Water Management and Sustainability in Asia: Volume 23

This study assesses the effects of flood hazard on property price, which focus on residential property. The growth in the population has resulted in more areas being explored, including areas that are prone to flooding. The exploration of a new area for housing development also brings vulnerability to flood hazard. This research employed hedonic regression method to assess the impact of flood to property price between low-flood and non-flood areas. The case study areas are residential properties along Langar River, Selangor, Malaysia. The findings reveal that residential price in case study areas have only little impact in terms of price impact from the flood events. This study also establishes a new valuation model by considering flood hazard. It is expected that the impact from the flood to property price will be significant in future due to changes in property demand patterns as well as the increase in environmental issues.

In effort to understand and reduce flood consequences more effectively and strategically, flood risk assessment has been a cornerstone of a long-term flood management. One component of flood risk assessment is the estimation of a range of possible damage to an area exposed to flooding, that is, the vulnerability curve. The vulnerability curve can be depicted by a stage–damage relationship. This study attempts to investigate how vulnerability to flooding can be quantitatively assessed using a micro-scale approach in Malaysia’s vulnerable areas. A residential area in Kota Bharu was chosen as the case study area. Depth–damage relationships from a multiple regression function of Department of Irrigation and Drainage Malaysia and spatial variability of residential buildings were used for the micro-scale assessment. Final estimates of expected annual damage were then calculated for each building type at 1-, 3- and 5-day flood durations. Results show that the methodology adopted is feasible to be applied for local-scale assessment flood risk assessment in Malaysia. The results also suggest that applying the methodology is possible when given wider availability of resources and information. This is particularly important for a robust end-to-end flood risk assessment for long-term effective flood management in Malaysia.

Flood vulnerability is a complex concept involving the interactions between environment, social and economic dimensions. Indicator‐based vulnerability assessment is widely used in vulnerability studies to summarise complexity and multidimensionality issues to gauge the level of vulnerability. A set of 21 environmental and socio‐economic indicators is used to quantitatively assess the three factors of vulnerability, namely exposure, susceptibility and resilience to flood at the subnational level. The construction of the vulnerability index involved the selection of indicators, their normalisation, weightage and aggregation to a final index. In addition to the Flood Vulnerability Index, three sub‐indices namely Exposure Index, Susceptibility Index and Resilience Index were generated. Based on composite indicator approach, the vulnerability of the states in Malaysia was categorised from very low to very high. The source of vulnerability is due not only to the environmental exposure to flood hazard but also contributed by the internal status of the socio‐economic factors within the vulnerable systems.

Dams are constructed for many purposes such as for power generation, irrigation, water supply and flood control. However, dams can also impose risks to the public, and the situation could be disastrous if dam failure occurred. The study area, Bertam Valley, is located downstream of hydroelectric dam known as Sultan Abu Bakar Dam, Cameron Highlands. The key objectives of the study are to determine the potential risk area at downstream and to assess the flooding impact on damage to buildings and infrastructures due to dam break event. ArcGIS application and output from two-dimensional flood modelling have been used as an integrated approach to analyse the impact due to dam break flood, by creating flood severity grid analysis. The result obtained shows that the estimated inundated area is about 0.28 km², and almost 197 buildings are potentially affected. Results from this study show that in the event of dam break, the huge volume of impounding water will pound to the downstream areas, threatening the populations, and environment along its path. The finding is useful to assist the local authorities and emergency responders in formulating an emergency procedure to save the people during an emergency.

The objective of this study is to propose a functional framework for hydrological applications by treating flood hydrographs as functional data. Discrete flow data are transformed into a smoothing hydrograph curve, which can be analysed at any time interval. The concept of functional data considered the entire curve concerning time as a single observation. This chapter briefly discussed the idea of descriptive statistics, principal components and outliers in a functional framework. These methods were illustrated in the flood study at Sungai Kelantan River Basin, Malaysia. The results showed that five main components accounted for almost 73.8% of the overall flow variance. Based on the results of the factor scores, the hydrograph curves for the years 1988, 1993 and 2014 may be said to have a unique cluster of their own, while the rest of the years which consider having the same pattern. Due to various shapes and magnitudes, the hydrograph curves of 1988 and 2014 are considered outliers. In conclusion, the functional framework has shown that it is capable of representing a wide range of hydrographs and is capable of extracting additional information found in the hydrograph curve that cannot possibly be captured using classical statistical methods.

