ANALISIS ABRASI DAN AKRESI PERAIRAN PANTAI BARUS TAPANULI TENGAH DENGAN MODEL CEDAS 2.0

Barus is an area where most of the people are fishermen, this is because Barus is an area located on the coast. The existing condition shows the shoreline on the east side of the seawall building, the condition of the shoreline is experiencing abrasion resulting in the retreat of the coastline and almost reaches the fisherman's flat building area, this is due to the port building in the form of a massive trester jutting into the sea resulting in sediment supply to the retained flat towers and the coastline has declined.To maintain the stability of the coastline, it is necessary to make an effort to control the damage to water in this area. The shoreline model is a numerical forecast model based on the sediment continuity equation and the sediment transport rate equation along the coast. Sediment transport rates along the coast are a function of the variation in height and direction of waves along the coast formed by the effects of refraction and diffraction. The results of the shoreline change model with the protection of the fisherman's flat area from waves by building sea walls is the east side of the fisherman's towers abrasion ± 7 m and sedimentation ± 5 m, the front area of the fisherman's towers does not occur sedimentation or abrasion, the western side of the fisherman's towers does not sedimentation and abrasion occurred, the east side of Barus Jetty did not occur abrasion or sedimentation, the area of Barus Jetty occurred ± 20 m sedimentation, and the west side of Barus Jetty occurred sedimentation ± 9 m. These results indicate that for handling conditions by making a seawall in front of the flat area shows that the location is safe from scouring of waves

Variation Tendency of Coastline under Natural and Anthropogenic Disturbance around the Abandoned Yellow River Delta in 1984–2019

The coast around the Abandoned Yellow River Delta underwent significant changes under anthropogenic disturbance. This study aims to reveal the variation of the coastline, tidal flat area, and intertidal zone slope before, during, and after extensive reclamation during the period of 1984–2019 using satellite remote sensing images. In order to eliminate the influence of the varying water level, a new coastline correction algorithm had been proposed under the condition of insufficient accurate slope and water level data. The influence of seawalls on slope estimation were considered in it. The spatiotemporal evolution of coast had been analyzed and confirmed to be reasonable by comparing with the observed data. The results show that the coast can be roughly divided into a north erosion part and a south deposition part. Affected by reclamation, their tidal flat area in 2019 is reduced to only 43 and 27% of original area in 1984, respectively, which results in a continuous decrease in the tidal flat width. The adjustment of the tidal flat profile makes the slopes steeper in the erosion part, while the slopes in the deposition part remain stable. The reclamation has stimulated a cumulative effect as the disappearance of the intertidal zone, which may lead to the destruction of biological habitats.

Intelligent restoration of ancient murals based on discrete differential algorithm

Many defects now appear in ancient murals due to both natural and man-made factors. To better repair the damaged ancient murals, this paper improves the existing intelligent restoration method. It identifies and marks the crack-producing area, categorizes the mural image into two types – texture area and flat area according to the local gradient features, decides the initial sample block and calculates the weight, analyzes the extracted pixel data and applies discrete differential algorithm to supplement image defects. Through experiments, the method is validated in meeting the needs of image continuity law and human vision. It can shorten the repair time and restore mural cracks in an intelligent way.

Pemetaan Kompleksitas Habitat Dasar Perairan Menggunakan Data Batimetri di Perairan Pulau Kemujan Karimunjawa

The complexity of the substrate of the bottom waters describes the diversity of the bottom structure of the waters. The structure of the complexity of bottom waters can be measured by the rugosity. Manual method for measuring rugosity can be used chain method. Besides that rugosity can be calculated using bathymetry data using Surface Area from Elevation Grid Extension tools that integrated in ArcGIS which produces Arc-chord ratio (ACR) rugosity. Based on this method, a flat area has rugosity close to 1, while an area with high elevated will show rugosity value higher then 1 (>1). Measurement of the complexity of the bottom waters is carried out to see the condition of benthic habitat in the shallow waters of Kemujan Island, Karimunjawa Islands. Based on the rugosity index, conditions of bottom waters of the Kemujan Island are quite complex (ACR rugosity index, 2-2.044). The ACR rugosity index correlated quite well with the rugosity index of the field measurement (r = 0.76). Kompleksitas dasar perairan menggambarkan keragaman struktur dasar perairan. Struktur kompleksitas suatu dasar perairan dapat diukur dengan tingkat kekasaran (rugosity) dasar perairan. Metode pengukuran rugosity secara manual dilakukan dengan menggunakan metode rantai (chain). Selain itu rugosity juga dapat dihitung dengan menggunakan data kedalaman dengan menggunakan Surface Area from Elevation Grid Extension yang terintegrasi pada ArcGIS yang menghasilkan Arc-chord ratio (ACR) rugosity. Berdasarkan metode ini daerah datar memiliki nilai rugosity mendekati 1, sedangkan area dengan relief tinggi akan menunjukkan nilai rugosity yang lebih tinggi (>1). Pengukuran kompleksitas dasar perairan dilakukan untuk melihat kondisi habitat dasar di perairan dangkal Pulau Kemujan Kepulauan Karimunjawa. Berdasarkan indeks rugosity, kondisi dasar perairan Pulau Kemujan memiliki kompleksitas yang cukup tinggi (indeks ACR rugosity 2-2.044). Hal tersebut menggambarkan kondisi dasar perairan di sekitar lokasi penelitian cukup beragam. Indeks rugosity ACR berkorelasi cukup baik dengan indeks rugosity hasil pengukuran lapangan (r=0.76).

