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The coastline is constantly changing over time. The process of change that occurs continuously makes the coastline dynamic. Shorelines are vulnerable to changes caused by natural and human factors. One of the causes of shoreline changes due to natural factors is tidal flooding. Tidal floods cause abrasion of the coastline and create inundation on land. The coast of Meulaboh City has experienced tidal floods in 2020. The tidal floods that occur make the coastline abrasion and residential areas inundated. This study aims to determine the shoreline changes and the shoreline recovery process due to abrasion and accretion after tidal floods from 2020 to 2021. The shoreline in July 2019, 2020 and 2021 were analysed using DSAS tools to see horizontal shoreline changes. Measurement of the transverse profile of the beach was carried out 17 times in 12 transverse profiles. This measurement aims to map the profile condition after the tidal flood in July 2020. Measurement data for each profile was analysed using the EOF method to see vertical shoreline changes one year after the July 2020 tidal flood. Based on DSAS analysis, the shoreline conditions after tidal flooding (2019-2020) regressed with an average regression of 25.48 m and showed an accretion process after a year (2020-2021) with an average accretion of 14.38 m. Shoreline recovery due to tidal flooding can be seen well based on measurements for 1 (one) year and the results of Empirical Orthogonal Function (EOF) analysis. The recovery pattern is visible after 4 months of tidal flooding in July 2020. The beach profile tends to experience an accretion process in the 8th to 13th measurements and tends to experience abrasion in the 16th to 17th measurements. This shows that the accretion process on the transverse coastal profile is influenced by the east wind season, and the abrasion process generally occurs in the west wind season.

In Central Aceh District Head Regulation Number 47 of 2021 Concerning Detailed Spatial Plans for the Takengon Urban Area in Central Aceh District for 2020-2040, the Takengon Urban Area consists of 3 (three) District areas and 47 (Forty Seven) Village areas. In Central Aceh District Qanun Number 2 of 2016 concerning the Central Aceh District Spatial Plan for 2016-2036 that Takengon Urban is designated as a District Strategic Area based on the point of view of economic growth. In the Central Aceh District, the Planning Area Section of Takengon Urban Area aims to realize Takengon Urban as a competitive environment-based agribusiness and tourism development area supported by good urban infrastructure and facilities by demonstrating local wisdom. This study aims to identify the condition of Public Infrastructure, Facilities and Utilities and identify public perceptions of the availability and need for the provision of IFP in the Urban Area of Lut Tawar District. The research results from observations show that for the existing conditions of the IFP, almost all of them comply with regulations and there is still a small part that needs to be procured and repaired. The public's perception of the condition of the availability of roads, drainage, waste water, solid waste, drinking water, street lighting, health facilities, educational facilities and trade/trade facilities is mostly adequate. For procurement and repair, most of the respondents also hoped that there would be a supply of IFP because it was still needed.

The Trumon watershed one of critical watershed in Aceh Province had an increase in historical flood episodes during the past 25 years. This is consistent with the expansion of oil palm plantations within the 53,653 Ha watershed basin dominated by peatlands. According to earlier research, changes in land use in peatland regions may cause subsidence. This research looks at the connection between flood events and the subsidence of ground caused by oil palm plantation land clearing. The satellite imagery interpretation reveals a remarkable land use change of previously 5091.25 Ha peatland forest observed in 1995, to become a 13,753.43 Ha palm oil plantation in 2021. From DEMs analysis, those changes are associated with a subsiding land elevation up to 1.23 m. Despite being less than 20% of the watershed area, the land subsidence effect striking change in the watershed boundary, i.e., from only 53,653 Ha to 786,675 Ha which led to an increase in flood inundation from 3,443.04 Ha to 47,924.92 Ha. and flood depth from 0.5 – 1.0 m, to up to 4.0 m. This current situation has made the Trumon area subjected to frequent floods, i.e., from a five-year return period to become an annual event.