The Best Management Practices for Sustainable Urban Drainage System including On-Site Detention have been introduced in the Storm Water Management Manual for Malaysia. Flash floods are becoming frequent in the urbanised areas in this country. Inefficient drainage system has been highlighted as one of the factors. Urban drains were reported incapable of coping with the unexpected heavy rainfall. Concrete drains are favourable in construction industry for economic reasons. An experimental research was conducted out to investigate the effectiveness of infiltration integration with drainage system to reduce flash flood. This laboratory research was conducted in the Universiti Teknologi Malaysia. Experiments were performed for selected drainage bed slopes and focussed on several spacing between precast drain sections along the system. The total and infiltrated flow rates, water surface and velocity profiles were examined. The results showed that drain flow rates were reduced by 60.9%–89.6% when the spacing between drain sections were enlarged. Meanwhile, the flow depths in drain sections were dropped by 48.2%–68.9%, and the water velocity was lowered up to 49% as the spacing between drain sections were increased. The study found that the drainage bed slope also influenced the performance of the infiltrated concrete drainage system.

Climate change is expected to alter the major components of hydrological regime such as streamflow and water availability. The magnitude and their impacts are still uncertain. Therefore, it is highly required to study streamflow and flood vulnerability in tropical river basins particularly urbanised basin such as Langat River Basin. This study aims to model the future streamflow of Langat River Basin due to climate change using Rainfall-Runoff Inundation (RRI) model. Daily rainfall data obtained from Department of Irrigation and Drainage Malaysia and topographic data from HydroSHEDS at 15-second resolution were used. The projected future rainfall (2075–2099) is extracted from MRI-AGCM3.2s under the worst carbon emission scenario, RCP8.5. The annual maximum series of 1-day rainfall is selected for statistical bias correction using Quantile Mapping. The General Circulation Model data were found to be greatly corrected with reasonable Nash–Sutcliffe efficiency, Percent bias and Root Mean Square Error values. The mean of maximum 1-day future rainfall in Langat River Basin is found to be inconsistent where parts of the upstream will experience an increment at about 7% while other parts decrease at 8%. Meanwhile, the rainfall at downstream area are expected to decrease at 40%. Based on RRI simulation, the future streamflow can achieve up to 92% increment.

This study explores the concept of hydraulic flushing gate with an automated control system as a flow control structure of the urban storm water system. The research team has implemented a flush gate with the automated control system to the flow of the water in a drainage channel. The flow control structure was used to determine the effectiveness of such design by applying the concept of virtually on a real-world drainage system at Jalan Astana, Kuching. Computer representations of the existing drainage system and flow control structure were built using EPA SWMM 5.0 model. The series of flow control structure was proven to hold the runoff from 10-year storm. The modelling result shows that there is 25.9% of flow reduction at outlet node. As a modification of the existing drainage system in the urban area involves high construction cost, by installing a flow control structure in the drainage system is an innovative way to control the flow of the water.

Rainfall–runoff relationship is one of the most complex hydrological phenomena. A conventional neural network (NN) with backpropagation algorithm has successfully modelled various non-linear hydrological processes in recent years. However, the convergence rate of the backpropagation NN is relatively slow, and solutions may trap at local minima. Therefore, a new metaheuristic algorithm named as cuckoo search optimisation was proposed to combine with the NN to model the daily rainfall–runoff relationship at Sungai Bedup Basin, Sarawak, Malaysia. Two-year rainfall–runoff data from 1997 to 1998 had been used for model training, while one-year data in 1999 was used for model validation. Input data used are current rainfall, antecedent rainfall and antecedent runoff, while the targeted output is current runoff. This novel NN model is evaluated with the coefficient of correlation (R) and the Nash–Sutcliffe coefficient (E²). Results show that cuckoo search optimisation neural network (CSONN) is able to yield R and E² to 0.99 and 0.94, respectively, for model validation with the optimal configuration of number of nests (n) = 20, initial discovery rate of alien eggs (painitial) = 0.6, hidden neuron (HN) = 100, iteration number (IN) = 1,000 and learning rate (LR) = 1 for CSONND4 model. The results revealed that the newly developed CSONN is able to simulate runoff accurately using only precipitation and runoff data.

