An Analysis of Abrupt Change in Rainfall and the Occurrence of Extreme Events

Extreme events are normally apparent as they considerably and deviate from the normal condition. In some parts of the world increases in extreme events are apparent, while in others there appears to be a decline. It is of great attention to explore and understand the changes (if any) for an area from the previous history before undertaking any further studies. These abrupt changes may indicate a shift into another rainfall regime. In the current study, abrupt changes in historic rainfall variability were investigated using Sequential Mann-Kendall test at five (5) selected stations. Four out of the five stations (Edenhope, Kerang, Malmsbury and Yanac) selected showed significant abrupt increases in rainfall. The Melbourne Regional Office (MRO) station identified an abrupt increase in 1916, however, it was not significant. In addition, Standardised Precipitation Index (SPI) was applied to identify the historical extreme events, namely droughts and floods. It is observed that the annual rainfall had an increasing change in early 1990s due to flood events. The floods of 1946 was one of the worst events recorded in history and most of the stations undergone large increases in rainfall. This study reveals that the Sequential Mann-Kendall test detected the change point well and the results were consistent with the SPI

Climate Change Assessment on Flood Occurrence in Kota Tinggi, Johor

Flood is associated with the climatic change where the climate variable has detrimental impact on hydrologic cycle.  Johor is among the affected states by flood catastrophe for almost every year. Over the year, Johor has experienced increasing amount of rainfall. However, studies on future rainfall pattern in Johor are still quite limited. Thus, this study was carried out to identify climate change impacts by projecting rainfall data using Statistical Downscaling Model (SDSM) and predicting flood events utilizing the Standardised Precipitation Index (SPI). Through SDSM, the rainfall data was projected in corresponding with General Circulation Models (GCM) predictor under three different representative concentration pathway (RCP) of RCP2.6, RCP4.5 and RCP8.5 that consider different emission level in future. Future observation in the upcoming 30 years for both studied stations at Kota Tinggi, Johor recorded increasing trend in the projected mean annual rainfall under three scenarios where the highest change in projection was +12.2% under RCP8.5 at Ladang Telok Sengat station. From SPI analysis, it is predicted that there will be frequent occurrence of flooding in the upcoming 30 years due to more positive SPI values (> 1) indicated by the studied stations. From the study, the authorities can come up with better mitigation plan to supervise the flood event in the future

Monitoring Water Level and Water Quality in Rainwater Harvesting Tank using Internet of Things (IoT) Device

 In the content of Fourth Industrial Revolution (4IR), the Internet of Things (IoT) is encouraged to be implemented in various areas of the industry, including the hydrology industry. The water quality parameters such as pH value and turbidity of water can be monitored via the IoT device. Thus, in this study, the objectives are to monitor the water level, pH value and turbidity of water in the rainwater harvesting (RWH) storage tank built using IoT devices, and to estimate the suitable volume of RWH storage tank on the rooftop of Kumpulan Perubatan Johor (KPJ) Batu Pahat Specialist Hospital. The combination of ultrasonic sensors, pH sensors, turbidity sensors and rain gauge with the Arduino were utilized for the water monitoring system installed at the RWH storage tank at KPJ Batu Pahat Specialist Hospital. The output of the data, including water level, pH value, turbidity and rainfall depth were monitored through the online portal of MyAgriTECH Monitoring System within six months from November 2020 to April 2021. The time interval for the measurement of the parameters was every 10 minutes, from the beginning until the end. The water level obtained ranged from 132.15 cm to 184.11 cm. The pH value recorded were ranged from 5.45 to 12.38, whereas the lowest turbidity and highest turbidity was 9.25 NTU and 67.11 NTU, respectively. For the estimation of optimum size for rainwater harvesting storage tank, the results obtained was 5 m3. The use of IoT device in monitoring water level and water quality in RWH tank can be implemented due to RWH system is indeed one of the alternatives to solve the problem of water supply

