Characteristics of suspended sediment and river discharge during the beginning of snowmelt in volcanically active mountainous environments

AbstractTo better understand instream suspended sediment delivery and transformation processes, we conducted field measurements and laboratory experiments to study the natural function of spatial and temporal variation, sediment particles, stable isotopes, particle size, and aspect ratio from tributary to mainstream flows of the Sukhaya Elizovskaya River catchment at the beginning of and during snowmelt. The Sukhaya Elizovskaya River is located in the Kamchatka Peninsula of Russia and is surrounded by active volcanic territory. The study area has a range of hydrological features that determine the extreme amounts of washed sediments. Sediment transported to the river channels in volcanic mountainous terrain is believed to be strongly influenced by climate conditions, particularly when heavy precipitation and warmer climate trigger mudflows in association with the melting snow. The high porosity of the channel bottom material also leads to interactions with the surface water, causing temporal variability in the daily fluctuations in water and sediment flow. Field measurements revealed that suspended sediment behaviour and fluxes decreased along the mainstream Sukhaya Elizovskaya River from inflows from a tributary catchment located in the volcanic mountain range. In laboratory experiments, water samples collected from tributaries were mixed with those from the mainstream flow of the Sukhaya Elizovskaya River to examine the cause of debris flow and characteristics of suspended sediment in the mainstream. These findings and the geological conditions of the tributary catchments studied led us to conclude that halloysite minerals likely comprise the majority of suspended sediments and play a significant role in phosphate adsorption. The experimental results were upscaled and verified using field measurements. Our results indicate that the characteristics of suspended sediment and river discharge in the Sukhaya Elizovskaya River can be attributed primarily to the beginning of snowmelt in volcanic tributaries of the lahar valley, suggesting a significant hydrological contribution of volcanic catchments to instream suspended sediment transport. Daily fluctuations in discharge caused by snowmelt with debris flow were observed in this measurement period, in which suspended sediment concentration is ~10mg/l during nonflooding periods and ~1400mg/l when flooding occurs. The oxygen and hydrogen isotope measurements, when compared with Japan, indicated that the Kamchatka region water is relatively lightweight, incorporating the effects of topography; and the water from the beginning of the snowmelt is relatively lightweight when compared with water from the end of the snowmelt. The trend line of isotopes from the beginning of the snowmelt was defined by a slope of 6.88 (n=12; r2=0.97), significantly less than that of isotopes from the snowmelt (8.72). The sediment particles collected during the snowmelt were round in shape caused by the extreme flows and high discharge. The shape of the sediment particles collected at the beginning of the snowmelt, assumed to be fresh samples from the hillslope, was sharper caused by the relatively small discharge by moderate snowmelt. Finally, the relationship between river discharge and suspended sediment concentration was indicated. The results are compared with mountainous rivers of Japan and Malaysia. A new diagram is proposed to describe the relationship between suspended sediment concentration and river discharge

暦年水文データ解析と数値シミュレーションによるマレーシア・ケランタン川流域の早期洪水予測に関する研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 登坂 博行, 東京大学教授 六川 修一, 東京大学准教授 北澤 大輔, 東京大学准教授 中村 謙太郎, 筑波大学教授 辻村 真貴University of Tokyo(東京大学

Predicting spatial and decadal of land use and land cover change using integrated Cellular Automata Markov chain model based scenarios (2019–2049) Zarriné-Rūd River Basin in Iran

Effective land use and land cover (LULC) change assessment requires tools to measure past, current, and based on them to create a future scenario. LULC changes are unavoidable in the world, particularly in developing countries. Since LULC are too dynamic and complicated without the identification of appropriate methods and approaches the future perdition will be less accurate. Therefore, the integrated Cellular Automata Markov chain (CA-Markov) model is known as a capable estimator. In this study, LULC changes in Zarriné-Rūd River Basin (ZRB) in Iran was analyzed based on different images and data extracted from satellite data in 1989 and 2019 to create the LULC scenario in 2049. The model was validated using actual and projected to 2019. The overall agreement on two extracted maps was 97.85% in 1989 and 96.55% in 2019. The more detailed analysis of validation of calibration based on the kappa showed the highest data reliability of 0.98 in 1989 and 0.95 in 2019, respectively. According to the transition matrix of probabilities, the most significant changes in the ZRB based on the past scenario (1989–2019) is in rainfed and built up land classes of LULC in 2049. Concurrently, the other classes continue to decline except irrigated agriculture and water bodies. The results obtained showed that the pasture and mountain LULC class had continued to reduce more than other classes. Furthermore, water resources and the amount of the precipitation in past and future are important to spatial and temporal expansion on LULC classes

Investigation of Air Pollution Impact on Kinta River Water Quality at a Tropical Region

Critical air quality levels lead to an unhealthy environment which disrupts physical activities and human health. Wet deposition of air pollutants might cause a high concentration of water pollution due to rain water washout of nitrate and particulate matter (PM). This study aimed to investigate the impacts of air pollutants deposition on river water quality in Malaysia. The methodology involved in the analysis of secondary data (January to December 2013) for air quality and river water quality using factor, correlation, and regression. Parameters of air quality were PM10, Nitrate (NO3), ozone (O3) and temperature while water quality data were turbidity, Nitrate and PM10 (Ca, As, Hg, Cd, Cr, Pb, Zn, Cl, Fe, K, Mg, Na). The results show that there were positive correlations between air quality indicators and Kinta river water quality parameters. Correlation matrix shows that in terms of turbidity, air and water data were having 96% similarities. Regarding Nitrate concentrations, air and water records had only 30% of correlation matrix, which can be due to other sources of Nitrate which was agriculture activities near Kinta River. The factor analysis results showed that PM was the main contributor to river water quality particles with 94%. © 2020 Published under licence by IOP Publishing Ltd