Time of concentration (T_c) is one of the main inputs in rainfall–runoff model which depends on catchment length, slope, soil properties and surface cover. Factor such as floodplain also has a significant contribution on the flood wave travel time. Floodplain which influences the flow and the travelling time is not possible to be calculated using common T_c formulae. One approach to handle this complex behaviour is to deploy the hydrodynamic model as part of the rainfall–runoff model. This chapter explains the application of hydrodynamic approach to determine T_c for large catchment with the effect of floodplain. A hydrodynamic river model for Sg Relai was developed as part of the rainfall–runoff model covering 460 km² catchment area. It includes channels covering 90 km long which is extended to the floodplain based on the digital terrain model. The simulation results show that once the flood water spill to the floodplain, the channel travelling time is delayed by several hours. The delay of the travel time increases as the rainfall intensity increase which demonstrates that hydrodynamic modelling with the integration of floodplain is capable to compute the variation of T_c.

Heavily subsidised irrigation systems have been the government’s measure to improve the farmer’s lives. However, evaluation of the performance of these systems was often overlooked. Thus, this study aims to assess the efficiency of irrigation systems in Davao del Sur, Philippines, according to agricultural, social and economic aspects, namely cropping intensity, functionality and production and monthly average income per hectare, respectively. More than half of the national irrigation schemes exhibited outstanding functionality based on organisation, system and operation and maintenance areas, while almost 75% of the communal schemes have exhibited the same. On the other hand, communal systems have higher cropping intensities (wet – 106% and dry – 116%) than those of the national schemes (wet – 89.8% and dry – 89.1%). Results show that communal systems perform better than those managed by Irrigation Administration. The former have been given the full control over their farm areas, where it is expected that members of the association are able to fully articulate in the decision-making and participate in their activities. Although irrigation managers of the said agency have key roles in the capacity building and management of the irrigation systems, performances of such systems largely depended on how well farmers manage the irrigation association.

This study provides a performance analysis of using a rainwater harvesting system (RWHS) to supply water for toilet flushing and garden watering, with reference to a student accommodation hall in the University of Nottingham Malaysia in Semenyih, Selangor, Malaysia. Three different models were used in this analysis, in which the monthly analysis was based on the mass-balance approach, while the daily analysis was based on the yield before spillage and yield after spillage algorithms to define the tank release rule based on different sizes of storage tank (i.e. 3, 5, 7 and 10 m³). The performances of the various storage tanks were presented for water saving and reliability. The monthly analysis found promising results of collectable water on the demand, in which the average reliability is higher than 50%. Also, the daily water balance simulation verified the results from the monthly analysis. A cost analysis was performed that the best storage rainwater harvesting tank size was 10 m³ for the combined demand of toilet flushing and garden watering. Based on the findings, the proposed implementation of RWHS in the chosen campus university was reliable, not only environmentally beneficial but also economically viable.

This project analyses water consumption data in residential college of Universiti Kebangsaan Malaysia (UKM) by eliciting the main water metre reading from each residential college. The study found that the average water consumption per student in colleges ranged above 200 litres/day, much higher than the World Health Organization’s recommended level of 165 litres/day. The high water consumption could be related to irrational use of water among the students and staff as well as water loss due to leakage. To detect the water loss in a water network, the reading of water metre during minimum night flow (MNF) time was taken between 1 a.m. and 5 a.m. From the study, it could be seen that most of the residential colleges recorded high MNF level (more than 0.97 litres/second), which indicates the presence of leakage within the water network in the college. The findings from this study indicated that the water consumption in UKM can be reduced by minimising the loss of non-revenue water and educating the people to use water moderately. Saving the water resources will help to reduce water utility bill and strengthen UKM against the threat of water crisis.

