Accuracy of The Level of Critical Water Catchment Area for Flood Mitigation Around Bengkulu City, Indonesia

Disaster mitigation activities require the availability of a potentially flooded area (PFA) map. One of the causes of flooding is the criticality of water catchment areas; the higher the criticality level, the higher the flooding potential. This study aims to determine the accuracy of the model for determining the PFA around Bengkulu City, which was derived from the Level of Critical Water Catchment Area (LCWCA) model developed by the Ministry of Forestry. After obtaining the LCWCA Map, another analysis was performed in order to obtain the PFA Map. Furthermore, the overlaying was carried out with the Existing Flood Map in such a way that the level of accuracy is known. The threshold values from Justice are used to justify the level of accuracy in three categories, namely Good (> 85%), Moderate (70 - 85%), and Poor (<70%). The results showed that in the eight sub-watersheds around the city of Bengkulu, there were two sub-watersheds with reasonable accuracy (> 85%), which means that there was > 85% overlap between areas on the Potentially Flooded Area Map as a result of the analysis of The LCWCA with the area on the Existing Flood Map. There are three sub-watersheds with Moderate accuracy (70 - 85%) and three sub-watersheds with Poor accuracy (<70%)

Polygon-based Landslide Inventory for Bandung Basin Using Google Earth

A landslide inventory representing landslide locations is used as a key factor in landslide susceptibility assessment. This paper explores Google Earth (GE) for generating a polygon-based landslide inventory in Bandung Basin. How far GE can identify landslides and their boundaries, source areas, and types were discussed here. Visual interpretation of GE images supported by path tool in GE, official landslide reports, previous research papers, and media was performed. The result is a polygon-based landslide inventory consisting of 194 landslide areas and 194 landslide source areas during 1993-2020. The limitations of GE in preparing the landslide inventory are (1) not covering the timing of the landslide occurrences, (2) tricky to identify small landslides (<100 m2) in anthropogenically transformed areas, and (3) not able to distinguish between earth and debris of landslide material.

Ecosystem Services Dynamics in Bogor Regency

The decline in the quality of ecosystem services in Bogor Regency is indicated by the existence of various natural disasters in recent years. Prudent development must be carried out to minimize the impact of a decrease in the ecosystem services index. The purpose of this research is to map ecosystem services for food supply, water supply, water and flood management, and tourism aspects within 2000-2017. The data used were land cover and land facet maps at a scale of 1:25,000 obtained from BIG, accompanied by a reinterpretation process. The data sources were Indonesia's topographic maps (RBI), Citra SPOT 7, DEMNAS, and field surveys. The ecosystem services index (ESI) is calculated based on an analysis of changes in land use and land facets. The value of ESI was weighted using analytic hierarchy process approaches to each of the variables assessed by experts. The results showed that the largest changes in land use occurred in residential and forest areas. The residential area increased by 1.96%, while the forest area decreased by 1.8% in 17 years. Bogor Regency is dominated by forest and rice fields which are spread over four main landforms, namely volcanic, structural, fluvial, and karst. The most significant increase of 5.65% was found in the clean water provisioning function, while the most significant decrease of 38.47% was found in the tourism and ecotourism sector. Accumulatively, the increase in ESI was 23%, while the decrease was 20.64%. Mitigation efforts that can be done are to maintain the availability of green open space by implementing strong regulations.

A Preliminary Study of the Physico-Chemical Parameters and Potential Pollutant Sources in Urban Lake Rawa Besar, Depok, Indonesia

