•Aggregated impacts of global and urban micro-climate on urban floods are reviewed.•Pros and cons of low impact development in urban flood mitigation are summarized.•Low impact development can lessen ...climate-change-induced urban flood impacts.•Site-specific selection and optimization are the major challenges of its success.
The severity and frequency of short-duration, but damaging, urban area floods have increased in recent years across the world. Alteration to the urban micro-climate due to global climate change impacts may also exacerbate the situation in future. Sustainable urban stormwater management using low impact development (LID) techniques, along with conventional urban stormwater management systems, can be implemented to mitigate climate-change-induced flood impacts. In this study, the effectiveness of LIDs in the mitigation of urban flood are analyzed to identify their limitations. Further research on the success of these techniques in urban flood mitigation planning is also recommended. The results revealed that LIDs can be an efficient method for mitigating urban flood impacts. Most of the LID methods developed so far, however, are found to be effective only for small flood peaks. They also often fail due to non-optimization of the site-specific and time-varying climatic conditions. Major challenges include identification of the best LID practices for the region of interest, efficiency improvements in technical areas, and site-specific optimization of LID parameters. Improvements in these areas will allow better mitigation of climate-change-induced urban floods in a cost-effective manner and will also assist in the achievement of sustainable development goals for cities.
Changes in bioclimatic indicators can provide valuable information on how global warming induced climate change can affect humans, ecology and the environment. Trends in thermal bioclimatic ...indicators over the diverse climate of Iran were assessed in this study to comprehend their spatio-temporal changes in different climates. The gridded temperature data of Princeton Global Meteorological Forcing with a spatial resolution of 0.25° and temporal extent of 1948–2010 was used for this purpose. Autocorrelation and wavelets analyses were conducted to assess the presence of self-similarity and cycles in the data series. The modified version of the Mann–Kendall (MMK) test was employed to estimate unidirectional trends in 11 thermal bioclimatic indicators through removing the influence of natural cycles on trend significance. A large decrease in the number of grid points showing significant trends was noticed for the MMK in respect to the classical Mann–Kendall (MK) test which indicates that the natural variability of the climate should be taken into consideration in bioclimatic trend analyses in Iran. The unidirectional trends obtained using the MMK test revealed changes in almost all of the bioclimatic indicators in different parts of Iran, which indicates rising temperature have significantly affected the bioclimate of the country. The semi-dry region along the Persian Gulf in the south and mountainous region in the northeast were found to be more affected in terms of the changes in a number of bioclimatic indicators.
Although a significant number of studies have evaluated the trends in different characteristics of precipitation in Iran, the trends in precipitation indicators related to bioclimate are still not ...explored. The 0.5° spatial resolution gauge-based gridded monthly precipitation data of global precipitation climatology centre (GPCC) for the period 1901–2016 was used in this study for the evaluation of the geographical distribution of the trends of bioclimatic precipitation indicators of Iran. The trends in the indicators due to global warming were estimated using modified Mann-Kendall (MMK) trend test which can estimate unidirectional trend by separating the natural variability in climate. Obtained results were compared with that found using classical Mann-Kendall (MK) test. Besides, gridded temperature data of climate research unit (CRU) was used to identify the warm/cold periods at each grid point to assess the trends in precipitation during warm/cold periods, considering a wide spatial variation in the onset time of different seasons in Iran. The results revealed that many of the trends in some of the precipitation indicators obtained in earlier studies were due to natural fluctuation of climate. Annual precipitation in Iran was found decreasing only in the northwest semi-arid region at a rate of − 12.1 to − 14.05 mm/decade, while the precipitation in the wettest month was found increasing in a large area in the southwest semi-arid region at a rate of 3.1 to 5.3 mm/decade. The most significant changes were observed in precipitation seasonality, which was found to increase in 22.4% area, mostly in the central dry and northeast semi-dry regions and decrease in 11.3% area, mostly in the northern wetter region. The study indicates that the long-term natural variability in large-scale atmospheric phenomena that influences the precipitation of Iran may be the cause of many significant changes observed in precipitation in previous studies.