Krueng Peuto sub-watershed, is a part of the Krueng Keureuto watershed in North Aceh that frequently experiences flooding. At the end of 2021, an embankment broke on the Peuto River and caused river overflow and submerged hundreds of houses in 33 villages around the sub-watershed. This study aims to analyze the critical circumstance of the Krueng Peuto sub-watershed which potentially lead to Peuto River overflow, using a 2D hydrodynamic model Geo-HECRAS. The validation of flood distribution points is based on historical floods conditions, i.e. depth and area of flood inundation, with modeling results for return periods scenarios of 2, 5, 10, 25, 50, and 100 years. From the modelling results, the flood inundation area at the 25-year return period was 25.514 km2, with a flood depth of 0-1 m covering an area of 8.35 km2 (32.73%), a depth of 1-2 m covering an area of 6.71 km2 (26.33%), and a depth of >2 m covering an area of 10.44 km2 (40.95%). The validation results of the 25-year return period flood inundation with flood distribution points show that in the flood inundation area there are 17 flood distribution points or the flood inundation area already represents 81% of flood distribution points.

Indonesia is currently embarking on a transition from a ‘risk retention’ to a ‘risk transfer’ strategy for managing the impact of disaster events. The risk transfer strategy, i.e., insurance policy and protection, requires high-level preliminary risk assessment, which requires detailed attention and analysis in producing hazard mapping. Improvement of methods requires, preferably, the non-deterministic index method in a GIS environment, to produce reasonably good quality hazard susceptibility mapping. Recently, a new spatial method has been developed to improve the parameterization of the spatial analysis method for watershed-scale flood hazard susceptibility mapping. Those parameters, which include the Topographic Wetness Index (TWI), Rainfall Intensity (R), Distance to rivers (D), Altitude (A), Land use (L), and Soil type (S), configure the proposed method called “TWIRDALS”. The present study aims at testing the spatial model TWIRDALS watershed at the Trumon Area, South Aceh Regency, Sumatra Island, Indonesia. Historical flood events associated with the watershed have escalated over the last 25 years in the Trumon watershed. Several steps of geospatial analysis in this study use multi-temporal satellite imagery from 1995 to 2021 to identify area changes in land use rendering over the watershed. The satellite imagery interpretation reveals a remarkable land use change, particularly of the previously 2130 ha of peatland forest observed in 1996, to become a 10,000 ha palm oil plantation in 2021. This current situation has made the Trumon area the recipient of more frequent floods, i.e., from a five-year return period to an annual event.

The damage to the Singkil watershed, one of the largest watersheds in Aceh Province, has become a concern for many parties, primarily due to increased flood events in the downstream area of the watershed. Based on previous studies, the problems which cause flooding are watershed damage due to illegal logging and high rainfall intensity reaching 3000-4500 mm/year, and increased erosion of 0.887 tons/ha/year, which causes a decrease in river capacity due to sedimentation. For this reason, this study aims to do 2D flood hydraulic modeling for five return periods of 2, 5, 10, 25, and 50 years which can be a reference for flood management in Aceh Singkil District. The hydrological analysis of the design flood discharge for several return period was carried out using Nakayasu and SCS-CN method. 1D-2D flood simulation generated using GeoHECRAS software to study flood hazard characteristic at downstream by combining tidal effects. The flood event in September 2012, a 10-year return period flood, became the basis for validating and calibrating the simulation model. Based on flood simulation result, it is known the downstream area of the Singkil watershed, Aceh Singkil districts is an area with a high flood potential and frequently occurs.

