Prediction of Shoreline Change for the Calculation of the Integrated Littoral Sediment Budget

The severe coastal erosions are being accelerated along the east coast of South Korea owing to the intermittent erosions and depositions caused by the imbalance between the effective sediment volume supplied from coasts and rivers and the sediment transport rate. Consequently, many studies are being conducted to develop coastal-erosion reduction measures. To accurately determine the cause of coastal erosion, the causes of the erosion and deposition should be accurately diagnosed, and a comprehensive evaluation system for the sediment transport mechanism in the watershed and sea while considering regional characteristics is required. In particular, realizing the evaluation of the effective sediment volume that flows from the river to the sea through observations is a highly challenging task, and various research and developments are required to realize it, as it is still in the basic research stage. The purpose of this study was to systematically analyze the comprehensive sediment budget for coastal areas. First, an analytical system was developed. Then, a shoreline model was constructed by considering the size of the mixed particles. The parameters required for developing the model were determined using the observation data to improve the shoreline model. A sediment runoff model was applied to evaluate the effective sediment volume supplied from the river to the sea, and the applicability of this model was evaluated by comparing it with the sediment supply volume according to the soil and water assessment tool model. The representative wave and the input parameters of the model were set using the observation data of several years. It was found that the prediction performance of the shoreline change model improved when the effective sediment volume was considered, and the particles of the sediment on the shore were assumed to comprise multiple sizes. In particular, the prediction performance improved when the balance of the sediment budget was adjusted by applying a groin having a structurally similar performance to take into consideration the geographic features of the Deokbongsan (island) in front of the river mouth bar. The model demonstrated a good performance in reproducing long-term shoreline changes when the characteristics of the sea waves and the effective sediment volume were considered.

Dynamics of Terrace Adoption, Propagation, Benefits & Challenges among Dryland Agro-Pastoralist Communities of West Pokot

Conventional approach of establishing soil conservation strategies in degraded drylands has had negligible success. This has been contributed by many constraints, including; lagging of farmers in technology adoption, inadequate resources, and lack of motivation. Thus, a study was conducted among three agro-pastoral community farmer groups in Korellach Parak, Kapkitony, and Kaporowo villages domiciled in Chepareria ward, West Pokot, Kenya, to assess contributory factors and consequences of adopting terracing as a soil conservation measure. Mixed methods comprising; one-on-one interviews, cross-sectional field measurements, and focus group discussions (FGDs), were used for data collection. Results indicate that the agro-pastoral communities are fully aware of soil degradation and its impacts. Besides terracing, farmers practice stone bands, enclosures, agroforestry, and ridges. Terracing is a recently adopted farm-level soil conservation practice achieved through organized farmer groups dubbed “Kemorokorenyo” (meaning let us reclaim our land) merry-go-round. Within the three villages, 60% of the households have their farms terraced with an average terrace volume of 103.8±21.45m3, 105.89±33.126m3, and 129.6±15.966m3 in Parak Kapkitony and Kaporowo, respectively. Rapid sedimentation of terraces dykes, which contributes to the reduced effectiveness of the terrace system was identified as the major challenge. The sediment volume significantly differs along the slope, with the highest sediment build-up experienced on high slopes as shown by the Kruskal Wallis test; H (2) =6.699, p=0.035. Terrace embankments reinforcement practice to counter sedimentation challenge has faced slow adoption. The poor reinforcement is attributable to the lack of knowledge on suitable local context multipurpose materials to meet the community’s needs.

Novel helical or coiled flocculator for turbidity reduction in drinking water treatment: a performance study

Helical or spiral coiled flocculator have not been applied in drinking water treatment yet in Indonesia. There were only a few articles discussed it with different themes like hydrodynamic, floc characteristic, and performance. This study was done to know the efficiency (performance) of helical flocculator with parameters velocity gradient, pipe and helical diameter, flowrate, detention time, coagulant dose. The study was divided into two steps: Jar test to determine the optimum dose of coagulant and flocculation experiments to evaluate the helical flocculator efficiency. Efficiencies were in the range of medium to high. On flowrate 13 ml/second was obtained good results for two pipe sizes but different in helical diameters. In 0.5 inch pipe with 0.8 m helical diameter the turbidity reduction efficiencies were 72.4% and 73.9% and sediment volume were 18.3 ml and 20.0 ml. In 0.625 inch pipe with 0.4 m helical diameter the turbidity reduction efficiencies were 76.7% and 78.5% and sediment volume were 14.3 ml and 19.7 ml. The optimum velocity gradient about 64.9–69.6 persecond and detention time about 438–649 seconds. The results showed that helical flocculator was effective for floc formation. Flowrate, pipe diameter, helical diameter were three key parameters to perform helical flocculator.

