are trapped in the dams. This is also leading to the sinking of the deltaic plain because subsidence and eustatic sea level rise are not compensated by new sediments. The high productivity of two bays and the coastal zone adjacent to the delta is related to influx of freshwater from irrigation channels, used in rice cultivation and the river. In the new National Hydrological Plan, a withdrawal of water upstream from the delta of 2012 hm3/year (15% of the mean annual discharge) is planned as well as the construction of 49 new reservoirs, mainly for irrigation purposes. A minimum river flow of 100 m3/s will be established by the Plan. If the plan is carried through, due to the water abstraction, forecasts based on ecological studies in the area predict: (1) increased presence of the salt wedge in the final 18 km of the river with detrimental effects on river fauna and flora; (2) serious threats to aquaculture and fisheries in the bays; (3) reduction of fish and crayfish production in the platform area; (4) further reductions in sediment and freshwater inputs to delta; (5) salinization of fields under cultivation; and (6) detrimental side effects on deltaic ecosystems.

Survival and cause-specific mortality of the female eastern wild turkey at its northern range edge

2014 ◽  
Vol 41 (7) ◽  
pp. 545 ◽  
Author(s):  
Britney Niedzielski ◽  
Jeff Bowman
Keyword(s):  
Management Strategies ◽  
Meleagris Gallopavo ◽  
Limiting Factors ◽  
Wild Turkey ◽  
High Productivity ◽  
Supplemental Food ◽  
Range Edge ◽  
The North ◽  
Wild Turkeys ◽  
Peripheral Areas

Context In an era of rapid environmental change, many species are shifting their distributions. As temperate-zone species’ expand their ranges north, different and potentially severe limiting factors may begin to affect their ability to survive and reproduce. The wild turkey (Meleagris gallopavo) is one example of a species undergoing rapid northern expansion. Aims An improved understanding of wild turkey demography at the species’ northern range periphery would facilitate effective management of this important game species. Therefore, we undertook a study to evaluate survival, causes of mortality, and behavioural strategies that may govern survival of female wild turkeys. Methods We captured 53 female wild turkeys, and used backpack transmitters to monitor their individual fates during 2012–13. Key results The annual survival estimate was 0.37 (95% CI: 0.25–0.55), with the lowest seasonal survival in the winter. The most frequent cause of mortality was mammalian predation, predominately by coyotes (Canis latrans). Age, proximity to supplemental food, and habitat use did not affect risk of mortality. Conclusions Northern wild turkeys in our study exhibited lower survival and suffered higher predation than did populations in the species’ historic range. Despite our findings, the wild turkey has expanded its range northwards and continues to exist in these peripheral areas. This may be due to high productivity or a source–sink dynamic, whereby high mortality is offset by immigration from the south. Implications The low survival and high predation of wild turkeys in the north must be considered when developing management strategies, particularly if interest exists in translocating turkeys farther north. Further research is needed to better understand whether northern turkey populations persist as sinks.

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 The correlation of respiratory system compliance and mortality in COVID-19 acute respiratory distress syndrome: do phenotypes really exist?

2021 ◽  
Vol 8 (2) ◽  
pp. 67-74
Author(s):  
Rachel L. Choron ◽  
Stephen A. Iacono ◽  
Alexander Cong ◽  
Christopher G. Bargoud ◽  
Amanda L. Teichman ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory System ◽  
Management Strategies ◽  
Respiratory System Compliance ◽  
Risk Of Death ◽  
Mortality Difference ◽  
Ventilator Management ◽  
Observational Cohort ◽  
Multivariable Regression ◽  
The Mean

