scholarly journals FACTORS INFLUENCING ESTUARY SEDIMENT DISTRIBUTION

1976 ◽  
Vol 1 (15) ◽  
pp. 120 ◽  
Author(s):  
Mary P. Kendrick ◽  
B.V. Derbyshire
Keyword(s):  
River Flow ◽  
Saline Water ◽  
Climatic Conditions ◽  
Seasonal Fluctuations ◽  
Short Term ◽  
Sediment Distribution ◽  
Sea Levels ◽  
Subsequent Period ◽  
Estuary Sediment

Many factors combine to determine the way in which sediments are distributed throughout an estuary. Most fundamental are those which produce the natural rhythm of diurnal (or semi-diurnal), bi-monthly and seasonal fluctuations due to predictable variations in tide and weather. This group includes tidal discharge, fresh river flow and the resultant distribution of saline water. When considered together with such factors as the availability and properties of sediments within and beyond the landward and seaward limits of an estuary, they determine how the available material shall be eroded, transported and deposited during the course of the natural cycle. Superimposed on these regular fluctuations are the effects of other factors which may or may not be predictable, are not necessarily regular in occurrence and may be either natural or man-made. These include secular trends, such as long-term adjustments in land/sea levels or climatic conditions, which have a small but continuing effect on some of the factors in the first group. They also include sudden, short-term events like earthquakes or hurricanes which impose a shock to the system that may involve the movement of large quantities of material during the subsequent period of readjustment.

scholarly journals EVALUATION OF POSSIBLE CHANGES IN THE RIVER LINE OF THE OKA BASIN FOR THE COMING PERIOD OF THE FIRST HALF OF THE XXI CENTURY

2020 ◽  
Vol 1 (5) ◽  
pp. 71-75
Author(s):  
G. Kh. Ismaiylov ◽  
◽  
N.V. Muraschenkova ◽  
Keyword(s):  
River Basin ◽  
21St Century ◽  
River Runoff ◽  
River Flow ◽  
Climatic Conditions ◽  
Global Changes ◽  
The Future ◽  
Seasonal Runoff ◽  
The City

A retrospective analysis and assessment of long-term changes in the annual and seasonal runoff of the Oka River basin over a long 131-year observation period (1881 / 1882–2011/2012) was performed. The changes in the annual distribution of the Oka river runoff over the seasons of the year (spring flood, summer-autumn and winter low water) from its annual value for the selected time periods (before and after 1976/1977) are considered. It has been noted that over the past decades, river runoff has been formed in new climatic conditions associated with global changes and, as a result, regional climate. The assessment of possible changes in the annual and seasonal runoff of the Oka River basin (to the final alignment – the city of Kaluga, with a basin area of 54,900 km2 ) in the first half of the 21st century is carried out. In assessing changes in the river flow of the Oka basin for the future period, the method of trends (trends) is used, based on the identification of cycles in fluctuations in hydrological characteristics and unidirectional trends (trends) inherent in individual phases (ups and downs) of these cycles, as well as to the establishment of functional (correlation) relationships between environmental factors (climatic, anthropogenic) and the nature of the response (river flow). In this case, the trend model serves as an alternative to the homogeneity hypothesis of long-term fluctuations in river flow. The change in the future values of the river flow of the Oka basin was estimated using averaged data of 30-year periods of time characterized by relative stationarity of climatic and hydrological conditions. The dynamics of the average 30-year values of the annual runoff in the upper reaches of the Oka River (the closure target is the city of Kaluga for the period 1881/1882–2011/2012) is considered. Possible forecasted mean annual values of the annual flow of the Oka River for the first half of the 21st century are obtained

scholarly journals The influence of decadal-scale variability on trends in long European streamflow records

2013 ◽  
Vol 10 (2) ◽  
pp. 1859-1896 ◽  
Author(s):  
J. Hannaford ◽  
G. Buys ◽  
K. Stahl ◽  
L. M. Tallaksen
Keyword(s):  
Eastern Europe ◽  
River Flow ◽  
Interdecadal Variability ◽  
Trend Detection ◽  
Quality Data ◽  
Mean Flow ◽  
Short Term ◽  
Decadal Scale ◽  
Multi Temporal

