Mangrove migration due to sea level rise

The coastal zone of Pulau Kukup is characterized by muddy substrates and is classified as a micro -tidal coast. P otential impacts of sea level rise were studied to relate the effects of tidal inundati on regime ass o ciated with accelerated SLR and mangrove migrati on fo r the next centuries. The primary objective of this research is to simulate and estimate the potential mangroves migrati on under several conditi ons of sea level rise scenari o s projected for the years 2025, 2050 and 2100. Another go al of this study is to evaluate the C oastal Vulnerability Index (CVI) and devel op the supplementary maps for the island. Vegetati on map were devel oped from WorldView-2 data within SPRING 5.2 software. The Digital Terrain Model from IFSAR data, were processed in ArcGIS 9.3 to produce the mangrove migrati on map. The CVI study showed that the northern and s outhern sectors are highly vulnerable risk to sea level rise and this accounted for 42% from Pulau Kukup shorelines. From the field survey analyses and mangrove vegetati on map, Rhizophora apiculata and Rhizophora mucronata dominates an outer part of the mangrove belts, accounting for 89% from the total sampled trees. The study concluded that, mangrove plant will t olerate to the inundati on change in o rder o f Sonneratia alba, Rhizophora mucronata, Rhizophora apiculata, Bruguiera parviflora, Brugueira cylindrica and Xylocarpus moluccensis. A series of mangrove migrati on map for 2025, 2050 and 2100 sea level rise scenari os sh ows an adjustment to tidal inundation class due to increase of seawater level. Mangroves from the l ower zones (Z2 and Z3) migrate into the higher z one (Z4) as a resp onse t o sea level rise. In the wo rst case scenari o, more than 25% of the mangrove forest will be c onverted t o the o pen water due to a 1.3 metre sea level rise. The t otal land l oss in the year 2100 was estimated at 69.75 hectare (Case study 1), 73.52 hectare (Case study 2) and 148.92 hectare (Case study 3). The worst case scenari os will p ossibly lead to the extinction of Xylocarpus moluccensis at Pulau Kukup when zone Z4 was begin to disappear from the year 2050 SLR projecti on. In c onclusi on, the findings sh owed that the mangrove migrati ons will occur if the tidal inundation were mo dified by future sea water level. It is a strategic response devel oped by mangrove species to maintain the preferable conditi on for their optimal growth and species col onisati on. This research approach can be applied t o other mangrove forest at regi onal scale to identify the p otential mangro ve resp onse in a simple way for basic information of future development and planning for scientist, engineer, researchers and decisi on makers

Analytical and statistical approaches to study the impacts of shoreline change towards mangroves at Kukup Island National Park, Johor

Shoreline and mangroves form a dynamic ecosystem to coastal area. They support and supply various foods and protections to ensure the sustainability of coastal ecosystem around the world. Despite these, information that exclusively emphasize on the interaction of shoreline change and mangroves on an island is still lacking, making assessment and observation towards coastal areas on island less significant. Hence, this study is significant to provide a first view of the interaction and the relationship and response of shorelines change towards mangrove physical characteristics. GIS, remote sensing as well as statistical analysis such as DSAS and linear regression were applied to support the study that consisted of three main stages which involve data collection, data processing and comparison of mangroves physical characteristics towards the changes in shoreline positions. Finding revealed that during the time span of 2005-2011, shoreline near to Sg Ular has experienced more erosion, resulted in the shoreline shifting that was ranged between -0.02 m/y and -1.52 m/y. Further analysis of shoreline change and mangroves physical characteristic unveiled that a significant relationship of mangrove characteristics and shoreline changes rates occurred at Sg Ular. It was found that mangroves communities along the shoreline of Sg Ular was negatively influenced by the shoreline change, possibly due to mild erosion along the shoreline towards the river mouth of Sg Ular