Ground-penetrating radar (GPR) offers an efficient and non-invasive method of identifying and characterising subsurface features. It has previously been used to investigate both tsunami deposits and marine erosion surfaces from tsunamis as well as the structure of the structure of prograding beaches. The present study investigates beach deposits at Meulaboh, western coast of Aceh Province in Sumatra Island of Indonesia, to estimate the volume of sediment that has been deposited since the 2004 Indian Ocean Tsunami, using the GPR with an antenna of 200 MHz. Two profiles perpendicular to the coastline were collected, one 93 m long and the other 30 m long, to capture the internal profile of beach ridge deposition. From the GPR measurement the amount of 1,190,191,716 tons of sediment redeposited along the 1092 m coastline since the 2004 tsunami, with a prograding length of 73 m per year. As beaches provide a good form of tsunami protection the rapid beach recovery and the return of a large amount of sediment helps provide much needed coastal protection to the area.

Flood events have been escalating in the last decade at the Kluet River, one of the major rivers in the South Aceh district, Aceh Province, Indonesia. The frequent flood events have made remarkable changes to the river morphology including river meander and delta particularly at the downstream. One of the interplaying parameters contribute to flood events is the land use changes in the watershed. This study aimed to analyze the land use changes of Krueng Kluet Watershed using the Normalized Difference Vegetation Index (NDVI). The satellite image data series were obtained to remotely monitor the land use change over 20 years period (1998-2018). NDVI was used in classifying the vegetation density distribution value of the Krueng Kluet Watershed. The output of the study explained that there were increase in the plantation, bareland, grassland, water and settlement areas, while in contrary the forest area and bush. There was an increase by 8.05%, 0.15%, 0.14%, 0.10%, and 0.07% respectively to the plantation, bareland, grassland, water, settlements/urban areas, during the period of 1998-2018. On the other hand, the forest and bush were significantly decreased by 8.25%, and 0.3, respectively in the same period. Overall, the land use changes have also increased the Curve Number (CN) of Krueng Kluet Watershed from 61.8 in 1998 to 62.1 in 2008 and to 62.5 in 2018. This suggests the land use change as an important parameter to take into account in flood risk assessment of the Krueng Kluet Watershed

Post tsunami 26 December 2004, rising damp and salt attack are two underestimated phenomena emerging on building construction on the tsunami-affected areas in Banda Aceh city, Aceh Province of Indonesia. The severity of building quality deterioration, particularly on the typical masonry walls, has never been observed by local inhabitants to have been escalated before the tsunami event. Such phenomena persistently present even after approaching the second decade of the post-tsunami event. The present study is the first attempt to explore the evidence of rising damp and salt attacks of the houses around the Banda Aceh city. Forty-five houses were purposively sampled based on their visual appearances being affected by the salt attack and rising damp, the heights of the rising damp, and also groundwater salinity in the vicinity of the sampled houses. The results show that the rising damp heights on the walls are relatively high in any location within the tsunami inundation boundary 500 m from the shoreline. However, a turning point where rising damp height reduced remarkably to less than 1 meter was identified as the distance of houses increased beyond 500 m from the shoreline. Overall, the high level of water salinity brought by tsunami inundation during the early post-tsunami has been an important controlling factor contributing to the salt attack and rising damp, regardless of the houses’ distance to the shoreline, but may have been indirectly influenced those phenomena in the long run.

Shoreline changing position along the coast is an immediate and long-term indicator determined by the interplaying driving forces across the dry and wet parts of coastal areas. Extreme waves, such as tsunamis, may result in a remarkable shift of shoreline position and a change of sediment transport regime, thus potentially inducing coastal hazards. This work investigates the multi-temporal changes and development of shorelines at the tsunami-affected coast nearly two decades after the Indian Ocean tsunami on 26 December 2004. Additionally, the dynamic responses of the coast to the man-made coastal structures as a means of protection measures during the observed period are also evaluated. This study uses the US Army's Digital Shoreline Analysis System (DSAS) extension in the ArcGIS to calculate the multi-temporal shoreline changes and erosion/accretion rates. Multi-temporal shoreline vectors delineated from the LANDSAT satellite images are utilized to calculate the Net Shoreline Movement (NSM), End Point Rate (EPR), and Linear Regression Rate (LRR) for the respective short-term and decadal-term shoreline change analysis. The shoreline change rates are examined at the three shoreline segments at Aceh coast, the north tip of Sumatra Island of Indonesia. The results show that Segment A has the highest erosion rate due to the 2004 tsunami (− 395.19 m/year) compared to Segment B (− 26.46 m/year) and Segment C (− 74.26 m/year). The 2004 tsunami has changed the coastal states from erosional coast prior to the tsunami to accretional coast in Segment A and C, and the eastern side of Segment B in almost two decades since the tsunami. Consequently, ignoring such phenomena in designing coastal protection measures may lead to structural failures such the ones identified in the investigated coast. Thus, a thorough investigation of shoreline change is fundamental for coastal managers, particularly in determining appropriate coastal protection measures. [ABSTRACT FROM AUTHOR]