New Workflow of Sediment Mass Balancing, from Local Datasets, for Predicting Basin Scale Trends

Objectives/Scope Sediment volumetric budget estimates are very important input parameters for process-based depositional modelling (forward stratigraphic modelling). This paper presents a new integrated approach for analyze sediment volumetric budgets in sedimentary basins that is based on the reconstruction of regional grain size trends. In subsurface studies of sediment routing systems, noticeable uncertainties in estimated total sediment volumes occur when available datasets are limited to local areas that do not cover the entire sediment routing system. These uncertainties also affect models of catchment areas, structural uplift, and denudation rates as well as net:gross predictions. Methods, Procedures, Process The new integrated approach focuses on reconstructing sediment budgets for entire sediment fairways from limited local datasets. It uses a combination of sediment mass balancing and local grain size distributions to predict basin-wide grain size distributions. The comparison of local grain size to fairway-scale grain size trends is key in correcting sediment volumetrics for significantly reduced uncertainties in catchment reconstruction and net:gross ratios predictions at the scale of sediment fairways, sub-basins, prospects and exploration/production fields. Results, Observations, Conclusions The new approach has been applied successfully to two subsurface continental to marine delta systems. They cover periods of approximately 7 My in total and include four limited local areas of interest (AOI). These local AOIs measure 200×200 km, while the entire sub-basin measures 500×800 km. The new approach indicates that only up to 40% of the total sediment volume of each fairway could be captured by previous methodologies with limited local areas of interest. A maximum of 70% of the entire sink sediment volume could be incorporated in local areas of interest. The new approach presented in this paper significantly lowers the uncertainties in sediment volume estimates, depositional rates and lithology distribution input parameters in forward stratigraphic modelling. For the two case studies, previous sediment flux models indicated rates of 10,000 km/Myr. The new integrated approach indicates that sediment flux actually reached 30,000 km/Myr with major implications for sediment distribution, net:gross prediction and catchment size and denudation rates estimates. Novel/Additive Information The new integrated approach reduces uncertainties in catchment size and tectonic exhumation rate estimates for clastic depositional systems. It provides lower uncertainty parameters (sediment volume, source locations, sediment fractions, diffusion coefficients) for forward stratigraphic modelling, e.g., for reservoir quality prediction in hydrocarbon exploration. In fundamental research, provenance analyses can be better constrained by improved catchment size prediction and sediment grain size distribution models for sink areas

Micro-Fabric Transformations of Ball Clay in Alkaline Environment

Based on the strong evidence of case histories, this study focused on mineralogical and morphological changes of an artificial kaolinitic soil -Ball clay, when exposed to different concentrations of sodium hydroxide (0.1N, 1N, 4N, and 8N) under different curing periods (7, 28 and 100 days). Sediment volume tests are conducted on Ball clay with all combinations and results are analyzed with the help of analytical techniques. XRD and SEM studies are analyzed to understand the micro-level changes of alkali contaminated Ball clay. Mineralogical and morphological transmutations of Ball clay are investigated for 7, 28, and 100 days curing period. Results revealed new mineral formations like Sodalite under 4N and 8N concentrations of NaOH with 100 days interactions are well observed. The morphological transformation from needle shape to pellet shape is clear evidence of the rate of dissolution and precipitation of minerals under 100 days curing periods.

