Evolution of the Ofanto River delta from the ‘Little Ice Age’ to modern times: Implications of large-scale synoptic patterns

The Holocene ◽  
2018 ◽  
Vol 28 (12) ◽  
pp. 1948-1967 ◽  
Author(s):  
Vincenzo De Santis ◽  
Massimo Caldara ◽  
Antonella Marsico ◽  
Domenico Capolongo ◽  
Luigi Pennetta
Keyword(s):  
Large Scale ◽  
Low Pressure ◽  
River Delta ◽  
Ice Age ◽  
Aerial Photographs ◽  
Anthropogenic Factors ◽  
Synoptic Patterns ◽  
Delta Evolution ◽  
Circulation Mode

We reconstruct the evolution of the Ofanto River delta from the 17th century to the present using historical maps (1600–1850), official IGM topographic maps (1850–1980) and recent aerial photographs (2015), and we compare long-term morphological changes with the evolution of the delta of the Volturno River during the same time period. The aim of this study is to define the role of climatic (flood frequency, synoptic pressure patterns) and anthropogenic factors (deforestation, anthropogenic sediment subtraction of river sediment) in the evolution of the Ofanto delta. We analysed the importance of each factor on the evolution of the delta and compared them with the simultaneous behaviour of the Volturno delta to highlight the role of large-scale synoptic pressure patterns. We found that the main driver of different delta evolution phases is weather-climatic condition, while anthropogenic factors interacted with the delta evolution in different ways but did not control the first-order evolution. In particular, analysing the data on recent floods, we found that the most favourable situations for both rivers are omega-blocking, deep low-pressure trough and strong meridional circulation (mode Ω) which create Mediterranean low-pressure systems. Instead, a zonal circulation (mode W) can only cause floods on Volturno. Because the evolution of a delta is driven by the frequency of floods, and because we found that the frequency of floods is guided by synoptic patterns, a relationship can be established between delta evolution and synoptic patterns in the past. Consequently, past phases of the contemporary progradation of the Ofanto and Volturno deltas suggest the increasing frequency of mode Ω, while phases of simultaneous progradation of the Volturno delta and stability and/or retreat of the Ofanto delta are indicative of the increasing frequency of mode W. The only exception occurred during the last evolutionary phase (60 years), when anthropogenic sediment subtraction was prevalent.

The scientific issues surrounding remote detection of submerged coral ecosystems

1998 ◽  
Vol 22 (2) ◽  
pp. 190-221 ◽  
Author(s):  
Heather Holden ◽  
Ellsworth LeDrew
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Coral Reefs ◽  
Large Scale ◽  
Aerial Photographs ◽  
Coastal Zones ◽  
Global Status ◽  
Coral Reef Ecosystems ◽  
Remote Estimation

According to the 1993 colloquium on the ‘Global status of coral reefs', our understanding of the global role of coral reefs is inadequate. To increase our understanding, an accurate large-scale mapping and monitoring programme is necessary. Historically, coastal zones have been mapped using traditional surveying tools such as topographic maps, nautical charts, existing aerial photographs and direct observations. Although less expensive than digital imagery, exclusive use of these traditional tools may not be practical for monitoring large or remote coral reef ecosystems accurately. Researchers are attempting to develop an adequate coral reef mapping system based on digital remote sensing, but are impeded by issues such as effects of the intervening water column and spectral distinction of bottom types. The two variables discussed, which will contribute to our understanding of the global role of coral reefs, are: 1) remote sensing of submerged coral reefs in general; and 2) remote sensing of coral bleaching in particular. A summary of radiative transfer theory is presented and case studies of attempts at mapping remotely the geographic extent and health of submerged ecosystems, as well as a discussion of the remote estimation of water depth and quality. Problems in the translation and delivery of information to the end user are presented, and possible solutions suggested.

scholarly journals The role of anthropogenic factors in forest transformation in Southern Sakhalin

2021 ◽  
Vol 946 (1) ◽  
pp. 012044
Author(s):  
R N Sabirov
Keyword(s):  
Large Scale ◽  
Forest Cover ◽  
Oil And Gas ◽  
Anthropogenic Factors ◽  
Natural State ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Southern Sakhalin ◽  
Southern Island