Lake Rawa Besar is an urban lake surrounded by dense settlements and commercial areas that are currently experiencing physical and ecological pressures due to uncontrolled land-use change around the lake. Therefore, this preliminary study aimed to investigate the sustainable management of the lake in order to create a recreational destination area. It was carried out by ascertaining the lake water quality status through the analysis of the physical and chemical parameters and identifying the potential pollutant sources due to land use and human activities. The physical parameters include TDS, TSS, Turbidity, while the chemical parameters include Nitrate-N, Total Phosphate-P, and BOD. Furthermore, field surveys on 30 water samples were conducted once at noon and statistical analysis was used to ascertain the correlation between the physical and chemical parameters. Finally, Geographic Information System (GIS) tools were used to investigate the spatial distribution of the Physico-chemical parameters and the potential pollutant sources. The results showed that based on the six parameters of the water quality status, the lake was lightly polluted. It also showed that three parameters such as Turbidity, BOD, and TSS exceed the permissible limit with 93.3, 66.7, 43.7% of the total samples, respectively. Additionally, a strong correlation existed between BOD and Turbidity with r=0.95, while a medium correlation existed between Nitrate-N and Phosphate-P with r=0.40. The spatial distribution of the concentration of the physico-chemical parameters generally had a varied pattern, however, Turbidity and BOD had a similar pattern, especially in the bank areas. Finally, domestic and organic wastes were indicated as pollutant sources, which increased eutrophication in the lake.

Climatic Anomalies and Glacial Dynamics in the Himalayan Region Northern Pakistan: A Spatio-Statistical Approach

Glaciers are always climate-sensitive and affected by minor changes in temperature and other climatic elements. Past studies on the northern mountain ranges of Pakistan reveal changes in climatic patterns in and around these ranges. In this study, an attempt is made to explore and assess the temporal and spatial fluctuations occurring in the ice cover of the Himalayan Region of Pakistan as a result of changes in climatic pattern. Satellite imageries and meteorological data were used to explore the dynamics of both the ice cover and climatic elements. Remote Sensing and Geographical Information System were used to detect changes in snow cover both spatially and temporally. Various statistical techniques, mainly Mann Kendall Trend Test and Sen’s Slope Estimator, were used to analyze the temporal trend of climatic elements. Moreover, correlation and regression analysis were applied to establish the relationship between climate and ice cover. Analysis of the data reveals that the temporal trend in ice cover is not monotonic as there is glacial advancement in certain years while retreating in others. Moreover, it was found out that climatic elements such as temperature and precipitation have recorded changes during the past few decades.

A Shoreline Change Detection (2012-2021) and forecasting Using Digital Shoreline Analysis System (DSAS) Tool: A Case Study of Dahej Coast, Gulf of Khambhat, Gujarat, India

Shoreline is one of the coastal landforms which continuously changing in nature. Hence, monitoring of shoreline change is very obligate to understand and manage the coastal process. The objectives of the present study were i) to identify the shoreline change detection (2012 to 2021) based on various statistical methods along Dahej coast, Gujrat. ii) to forecast the shoreline position after 10 years. DSAS tool and Multi-dated satellite images (Sentinel-2 and LISS-IV) were used in present study. The result shows that, the pattern of rate of change was more or less similar with little variation in the values for the 3 different methods. Highest erosion rate was for End Point Rate, Linear Regression Rate and Weighted Linear Regression rate found -33m, -31m, -31m respectively at transect no 54. Highest accretion rate was 38m (EPR), 50m (LRR), 51m (WLR) along a particular transect. The forecast of shoreline position for the year 2032 observed through Kalman Filter Model. Seasonal analysis for 3 years (2016, 2017, 2018) shows the region not having any seasonal pattern.

Transformational Adaptation in Agriculture under Climate Change: A Case Study in the Dry Zone of Sri Lanka

Transformational adaptation defines as 'changes the fundamental attributes of a system in response to climate and its effects.' Farmers deal with the natural environment and its components such as rainfall, temperature, humidity, and soil condition, which have a high range of variability and uncertainty for their cultivation. The present study focused on the impacts of climate change on the settler community who engage in agriculture as their mainstay and respond to the scenario. Quantitative and qualitative methods have been applied. Twenty samples from a village in the NCP have been selected. Primary outcomes of this study are (a) total awareness of perceptions on climate change; (b) the ambient temperature has been increasing and resulting in more heat stress; (c) frequent and severe occurrence of extreme rainfall anomalies and increasing trend of natural calamities. The area farmers have been adopting several strategies to overcome the negative impacts of climate change, such as transforming from intensification to more intensification that can be identified as Climate Smart Agriculture; crop diversification and adaptation of drought tolerance crops; transforming from agriculture to animal husbandry, and out-migration of unemployed or evicted youth from agriculture to non-agriculture. Institutional involvement is essential to strengthening the adaptative strategies of the people by providing an appropriate crop calendar and suitable crop combination and aware of the way of improving the use of the efficiency of available water for improving the living standard of the people.