Tidal Flat Extraction and Change Analysis Based on the RF-W Model: A Case Study of Jiaozhou Bay, East China

Coastal tidal flats are important ecological resources. As the dividing line between marine and terrestrial ecosystems, tidal flats provide a large number of ecosystem services. However, with the excessive development of coastal areas, tidal flat resources have been drastically reduced, leading to the deterioration of coastal ecosystems. There is an urgent need to acquire accurate information on the changes in tidal flat resources. This research proposes a tidal flat extraction model (RF-W model) that combines the random forest (RF) method and waterline method, which aims to improve the accuracy of tidal flat extraction. This method can effectively eliminate the shortcomings of the RF method in determining the lower boundary of tidal flats and those of the waterline method in distinguishing river channels and tidal flats. The tidal flat extraction of Qingdao Jiaozhou Bay in 2020 is performed as an example of the model. The results show that the user’s and producer’s accuracies of the RF-W model were both the highest, indicating that the improved model can accurately extract tidal flat information. Then, we used the RF-W model to extract tidal flat information for Jiaozhou Bay in seven periods (1990, 1995, 2000, 2005, 2010, 2015, and 2020) and to study the spatiotemporal changes in the tidal flats and influencing factors from 1990 to 2020. The tidal flat area of Jiaozhou Bay showed an overall downward trend before 2015, and the area decreased by 21.9 km2, with a reduction in the rate of approximately 1.1%/year. After 2015, the tidal flat area rebounded slightly. The overall change in Jiaozhou Bay showed reclamation and expansion toward the sea. The reduction in the sand content of the rivers entering the sea, reclamation and cultivation, and land development were the main factors contributing to the reduction in the tidal flat area in Jiaozhou Bay. In addition, sea level rise due to climate warming is a long-term potential factor.

Submarine groundwater discharge (SGD) in the springs of Sahlenburg tidal flat, Germany: a geochemical approach.

<p>Submarine groundwater discharge (SGD) is an important connection between fresh groundwater and the marine ecosystem. The scientific interest in SGD has grown considerably during the last decades due to the recognition of SGD in coastal environments as a significant source of nutrients and pollutants.  The Sahlenburg area (Northern Germany) is known by its highly permeable sediments and high rainfall precipitation that produces a large reservoir of groundwater.  Such characteristics are essential for industry, agriculture and drinking water supply with a large regional importance. In addition, this groundwater discharges in the form of highly productive springs directly into the adjacent tidal flats, with so far unknown effects on the local biogeochemistry.  The aim of this study was to characterize the spatial distribution of salinity, fluorescence dissolved organic matter (FDOM), dissolved organic matter (DOC) and total dissolved nitrogen (TDN) of the springs of Sahlenburg tidal flat area in Cuxhaven, Germany. We hypothesize that the SGD composition is changing on its way through the tidal flat due to biogeochemical factors. This may affect the composition of the water in the final part of the pathway with more influence of seawater. Porewater springs were sampled in February 2019 during low tide in three different types of locations in the tidal flat area: nearshore where the springs are located close to the vegetated shoreline (salt marsh), offshore approximately 70 meters from the vegetation and in the middle from both locations. In addition, porewater from a nearby sandy beach (around 500 meters away from the area of spring sampling), and surface samples from a nearby lake and seawater, were obtained. Salinity and FDOM were measured in situ, and DOC and TDN in the laboratory.  The preliminary data showed low average values for salinity in all springs (0.2-1.4), as well as in beach porewater, indicating strong influence of fresh groundwater in the whole area. When comparing the three spring location types, the lowest salinities were found offshore, and the highest nearshore. This difference could be due to the size of the springs, since nearshore springs usually were smaller when compared to offshore springs. Furthermore, depressions in the tidal flat relief close to nearshore springs favored seawater retention in pools during low tide. Additionally, we found higher average values for DOC and FDOM in the nearshore when compared with the other spring areas, but lower compared to the lake, beach porewater and seawater. The average values for TDN (272-452 µmol L<sup>-1</sup>) in the groundwater springs were higher when compared to all other sample types (beach porewater, seawater, and lake water) in this study. These values suggest an anthropogenic input (e.g., agriculture influence) in the surrounding watershed and might stimulate primary productivity in the tidal flat. We conclude that groundwater springs in Sahlenburg tidal flat differ locally in their biogeochemistry due to different residence times, heterogeneity of sediment layers, and size of the springs.</p><p> </p>

