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Balqis Rehan
Department of Civil Engineering, Faculty of Engineering, Universiti Putra Malaysia, UPM Serdang 43400, Malaysia

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Journal article
Published: 07 May 2021 in Sustainability
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Good index selection is key to minimising basis risk in weather index insurance design. However, interannual, seasonal, and intra-seasonal hydroclimatic variabilities pose challenges in identifying robust proxies for crop losses. In this study, we systematically investigated 574 hydroclimatic indices for their relationships with yield in Malaysia’s irrigated double planting system, using the Muda rice granary as a case study. The responses of seasonal rice yields to seasonal and monthly averages and to extreme rainfall, temperature, and streamflow statistics from 16 years’ observations were examined by using correlation analysis and linear regression. We found that the minimum temperature during the crop flowering to the maturity phase governed yield in the drier off-season (season 1, March to July, Pearson correlation, r = +0.87; coefficient of determination, R2 = 74%). In contrast, the average streamflow during the crop maturity phase regulated yield in the main planting season (season 2, September to January, r = +0.82, R2 = 67%). During the respective periods, these indices were at their lowest in the seasons. Based on these findings, we recommend temperature- and water-supply-based indices as the foundations for developing insurance contracts for the rice system in northern Peninsular Malaysia.

ACS Style

Zed Zulkafli; Farrah Muharam; Nurfarhana Raffar; Amirparsa Jajarmizadeh; Mukhtar Abdi; Balqis Rehan; Khairudin Nurulhuda. Contrasting Influences of Seasonal and Intra-Seasonal Hydroclimatic Variabilities on the Irrigated Rice Paddies of Northern Peninsular Malaysia for Weather Index Insurance Design. Sustainability 2021, 13, 5207 .

AMA Style

Zed Zulkafli, Farrah Muharam, Nurfarhana Raffar, Amirparsa Jajarmizadeh, Mukhtar Abdi, Balqis Rehan, Khairudin Nurulhuda. Contrasting Influences of Seasonal and Intra-Seasonal Hydroclimatic Variabilities on the Irrigated Rice Paddies of Northern Peninsular Malaysia for Weather Index Insurance Design. Sustainability. 2021; 13 (9):5207.

Chicago/Turabian Style

Zed Zulkafli; Farrah Muharam; Nurfarhana Raffar; Amirparsa Jajarmizadeh; Mukhtar Abdi; Balqis Rehan; Khairudin Nurulhuda. 2021. "Contrasting Influences of Seasonal and Intra-Seasonal Hydroclimatic Variabilities on the Irrigated Rice Paddies of Northern Peninsular Malaysia for Weather Index Insurance Design." Sustainability 13, no. 9: 5207.

Preprint content
Published: 04 March 2021
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Damage functions are widely used to determine flood losses. National and international published damage functions are often used with little scrutiny or validation at local scales; a lack of understanding that unquestionably adds uncertainty to national flood risk assessment and investment planning. This paper examines the differences in aggregate flood damage estimates based on damage functions derived locally using local surveys and questionnaires, published national sector-based damage functions and land-use based damage functions published for Malaysia in the international literature. The paper is presented in two parts: firstly, the construction of a damage function from site-specific post-event flood surveys (covering a range of building types and flood hazard variables) and secondly, the comparison of these locally derived function with available national and international functions. A 0.05 km2 residential area located in Kuala Lumpur, Malaysia, which consists of sparsely located houses was selected for the study. It was used to drive the site-specific damage function and an associated estimate of flood damage for a range of observed and modelled flood events. The results show that at higher depths, the use of the site-specific function suggest an aggregate damage of approximately twice than an estimate based on national functions but much less (less than 100%) than would be estimated based on international published functions. The paper concludes that the international published damage functions should be used with care and condition using local (where possible) or national understanding of flood damages to avoid a significant over estimation of losses.

ACS Style

Balqis M. Rehan; Paul Sayers; A. Ulwan M. Alayuddin; M. Fadhil M. Ghamrawi; James D. Miller; Shabir A. Kabirzad; Alexandra Kaelin; Edmund C. Penning-Rowsell; Bakti H. Basri; Victoria A. Bell; Zed Zulkafli; Elizabeth J. Stewart. Flood vulnerability assessment: A critical comparison between site derived, national and international depth-damage functions and their use in assessing flood risk in Malaysia. 2021, 1 .

AMA Style

Balqis M. Rehan, Paul Sayers, A. Ulwan M. Alayuddin, M. Fadhil M. Ghamrawi, James D. Miller, Shabir A. Kabirzad, Alexandra Kaelin, Edmund C. Penning-Rowsell, Bakti H. Basri, Victoria A. Bell, Zed Zulkafli, Elizabeth J. Stewart. Flood vulnerability assessment: A critical comparison between site derived, national and international depth-damage functions and their use in assessing flood risk in Malaysia. . 2021; ():1.