Climate change assessment on flood occurrence in Kota Tinggi, Johor

Flood is associated with the climatic change where the climate variable has detrimental impact on hydrologic cycle. Johor is among the affected states by flood catastrophe for almost every year. Over the year, Johor has experienced increasing amount of rainfall. However, studies on future rainfall pattern in Johor are still quite limited. Thus, this study was carried out to identify climate change impacts by projecting rainfall data using Statistical Downscaling Model (SDSM) and predicting flood events utilizing the Standardised Precipitation Index (SPI). Through SDSM, the rainfall data was projected in corresponding with General Circulation Models (GCM) predictor under three different representative concentration pathway (RCP) of RCP2.6, RCP4.5 and RCP8.5 that consider different emission level in future. Future observation in the upcoming 30 years for both studied stations at Kota Tinggi, Johor recorded increasing trend in the projected mean annual rainfall under three scenarios where the highest change in projection was +12.2% under RCP8.5 at Ladang Telok Sengat station. From SPI analysis, it is predicted that there will be frequent occurrence of flooding in the upcoming 30 years due to more positive SPI values (> 1) indicated by the studied stations. From the study, the authorities can come up with better mitigation plan to supervise the flood event in the future

HEC-RAS hydraulic model for floodplain area in Sembrong river

The study of floodplain is significant to human life and social economy. It can be seen that by using most computer models, locations of structures affected by floodwaters, such as bridges and roads cannot be effectively compared to the floodplain location in stream floodplain analysis. The purpose of this study is to develop an output of Hydrologic Engineering Center’s River Analysis System (HEC-RAS) hydraulic model and to enable one dimensional steady flow analysis. This study is applied to Sembrong river catchment area, located in Batu Pahat. Floodplain data features such as length of streams, bank position, streamline and cross-sections were used to produce river flow and its cross-sectional shape for each station along the study area. Total of 7 flow rate values were used to indicate an increase in the water level in order to accommodate the additional amount of water that flow into river. The results show that water will overflow into the floodplain at maximum flow rate of 24 m3 /s. The hydraulic model had indicated that 33 out of 65 stations were unable to accommodate the maximum flow rate and thus will led to flooding. By developing the hydraulic model, it clearly shows that the results are more reliable and the affected area can be easily identified. The developed flood model can be a very useful tool in flood management of Sembrong river in terms of river development planning, flood mitigation measures, flood evacuation planning and addressing public awareness. This study proved that HEC-RAS is one of effective instrument for analysis and modeling

A review on short-term prediction of air pollutant concentrations

In the attempt to increase the production of the industrial sector to accommodate human needs; motor vehicles and power plants have led to the decline of air quality. The tremendous decline of air pollution levels can adversely affect human health, especially children, those elderly, as well as patients suffering from asthma and respiratory problems. As such, the air pollution modelling appears to be an important tool to help the local authorities in giving early warning, apart from functioning as a guide to develop policies in near future. Hence, in order to predict the concentration of air pollutants that involves multiple parameters, both artificial neural network (ANN) and principal component regression (PCR) have been widely used, in comparison to classical multivariate time series. Besides, this paper also presents comprehensive literature on univariate time series modelling. Overall, the classical multivariate time series modelling has to be further investigated so as to overcome the limitations of ANN and PCR, including univariate time series methods in short-term prediction of air pollutant concentrations

Impacts of Climate Change on Rainfall Trends Under RCP Scenarios in Johor, Malaysia

Changes in the spatial and temporal rainfall pattern affected by the climate change need to be investigated as its significant characteristics are often used for managing water resources. In this study, the impacts of climate change on rainfall variability in Johor was investigated by using General Circulation Model (GCM) on the availability of daily simulation for three representative concentration pathways (RCP) scenarios, RCP 2.6, RCP 4.5 and RCP 8.5 for interval year of Δ2030, Δ2050 and Δ2080. In addition, the annual future rainfall trend for the first interval year of Δ2030 was also made. Daily rainfall series from eight (8) stations in Johor, Malaysia capturing 30 years period (1988-2017) with less than 10% missing data were chosen. The annual mean rainfall for RCP 2.6, 4.5 and 8.5 was predicted increase by 17.5%, 18.1% and 18.3%, respectively as compared to historical data. Moreover, the Mann-Kendall (MK) test was used to detect the trend and resulted in no trend for RCP 2.6. Even so, RCP 4.5 showed a significant upward trend in Muar and Kota Tinggi, and for RCP 8.5, all regions were detected to have an upwards trend except for Pontian and Kluang. In general, the concentration of greenhouse gases from RCP 8.5 gave the highest rainfall in future

