Best management practices for erosion and sedimentation control of The Sermo Watershed

Erosion and sedimentation problems caused by human activities disturbed the primary conditions of the watershed. This situation was also influenced by significant hydrometeorological shifts and high rainfall, which increased soil erosion. These inclement watershed conditions resulted in high sedimentation rates and caused severe problems for the quality and quantity of water in the reservoir. This study aims to solve the Sermo watershed problems by calculating the value of erosion and sedimentation, then providing a solution to deal with these problems in the form of Best Management Practices (BMP). This research used a USLE method to calculate the erosion and sedimentation rate. The calculation results showed that 40.86% of Sermo Reservoir within 809.12 hectares was classified as a high level of erosion. Further recommendations for overcoming this condition were made by referring to BMP for erosion and sediment control, including structures and soil water conservation. Further recommendations to address this condition were made regarding BMP for controlling water, maintaining soil stability, controlling sedimentation, and managing and maintaining optimal watersheds.

Sea cucumber species found in Soft-bottom of Wulan Estuary-Demak, Central Java

Indonesia has been known to have a high diversity of sea cucumber, but data and information are mostly on high-economic-value species. Sea cucumber living in soft-bottom substrates is less studied and unexploited. Wulan estuary located in the Demak Regency of Central Java was experiencing high sedimentation, which was consisted of fine material, and acted as a habitat for many macrozoobenthos, amongst others sea cucumbers. The objective of the present research was to identify the species of sea cucumber in the soft bottom of the Wulan estuary. The collection of sea cucumber specimens was done using a dredge. A total of 132 specimens were collected, examined, and identified through their morphological characters. The holothuroids found in the soft-bottom of the Wulan estuary represent five genera (Acaudina, Colochirus, Holothuria, Paracaudina, Phyllophorus,) in four families (Caudinidae, Cucumariidae, Holothuriidae, and Phyllophoridae) belonging to three orders (Molpadida, Dendrochirotida, and Aspidochirotida). The species were Acaudina sp., A. molpadioides, Colochirus quadrangularis, Holothuria cf. impatiens, Paracaudina sp., Paracaudina chilensis, P. australis, and Phyllophorus spiculata. A. molpadioides is presented as the most frequently found species. Although sea cucumber found in the Wulan estuary has not been exploited, it still needs to be managed to sustain its population.

Impact of large volcanic events on the marine environment recorded in marine cores

<p>Explosive silicic volcanic eruptions blanket widespread terrestrial and marine areas in ash, and have a profound effect on climate and local ecosystems. Short-term climate effects are caused by the dispersal of ash, but the injection of gas into the stratosphere, with sulphur being particularly important, drives a cooling of the climate that can last several years. These prolonged perturbations have been observed and recorded in recent decades, but despite the importance of the ocean in regulating global atmospheric climate, little is known about how and to what extent the climate signal produced by volcanic eruptions alters the oceanic environment. As the composition of foraminifera tests is highly sensitive to changes in the surrounding environment, a significant sea surface temperature decrease following a large silicic volcanic eruption may be recorded in the tests of live planktic foraminifera, now preserved in marine sediments. This study examines marine cores (and foraminifera within) that contain tephra units from three major volcanic events to determine if changes can be resolved in ocean temperature and/or foraminifera test morphology following large silicic eruptions. The Holocene Taupo, Waimihia and Mamaku tephra units have been identified in a series of marine sediment cores collected from areas with high sedimentation rates off the east coast of North Island, New Zealand. The sources of these eruptions were from two calderas within the Taupo Volcanic Zone, one of the most active and important rhyolitic regions in the world. Sampling of sediment and foraminifera from these cores has been undertaken at 0.5 cm intervals above and below each tephra. This equates to varying sampling resolutions between cores of 5-30 years, with sufficient sampling taken to establish a stratigraphic record of >100 years either side of each tephra unit. A detailed stratigraphy was undertaken on the sediment surrounding all tephra units, including grain size and CaCO₃ analyses, to identify primary and secondary tephra deposits. One core, Tan0810-12 that contained solely Taupo tephra, was selected for foraminiferal analyses to determine changes in ocean temperature and foraminifera test morphology following this eruption. This core was selected based on the results of the stratigraphic analyses that identified the tephra as a primary deposit with minimal bioturbation above the ash layer and a very high sedimentation rate that enabled sub-decadal scale sampling. Scanning electron microscope imaging was employed to identify the presence of surface contaminants on and within the foraminifera tests and allowed observations of test morphology and size. The morphologies of planktic foraminifera species Globigerinoides ruber and Globigerina bulloides showed no obvious change following the Taupo eruption. The Globigerinoides ruber test sizes distinctly decreased for a period after the eruption, while Globigerina bulloides tests slightly increased in size, correlating well with a decrease in sea surface temperature after the eruption as these species prefer warmer and colder temperatures, respectively. This suggests there is potential for test size to be employed as a proxy for temperature change in conjunction with geochemical analyses. Mg/Ca temperature analyses were conducted in situ using laser ablation inductively coupled plasma mass spectrometry. Both species indicated a decrease in sea surface temperatures when comparing results from tests collected below the tephra deposit to those above. Further results indicate ocean temperature may not have recovered for more than 65 years after the eruption. Such a rapid change in the oceanic environment not only has drastic implications for marine ecosystems but also atmospheric climate, and therefore, terrestrial ecosystems. To reduce the margin of error and determine a more exact value of temperature change following the eruption a greater population of foraminifera is needed. Nonetheless, this study highlights the potential of this method in determining how the oceans are impacted by volcanism and how further research is needed to determine the effects of volcanic eruptions on past and future climate.</p>

