Sediment transport modeling at Stono Inlet and adjacent beaches, South Carolina

This report documents a numerical modeling investigation for dredged material from nearshore borrow areas and placed on Folly Beach adjacent to Stono Inlet, South Carolina. Historical and newly collected wave and hydrodynamic data around the inlet were assembled and analyzed. The datasets were used to calibrate and validate a coastal wave, hydrodynamic and sediment transport model, the Coastal Modeling System. Sediment transport and morphology changes within and around the immediate vicinity of the Stono Inlet estuarine system, including sand borrow areas and nearshore Folly Beach area, were evaluated. Results of model simulations show that sand removal in the borrow areas increases material backfilling, which is more significant in the nearshore than the offshore borrow areas. In the nearshore Folly Beach area, the dominant flow and sediment transport directions are from the northeast to the southwest. Net sediment gain occurs in the central and southwest sections while net sediment loss occurs in the northeast section of Folly Island. A storm and a 1-year simulation developed for the study produce a similar pattern of morphology changes, and erosion and deposition around the borrow areas and the nearshore Folly Beach area.

Spatial and Temporal Variability in the Occurrence and Abundance of European Hake Larvae, Merluccius merluccius, on the Galician Shelf (NE Atlantic)

The European hake (Merluccius merluccius) is represented as one of the most valuable fisheries in the Galician shelf. We analyzed the distribution, abundance, and environmental conditions of the southern-stock European hake larvae from the Galician shelf during the two main spawning peaks, winter-spring and summer, based on the data from three ichthyoplankton surveys (March 2012, March 2017, and June 2017). A total of 395 larvae in March 2012, 121 in March 2017, and 69 in June 2017 were captured. The northeast section of the study area, close to Estaca de Bares, primarily between 100 and 200 m isobaths, had the highest presence of the European hake larvae in all surveys. Generalized additive models (GAMs) indicated that the occurrence of larvae was significantly different between the surveys and was associated negatively with the temperature, while the abundance of larvae was significantly different between sampling years and was the highest at a temperature around 13.36°C and at sea surface heights of about −0.48 m. Studies of the distribution of early life stages and their relation to external conditions are essential to the understanding of the complex process of recruitment, especially in the exploited species and in highly dynamic environments like the Galician shelf.

GEOSPATIAL ANALYSIS OF THE FOREST LAND OF FOOTHILL AND LOWLAND PARTS OF THE UKRAINIAN CARPATHIANS (ON THE EXAMPLE OF DROHOBYCH DISTRICT, LVIV REGION)

The forest cover of Drohobych district is vectorized with the help of remote sensing of the Earth based on space images QuickBird. The geospatial analysis of forest lands of the foothills and lowlands of the Ukrainian Carpathians has been carried out. It is found that the proportion of forest throughout the region is higher than the average forest cover of Lviv region and more than doubled the average forest cover of Ukraine. Even though the forest cover of Drohobych district is more than optimal indicators for this natural area, forest land is extremely unevenly distributed. A created schematic map of forest resources has shown that the most forested is the mountainous part of the region with the absolute height between 500-1000 m, which decreases in the direction from southwest to northeast. Forest area significantly decreases at the changeover to Drohobych Upland, because of the extension of the boundaries and areas of influence of the Drogobych agglomeration increasing densities of human settlements. In the northeast section of the region, the forest is almost missing due to the significant agricultural development in the plains with a superior absolute height between 250–300 m. For the better analysis of the forest cover of the territory, the geoinformation model of the forest cover of Drohobych district from the perspective of administrative units is created and analyzed. This model allows to classify administrative units according to the proportion of forest land in 6 categories because a considerable variation of indicators is seen in the region. From completely deforested administrative units to rural councils in mountainous areas, where the proportion of forest areas is more than 70%. Administrative units with an insufficient level of reforestation, which are half of all in Drohobych district and with the reforestation level lower than average in Ukraine, are featured. Features of the geospatial distribution of such indicators are noted. It is analyzed that forest cover in urban and rural councils changes from significant in the town council of Boryslav to almost missing forest areas in the rural council of Medenychi. The reasons for such differences between the indicators are identified and the peculiarities of household land development of the territories that belong to urban and rural councils are stated. Key words: forest cover; decryption of ERSD; geoinformation modeling; optimization of natural resources.

Morphological and ice dynamic changes induced by the formation of proglacial lakes in Exploradores Glacier, Patagonia.