Perencanaan Pembangunan

Abstarct.Ambon city, which mostly consists of hilly areas, is an area that is very highly susceptible to the occurrence of debris mass movements, both in the form of debris flows and landslides (debris flows, erosions, and slope failures). In the city of Ambon, rivers are passed such as Way Ruhu, Way Batu Merah, Way Tantui, Way Tomu, Way Batu Gajah and Way Batu Hang. The purpose of this paper is to plan the check dam building for Way Batu Merah – Ambon City. The method used is Hydrological Analysis: hydrology as the basis for planning the Q25 Check Dam Building, which consists of rainfall analysis and the basis for calculating the planned discharge used in planning, using the Sabo Technical Center method. From the calculation results, it is obtained that the planned Q25 flood discharge of the Way Batu Merah River is 516.43 m / year with a return period of 25 years, the sediment volume can be accommodated 22,102 m / year and controlled by the Check Dam 56,050 m / year, then with a sediment discharge of 60,685 m³ / year . By comparing the amount of sediment that enters the Check Dam with the capacity of the Check Dam, it is dredged again for 3.5 years.Keywords: Sediment; Hydrological Analysis; Checkdam; Sediment Discharge

PEMETAAN MORFOLOGI DASAR PERAIRAN UNTUK PEMANTAUAN SEDIMENTASI DI DERMAGA PERIKANAN ULEE LHEU MENGGUNAKAN SINGLE BEAM ODOMETER DUA FREKUENSI

ABSTRACTUlee Lheu Fishing Port Jetty is an important port in Banda Aceh City which functions as a crossing, loading and unloading port. The issue of sedimentation is the main problem. This study aims to determine the morphology of the seabed as the basis for monitoring sedimentation at the Ulee Lheu Fishing Port Jetty. Bathymetric surveys were carried out in the dock pool using a single beam echotrack odometer. Tides were obtained using the IOC Sea Level Monitoring for 29 days and analyzed using the admiralty method. The results of the processing showed that there was sedimentation in the area of the Ulee Lheu Fishing Port Jetty. The depth of the wharf pool ranges from 0-7,7 meters with a sediment volume of 250.117,15 m3. Meanwhile, the tidal water type is included in the double daily tidal type with a value of F = 0,15 and the tidal distance is 2,38 meters and is included in the micro tidal range category and there is sedimentation in the Ulee Lheu Fishing Port Jetty.Keywords: Bathymetry, sedimentation, morphology, Ulee Lheu Port, tidal rangeABSTRAKDermaga Perikanan Ulee Lheu merupakan pelabuhan penting di Kota Banda Aceh yang difungsikan sebagai pelabuhan penyeberangan maupun sebagai pelabuhan bongkar muat. Isu sedimentasi menjadi masalah utama di dermaga ini. Penelitian ini bertujuan untuk mengetahui morfologi dasar laut sebagai dasar pemantauan sedimentasi di Dermaga Perikanan Ulee Lheu. Survei batimetri dilakukan di kolam dermaga menggunakan echotrack odometer single beam. Pasang surut diperoleh menggunakan dari IOC Sea Level Monitoring selama 29 hari serta dianalisa menggunakan metode admiralty. Hasil pengolahan menunjukan terjadi sedimentasi di areal Dermaga Perikanan. Kedalaman kolam dermaga berkisar antara 0-7,7 meter dengan volume sedimen berkisar 250.117,15 m3. Sementara tipe pasang surut perairan termasuk dalam tipe pasang surut harian ganda dengan nilai F=0,15 serta jarak tunggang pasut sebesar 2,38 meter dan termasuk dalam kategori mikro tidal range dan terdapat sedimentasi di bagian Dermaga Perikanan Ulee Lheu.Kata Kunci : Batimetri, Sedimentasi, Morfologi, Dermaga Perikanan Ulee Lheu, tunggang pasang surut

Modelling and forecasting reservoir sedimentation of irrigation dams in the Guinea Savannah Ecological Zone of Ghana