Chicago/Turabian Style

Balqis M. Rehan; Paul Sayers; A. Ulwan M. Alayuddin; M. Fadhil M. Ghamrawi; James D. Miller; Shabir A. Kabirzad; Alexandra Kaelin; Edmund C. Penning-Rowsell; Bakti H. Basri; Victoria A. Bell; Zed Zulkafli; Elizabeth J. Stewart. 2021. "Flood vulnerability assessment: A critical comparison between site derived, national and international depth-damage functions and their use in assessing flood risk in Malaysia." , no. : 1.

Conference paper
Published: 29 November 2019 in Proceedings of EECE 2020
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Floods pose serious threats worldwide. During this disaster, civil engineering structures, such as buildings, bridges, dams, water supply, coastal structures, infrastructure facilities are severely affected, causing immense inconvenience to people and disrupting routine life. In the context of water-food security, floods have been a major source of natural disturbance to rice productivity in Malaysia. The consequences of floods will bring losses to the rice production and cause instability. The damage of paddy production due to floods needs to be handled seriously as the negative impact could lead to insufficient food supplies in the country. The purpose of this paper is to estimate flood risk in paddy production considering different flood inundation durations and plant’s ages. The calculation of risk considers the probability of extreme flood levels and fine cell resolution of paddy field in the total loss estimation. The location used for this study is in Kedah, where rice production is among the most prominent in Malaysia. Flood risk is expected mounting to nearly half a million ringgits for the 330 ha plots considering the current condition. This emphasize on an effective long-term flood risk management in order to reduce flood risk to paddy production.

ACS Style

Balqis M. Rehan; Ainun M. Yusuf; Iffah L. Idham. Flood Risk Estimation of Paddy Production Considering Plants’ Age and Flood Durations. Proceedings of EECE 2020 2019, 1163 -1174.

AMA Style

Balqis M. Rehan, Ainun M. Yusuf, Iffah L. Idham. Flood Risk Estimation of Paddy Production Considering Plants’ Age and Flood Durations. Proceedings of EECE 2020. 2019; ():1163-1174.

Chicago/Turabian Style

Balqis M. Rehan; Ainun M. Yusuf; Iffah L. Idham. 2019. "Flood Risk Estimation of Paddy Production Considering Plants’ Age and Flood Durations." Proceedings of EECE 2020 , no. : 1163-1174.

Journal article
Published: 07 September 2019 in Water
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Natural rivers have many branching junctions. The flow in branching junctions is complex, owing to significant changes associated with flow dynamics and sediment transport that result in erosion and deposition problems. A branching channel of the Tigris River in Missan, Iraq, was selected for investigation of the scouring and deposition zones. A two-dimensional (2D) numerical model was used to simulate the hydro-morphodynamics in the branching channel, where hypothetical vanes as control structures were included at the junction to control the scouring and deposition zones. The simulation results suggest the most effective location, dimension, and angle of the introduced vanes. For the studied junction, controlling morphological features was achieved by introducing a single vane with an inclination angle of 90° on the flow direction of the Tigris River. The most effective location of the introduced vane was the location that caused considerable enhancement in the flow depth and velocity distribution.

ACS Style

Hydar Lafta Ali; Badronnisa Yusuf; Thamer Ahamed Mohammed; Yasuyuki Shimizu; Mohd Shahrizal Ab Razak; Balqis Mohamed Rehan. Enhancing the Flow Characteristics in a Branching Channel Based on a Two-Dimensional Depth-Averaged Flow Model. Water 2019, 11, 1863 .

AMA Style

Hydar Lafta Ali, Badronnisa Yusuf, Thamer Ahamed Mohammed, Yasuyuki Shimizu, Mohd Shahrizal Ab Razak, Balqis Mohamed Rehan. Enhancing the Flow Characteristics in a Branching Channel Based on a Two-Dimensional Depth-Averaged Flow Model. Water. 2019; 11 (9):1863.

Chicago/Turabian Style

Hydar Lafta Ali; Badronnisa Yusuf; Thamer Ahamed Mohammed; Yasuyuki Shimizu; Mohd Shahrizal Ab Razak; Balqis Mohamed Rehan. 2019. "Enhancing the Flow Characteristics in a Branching Channel Based on a Two-Dimensional Depth-Averaged Flow Model." Water 11, no. 9: 1863.

Journal article
Published: 01 January 2019 in Resources
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Controlling the flow and bed morphology in a river confluence is important in training and navigation works. The flow in river confluence is highly complex due to crucial and rapid changes associated with flow dynamics, sediment transport, and geomorphology. The flow in Malaysia’s rivers has many confluence junctions in natural drains of catchment areas. The confluence between Kurau and Ara Rivers, in Perak, Malaysia, is selected to investigate the scour hole that usually forms in the erosion zone and the bar that forms in the deposition zone. A 2D numerical model is used in simulating hydro-morpho dynamics in the rivers confluence to mitigate the erosion and deposition zones by adopting vanes as control structures. Simulation results suggest that the most effective location, dimension, and angle of vanes can be decided based on their performance in scouring and deposition zones. The distribution velocity and flow vectors can help in deciding the location of the vanes.

ACS Style

Hydar Lafta Ali; Badronnisa Yusuf; Thamer Ahamed Mohammed; Yasuyuki Shimizu; Mohd Shahrizal Ab Razak; Balqis Mohamed Rehan. Improving the Hydro-Morpho Dynamics of A River Confluence by Using Vanes. Resources 2019, 8, 9 .