Trends in reference evapotranspiration (ETo) have been found highly diverse in different regions of the globe due to the contradictory changes in the meteorological variables that define ETo. Despite ...a significant impact of ETo in water resources and ecology, knowledge on the changes and the cause of the changes in ETo is very limited in tropical regions. The trends in ETo, the factors influencing the changes in ETo and the change point (year) that made the trend significant were evaluated in this study for tropical peninsular Malaysia. The modified version of Mann-Kendall (MK) test was used for the assessment of unidirectional changes in ETo and the driving meteorological variables. The innovative trend analysis (ITA) was conducted to understand the variations in change with time. Sobol's method was used to measure the sensitivity of ETo to different meteorological factors and the Sequential MK test was employed to identify the change point. The study revealed an increase in annual (0.009–0.026 mm/year) and seasonal (0.014–0.027 mm/year during southwest monsoon and 0.015–0.074 during northeast monsoon) ETo in peninsular Malaysia which contradicts to evapotranspiration paradox found in many regions. The minimum temperature (31.5–48.2%) was found as the most influencing factor followed by wind speed (15.1–32.8%.) in defining ETo in peninsular Malaysia. Analysis of ITA and sequential MK test results revealed that the rise in minimum temperature is the major cause of the increase in ETo in peninsular Malaysia. A faster rise in minimum temperature after 1981–1985 caused an increase in ETo after 1993–1996 in most of the locations. The minimum temperature in the region was noticed to rise much faster compared to the global average which indicates a large and continuous increase in ETo due to global warming and thus, reduction in atmospheric water balance in peninsular Malaysia.
•The factors influencing the changes in reference evapotranspiration (ETo) are evaluated for tropical peninsular Malaysia.•Modified MK test, innovative trend analysis, sequential MK test and Sobol's global sensitivity analysis are used .•Minimum temperature is the most influencing factor of ETo changes followed by wind speed in peninsular Malaysia•A faster rise in minimum temperature after 1981–1985 caused an increase in ETo after 1993–1996 in most of the stations.
The spatial and temporal changes in annual and seasonal aridity, the shift of land from one arid class to another and the effect of this shift on different landuses in Iran during 1951–2016 have been ...assessed in this study. The monthly rainfall data of global precipitation climatology center (GPCC), and the monthly mean temperature and potential evapotranspiration (PET) data of climate research unit (CRU) having a spatial resolution of 0.5° were used for this purpose. The novelty of the study is the assessment of the significance in the shift of arid land between 1951–1980 and 1987–2016. Besides, the association of rainfall and temperature with aridity in different arid zones were assessed to understand the driving factors of the shift of arid lands. The results revealed an increase in annual and seasonal aridity in Iran, which caused expansion of arid land. The most remarkable changes include conversion of 4.84% semi-arid land to arid land due to an increase in annual aridity, shift of 4.84% arid land to hyper-arid during summer and 6.45% semi-arid land to arid during winter. However, only the expansion of semi-arid land to dry-subhumid land was found statistically significant. Analysis of results revealed different contributions of rainfall and temperature in the expansion of different classes of arid lands. The decrease in rainfall was the cause of the increasing aridity in the arid and semi-arid region, while the increasing temperature was found to play a major role in increasing aridity in the humid region. The overlapping of landuse map on aridity shift map revealed that the rangelands and farmlands in the north and the northwest were more affected by the expansion of aridity which might have severe consequences on agricultural production and food security of the country.
•The shift of dry lands from one arid class to another in Iran during 1951–2016 was investigated•The spatial and temporal trends in aridity and the significance in the shift of arid lands were evaluated.•The association of rainfall and temperature with aridity was assessed to understand the driving factors of aridity shift.•About 4.84% semi-arid land was found to become arid due to increase in annual aridity.
Reliable prediction of rainfall extremes is vital for disaster management, particularly in the context of increasing rainfall extremes due to global climate change. Physical-empirical models have ...been developed in this study using three widely used Machine Learning (ML) methods namely, Support Vector Machines (SVM), Random Forests (RF), Bayesian Artificial Neural Networks (BANN) for the prediction of rainfall and rainfall related extremes during Northeast Monsoon (NEM) in Peninsular Malaysia from synoptic predictors. The gridded daily rainfall data of Asian Precipitation—Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) was used to estimate four rainfall indices namely, rainfall amount, average rainfall intensity, days having >95-th percentile rainfall, and total number of dry days in Peninsular Malaysia during NEM for the period 1951–2015. The National Centers for Environmental Prediction (NCEP) reanalysis sea level pressure (SLP) data was used for the prediction of rainfall indices with different lead periods. The recursive feature elimination (RFE) method was used to select the SLP at different NCEP grid points which were found significantly correlated with NEM rainfall indices. The results showed superior performance of BANN among the ML models with normalised root mean square error of 0.04–0.14, Nash-Sutcliff Efficiency of 0.98–1.0, and modified agreement index of 0.97–0.99 and Kling-Gupta efficient index 0.65–0.96 for one-month lead period prediction. The 95% confidence interval (CI) band for BANN was found narrower than the other ML models. Almost all the forecasted values by BANN were also found with 95% CI, and therefore, the p-factor and the r-factor for BANN in predicting rainfall indices were found in the range of 0.95–1.0 and 0.25–0.49 respectively. Application of BANN in prediction of rainfall indices with higher lead time was also found excellent. The synoptic pattern revealed that SLP over the north of South China Sea is the major driver of NEM rainfall and rainfall extremes in Peninsular Malaysia.