Effective management of reservoir sedimentation requires models which can predict sedimentation of the reservoirs. In this study, linear regression, non-linear exponential regression and artificial neural network models have been developed for the forecasting of annual storage capacity loss of reservoirs in the Guinea Savannah Ecological Zone (GSEZ) of Ghana. Annual rainfall, inflows, trap efficiency and reservoir age were input parameters for the models whilst the output parameter was the annual sediment volume in the reservoirs. Twenty (20) years of reservoirs data with 70% data used for model training and 30% used for validation. The ANN model, the feed-forward, back-propagation algorithm Multi-Layer Perceptron model structure which best captured the pattern in the annual sediment volumes retained in the reservoirs ranged from 4-6-1 at Karni to 4-12-1 at Tono. The linear and nonlinear exponential regression models revealed that annual sediment volume retention increased with all four (4) input parameters whilst the rate of sedimentation in the reservoirs is a decreasing function of time. All the three (3) models developed were noted to be efficient and suitable for forecasting annual sedimentation of the studied reservoirs with accuracies above 76%. Forecasted sedimentation up to year 2038 (2019–2038) using the developed models revealed the total storage capacities of the reservoirs to be lost ranged from 13.83 to 50.07%, with 50% of the small and medium reservoirs filled with sediment deposits if no sedimentation control measures are taken to curb the phenomenon.

Short-term seasonal changes of the Dzita beach of Ghana using geographic information system and photogrammetry

Coastal erosion has become an issue globally. As the sea level continues to rise due to global warming, projections are that erosion would increase. To address the issue sustainably, relevant scientific information such as sediment transport and shoreline dynamics is required at local scales. Over the years, erosion at the eastern coast of Ghana has been mainly evaluated using low-resolution imagery due to the challenges in retrieving high-resolution data in the nearshore region. An unmanned aerial vehicle (UAV) approach was used to assess beach evolution on a seasonal and short-term basis between May 2018 and December 2019. Using the UAV approach, shoreline changes, sediment volume changes, and profile elevation parameters were extracted for the Dzita beach of Ghana. Shoreline changes indicated the dominance of erosion during the first and third phases (May 2018 to December 2018 and June 2019 to December 2019, respectively) at a rate of −7.23 ± 0.23 and −4.85 ± 0.23 m/yr, whereas the second phase showed accretion of +8.44 ± 0.23 m/yr. Beach profiles from the first, second, and third phases had steep and gentle slopes, respectively. From these observations, it was recommended that soft engineering approaches such as beach nourishment should be implemented to protect the shoreline and strict prevention of nearshore sand mining and gravel mining. It is also possible that the beach could go through a cycle of changes. Further studies using this same approach should be done as well as probing into other parameters such as nearshore bathymetry to have a better understanding of beach dynamics as envisaged.

Effects of Beach Nourishment Project on Coastal Geomorphology and Mangrove Dynamics in Southern Louisiana, USA

Relative sea-level (RSL) rise associated with decreased fluvial sediment discharge and increased hurricane activity have contributed to the high rate of shoreline retreat and threatened coastal ecosystems in Port Fourchon, Louisiana, USA. This study, based on QuickBird/drone images (2004–2019) and LIDAR data (1998–2013), analyzed the impacts of shoreline dynamics on mangroves (Avicennia germinans) and marshes before and after the initiation of a beach nourishment project in 2013. The coastal barrier and dune crest migrated landward between 1998 and 2013. Meanwhile, the dune crest height increased between 1998 and 2001, then decreased in 2013, probably due to hurricane impacts. The total sediment volume along this sandy coastal barrier presented an overall trend of decline in the 1998–2013 period, resulting in a wetlands loss of ~15.6 ha along 4 km of coastline. This has led to a landward sand migration onto muddy tidal flats occupied by Avicennia germinans (1.08 ha) and Spartina (14.52 ha). However, the beach nourishment project resulted in the advancement of the beach barrier from Nov/2012 to Jan/2015, followed by a relatively stable period between Jan/2015 and Mar/2019. Additionally, both the dune crest height and sediment volume increased between 2013 and 2019. This set of factors favored the establishment and expansion of mangroves (3.2 ha) and saltmarshes (25.4 ha) along the backbarrier environments after 2013, allowing the tidal flats to keep pace with the RSL rise. However, waves and currents caused shoreline erosion following the beach nourishment project between Oct/2017 and Nov/2019, threatening wetlands by resuming the long-term process of shoreline retreat.