Abstract. Recently the sensing data for urban mapping used is in high demand together with the accessible of very high resolution (VHR) satellite data such as Worldview and Pleiades. This article presents the use of very high resolution (VHR) remote sensing data for urban vegetation mapping. The research objectives were to assess the use of Pleiades imagery to extricate the data of urban vegetation in urban area of Kuala Lumpur. Normalized Difference Vegetation Index (NDVI) were employs with VHR data to find Vegetation Index for classification process of vegetation and non-vegetation classes. Land use classes are easily determined by computing their Normalized Difference Vegetation Index for Land use land cover classification. Maximum likelihood was conducted for the classification phase. NDVI were extracted from the imagery to assist the process of classification. NDVI method is use by referring to its features such as vegetation at different NDVI threshold values. The result showed three classes of land cover that consist of low vegetation, high vegetation and non-vegetation area. The accuracy assessment gained was then being implemented using the visual interpretation and overall accuracy achieved was 70.740% with kappa coefficient of 0.5. This study gained the proposed threshold method using NDVI value able to identify and classify urban vegetation with the use of VHR Pleiades imagery and need further improvement when apply to different area of interest and different land use land cover characteristics. The information achieved from the result able to help planners for future planning for conservation of vegetation in urban area.
Flooding appears to be increasing in Kelantan, Malaysia, in terms of frequency as well as magnitude. This is likely to be due to changes in precipitation, but may also be contributed to by land use change. The Mann-Kendall non-parametric method was used to test for trends in streamflow and precipitation at the 90% significance level. Several significant trends in streamflow were found for the upstream (River Galas) and downstream (River Kelantan) sub-catchments for all variables (annual, seasonal and monthly time-series). In particular, streamflow increased in all seasons in the upstream sub-catchment, but increased in the wet season and decreased in the dry season downstream. Several trends were also observed for precipitation. Precipitation trends were increasing in the wet season and decreasing in the dry season for both upstream and downstream sub-catchments. Analysis of land use change revealed that most changes occurred through conversion of forest to agricultural land (i.e. rubber and oil palm), predominantly in the upstream sub-catchment. The analysis suggests a clear association between streamflow change and precipitation change, but also reveals that land use change may be an important contributing factor, particularly in the upstream sub-catchment.
This research aimed to quantify the effects of precipitation and land use changes on the hydrological response (peak discharge and runoff volume) in the River Kelantan catchment, Malaysia. Two periods were studied, involving the years 1988 (lower hydrological response) and 2004 (greater hydrological response). Rainfall and land use observed for the year 1988 was used in the calibrated and validated model for 1988, but also used in the calibrated 2004 runoff model to simulate the impact of changes in these two factors on runoff generation. For the upstream gauge, differences in peak discharge and runoff volume were affected more by land use change compared to climate‐related changes (i.e. precipitation). However, changes in hydrologic response in the downstream catchment were much more associated with precipitation changes. From these findings, we suggest that both land use and climate changes (i.e. precipitation) contributed to changes in hydrologic response in the Kelantan monsoonal catchment, but that for the downstream catchment, which is more prone to flooding, with associated potential socio‐economic impacts, precipitation change is the major driver. The results have clear implications for planning and management decision‐making.
The erosion in Malaysia has brought attention to many authorities especially the coastline in the eastern part of Peninsular Malaysia. Although the erosion in the northern part of Peninsular Malaysia does not receive as much attention as the eastern part of Peninsular Malaysia, however, the issue should not be neglected. High spatial resolution satellite imageries were used for the extraction of coastline and classification level of erosion rate along with the Pulau Tuba. The coastline data was extracted using two different methods known as Maximum Likelihood (ML) and On-Screen Digitizing (OSD) in the determination of the best approach of coastline detection from the Sentinel-2 data of the year 2016 and 2019. Furthermore, the level of erosion is made based on the physical and economic parameters outlined by the National Coastal Erosion Study 2015 (NCES). Due to some inevitable constraints of Movement Control Order by the Malaysian government due to the COVID-19 pandemic, physical observation data of Pulau Tuba were collected via Google Maps. The information acquired includes type of coastal geomorphology, land use, development on the area, activities conducted, and adaptation of erosion if any. These data were utilized to determine the erosion rate and categories using the proposed model by NCES for five divided management units (MU) of the Pulau Tuba areas utilizing Erdas Imagine and ArcGIS software. The analysis found that the ML approach has under-detected the coastline length between 3.19% to 45.0% as compared to OSD for both years of 2016 and 2019. Rate of erosion for Pulau Tuba based on the NCES approach found that the highest erosion rate occurred at the MU1 (Pulau Dayang Bunting- Pulau Tuba causeway) with 2.91% and classified as K1 (critical erosion category) with a value of 4.39 m/yr−1 and the highest accretion rate at the MU3 with 3.06%. The critical erosion category was associated with the MU that has significant development and on-going activities that occurred in the area especially in MU 4 (Pulau Tuba) and MU 5 (Teluk Berembang). Other than that, the high number of erosions occurred in that section is due to the exposure of waves, wind, currents, and tides.
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