Background: Recent literature suggests respiratory system compliance (Crs) based phenotypes exist among COVID-19 ARDS patients. We sought to determine whether these phenotypes exist and whether Crs predicts mortality. Methods: A retrospective observational cohort study of 111 COVID-19 ARDS patients admitted March 11-July 8, 2020. Crs was averaged for the first 72-hours of mechanical ventilation. Crs<30ml/cmH2O was defined as poor Crs(phenotype-H) whereas Crs≥30ml/cmH2O as preserved Crs(phenotype-L). Results: 111 COVID-19 ARDS patients were included, 40 phenotype-H and 71 phenotype-L. Both the mean PaO2/FiO2 ratio for the first 72-hours of mechanical ventilation and the PaO2/FiO2 ratio hospital nadir were lower in phenotype-H than L(115[IQR87] vs 165[87], p=0.016), (63[32] vs 75[59], p=0.026). There were no difference in characteristics, diagnostic studies, or complications between groups. Twenty-seven (67.5%) phenotype-H patients died vs 37(52.1%) phenotype-L(p=0.115). Multivariable regression did not reveal a mortality difference between phenotypes; however, a 2-fold mortality increase was noted in Crs<20 vs >50ml/cmH2O when analyzing ordinal Crs groups. Moving up one group level (ex. Crs30-39.9ml/cmH2O to 40-49.9ml/cmH2O), was marginally associated with 14% lower risk of death(RR=0.86, 95%CI 0.72, 1.01, p=0.065). This attenuated (RR=0.94, 95%CI 0.80, 1.11) when adjusting for pH nadir and PaO2/FiO2 ratio nadir. Conclusion: We identified a spectrum of Crs in COVID-19 ARDS similar to Crs distribution in non-COVID-19 ARDS. While we identified increasing mortality as Crs decreased, there was no specific threshold marking significantly different mortality based on phenotype. We therefore would not define COVID-19 ARDS patients by phenotypes-H or L and would not stray from traditional ARDS ventilator management strategies.

scholarly journals Assessment of genetic diversity among surian Toona sinensis Roem in progenies test using random amplified polymorphic DNA markers

2018 ◽  
Vol 22 (1) ◽  
pp. 22
Author(s):  
Jayusman Jayusman ◽  
Muhammad Na’iem ◽  
Sapto Indrioko ◽  
Eko Bhakti Hardiyanto ◽  
ILG Nurcahyaningsih
Keyword(s):  
Genetic Diversity ◽  
Dna Markers ◽  
Rapd Markers ◽  
Random Amplified Polymorphic Dna ◽  
Management Strategies ◽  
Genetic Distances ◽  
Sampled Data ◽  
Toona Sinensis ◽  
The Mean ◽  
Individual Trees

Surian Toona sinensis Roem is one of the most widely planted species in Indonesia. This study aimed to estimate the genetic diversity between a number of surian populations in a progeny test using RAPD markers, with the goal of proposing management strategies for a surian breeding program. Ninety-six individual trees from 8 populations of surian were chosen as samples for analysis. Eleven polymorphic primers (OP-B3, OP-B4, OP-B10, OP-H3, OP-Y6, OP-Y7, OP-Y8, OP-Y10, OP-Y11, OP-Y14, and OP-06) producing reproducible bands were analyzed for the 96 trees, with six trees per family sampled. Data were analyzed using GenAlEx 6.3, NTSYS 2.02. The observed percentage of polymorphic loci ranged from 18.2% to 50%. The mean level of genetic diversity among the surian populations was considered to be moderate (He 0.304). Cluster analysis grouped the genotypes into two main clusters, at similarity levels of 0.68 and 0.46. The first two axes of the PCoA explained 46.16% and 25.54% of the total variation, respectively. The grouping of samples into clusters and subclusters did not correspond with family and their distances, but the grouping was in line with the genetic distances of the samples.

scholarly journals WATER EXCHANGE IN THE ESTUARY OF THE RAZDOLNAYA RIVER (AMUR BAY, JAPAN SEA) IN THE ICE COVERED PERIOD

2019 ◽  
Vol 196 ◽  
pp. 123-137 ◽  
Author(s):  
P. Yu. Semkin ◽  
P. Ya. Tishchenko ◽  
V. B. Lobanov ◽  
Yu. A. Barabanshchikov ◽  
T. A. Mikhailik ◽  
...  
Keyword(s):  
Water Exchange ◽  
Salt Water ◽  
Groundwater Discharge ◽  
River Mouth ◽  
Japan Sea ◽  
Bottom Layer ◽  
Additional Source ◽  
Flow Through ◽  
Limited Water Exchange ◽  
Annual Discharge