Abstract The article analyzes the forests changes in the south part of Sakhalin Island from the original, natural state as a result of its habitation and economic development. The most essential disturbances of forest cover occurred in the first half of the last century when 9 pulp-and-paper mills were built by Japanese in southern island. All acceptable and more productive dark coniferous forests for providing these mills were cut down. Moreover, significant share of the forests was destroyed because of repeated and large-scale fires, creating agricultural lands and habitable territories, construction of roads, power lines, oil-and-gas pipelines, etc. The most considerable forests transformation was on the territory of Yuzhno-Sakhalinsk, and also in Korsakovsky, Dolinsky, Anivsky, Kholmsky and Nevelsky districts.

scholarly journals ТРАНСФОРМАЦИЯ РАСТИТЕЛЬНОСТИ ДОЛИНЫ В СРЕДНЕМ ТЕЧЕНИИ Р. РАЗДОЛЬНАЯ (ПРИМОРСКИЙ КРАЙ) ПО ДАННЫМ СПОРОВО-ПЫЛЬЦЕВОГО АНАЛИЗА

2019 ◽  
Author(s):  
T.V. Kornyushenko
Keyword(s):  
Pinus Densiflora ◽  
Agricultural Landscapes ◽  
Ice Age ◽  
Anthropogenic Factors ◽  
Vegetation Development ◽  
Surrounding Areas ◽  
The Impact ◽  
Natural And Anthropogenic Factors ◽  
Birch Forests

Изучен характер изменений растительности в результате климатических осцилляций в среднем течении р. Раздольная и близлежащих водораздельных пространств, начиная с конца среднего голоцена и при неоднократной трансформации ландшафтов при сельскохозяйственном освоении. Развитие растительности проходило в контрастных климатических условиях, наиболее сильно изменялась увлажненность. Детально реконструкции проведены для последних 2 тыс. кал. л. Изучение споровопыльцевых комплексов позволило выделить шесть споровопыльцевых зон, а также определить специфику формирования палиноспектров, которые включают пыльцу и споры растений, произраставших на данной территории, и пыльцу, принесенную воздушными и водными потоками, в том числе древнюю из нижнемеловых и палеогеннеогеновых отложений. Разрезы включают погребенную почву, сформированную в засушливый период во второй половине позднего голоцена. В это время были широко распространены остепненные полынные, разнотравные луга и березовые редколесья. Климатические условия в конце VIIX вв. постепенно стали более теплыми и влажными. Снижение температуры при высоком увлажнении в малый ледниковый период с постоянным обновлением субстрата на пойме во время наводнений привело к увеличению площадей, занятых сообществами березы овальнолистной. В лесной растительности низкогорья увеличилось участие сосны густоцветковой и берез. Споровопыльцевые комплексы включают пыльцу темнохвойных, в том числе кедра корейского, принесенную во время наводнений из верховий бассейна. Слабо изученным вопросом является оценка воздействия человека на природную среду в средневековье и более ранние эпохи. Не всегда есть информация о том, какой природный облик имела растительность до преобразования в ходе хозяйственной деятельности. Район работ был выбран около Старореченского городища, что дало возможность оценить влияние природопользования во времена Бохайского государства на основе анализа споровопыльцевых комплексов. Проанализирована роль антропогенного фактора в развитии растительности во время заселения долины первопоселенцами XIXначала XX века и при развитии современных агрокомплексов.Studies of floodplain section provided materials for reconstructing a relative importance of natural and anthropogenic factors in the vegetation development in the Razdolnaya (Suifun) River basin near the Starorechenskoye site attributed to the Bohai culture. The transformation of vegetation in the middle reaches of the Razdolnaya River and surrounding areas was influenced by climate change, since the end of the middle Holocene, the impact on vegetation has increased under the influence of agricultural activities. Six pollen zones were distinguished. The studied sequences include a paleosol that developed during a prolonged period of drought at the 2nd half of the late Holocene. The period was noted for a wide occurrence of steppe and forb meadows with wormwood, and open birch forests. The climate became gradually warmer and more humid since the late 7th to 10th centuries. A decrease in temperature at a sufficiently high humidity in the Little Ice Age (the 13th 19th centuries) led to an increase in the areas occupied by the Betula ovalifolia communities. The pollen assemblages display an appearance of dark conifers and Korean pine pollen brought by floods from the upper reaches of the river. In Pinus densiflora and birches gained in importance in the forests of mountain. The recent pollen spectra are indicative of the wide development of agricultural landscapes. The anthropogenic influence to the vegetation was connected with Bohai settlers. The role of the anthropogenic factor in the development of vegetation during the settlement of the valley by the first settlers of the XIXearly XX century and the development of modern agrocomplexes is analyzed.