Variations of riparian vegetation along the river corridors of Sg. Johor

Riparian vegetation has been recognized for its remarkable environmental and management implications. Occurred within the dynamic tract of river systems, riparian vegetation is a complex character that often exposed to the changes of river water and river beds. Their spatial extent is strongly controlled by inundation and flood disturbance, which result in the riparian vegetation migration to the point of destruction, if the competition for the area and other sources are lacking. This paper presents the findings of collected riparian vegetation information along Sg. Johor at the upstream and downstream of Kota Tinggi. Using Point-Centre-Quarter Method, the vegetation’s species, density, basal area, diameter at breast height and relative composition were recorded, identified and classified. Vitex pubescens and Drypetes spp. dominantly occurred along the upstream and downstream of this river, respectively. Species like Gymnacranthera bancana, Endospermum Malaccense, and Aquilaria Malaccensis are also found inhabit along Sg. Johor bank. Classified as woody vegetation, these vegetations are equipped with buttress roots that enable them to increase soil strength. This paper also suggests that proper study of riparian vegetation along river banks could promote a better understanding of the function of each species, to ensure the sustainability of riparian vegetation as part of river system engineer

Velocity structure of density currents propagating over rough beds

In most practical cases, density-driven currents flow over surfaces that are not smooth; however, the effects of bottom roughness on these currents have not been fully understood yet. Hence, this study aims to examine the velocity structure of density currents while propagating over rough beds. To this end, alterations in the vertical velocity profiles within the body of these currents were investigated in the presence of different bottom roughness configurations. Initially, laboratory experiments were carried out for density currents flowing over a smooth surface to provide a baseline for comparison. Thereafter, seven bottom roughness configurations were tested, encompassing both dense and sparse bottom roughness. The bottom roughness consisted of repeated arrays of square cross-section beams covering the full channel width and perpendicular to the flow direction. The primary results indicate that the bottom roughness decelerated the currents and modified the shape of velocity profiles, particularly in the region close to the bed. Additionally, a critical spacing of the roughness elements was detected for which the currents demonstrated the lowest velocities. For the spacings above the critical value, increasing the distance between the roughness elements had little impact on controlling the velocity of these currents. Moreover, using dimensional analysis, equations were developed for estimating the mean velocities of the currents flowing over various configurations of the bottom roughness. The findings of this research could contribute towards better parameterization and improved knowledge of density currents flowing over rough beds. This can lead to a better prediction of the evolution of these currents in many practical cases as well as improved planning and design measures for the control of such currents

Relative Influence of Meteorological Variables of Human Thermal Stress in Peninsular Malaysia

Climate change has significantly increased human thermal stress, particularly in tropical regions, exacerbating associated risks and consequences, such as heat-related illnesses, decreased workability, and economic losses. Understanding the changes in human thermal stress and its drivers is crucial to identify adaptation measures. This study aims to assess various meteorological variables’ spatial and seasonal impact on Wet Bulb Globe Temperature (WBGT), an indicator of human thermal stress, in Peninsular Malaysia. The Liljegren method is used to estimate WBGT using ERA5 hourly data from 1959 to the present. The trends in WBGT and its influencing factors are evaluated using a modified Mann-Kendall test to determine the region’s primary driver of WBGT change. The results indicate that air temperature influences WBGT the most, accounting for nearly 60% of the variation. Solar radiation contributes between 20% and 30% in different seasons. Relative humidity, zenith, and wind speed have relatively lesser impacts, ranging from −5% to 20%. Air temperature has the highest influence in the northern areas (>60%) and the lowest in the coastal regions (40%). On the other hand, solar radiation has the highest influence in the southern areas (20–40%) and the least in the north. The study also reveals a significant annual increase in temperature across all seasons, ranging from 0.06 to 0.24 °C. This rapid temperature rise in the study area region has led to a substantial increase in WBGT. The higher increase in WBGT occurred in the coastal regions, particularly densely populated western coastal regions, indicating potential implications for public health. These findings provide valuable insights into the factors driving WBGT and emphasize the importance of considering air temperature as a key variable when assessing heat stress