Abstract. This study seeks to provide a long-term context for the growing number of trend analyses which have been applied to river flows in Europe. Most studies apply trend tests to fixed periods, in relatively short (generally 1960s–present) records. This study adopts an alternative "multi-temporal" approach, whereby trends are fitted to every possible combination of start and end years in a record. The method is applied to 132 catchments with long (1932–2004) hydrometric records from northern and central Europe, which were chosen as they are minimally anthropogenically influenced and have good quality data. The catchments are first clustered into five regions, which are broadly homogenous in terms of interdecadal variability of annual mean flow. The multi-temporal trend approach was then applied to regional time series of different hydrological indicators (annual, monthly and high and low flows). The results reveal that the magnitude and even direction of short-term trends are heavily influenced by interdecadal variability. Some short-term trends revealed in previous studies are shown to be unrepresentative of long-term change. For example, previous studies have identified post-1960 river flow decreases in southern and eastern Europe: in parts of eastern Europe, these trends are resilient to study period, extending back to the 1930s; in southern France, longer records show evidence of positive trends which reverse from the 1960s. Recent (post-1960) positive trends in northern Europe are also not present in longer records, due to decadal variations influenced by the North Atlantic Oscillation. The results provide a long-term reference for comparison with published and future studies. The multi-temporal approach advocated here is recommended for use in future trend assessments, to help contextualise short-term trends. Future work should also attempt to explain the decadal-scale variations that drive short-term trends, and thus develop more sophisticated methods for trend detection that take account of interdecadal variability and its drivers.

scholarly journals The influence of decadal-scale variability on trends in long European streamflow records

2013 ◽  
Vol 17 (7) ◽  
pp. 2717-2733 ◽  
Author(s):  
J. Hannaford ◽  
G. Buys ◽  
K. Stahl ◽  
L. M. Tallaksen
Keyword(s):  
Eastern Europe ◽  
River Flow ◽  
Interdecadal Variability ◽  
Trend Detection ◽  
Quality Data ◽  
Mean Flow ◽  
Short Term ◽  
Decadal Scale ◽  
Multi Temporal

Abstract. This study seeks to provide a long-term context for the growing number of trend analyses which have been applied to river flows in Europe. Most studies apply trend tests to fixed periods, in relatively short (generally 1960s–present) records. This study adopts an alternative "multi-temporal" approach, whereby trends are fitted to every possible combination of start and end years in a record. The method is applied to 132 catchments with long (1932–2004) hydrometric records from northern and central Europe, which were chosen as they are minimally anthropogenically influenced and have good quality data. The catchments are first clustered into five regions, which are broadly homogenous in terms of interdecadal variability of annual mean flow. The multi-temporal trend approach was then applied to regional time series of different hydrological indicators (annual, monthly and high and low flows). The results reveal that the magnitude and even direction of short-term trends are heavily influenced by interdecadal variability. Some short-term trends revealed in previous studies are shown to be unrepresentative of long-term change. For example, previous studies have identified post-1960 river flow decreases in southern and eastern Europe: in parts of eastern Europe, these trends are resilient to study period, extending back to the 1930s; in southern France, longer records show evidence of positive trends which reverse from the 1960s. Recent (post-1960) positive trends in northern Europe are also not present in longer records, due to decadal variations influenced by the North Atlantic Oscillation. The results provide a long-term reference for comparison with published and future studies. The multi-temporal approach advocated here is recommended for use in future trend assessments, to help contextualise short-term trends. Future work should also attempt to explain the decadal-scale variations that drive short-term trends, and thus develop more sophisticated methods for trend detection that take account of interdecadal variability and its drivers.

Patterns of Population Movement and Long-Term Population Growth in Southwestern Colorado

1988 ◽  
Vol 53 (4) ◽  
pp. 773-793 ◽  
Author(s):  
Sarah H. Schlanger
Keyword(s):  
Population Growth ◽  
Local Level ◽  
Climatic Conditions ◽  
Population Increase ◽  
Population Movement ◽  
Water Control ◽  
Short Term ◽  
Population Movements ◽  
History Of

In spite of considerable fluctuations in the likelihood of agricultural success from place to place and from time to time, the southern Colorado Plateaus show a smooth increase in farming populations between A.D. 1 and 1150. At the local level, however, population curves in this region often register a pattern of short-lived occupations and abandonments that are tied to specific patterns of short-term and long-term climatic conditions. The prehistoric population record from the Dolores area, in the southwestern corner of Colorado, demonstrates how localized population adjustments to climatically sensitive environments can result in long-term population increases. Here, a 600-year history of population increase was maintained primarily through population movements between environmentally complementary places. When that strategy failed, due to a combination of adverse short-term and long-term climatic conditions, agricultural methods shifted from rainfall farming to intensified agriculture supported by water-control facilities.