A Hybrid Breaching-Filling method for sink removal adapted to parallel hydrological simulations

<p>Digital Elevation Models (DEMs) are approximations used for hydrological simulations and flood mapping. Usually, DEMs have sinks corresponding to actual landscape depressions and/or engineered structures such as bridges, road embankments, overhangs, dams... over or near to water bodies. These sinks often result from interpolation errors or measurement inaccuracies. Regardless of the source, sinks usually cause issues in hydrological simulations.</p><p>Classical filling and breaching methods have shown performance limitations. On one hand, a breaching method cannot deal with big sinks such as sinkholes and lakes in a fair manner as it may yield a long and deeply incised breach channel (lindsay 2016) . On the other hand, even though favored among practitioners, filling a sink may yield a flat area whose altitude is the same as its outlet. Therefore, hybrid methods combining breaching and filling were introduced. Lindsay (2016) presented a hybrid method called “Selective breaching” where a threshold sink depth is defined. As noted in Martz and Garbrecht (1999), a flat area near to the drainage basin outlet impacts the computation of flow direction and the subsequent hydrological simulation.</p><p>A watershed partition into hydrological sub-units, e.g. (Hariri 2019)  allows for the parallelization of hydrological simulations. However, the larger the number of drainage basins and outlets, the more opportunities of having flat areas near outlets are met.</p><p>As an automatic mitigation, we propose a hybrid method blending a carved DEM and a filled DEM based on the distance to the outlet to take advantage of both methods.</p><p>The impact of the different methods to deal with sinks are evaluated for the Moderbach watershed (89 km², Région Grand-Est, France) chosen for its numerous engineering structures (5 big reservoirs, 6 large dams, 3 flood detention areas, roads and highway) comparing the results produced by a mixed-hybrid finite element code for surface flow simulation (Younes 1999) and HEC-RAS (Brunner 1994). The results show that the hybrid method we proposed overcomes the limitations of the classic filling and breaching and it is well adapted for parallel computing.</p><p> </p><p> </p><p>Bibliography</p><p>Brunner GW. HEC river analysis system (HEC-RAS). US Army Corps of Engineers, Hydrologic Engineering Center. 1994.</p><p>Hariri S, Weill S, Gustedt J, Charpentier I. Pairing GIS and distributed hydrological models using Matlab 2. CAJG - 2nd Conference of the Arabian Journal of Geosiences. 2019 Nov.</p><p>Lindsay JB. Efficient hybrid breaching‐filling sink removal methods for flow path enforcement in digital elevation models. Hydrological Processes. 2016 Mar 15;30(6):846-57.</p><p>Martz LW, Garbrecht J. An outlet breaching algorithm for the treatment of closed depressions in a raster DEM. Computers & Geosciences. 1999 Aug 1;25(7):835-44.</p><p>Younes A, Mose R, Ackerer P, Chavent G. A new formulation of the mixed finite element method for solving elliptic and parabolic PDE with triangular elements. Journal of Computational Physics. 1999 Feb 10;149(1):148-67.</p>

Application of decomposition method for calculation of electrical conductivity of shungite based on the electron-microscopic cards of carbon distribution.

The outlook of using the shungite for covering large area which can protect something from electromagnetic radiation is described. As a main parameter which determines the efficiency of created screens is determined the specific electrical conductivity of shungite carbon. For the measuring of conductivity it is proposed to use the high-resolution raster electron microscopy which make be possible to obtain the card of carbon distribution in the scale of some nanometers. The method of binarization of this card is proposed. This binare card describes the spatial distribution of two phases – large-conducting and small-conducting. The large-conducting phase consist of graphene slides. The small-conducting phase consist of chaotic distributed atoms of carbon. On the basis of binare card it is constructed the flat-area block which is looked as net from square cells having two colours – black and white which correspond one by one to large and small-conducting phases. On the area of block it is selected tubes of current which consist of straight chains of black and white cells connected in succession. The whole resistance of block is determined by parallel connection of these tubes. It is proposed the procedure of constructing this symmetrical block along two coordinates. The scheme of this construction is proposed. The calculation of block resistivity along two coordinates is executed. On the basis of flat-area block it is constructed the space elementary block which has equal to each other resistance along three coordinates. For the determination of specific resistance of material as a whole it is carried out the procedure of decomposition which consist of presentation the unit volume of specimen as a set of elementary blocks. For the real specimens of shungite from two natural deposits it is made the calculation of specific resistance and specific conductivity of shungite carbon. It is established that the calculated data are coincide with data received by contact method in the accuracy of 30%. As a most advantage of proposed method it is established the possibility of conductivity measuring of carbon part of shungite in the scale of some units of nanometers.