AMA Style

Hydar Lafta Ali, Badronnisa Yusuf, Thamer Ahamed Mohammed, Yasuyuki Shimizu, Mohd Shahrizal Ab Razak, Balqis Mohamed Rehan. Improving the Hydro-Morpho Dynamics of A River Confluence by Using Vanes. Resources. 2019; 8 (1):9.

Chicago/Turabian Style

Hydar Lafta Ali; Badronnisa Yusuf; Thamer Ahamed Mohammed; Yasuyuki Shimizu; Mohd Shahrizal Ab Razak; Balqis Mohamed Rehan. 2019. "Improving the Hydro-Morpho Dynamics of A River Confluence by Using Vanes." Resources 8, no. 1: 9.

Original paper
Published: 18 January 2018 in Natural Hazards
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Economic damage assessment for flood risk estimation is established in many countries, but attentions have been focused on macro- or meso-scale approaches and less on micro-scale approaches. Whilst the macro- or meso-scale approaches of flood damage assessment are suitable for regional- or national-oriented studies, micro-scale approaches are more suitable for cost–benefit analysis of engineered protection measures. Furthermore, there remains lack of systematic and automated approaches to estimate economic flood damage for multiple flood scenarios for the purpose of flood risk assessment. Studies on flood risk have also been driven by the assumption of stationary characteristic of flood hazard, hence the stationary-oriented vulnerability assessment. This study proposes a novel approach to assess vulnerability and flood risk and accounts for adaptability of the approach to nonstationary conditions of flood hazard. The approach is innovative in which an automated concurrent estimation of economic flood damage for a range of flood events on the basis of a micro-scale flood risk assessment is made possible. It accounts for the heterogeneous distribution of residential buildings of a community exposed to flood hazard. The feasibility of the methodology was tested using real historical flow records and spatial information of Teddington, London. Vulnerability curves and residual risk associated with a number of alternative extents of property-level protection adoptions are estimated by the application of the proposed methodology. It is found that the methodology has the capacity to provide valuable information on vulnerability and flood risk that can be integrated in a practical decision-making process for a reliable cost–benefit analysis of flood risk reduction options.

ACS Style

Balqis M. Rehan. An innovative micro-scale approach for vulnerability and flood risk assessment with the application to property-level protection adoptions. Natural Hazards 2018, 91, 1039 -1057.

AMA Style

Balqis M. Rehan. An innovative micro-scale approach for vulnerability and flood risk assessment with the application to property-level protection adoptions. Natural Hazards. 2018; 91 (3):1039-1057.

Chicago/Turabian Style

Balqis M. Rehan. 2018. "An innovative micro-scale approach for vulnerability and flood risk assessment with the application to property-level protection adoptions." Natural Hazards 91, no. 3: 1039-1057.

Conference paper
Published: 20 October 2016 in E3S Web of Conferences
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Current practice in flood frequency analysis assumes that the stochastic properties of extreme floods follow that of stationary conditions. As human intervention and anthropogenic climate change influences in hydrometeorological variables are becoming evident in some places, there have been suggestions that nonstationary statistics would be better to represent the stochastic properties of the extreme floods. The probabilistic estimation of non-stationary models, however, is surrounded with uncertainty related to scarcity of observations and modelling complexities hence the difficulty to project the future condition. In the face of uncertain future and the subjectivity of model choices, this study attempts to demonstrate the practical implications of applying a nonstationary model and compares it with a stationary model in flood risk assessment. A fully integrated framework to simulate decision makers’ behaviour in flood frequency analysis is thereby developed. The framework is applied to hypothetical flood risk management decisions and the outcomes are compared with those of known underlying future conditions. Uncertainty of the economic performance of the risk-based decisions is assessed through Monte Carlo simulations. Sensitivity of the results is also tested by varying the possible magnitude of future changes. The application provides quantitative and qualitative comparative results that satisfy a preliminary analysis of whether the nonstationary model complexity should be applied to improve the economic performance of decisions. Results obtained from the case study shows that the relative differences of competing models for all considered possible future changes are small, suggesting that stationary assumptions are preferred to a shift to nonstationary statistics for practical application of flood risk management. Nevertheless, nonstationary assumption should also be considered during a planning stage in addition to stationary assumption especially for areas where future change in extreme flows is plausible. Such comparative evaluations would be of valuable in flood risk management decision-making processes.

ACS Style

Balqis M. Rehan; Jim W. Hall. Uncertainty and sensitivity analysis of flood risk management decisions based on stationary and nonstationary model choices. E3S Web of Conferences 2016, 7, 20003 .

AMA Style

Balqis M. Rehan, Jim W. Hall. Uncertainty and sensitivity analysis of flood risk management decisions based on stationary and nonstationary model choices. E3S Web of Conferences. 2016; 7 ():20003.

Chicago/Turabian Style

Balqis M. Rehan; Jim W. Hall. 2016. "Uncertainty and sensitivity analysis of flood risk management decisions based on stationary and nonstationary model choices." E3S Web of Conferences 7, no. : 20003.