scholarly journals Variability of low flow magnitudes in the Upper Colorado River Basin: identifying trends and relative role of large-scale climate dynamics

2014 ◽  
Vol 11 (7) ◽  
pp. 8779-8802 ◽  
Author(s):  
M. Pournasiri Poshtiri ◽  
I. Pal
Keyword(s):  
River Basin ◽  
Large Scale ◽  
River Flow ◽  
Colorado River ◽  
Colorado River Basin ◽  
Low Flow ◽  
Anthropogenic Factors ◽  
Relative Role ◽  
Water Abstraction

Abstract. Low flow magnitude in a head water basin is important for planners because minimum available amount of water in a given time period often leads to concerns regarding serious repercussions, in both up and downstream regions. This is a common scenario in arid region like Colorado River basin located in the southwestern US. Low flow variability in Colorado River is due to complex interactions between several natural and anthropogenic factors; but we aim to identify the relative role of climate on varying low flow magnitudes at different spatial locations. The research questions we aim to answer are: Is there a systematic variability in water availability during the driest time of a year or season? How does that vary across locations and is there a link between large-scale climate and low flow variations? Towards that aim we select 17 stream gauge locations, which are identified as "undisturbed" meaning that these stations represent near-natural river flow regimes in the headwater region of Colorado River, which provides a useful resource for assessment of climate and hydrology associations without the confounding factor of major direct (e.g. water abstraction) or indirect (e.g. land-use change) human modification of flows. A detailed diagnostic analysis gives us fair understanding on the variability of low flow magnitude that is explained by climate. We also present spatial heterogeneity of hydro-climatological linkages that is important for suitable adaptive management measures.

scholarly journals Historical glacier outlines from digitized topographic maps of the Swiss Alps

2017 ◽  
Author(s):  
Daphné Freudiger ◽  
David Mennekes ◽  
Jan Seibert ◽  
Markus Weiler
Keyword(s):  
Large Scale ◽  
Swiss Alps ◽  
Ice Age ◽  
Aerial Photographs ◽  
Topographic Maps ◽  
Data Repository ◽  
Glacier Mass Balance ◽  
European Alps ◽  
Glacier Area

Abstract. Since the end of the Little Ice Age around 1850, the total glacier area of the Central European Alps has considerably decreased. In order to understand the changes in glacier coverage at various scales and to model past and future streamflow accurately, long-term and large-scale datasets of glacier outlines are needed. To fill the gap between the morphologically reconstructed glacier outlines from the moraine extent corresponding to the time period around 1850 and the first complete dataset of glacier areas in the Swiss Alps from aerial photographs in 1973, glacier area from 80 sheets of a historical topographic map, so-called Siegfried map, were manually digitized for the publication years 1878–1918 (further called first period, with most sheets being published around 1900) and 1917–1944 (further called second period, with most sheets being published around 1935). The accuracy of the digitized glacier areas was then assessed through a two-step validation process: the data was (1) visually and (2) quantitatively compared to glacier area datasets of the years 1850, 1973, 2003, and 2010, which were derived from different sources. The validation showed that at least 70 % of the digitized glaciers were comparable to the outlines from the other datasets and were therefore plausible. Furthermore, the accuracy of the manual digitization was found to be lower than 5 %. The presented datasets of glacier outlines for the first and second periods were found to be valuable source of information for long-term glacier mass balance or hydrological modelling in glacierized basins if the uncertainty of the historical topographic maps is considered in the interpretation of the results. The datasets can be downloaded from the FreiDok plus data repository (https://freidok.uni-freiburg.de/data/12874, https://doi.org/10.6094/UNIFR/12874).