Fluvial and coastal landforms are indicative of landscape river delta evolution over time and provide clues for understanding coastal adjustments to sea-level and fluvial dynamics fluctuations, tectonic displacements, and extreme waves. We have mapped the surface and sub-surface footprints of fluvial and coastal geomorphological features in the Aceh River delta, northern Sumatra, using imagery dataset, vertical facies logging and helicopter electromagnetic surveys. The result is a geomorphological map at the scale of 1:75.000 which outlines the main features of the deltaic plain, including rivers, tidal and buried channels, fluvial levees, beach ridges, swales, tidal flats and lagoons. We compare their spatial distribution to the geometry of buried sediment bodies, revealed by boreholes and resistivity maps. Buried channel belts and floodplain deposits document the former locations of the distributary channels of the Aceh River. Coastal-parallel beach ridges evidence 7–8 km of asymmetric delta progradation since the mid-Holocene sea-level high stand. [ABSTRACT FROM AUTHOR]

Erosion and sedimentation have a very big influence on flooding. Floods are strongly influenced by land use and population activities that change the river's physical condition, including erosion and sedimentation. The river upstream was very steep, and the downstream was narrowing and meandering with high rainfall recorded. This study analyses erosion, sedimentation, and its handling using the eco-hydraulic base. The method involves input rainfall data, river hydraulics, land use, watershed area, and land cover. The analysis of hydrology, hydraulics, land use, flood discharge, and eco-hydraulic, inundation height, vegetation diameter, velocity reduced, and riverbank width measured in five bridges cross-sections along the river. The eco-hydraulic compares the width of existing riverbanks and design, high inundation, and the vegetation diameter to minimise flood discharge. Erosion in the right cliff is 22.73% and the left cliff is 37.04%, land erosion was 225.83 Mg·ha-1·year-1. The river's bottom is formed by rocks of 0.18-1.30 mm. The plantation land used around the Lae Kombih River grows mainly an oil palm with a diameter of 0.5-0.7 m. The riverbank design on 100 m for vegetation diameter of 0.1-1.0 m can retain flood discharge for five years return period up to 72.3%, resulting in discharge of 112.04209.43 m3·s-1. The largest erosion and sedimentation on the river border is Dusun Silak, so it is recommended to plant Vetiveria zizanioides, Ipomoea carnea and Bambusoideae. An inundation height of 0.9 m can be recommended to design an embankment to be used as flood mitigation. [ABSTRACT FROM AUTHOR]

Tsunami is a catastrophic event that affects coastlines on a large scale with heavy casualties. Recent tsunami deposits and processes are studied for a better understanding of the disastrous event to enhance hazard assessment of tsunami-prone coastal areas. This research paper explores the 2004 tsunami deposits at Meulaboh (Aceh) to identify the thickness of post- and pre-tsunami deposits to improve risk assessment. The study consists of 4 Ground Penetrating Radar (GPR) survey lines near the Meulaboh shore. Two pit holes were dug along the survey lines and the deposition sequences were recorded. Records of the pit holes show good correlations with the intensity changes of EM waves from the GPR profiles and provide a clear insight into the subsurface tsunami deposit sequences at Meulaboh coastal area. The GPR results show that the 2004 pretsunami sediment deposits can be identified with a thickness of 0.3-1.5 m, while post-tsunami 2004 sediment deposits were also identified with a thickness of 0.1-1.2 m. Both sediment deposits known as alluvium were caused by natural coastal processes and erosion with an estimated depositional rate of 0.007-0.09 m/year. The thickness of the 2004 tsunami sediment deposits was identified as 0.2-3 m. This study revealed that the thickness of all the sediment deposits is thicker when approaching the shore, and GPR is a very efficient technique in investigating shallow subsurface with high data resolution to distinguish different deposits with high accuracy. [ABSTRACT FROM AUTHOR]