•Physical-empirical models are developed using three machine learning methods for prediction of rainfall extremes.•Four rainfall indices in Peninsular Malaysia during northeast monsoon are forecasted with uncertainty levels.•The sea level pressure (SLP) data is used as predictors for the development of models.•The recursive feature elimination method is used for the selection of predictors to consider non-linearity in relationship.
The primary environmental impact caused by seawater intake operation is marine life impingement resulting from the intake velocity. Environmental Protection Agency (EPA) of United State has regulated ...the use of velocity cap fitted at intake structures to reduce the marine life impingement. The engineering design parameters of velocity cap has not been well explored to date. This study has been set to determine the fundamental relationships between intake velocity and design parameters of velocity cap, using computational fluid dynamic (CFD) model. A set of engineering design criteria for velocity cap design are derived. The numerical evidence yielded in this study show that the velocity cap should be designed with vertical opening (Hvc) and horizontal shelf (ℓvc). The recommended intake opening ratio (Or) shall be 0.36 Vr−0.31, where Or = Hvc/ℓvc and Vr =V0/Vpipe. Vo is the velocity at the intake window and Vpipe is the suction velocity at the intake pipe. The volume ratio (ωr) between the velocity cap (ωvc) and intake tower (ωIT) is recommended at 0.11 Vr−1.23. The positive outlooks that yielded from this study can be served as a design reference for velocity cap to mitigate the detrimental impacts from the existing intake structure.
The tsunami is one of the deadliest natural disasters, responsible for more than 260,000 deaths and billions in economic losses over the last two decades. The footage of the devastating power of the ...2004 Indian Ocean tsunami perhaps remains vivid in the memory of most survivors, and Malaysia was one of the countries affected by the unprecedented 2004 tsunami. It was the first time the Malaysian government had managed such a great disaster. This review, therefore, gathers the relevant literature pertaining to the efforts undertaken following the event of the 2004 tsunami from Malaysia’s perspective. A compilation of post-event observations regarding tsunami characteristics is first presented in the form of maps, followed by building damage, including damage modes of wall failure, total collapse, debris impact and tilting of structures. In addition, hazard assessments and projections regarding a hypothetical future tsunami towards vulnerable hazard zones in Malaysia are reviewed. It is observed that future tsunami risks may originate from the Indian/Burma Plate, Andaman Island, Sunda Trench, Manila Trench, Sulu Trench, Negro Trench, Sulawesi Trench, Cotabato Trench and Brunei slide. A rundown of post-2004 measures and tsunami research undertaken in the country is also included in this review, serving as a reference for disaster management globally. Overall, the outcomes of this review are important for understanding tsunami vulnerability and the resilience of coastal infrastructures, which will be crucial for continued progress in the future.
Hydrological data of a drained tropical peat catchment have been analysed through conventional quantitative hydrological approaches to characterize its hydrological behaviours and changes due to ...continuous drainage for a long period. The results show that the hydrology of the catchment is extremely dynamic and the catchment is flashy in nature. A decreasing trend in peak flow amount and an increasing trend in baseflow amount was observed in the catchment, indicating that continuous drainage has reduced the risk of both flooding and water scarcity in the catchment. Correlation analysis among rainfall, runoff and groundwater table reveals that saturation excess-near surface flow is the dominant mechanism responsible for rapid runoff generation in the catchment. Therefore, any physical alterations or disturbances to the upper part of the peat profile would definitely affect the overall hydrological behaviour of the peat catchment. Editor Z.W. Kundzewicz; Associate editor D. Hughes Citation Katimon, A., Shahid, S., Abd Wahab, A.K., and Ali, M.H., 2013. Hydrological behaviour of a drained agricultural peat catchment in the tropics. Part 1: Rainfall, runoff and water table relationships. Hydrological Sciences Journal , 58 (6), 1297–1309.
Seawater intake structures are often used at coastal power plant to draw ambient seawater into the cooling system for operation. However, improper selection of water intake location will lead to ...sediments deposition at the intake structure causing lower intake flow rate, clogging of water filtration devices and reduces the efficiency of the power plant. A 2D process-based model is developed to investigate the morphodynamic behavior of the Kapar coast. The model is developed by coupling the processes of hydrodynamic, waves and sediment transport. The processes are interacted dynamically with bathymetry and lead to the morphological changes. The model is input with the schematisation of seasonal wind-wave conditions and a representative morphological tide. Morphological acceleration technique is used to simulate the long-term morphodynamic changes with acceptable computational times. Sedimentation and erosion patterns are represented by the model and suitable intake location is determined based on the long-term morphodynamic investigation.
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