scholarly journals The role of debris cover in the evolution of Zmuttgletscher, Switzerland, since the end of the Little Ice Age

2019 ◽  
Author(s):  
Nico Mölg ◽  
Tobias Bolch ◽  
Andrea Walter ◽  
Andreas Vieli
Keyword(s):  
Ice Age ◽  
Aerial Photographs ◽  
Volume Loss ◽  
Glacier Surface ◽  
Ablation Area ◽  
Slowing Down ◽  
Debris Cover ◽  
Historic Maps ◽  
Length And Area

Abstract. Debris-covered glaciers often exhibit large, flat tongues. Many of these glaciers show high thinning rates today despite thick debris cover. Due to lack of observations, most existing studies have neglected the dynamic interaction between debris cover and glacier evolution over longer time periods. The main aim of this study is to reveal this interaction by reconstructing changes of debris cover, glacier geometry, flow velocities, and surface features of Zmuttgletscher (Switzerland), based on historic maps, satellite images, aerial photographs, and field observations. We show that debris cover extent has increased from ~ 13 % to > 32 % of the total glacier surface since 1859 and that the debris is sufficiently thick to reduce ablation compared to bare ice over much of the ablation area. Despite the debris cover the volume loss of Zmuttgletscher is comparable to that of debris-free glaciers located in similar settings whereas changes in length and area have been small in comparison. Increased ice mass input in the 1970s and 1980s resulted in a temporary velocity increase, as well as a lowering of the upper margin of debris cover and exposed-ice area, and a reduction of ice cliffs. Since ~ 2001, the lowest ~ 1.5 km are stagnant despite a slight increase in surface slope of the glacier tongue. We conclude that the debris cover governs the pattern of volume loss without changing its magnitude, which is due to the large ablation area and strong thinning in regions with thin debris further up-glacier and in the regions of meltwater channels and ice cliffs. At the same time rising temperatures lead to increasing debris cover and decreasing glacier dynamics, thereby slowing down length and area losses.

scholarly journals Historical glacier outlines from digitized topographic maps of the Swiss Alps

2018 ◽  
Vol 10 (2) ◽  
pp. 805-814 ◽  
Author(s):  
Daphné Freudiger ◽  
David Mennekes ◽  
Jan Seibert ◽  
Markus Weiler
Keyword(s):  
Large Scale ◽  
Swiss Alps ◽  
Ice Age ◽  
Aerial Photographs ◽  
Topographic Maps ◽  
Glacier Mass Balance ◽  
European Alps ◽  
Glacier Area ◽  
Basin Scale

Abstract. Since the end of the Little Ice Age around 1850, the total glacier area of the central European Alps has considerably decreased. In order to understand the changes in glacier coverage at various scales and to model past and future streamflow accurately, long-term and large-scale datasets of glacier outlines are needed. To fill the gap between the morphologically reconstructed glacier outlines from the moraine extent corresponding to the time period around 1850 and the first complete dataset of glacier areas in the Swiss Alps from aerial photographs in 1973, glacier areas from 80 sheets of a historical topographic map (the Siegfried map) were manually digitized for the publication years 1878–1918 (further called first period, with most sheets being published around 1900) and 1917–1944 (further called second period, with most sheets being published around 1935). The accuracy of the digitized glacier areas was then assessed through a two-step validation process: the data were (1) visually and (2) quantitatively compared to glacier area datasets of the years 1850, 1973, 2003, and 2010, which were derived from different sources, at the large scale, basin scale, and locally. The validation showed that at least 70 % of the digitized glaciers were comparable to the outlines from the other datasets and were therefore plausible. Furthermore, the inaccuracy of the manual digitization was found to be less than 5 %. The presented datasets of glacier outlines for the first and second periods are a valuable source of information for long-term glacier mass balance or hydrological modelling in glacierized basins. The uncertainty of the historical topographic maps should be considered during the interpretation of the results. The datasets can be downloaded from the FreiDok plus data repository (https://freidok.uni-freiburg.de/data/15008, https://doi.org/10.6094/UNIFR/15008).

scholarly journals Assessing the Rain estimate from the reflectivity of Nha Be Radar