Big data have rapidly developed as a viable solution to many problems faced in engineering industries. Specifically, in the industry of water resource engineering, where there is a tremendous amount of data, various big data techniques could be applied to achieve innovative and efficient solutions for the industry. This study reviewed the proposal of big data as potential approaches to solve various difficulties encountered in managing water resources and related applications in Malaysia. The advantages and disadvantages of big data applications have also been discussed along with a brief literature review and some examples of case studies.

The evolution in developed countries has taken a role in global warming and natural disasters such as flash flood, El-Nino, earthquake and groundwater contamination. The underground storage tank leakage problems and spillage of hydrocarbon liquid leading to the contamination of non-aqueous phase liquids (NAPLs) into the groundwater could reduce the quality of groundwater. This chapter is intended to investigate the behaviour and the pattern of NAPL migrations in double-porosity soil under vibration and intact conditions. The experimental model is developed by using kaolin soil type S300 and toluene as NAPLs. The kaolin soil was mixed with 25% of moisture content to produce kaolin granules in the soil column and vibrate under 0.98 Hz of frequency within 60 seconds. As a result, both specimen liquids completely migrated to the bottom of soil column: sample 1 has higher permeability compared to sample 2. This is due to the fracture in double-porosity soil under vibration effect and loosened the soil structure in sample 1 compared to good intact soil sample 2 with stronger and compact soil structure. In conclusion, this study proves that the dangerous hydrocarbon NAPL migration in fractured double-porosity soil has very harmful effect on the environment and groundwater resources.

The impact of climate change towards water surface resources is crucial, particularly in developing and non-developing countries. Groundwater as a main water resource is thus an essential. However, contamination due to hydrocarbon spills affects the groundwater as a water resource, especially as a main source of drinking water. This chapter investigates the light non-aqueous phase liquid (LNAPL) penetrations in double-porosity soil with different moisture contents and with or without vibration impact. It also explains the LNAPL penetration phenomena by employing image analysis. The physical laboratory experiments were implemented using an acrylic cylinder, a mirror, toluene and a Nikon D90 DSLR digital camera. Prepared soil was poured in an acrylic cylinder and compressed with compressor until it became 10 cm in height. LNAPL was then poured instantaneously onto the acrylic cylinder that was filled with soil sample. The LNAPL penetration patterns were recorded and monitored using a Nikon D90 DSLR digital camera. The processing technique was conducted at predetermined time intervals using Surfer software and Matlab routine to plot the LNAPL pattern. The results showed that a higher penetration rate of LNAPL occurred with higher moisture content and without vibration impact. The penetration time for LNAPL to reach the bottom of the soil sample was found to be longer for the soil that had low moisture content and with vibration impact.

Southeast Asia has been actively undergoing land conversion into agricultural lands over past few decades. This creates the challenges to the nation in dealing with the non-point source pollutants in many fluvial systems, thus requiring an effective approach in sediment source apportionment for an appropriate target mitigation procedure. The trace element property from different source points was used for catchment classification of Galas River. Sediment sample collection was carried out at the sources and sink areas of the catchment system. Fine sediment was analysed using X-ray fluorescence to obtain elemental composition followed by the statistical test and numerical model. Out of 83 elements, 12 elements (Mn, Ca, Cr, Ga, Dy Hf, Y, V, Th, Pb, Zn and Sr) have been selected as best tracer signatures. The solver model has indicated Pergau River as the major sediment contributor to this large catchment system. The model output could directly be proportional with the land-use practice, indicating excessive terrestrial alteration has taken place within the sites for agricultural plantation purposes. Thus, this highly recommends for the decision-making use to the targeted areas to overcome the serious sedimentation issues caused by the tillage operation in affected stream points and to improve the watershed quality.