This paper presents a post-earthquake damage assessment of the 6.5 Mw earthquake in Pidie Jaya, Indonesia which occurred on December, 7th 2016. The earthquake killed 112 people and caused the collapse of about 3000 buildings. The assessment started on the day after the earthquake. The survey covered nine sub-districts of Pidie Jaya regency in the Province of Aceh, northern Sumatra. The post-event damage assessment was conducted by a team of researchers from Syiah Kuala University and local authorities. The damage survey assessed the damage levels of residential houses, school buildings and markets. The most common construction damages reported in this article are failures of reinforced concrete, confined masonry and timber structures. The ground motion field was modeled using Openquake application and the site response employed Vs30 values inferred from topography. This calculated ground motion was compared to data from post-earthquake field assessment reports. The highest percentage of heavy damage was recorded in the area of the fault rupture and along the shorelines area. The types of failure observed are summarized in the context of Indonesian construction practice, with particular reference to the seismic resilience of the Rumoh Aceh traditional wood construction. [ABSTRACT FROM AUTHOR]

Ease of accessing and using earthquake and tsunami early warning applications is a priority in this study. It is related to the more time the community prepares for disaster mitigation. The purpose of this research is to produce an Android-based earthquake and tsunami early warning application. The availability of this fast android-based earthquake and tsunami early warning application can help in quicker and more reliable earthquake and tsunami early warning for short distances to areas that have the potential to impact a tsunami. The research method used in this research is the ADDIE development method (Analysis, Design, Development, Implementation, and Evaluation. In the first year, the focus of the development of the Rapid Tsunami Early Warning Application about 4 minutes after O.T. Our previous research results, which have supported many events this application will make it easier for us to complete the prototype target. The prototype of the Android-based earthquake and Tsunami, early warning application, has been tested in real-time at the Faculty of Mathematics and Natural Sciences, Surabaya State University, Indonesia. The results of the trial have shown the eligibility requirements. [ABSTRACT FROM AUTHOR]

Effective early warning at local to regional distances is maximum 10 minutes after the OT. The shorter the tsunami early warning time that is announced, of course, the more time the community will have to prepare for mitigating the disaster. The purpose of this study is to develop a tsunami application and show the current real-time data available in most tsunami hazard areas in Indonesia - in particular, earthquake location, magnitude and tsunami discriminant Td, T50Ex, T0, Td x T50, and Td x T0 can be determined about four minutes after the earthquake occurs. This process will be implemented and continues in real-time in earthquake monitoring and tsunami early warning installed by the Meteorology Climatology and Geophysics Council. The availability of this rapid tsunami application (about 4 minutes after the OT) can help in tsunami early warning that is faster and more reliable for short distances to areas that have the potential of having the a tsunami impact. The purpose of this study is to produce a tsunami early warning application 4 minutes after the earthquake. The research method used in this study is the ADDIE development method (Analysis, Design, Development, Implementation and Evaluation). In the first year, the focus of the development of rapid tsunami early warning applications was about 4 minutes after the OT. Our previous research results have supported a lot of development this application and make it easier for us to complete the prototype target, it has been obtained the results of the tsunami application prototype 4 minutes after the OT which is currently being tested in real time at the Meteorology Climatology and Geophysics Council Research and Development Center in Jakarta, Indonesia. [ABSTRACT FROM AUTHOR]