Impact of large volcanic events on the marine environment recorded in marine cores

<p>Explosive silicic volcanic eruptions blanket widespread terrestrial and marine areas in ash, and have a profound effect on climate and local ecosystems. Short-term climate effects are caused by the dispersal of ash, but the injection of gas into the stratosphere, with sulphur being particularly important, drives a cooling of the climate that can last several years. These prolonged perturbations have been observed and recorded in recent decades, but despite the importance of the ocean in regulating global atmospheric climate, little is known about how and to what extent the climate signal produced by volcanic eruptions alters the oceanic environment. As the composition of foraminifera tests is highly sensitive to changes in the surrounding environment, a significant sea surface temperature decrease following a large silicic volcanic eruption may be recorded in the tests of live planktic foraminifera, now preserved in marine sediments. This study examines marine cores (and foraminifera within) that contain tephra units from three major volcanic events to determine if changes can be resolved in ocean temperature and/or foraminifera test morphology following large silicic eruptions. The Holocene Taupo, Waimihia and Mamaku tephra units have been identified in a series of marine sediment cores collected from areas with high sedimentation rates off the east coast of North Island, New Zealand. The sources of these eruptions were from two calderas within the Taupo Volcanic Zone, one of the most active and important rhyolitic regions in the world. Sampling of sediment and foraminifera from these cores has been undertaken at 0.5 cm intervals above and below each tephra. This equates to varying sampling resolutions between cores of 5-30 years, with sufficient sampling taken to establish a stratigraphic record of >100 years either side of each tephra unit. A detailed stratigraphy was undertaken on the sediment surrounding all tephra units, including grain size and CaCO₃ analyses, to identify primary and secondary tephra deposits. One core, Tan0810-12 that contained solely Taupo tephra, was selected for foraminiferal analyses to determine changes in ocean temperature and foraminifera test morphology following this eruption. This core was selected based on the results of the stratigraphic analyses that identified the tephra as a primary deposit with minimal bioturbation above the ash layer and a very high sedimentation rate that enabled sub-decadal scale sampling. Scanning electron microscope imaging was employed to identify the presence of surface contaminants on and within the foraminifera tests and allowed observations of test morphology and size. The morphologies of planktic foraminifera species Globigerinoides ruber and Globigerina bulloides showed no obvious change following the Taupo eruption. The Globigerinoides ruber test sizes distinctly decreased for a period after the eruption, while Globigerina bulloides tests slightly increased in size, correlating well with a decrease in sea surface temperature after the eruption as these species prefer warmer and colder temperatures, respectively. This suggests there is potential for test size to be employed as a proxy for temperature change in conjunction with geochemical analyses. Mg/Ca temperature analyses were conducted in situ using laser ablation inductively coupled plasma mass spectrometry. Both species indicated a decrease in sea surface temperatures when comparing results from tests collected below the tephra deposit to those above. Further results indicate ocean temperature may not have recovered for more than 65 years after the eruption. Such a rapid change in the oceanic environment not only has drastic implications for marine ecosystems but also atmospheric climate, and therefore, terrestrial ecosystems. To reduce the margin of error and determine a more exact value of temperature change following the eruption a greater population of foraminifera is needed. Nonetheless, this study highlights the potential of this method in determining how the oceans are impacted by volcanism and how further research is needed to determine the effects of volcanic eruptions on past and future climate.</p>

Interpretation of the Geological Romance of Kendari Bay Using Landsat 5 TM

Kendari Bay is part of Kendari City. Kendari Bay is a city landmark in addition to its economic and environmental functions.. The condition of Kendari Bay is experiencing a fairly high sedimentation problem, so that it begins to cause problems with land availability and space utilization patterns in the Kendari Bay area. The endogenous process of dynamic earth activities is a part that needs to be considered in managing that problems. This study aims the geological conditions of Kendari Bay by using remote sensing as a form of studying the geological conditions of Kendari Bay. Using Landsat 5 TM imagery in 1990, it was used to see the natural geological conditions of Kendari Bay, using the false color composite method and interpretation of photo images visually and validated through field observations. Landsat image processing and interpretation using Quantum GIS, resulted in Kendari bay can be divided into several physiography, namely coastal zone, estuary zone, fluvial zone, plain zone, hill zone, and mountain zone (Head land). The physiography can be seen from the geological characteristics such as the lithology which is composed of alluvial deposits to limestone. The results of interpretation of composite color images and validation of direct observation data in the field show a qualitative suitability.