2018 ◽  
Vol 34 (1S) ◽  
Author(s):  
Cong Thanh ◽  
Nguyen Nhu Quy ◽  
Mai Van Khiem
Keyword(s):  
Large Scale ◽  
Low Pressure ◽  
Southwest Monsoon ◽  
Intertropical Convergence Zone ◽  
Radar Observation ◽  
Convergence Zone ◽  
Rainfall Estimation ◽  
Synoptic Patterns ◽  
Pressure Area ◽  
Southeasterly Direction

Abstract: This study evaluates the estimated rainfall from Nha Be radar observation according to different experimental formulas. The results show that in six estimation formulas used, the formulation of Joss's large-scale rainfall estimation and Marshall-Plamer's formulation can be used to estimate the precipitation for the single southwest monsoon with an error about 5 mm/h and usually less than the observed value. The rainfall estimation formulas by Nguyen Huong Dien is the optimum estimation for the 9 synoptic rainfall patterns: Intertropical Convergence Zone, Southwest monsoon associated with Intertropical Convergence Zone, low-pressure area, thunderstorm, disturbance in East winds, low-pressure area associated with Southwest monsoon, low-pressure troughs have a Northwestern-Southeasterly direction and other synoptic patterns with errors: 5mm/h, 9.5 mm/h, 14 mm/h, 7mm/h, 19 mm/h, 8 mm/h, 8.5 mm/h, 9.5 mm/h and 14.7 mm/h, respectively. Keywords:  Radar, rain estimate.

Coastal morphodynamics in an Arctic fluvial-tidal transition zone in the deglaciated Dicksonfjord, Svalbard

2020 ◽  
Author(s):  
Dohyeong Kim ◽  
Joohee Jo ◽  
Kyungsik Choi
Keyword(s):  
Transition Zone ◽  
Large Scale ◽  
Sediment Flux ◽  
Ice Age ◽  
Aerial Photographs ◽  
Coarse Grained ◽  
The Arctic ◽  
Survey Period ◽  
Sediment Delivery ◽  
Coastal Morphodynamics

<p>Pronounced morphologic changes such as coastal retreat and delta progradation occur widely along the Arctic coastal regions in response to increased sediment flux, freshwater runoff, and wave activity caused by climate changes. Compared to open coast and large-scale deltas in the Arctic region, the coastal morphodynamics and associated sediment transport in the Arctic fluvial-tidal transition zone (FTTZ) are less well understood. A series of recurved spits are developed on the upper intertidal zone of microtidal flats in the FTTZ of deglaciated Dicksonfjorden, Svalbard. The morphodynamics and sediment fluxes of the spit complexes were quantified using unmanned aerial vehicle (UAV)-assisted photogrammetry and Real-Time Kinematic GPS. Repeated annual survey indicates that the spits have elongated at 22 m yr<sup>-1</sup> and have migrated landward at 4.3 m yr<sup>-1</sup> over the last four years. The growth and migration rate of the spits increases seaward, where coastal cliffs consisting of an unconsolidated mixture of angular gravels and muds retreats at 0.2 m yr<sup>-1</sup> with net erosion rate of 0.02 m yr<sup>-1</sup> and provides local sediment source for the spits. In contrast, isolated gravel ridges, i.e., cheniers, on the tidal flats in the further landward did not migrate during the survey period. Archives of aerial photographs indicate that the cheniers had remained stationary since the 1930s, when a shoreline was located near the cheniers. The present study demonstrates that wave-induced overwash and longshore drift of coarse-grained sediments originated from the retreating cliffs are vital to the annual spit morphodynamics even in the innermost part of the fjord. Tidal flat progradation accelerated since the Little Ice Age with global warming trends by increased runoff from snow-fed rivers and alluvial fans, controls the centennial spit morphodynamics and distribution of wave-built morphology in the FTTZ of glacier-free Dicksonfjorden by regulating episodic sediment delivery via a seaward-shift in the locus of wave shoaling.</p>

The Role of Sense of Direction and Other Factors During Navigation in a Large-Scale, Unconstrained Environment

2013 ◽  
Author(s):  
Elisabeth J. Ploran ◽  
Ericka Rovira ◽  
James C. Thompson ◽  
Raja Parasuraman
Keyword(s):  
Large Scale ◽  
Sense Of Direction
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