Environmental conditions in the Razdolnaya/Suifen Estuary and adjacent marine area were monitored from 2008 to 2018, by seasons, including winter observations in January 2014 and January 2018. The river discharge in winter was low: 6 m3 /s (mean annual discharge is 73 m3 /s). The estuary was covered by ice. The cline of salt water at the bottom was traced upstream up to 28 km from the river mouth. The currents in the estuary changed in tidal cycle. Increasing of salinity and temperature (> 2о ) at the bottom was observed in the distance 20–24 km from the river bar (this area was distinguished by relatively thin ice, 20 cm, against 40–70 cm in the rest of estuary). Modeling of the water balance in the estuary showed an additional source of salt water in the internal estuary, beyond the direct exchange with the sea over the river bar, that was presumably the water flow through the aquifer. This groundwater discharge was responsible for supporting of the salted bottom layer and for temperature and salinity increasing in the internal estuary during the ebb phase in conditions of limited water exchange by two-layered estuarine circulation because of ice cover at the river mouth.

scholarly journals Using an Isohaline Flux Analysis to Predict the Salt Content in an Unsteady Estuary

2017 ◽  
Vol 47 (11) ◽  
pp. 2811-2828 ◽  
Author(s):  
Matthew D. Rayson ◽  
Edward S. Gross ◽  
Robert D. Hetland ◽  
Oliver B. Fringer
Keyword(s):  
River Flow ◽  
Salt Content ◽  
Box Model ◽  
Flux Analysis ◽  
Galveston Bay ◽  
Exchange Flow ◽  
Salt Intrusion ◽  
Adjustment Time ◽  
The Mean ◽  
Salinity Difference

AbstractAn estuary is classified as unsteady when the salinity adjustment time is longer than the forcing time scale. Predicting salt content or salt intrusion length using scaling arguments based on a steady-state relationship between flow and salinity is inaccurate in these systems. In this study, a time-dependent salinity box model based on an unsteady Knudsen balance is used to demonstrate the effects of river flow, inward total exchange flow (tidal plus steady), and the salinity difference between inflow and outflow on the salt balance. A key component of the box model is a relationship that links the normalized difference between inflowing and outflowing salinity at the mouth and the mean salinity content. The normalized salinity difference is shown to be proportional to the mean salinity squared, based on theoretical arguments from the literature. The box model is validated by hindcasting 5 years of mean salinity in Galveston Bay (estimated from coarse observations) in response to highly variable river discharge. It is shown that this estuary typically has a long adjustment time relative to the forcing time scales, and, therefore, the volume-averaged salinity rarely reaches equilibrium. The box model highlights the reasons why the adjustment time in a large, partially mixed estuary like Galveston Bay is slower when the mean salt content is higher. Furthermore, it elucidates why the salt content in the estuary is more responsive to changes in river flow than in landward exchange flow at the estuary mouth, even though the latter quantity is usually several times larger.

scholarly journals Analyses of Monthly Discharges in Slovakia Using Hydrological Exploratory Methods

Proceedings ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 18
Author(s):  
Mária Ďurigová ◽  
Dominika Ballová ◽  
Kamila Hlavčová
Keyword(s):  
Change Points ◽  
Hydrological Data ◽  
Pettitt Test ◽  
The Mean ◽  
Monthly Discharge ◽  
Meteorological Elements ◽  
The Relationship ◽  
Annual Discharge ◽  
Hydrological Regimes

Detailed analyses of hydrological data are necessary in order to prove changes in their character. This article focuses on an analysis of the average monthly discharges of 14 stage-discharge gauging stations in Slovakia. The measured period is from 1931 to 2016. The approaches used are hydrological exploration methods, which were created by hydrologists to describe the behavior of hydrological time series. The methods are used to identify a change-point using an analysis of any residuals, the Pettitt test, and an analysis of the relationship between the mean annual discharge deviations from the long-term annual discharge and the deviations of the average monthly discharge from the long-term average monthly discharge. A considerable number of change-points were identified in the 1970s and 1980s. The results of the analyses show changes in the hydrological regimes, but to confirm the accuracy of the outcomes, it is also necessary to examine other hydrological and meteorological elements such as, e.g., precipitation and the air temperature.

scholarly journals The possible negative consequences of underground dam and reservoir construction and operation in coastal karst areas: an example of the hydro-electric power plant (HEPP) Ombla near Dubrovnik (Croatia)