Ascidians Outbreak: A Threat For Coral Reefs in Panjang Island, Jepara

Eutrophication and sedimentation have become a major threat to coral reefs in nearby areas with anthropogenic activities. These threats are often accompanied by shifting ecosystems from coral-rich to fast-growing algae-dominated water, and high prevalence of coral disease. In Panjang Island, Jepara, we observed the outbreak of photosynthetic ascidians along with a high sedimentation at the eastern part of the island. The ascidians were seen overgrowing most substrates including corals, macroalgae, dead-coral-algae, and rubbles in April to May 2019. In July and August 2019, observation and data collection using quadrant transect were conducted to monitor the outbreak. The result showed that ascidians were still present in the area, despite becoming pale and smaller. This report shows that the outbreak of these photosynthetic ascidians was not persistent, however, the effect on coral reef health should not be overlooked.

Analysis of Sedimentation as Implications of Beach Accretion using Spatial Analysis in the Coastal Area of Banyuasin South Sumatra, Indonesia

This study was conducted in the coastal area of ​​Banyuasin (CAB) which was considered to have a variety of sedimentation classes originating from fluvial and marine processes. The study aimed to observe/determine changes in the morphology of coastal areas related to sedimentation in the CAB and to make maps related to oceanographic parameters, changes in the land cover and identification of the distribution of sedimentation occurring in the CAB, and the dominant factors influencing the change. This study used imagery interpretation method and the sediment data collection used sediment traps to determine the occurrence of accretion and abrasion. The results of the study showed that there was a change in the environment based on the analysis of Landsat imagery, that have undergone changes are Ekor Tikus island (PET), Tg Api-api (TAA), and the Bungin River (SB), which are affected by the land conversion, sedimentation, and tidal currents. There has been an environmental change in the CAB, especially at the Banyuasin estuary (PET) with a high sedimentation rate. The changes also occurred in TAA and SB, with the dominant factor being the decline in mangrove forests. As a result, it is necessary to conduct a more detailed study and time series related to mangroves.

Community Based Assessment of the Changes of Provisioning Ecosystem Services of Aral Haor of Sylhet District

Haor is a well-known wetland feature in Bangladesh because of its dynamic ecosystem which is changeable with the seasonal variation. The majority people of the community are critically dependent on the haor. This paper attempts to analyse the provisioning ecosystem services of Aral Haor of Sylhet District, their changes and why the changes occurred during the last 30 years since 1990 to 2020 through community assessment. The papers argues that the community based approach integrates the local people to reveal the actual scenario of the livelihood dependency on the provision ecosystem services as they are the main user of the provisioning services. Thus the primary data were collected through observation, FGD, Community Mapping and interview with experts. The study found that community the service providing area of the Aral haor have not been changed in mentionable level over the 30 years, however the shape of the haor have been changed slightly due to high sedimentation. Along with rice cultivation during dry season, natural irrigation, fishing and bird nesting were most important to provisoing services to the community which have been changes due to both natural and anthropogenic activities. The study concludes that even having importance of the Aral hoar, not any measurer has been taken by local authority to conserve the Aral hoar ecosystem services those are very vital for the livelihood of the thousands of community people living nearby.

Reconstructing the Climate Variability During the Last 5000 Years From the Banni Plains, Kachchh, Western India

The climatic conditions during the beginning of the last 5,000 years have been discussed, debated, and documented from various parts of the Indian subcontinent, due to the human–climate interrelationship. In the present study, we report a multi-proxy dataset encompassing the widely used ∼ geochemical and mineral magnetic proxies supported by radiocarbon and optical chronologies from the Banni Plains of the Rann of Kachchh, western India. Our results support the earlier observations of the prolonged wetter climatic condition synchronous with the mature phase of Harappan era which witnessed a short and intense arid condition at the terminal part of the mature Harappan phase. The climate system dramatically fluctuated during the last five millennia from pulsating between relatively arid (4,800–4,400 years BP, 3,300–3,000 years BP, and at 2,400 years BP) and relatively humid phases (&gt;4,800 years BP, 4,000–3,300 years BP, 1900–1,400 years BP, and 900–550 years BP). The multi-proxy dataset shows a gradual strengthening of the monsoonal conditions from the Banni Plains during the late Harappan phase. Apart from this, the high sedimentation rate (&gt;1 mm/yr) recorded from the Banni Plains suggests it can be tapped as a robust archive to reconstruct multi-decadal to centennial climatic events spanning the Holocene epoch.