<p>Glacier dynamics are sensitive to the formation and expansion of proglacial lakes. Proglacial lakes development can accelerate glacier retreat rate by flotation of the terminus, formation of a calving front, and increased ice flow. Understanding the impacts of proglacial lakes formation and development, which are reported to be growing in number in Patagonia and other regions, is relevant to improve the understanding and prediction of glacier response to climate change.</p><p>This study aims to characterize and monitor recent spatial and temporal changes in the lower section of the Exploradores Glacier (15 km2), located at the northeast section of the Northern Patagonian Icefield. A proglacial lake located at the east margin has been expanding by calving since the early 2000s, and supraglacial ponds located at the front of the glacier could coalesce to form a larger proglacial lake.</p><p>We performed repeated unmanned aerial vehicle (UAV) surveys to obtain a series of high-resolution orthoimages (10cm/pixel) and digital elevation models (DEM) of the lower section of Exploradores Glacier. The series consists in 7 orthoimages and DEMs across one year (March 2019 to March 2020), forming in a dataset that is the first of its kind for a Patagonian glacier. The images are processed by photogrammetric technique structure from motion using Pix4D software, and are co-registered using stable off glacier tie-points. Next, the orthoimages are correlated using a feature tracking algorithm (IMCORR) to derive glacier flow velocities. Surface lowering and morphological changes is obtained by DEM differencing analysis. In addition, an aerial photographic archive (Aniya et al. 2017) providing a 20-year observation record is incorporated in the analysis. The results of the imagery analysis are compared with in-situ ablation stakes measurement during the summer season 2019-2020, which indicates downwasting rates up to 100mm/day. This allows estimating rates of proglacial lake expansion at the east margin, supraglacial lakes coalescence, and increase in debris-covered area.</p><p>This study contributes to a better understanding of the processes that occur during a relatively short period in a highly transient glacier. Future work will include modelling ice dynamics to better characterize and predict the response of the glacier to the development of proglacial lakes.</p>

Using current hydrological conditions to better understand holocene ecohydrological dynamics in oligotrophic peatlands of north-central Quebec, Canada

<p>The biogeographic limit of the peatlands in the central-north Quebec region (53°80’-53°85’N) corresponds to the ecotone between the open boreal forest and the forest-tundra.  At this latitude, peatlands are mainly represented by patterned fens that developed in topographic depressions of the Precambrian Shield. They are characterized by mildly minerotrophic conditions with  surface patterning similar to that observed in western Labrador, central Sweden and the aapa mires of northern Finland.  In eastern Canada,  patterned peatlands have shown  ecohydrologic disequilibrium during the last centuries expressed by a general water table rise with degradation of strings and expansion and coalescence of pools. It has been shown that peatlands in this region present a similar pattern of ecohydrological disequilibrium to those documented in the northeast section of the La Grande River watershed, subarctic Quebec (54°00’N-54°05’N) and this confirms the importance of investigating their ecohydrological vulnerability to natural and anthropogenic pressures in terms of hydrology and carbon balance. A multidisciplinary project was initiated to quantify the hydroclimatic changes that may have influenced the ecohydrologic disequilibrium phenomenon using two peatlands control sites. The results presented here focus on the current water budget of the peatlands and aim at identifying the parameters that influence most significantly peatland hydrology and its connection to the surrounding aquifer. The two peatlands were instrumented with 15 piezometers (in the peat and in the aquifer) where groundwater levels were measured during two growing seasons. Peatland characterization included peat depths, peat hydraulic conductivities (six cores, Modified Cube Method), hydraulic gradients and surface outflow rates. Preliminary results from time series analyses and water budgets show indications of groundwater inflows at each site. If confirmed, these results would comfort the hypothesis that the peatlands are sensitive to hydro-climatic variations with more precipitation inducing higher groundwater levels and thus increased groundwater inflow to the peatlands. Using quantitative paleoclimate reconstructions (pollen, macrofossils and testate amoeba), it has been shown that the two peatlands have registered hydroclimatic periods with potential groundwater input sufficient to induce a shift from bog to fen in these ecosystems. Inversely, a recent shift from fen to bog during  the 20th century suggest that enhanced plant productivity with the lengthening of the growing season duration might influence a decrease of groundwater input in the peatlands The warmer climate shift under way is expected to induce even more of these changes, thus increasing further the large-scale phenomenon as observed in peatlands of northeastern Canada.</p>

APARICIÓN DEL PEZ LEÓN, PTEROIS VOLITANS (ACTINOPTERYGII: SCORPAENIDAE), EN LA CIÉNAGA GRANDE DE SANTA MARTA: CAÍDA DEL ÚLTIMO REDUCTO

Pterois volitans has invaded the continental Colombian Caribbean in less than four years, occurring in almost all coastal systems and structures. In September 2013, an adult specimen of this species was fihed in the Ciénaga Grande de Santa Marta, a large estuarine lagoon located in northern Colombia, Magdalena province, northeast section of the Magdalena River delta (10° 43’- 11° 00’ N and 74° 16’- 74° 43’ W). This, the fist record of this fih in that ecosystem, confims the complete occurrence of the invader in all the Colombian Caribbean ecoregions.