2013 ◽  
Vol 13 (8) ◽  
pp. 2041-2052 ◽  
Author(s):  
T. Roje-Bonacci ◽  
O. Bonacci
Keyword(s):  
Power Plant ◽  
Electric Power ◽  
Karst Aquifer ◽  
Grout Curtain ◽  
Negative Consequences ◽  
Karst Spring ◽  
Coastal Karst ◽  
Underground Dam ◽  
The Mean ◽  
Annual Discharge

Abstract. The Ombla Spring represents a typical abundant coastal karst spring located in the vicinity of the town of Dubrovnik (Croatia). Its outlet is at an altitude of 2.5 m above sea level (m a.s.l.) and the water from it immediately flows into the Adriatic Sea. The minimum and maximum measured discharges are 3.96 m3 s−1 and 117 m3 s−1, respectively. The Trebišnjica River traverses through its catchment. The mean annual discharge, after the canalization of over 60 km of its watercourse with spray concrete (in the time span 1981–2011), is 24.05 m3 s−1. Before massive civil engineering work which took place during 1968–1980, the mean annual discharge was 28.35 m3 s−1. There is a project for construction of the hydro-electric power plant (HEPP) Ombla, which will exclusively use groundwater from the Ombla Spring karst aquifer. The underground dam will be constructed about 200 m behind the existing karst spring outflow in the karst massif, by injecting a grout curtain. The top of the grout curtain is planned to be at an altitude of 130 m a.s.l. This karst system is complex, sensitive, vulnerable and ecologically extremely valuable. The grout curtain, as well as the HEPP Ombla development, could lead to extremely dangerous technical and environmental consequences. In this paper some probable, negative consequences of the HEPP Ombla construction and development are explained. The HEPP Ombla could result in many large and hard-to-predict negative consequences which are specific for this particular HEPP, for example (1) severe spring discharge change; (2) unpredictable regional groundwater redistribution; (3) threatening of endemic fauna; (4) induced seismicity; (5) induced sinkholes; (6) occurrence of landslides; (7) conflict regarding internationally shared karst aquifers; (8) intensification of karst flash floods; (9) sea water intrusion in coastal karst aquifer; etc.

Effects of bait collection on Nereis virens populations and macrofaunal communities in the Solent, UK

2007 ◽  
Vol 87 (3) ◽  
pp. 703-716 ◽  
Author(s):  
G.J. Watson ◽  
P. Farrell ◽  
S. Stanton ◽  
L.C. Skidmore
Keyword(s):  
Management Strategies ◽  
Species Conservation ◽  
Organic Content ◽  
Long Term Effects ◽  
Nereis Virens ◽  
Community Needs ◽  
General Decline ◽  
The Mean ◽  
Repeat Sampling

The Solent European Marine Sites contain many tiers of habitat and species conservation, but also high levels of bait collection. Effective management strategies must be founded on up-to-date and locally based information from relevant studies of the impacts; these have been lacking for the collection of Nereis virens, a key bait species. The impacts on macrofauna were assessed through two approaches; (a) undug and dug sites in the Solent were compared over two years of repeat sampling; and (b) monitoring the long-term effects of simulated bait collection at an undug site through five years of yearly sampling. Dug sites had significantly higher densities of N. virens, but the mean weight was found to be significantly lower than those collected from the undug sites, but percentage maturity was not different. Organic content and sediment particle sizes differed between sites, and only the presence of gravel had a significant positive correlation with density. No clear patterns of other macrofauna species present were evident, although there was a significantly lower density of the terebellid polychaete Neoamphitrite figulus at the dug sites. Simulated bait collection did not alter overall macrofauna diversity, but certain species were affected. Abundance of N. figulus and the commensal Harmothoë glabra remained consistently lower in the dug area, whilst Cerastoderma edule numbers were reduced initially, but recovered. Numbers of Nephtys hombergii declined in both areas, but at a significantly greater rate in the dug area. A general decline in the abundance of many species, irrespective of digging, occurred over the period. The importance of these changes in Nereis virens populations and in the macrofauna community needs to be investigated prior to any management decisions on collection.

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