Treatment of shallow groundwater quality for non-potable use: A case study in Parit Raja, Batu Pahat, Johor

Groundwater becomes an alternative water resource to meet up the demand of clean water in our country. Unfortunately, several contam-inants could present in groundwater make it unsafe for domestic used and drinking water purpose. Therefore, groundwater should be treated to acceptable level before it can be consumed for further use. The aim of this study was to improve the groundwater quality in terms of physical parameters and bring it within the acceptable level using simple and economical aeration and filtration methods. Gravel, ceramic and charcoal were used as filter materials. The removal efficiency was determined from the calculated percentage removal of the tested parameters. Based on the results, groundwater showed improvement in its physical quality with percentage removal of turbidity, BOD and COD at 92%, 73% and 79%, respectively. Parameter pH also showed good improvement from slightly acidic to neutral range. However, TDS gave different results. With the exception of TDS, all parameters comply with the Malaysia’s standard of raw and drink-ing water quality set by Ministry of Health

Impacts of Climate Change on Rainfall Trends Under RCP Scenarios in Johor, Malaysia

Changes in the spatial and temporal rainfall pattern affected by the climate change need to be investigated as its significant characteristics are often used for managing water resources. In this study, the impacts of climate change on rainfall variability in Johor was investigated by using General Circulation Model (GCM) on the availability of daily simulation for three representative concentration pathways (RCP) scenarios, RCP 2.6, RCP 4.5 and RCP 8.5 for interval year of Δ2030, Δ2050 and Δ2080. In addition, the annual future rainfall trend for the first interval year of Δ2030 was also made. Daily rainfall series from eight (8) stations in Johor, Malaysia capturing 30 years period (1988-2017) with less than 10% missing data were chosen. The annual mean rainfall for RCP 2.6, 4.5 and 8.5 was predicted increase by 17.5%, 18.1% and 18.3%, respectively as compared to historical data. Moreover, the Mann-Kendall (MK) test was used to detect the trend and resulted in no trend for RCP 2.6. Even so, RCP 4.5 showed a significant upward trend in Muar and Kota Tinggi, and for RCP 8.5, all regions were detected to have an upwards trend except for Pontian and Kluang. In general, the concentration of greenhouse gases from RCP 8.5 gave the highest rainfall in future

Forecasting of Rainfall Using General Circulation Model - Statistical Modelling in Johor

Changes in the spatial and temporal rainfall pattern which affected by the climate change need to be investigated as its significant characteristics are often used for managing water resources. This paper implemented the statistical modelling to study the spatial and temporal distribution changes of rainfall pattern in the long term analysis. A daily rainfall series from eight (8) stations in Johor capturing 30 years period (1988-2017) with less than 10% missing data were chosen. To build the predictor-predictand relationship, it depends on the monthly correlation coefficient (R) with the large scale of atmospheric characteristic and performances of calibrated and validated of statistical equation using Statistical Downscaling Model (SDSM). The results showed that the temperature (nceptemp), surface specific humidity (ncepshum) and near surface relative humidity (nceprhum) had strong influence in the local weather formations. As proved, all these stations were successfully produced low standard error (SE) ranged from 3.82% to 11.64%. The annual temporal rainfall was expected to increase to 3058.13 mm (15.4%) at the end of century. The eastern of Johor was expecting to receive higher rainfall intensity and then disperse to the western of Johor. The predictions of rainfall are a bit alarming, therefore, mitigation planning on climate change effects is needed