Development, Survival and Reproduction of Camnula pellucida (Scudder) (Orthoptera: Acrididae) in Relation to Climatic Conditions

1966 ◽  
Vol 98 (2) ◽  
pp. 158-169 ◽  
Author(s):  
R. Pickford
Keyword(s):  
Decisive Role ◽  
Climatic Conditions ◽  
Reproductive Capacity ◽  
Short Term ◽  
Rate Of Development ◽  
Weather Patterns ◽  
Survival And Reproduction ◽  
Hot Weather ◽  
Very High

AbstractField-rearing studies of Camnula pellucida (Scudder) conducted at Saskatoon from 1960 to 1962 indicated that marked differences often occurred in rate of development, survival and fecundity because of differing weather patterns. Grasshoppers usually developed more rapidly as they hatched later in the season when temperatures were rising. In addition, striking differences occurred in growth rates of grasshoppers hatched on similar dates in different years due to sharply contrasting climatic conditions. Although survival of nymphs was generally high, mortality was consistently greatest during early nymphal life. Precipitation or excessively hot weather during this period increased mortality considerably, yet did not affect the older nymphs. Survival of adults was also generally high whether they fledged early or late in the season. They were able to endure very high temperatures during mid-summer or below freezing temperatures during late autumn. The three-year average reproductive capacity of this grasshopper was approximately eight egg-pods or 176 eggs per female. The rate of oviposition varied with temperature, reaching a maximum per female of approximately one pod every four days during mid-summer when temperatures were high and declining thereafter as temperatures dropped. The average egg-pod contained 22.13 eggs which showed a tendency to increase as adults fledged later in the season.It is suggested that climatic conditions frequently play a decisive role in the short-term modification of grasshopper infestations as well as in the long-term cyclic rise and fall in populations; consistently favourable or unfavourable conditions throughout the grasshopper cycle could result in an explosive outbreak or in almost complete elimination of any threat to the crop.

scholarly journals Long-Term, Seasonal and Short-Term Fluctuations in the Water Level of the Southern Baltic Sea

2014 ◽  
Vol 33 (3) ◽  
pp. 181-197 ◽  
Author(s):  
Tomasz Wolski ◽  
Bernard Wiśniewski
Keyword(s):  
Baltic Sea ◽  
Water Level ◽  
Sea Level ◽  
Tide Gauges ◽  
Short Term ◽  
Sea Levels ◽  
Extreme Sea Levels ◽  
Solar Tide ◽  
Southern Baltic

Abstract Aim of this work are analyses of oscillations sea levels in the Southern Baltic on a scale of short-term changes, seasonal and long-term (age). The study was based on observational data in different periods time for tide gauges station of the Polish coast. On the example of some storm situations presents the part of the baric wave and the wind in the formation of extreme sea levels. The primary cause of the annual variability of sea levels was the characteristics of the annual and semi-annual oscillations (the annual and semi-annual solar tide). In the work also determined the rate of long-term sea-level rise for the Polish coast.

scholarly journals Examining the Export-led Growth Hypothesis: The case of Croatia

2015 ◽  
Vol 61 (3) ◽  
pp. 22-31 ◽  
Author(s):  
Vlatka Bilas ◽  
Mile Bošnjak ◽  
Sanja Franc
Keyword(s):  
Gross Domestic Product ◽  
Equilibrium State ◽  
Granger Causality ◽  
Domestic Product ◽  
Short Term ◽  
Goods And Services ◽  
Subsequent Period ◽  
The Relationship ◽  
Growth Hypothesis

Abstract This paper examines the relationship between gross domestic product and exports of goods and services in Croatia between 1996 and 2012. The research results confirmed unidirectional Granger causality from the exports of goods and services to gross domestic product. Following the Engle-Granger approach to cointegration, long-term equilibrium as well as short-term correlation between the observed variables was identified. Exports of goods and services and gross domestic product (GDP) in Croatia move together. If the two observed variables move away from equilibrium, they will return to their long-term equilibrium state at a velocity of 24.46% in the subsequent period. In accordance with the results, we found evidence supporting the export-led growth hypothesis in Croatia. As the outcomes indicated, to recover the economy, Croatia should put more emphasis on the development of exporting sectors.

scholarly journals A climate-based model for tick life cycle: an infinite system of differential equation approach

2021 ◽  
Author(s):  
Cyrine Chenaoui ◽  
Slimane Ben Miled ◽  
Mamadou Sadio Ndongo ◽  
Papa Ibrahima Ndiaye ◽  
Mourad Rekik ◽  
...  
Keyword(s):  
Physiological State ◽  
Adult Mortality ◽  
Climatic Conditions ◽  
Tick Population ◽  
Climatic Data ◽  
Temperature Dependent ◽  
Short Term ◽  
Climate Conditions ◽  
Survival And Development

AbstractThe distribution of ticks is essentially determined by the presence of climatic conditions and ecological contexts suitable for their survival and development.We have developed a general tick biology model to study the major trends due to climate change on tick population dynamics under different climate conditions.We build a model that explicitly takes into account stage into each physiological state through a system of infinite differential equations where tick population density are structured on an infinite discrete set. We suppose that intrastage development process is temperature dependent (Arrhenius temperatures function) and that larvae hatching and adult mortality are temperature and precipitations dependent.We analysed mathematically the model and have explicit the R0 of the tick population. Therefore, we performed a numerical analysis of the model under three different climate conditions (tropical, Mediterranean and subarctic climates) over the short term using climatic data from 1995 to 2005, as well as long-term simulations from 1902 to 2005.

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