The Impact of the Interaction between Madden-Julian Oscillation and Cold Surge, on Rainfall over Western Indonesia

The Madden-Julian Oscillation and Cold Surge phenomena have been known to cause increased rainfall, with the capacity to trigger hydrometeorological disasters, in western Indonesia. However, further investigations are required regarding the interaction between these phenomena on rainfall pattern. Therefore, this study aims to analyze the interaction between MJO and CS over western Indonesia, particularly by using land-based rainfall observation data from multiple stations, as previous studies were dominated by the use of gridded data from remote observations. This study utilized in-situ observation data obtained from 4329 weather observations and rain stations between 1989 and 2018. Subsequently, quality control performed based on data availability exceeding 70% over a 30-year period resulted in 303 selected stations to be used for further analysis. Meanwhile, the RMM index, as well as reanalysis data of mean sea level pressure and 925 hPa meridional wind, were also applied for MJO and CS identification. According to the composite analysis, the effect of CS on MJO phases tends to increase precipitation by about 50%, over western Indonesia, with maximum increase ranging from 200 to 400% over the northeastern coast of Sumatra, around Karimata Strait (Riau Islands and West Kalimantan), as well as the northern coast of Java. These areas are exposed to the sea and have direct access to the wind-terrain interaction. In addition, the highest rainfall anomaly due to the MJO-CS interaction occurs around Karimata Strait, followed by northern Sumatra and Java, with spatially averaged rainfall anomaly reaching 5 mm/day over the area.

Current Dynamics and Water Column Stability in Indonesian Waters Based on Hydrodynamics Model

Monsoon currents and Indonesian Throughflow (ITF) have an essential role in the current Indonesian water system. The movement of current/water masses with non-uniform bathymetric conditions will affect the water column's stability in Indonesian waters. Therefore, this study aims to obtain the current dynamics and stability of the water column in Indonesian waters, based on a hydrodynamic model termed the HAMburg Shelf Ocean Model (HAMSOM). The results of the model are data of current, temperature, salinity, and density. The data is used to study the dynamics of seawater in Indonesian waters. The water column's stability is examined by calculating the Brunt Väisälä frequency values (N2) based on the density data generated. The results show that monsoon currents were stronger in shallow waters because the stratification did not change. Meanwhile, the maximum N2 value occurs at the surface to a depth of 80-100 m with a range of 0.0000-0.0006 cycle s-1. The study also produces an understanding of the condition of Indonesia's stability (N2 positive), both spatially and temporally.

Comparison of Various Spectral Indices for Optimum Extraction of Tropical Wetlands Using Landsat 8 OLI

This research specifically aims to investigate the most accurate spectral indices in extracting wetlands geospatial information taking South Kalimantan, Indonesia, as an example of wetlands in tropical areas. Ten spectral indices were selected for testing their ability to extract wetlands, those are NDVI, NDWI, MNDWI, MNDWIs2, NDMI, WRI, NDPI, TCWT, AWEInsh, andAWEIsh. Tests were performed on Landsat 8 OLI path/row 117/062 and 117/063. The threshold method which was used to separate the wetland features from the spectral indices imagery is Otsu method. The results of this research showed that generally MNDWIs2 was the most optimal spectral indices in wetlands extraction. Especially tropical wetlands that rich with green vegetation cover. However, MNDWIs2 is very sensitive to dense vegetation, this feature has the potential to be detected as wetlands. Furthermore, to improve the accuracy and prevent detection of the dryland vegetation as wetlands, the threshold value should be determined carefully.