Analysis of Malaysia electricity demand and generation by 2040

Malaysia as an emerging country, increasing population, gross domestic product (GDP) growth and enhanced access to electricity lead to an expanding of demand. The crucial parameters to determine future energy demand and generation projections are GDP, population growth rates and weather implications due to climate change. The study aims to forecast the future trends based on the historical values and also to project the future electricity demand and generation. The electricity demand and generation growth evaluated based on 2 main elements which are population growth and weather parameters (maximum temperature and rainfall). The future trends are forecasted based on the historical values of population and weather parameters. There is 152.9% of population growth in 32 years. The population will keep on developing yet with the lower rate. The GDP trend and the population growth mirrors the pattern of emissions. The findings from Statistical Downscaling Model (SDSM) analysis shows that the rainfall distribution will diminish while the temperature will expand that depict the climate change impact as time passes by. In 2020, the most extreme temperature recorded is 31.7 °C while in 2040, the estimated greatest temperature is 32.3 °C. There will be a 0.6 °C increase in temperature in 20 years. The demand in 2040 will be expanded 50.3% more than demand in 2020. The estimated electricity demand per capita will continue expanding because of the augmentation of the populace and the significance of electricity in daily activities. The pattern shows that electricity demand and generation in Malaysia will be expanding massively year by yea

Analysis of rainfall distribution in Kelantan river basin, Malaysia

Using rainfall gauge on its own as input carries great uncertainties regarding runoff estimation, especially when the area is large and the rainfall is measured and recorded at irregular spaced gauging stations. Hence spatial interpolation is the key to obtain continuous and orderly rainfall distribution at unknown points to be the input to the rainfall runoff processes for distributed and semi-distributed numerical modelling. It is crucial to study and predict the behaviour of rainfall and river runoff to reduce flood damages of the affected area along the Kelantan river. Thus, a good knowledge on rainfall distribution is essential in early flood prediction studies. Forty six rainfall stations and their daily time-series were used to interpolate gridded rainfall surfaces using inverse-distance weighting (IDW), inverse-distance and elevation weighting (IDEW) methods and average rainfall distribution. Sensitivity analysis for distance and elevation parameters were conducted to see the variation produced. The accuracy of these interpolated datasets was examined using cross-validation assessment

Two-dimensional dam break modelling of Beris Dam using HEC-RAS

Dam is built for various functions such as water supply, flood and sediment control, electricity generation and irrigation. Floods due to dam breaches create higher peak flows than floods produced by heavy rainfall. When a dam collapses, the stored water may cause devastating catastrophe towards downstream areas by causing fatalities and property damages. The aim of this study is to perform a two-dimensional dam break modelling of Beris Dam due to probable maximum flood (PMF). The HEC-RAS software was used to predict the breach outflow’s hydrograph and produce the flood inundation and velocity map. Dam breach parameters were calculated using Froehlich and MacDonald and Langridge-Monopolis (MDLM) equations. A 4-day simulation conducted showed that a breach was initiated at almost 10.35 am, 34 hours and 35 minutes after the PMF scenario. Peak discharge during the PMF failure is 10,745.12 m3/s at 12.45 pm the next day which is after 2 hours and 10 minutes of dam breach initiation. Felda Lubuk Merbau, Kampung Betong, Jeniang, Padang Serai and Kota Kuala Muda are among the areas affected by the simulated Beris Dam break. Information obtained on flood velocity, depth and arrival time are useful to local authorities in order to respond effectively and immediately in the event of dam break

Flood forecasting model for Kelantan river basin, Malaysia using ifas and getflows

The effectiveness of real time flood forecasting systems in reducing flood damage would depend upon how accurately the estimation of future stages or flow of incoming flood and its time sequence at selected points along the river could be predicted. Warning of the approaching floods provides sufficient time for authorities to evacuate the affected people to a safer place and to make intense patrolling of flood protection works such as embankments. The Kelantan river basin, located in the north east of Peninsular Malaysia is one of the biggest watersheds in Malaysia spreading over 12,000 km2, and has been damaged seriously by monsoon floods/inundations in many places along the river and its tributaries in midstream to downstream areas. Thus constructing a reliable system for early warning and evacuation, as well as making countermeasures for reducing the magnitude of damages, is crucial requirement here. Basically there are two types of flood modelling developed in this study; inundation modelling and whole watershed modelling. In inundation modelling, flow of runoff prediction using Integrated Flood Analysis System (IFAS) starting with the observed rainfall and discharge and setting and tuning of PWRI distributed parameter for rainfall-runoff model. IFAS then will simulate the rainfall-runoff simulation using projected precipitation. IFAS will execute on the hydrological part and river analysis from the data feed from INFOBANJIR to convert the rainfall into runoff. The IFAS runoff output will be the input into General-Purpose Terrestrial Fluid Flow Simulator (GETFLOWS) model for the inundation analysis. The time for calculation is up to 6 hours ahead by GETFLOWS is within 10 min/site. Including graphic processing, the results will become available within around 15 min. Where as in whole watershed modelling, GETFLOWS is used to generate runoff output (longer calculation time compared to IFAS). The time calculation is up to 6 hours. Including graphic processing, the results will be available within around 25 minutes

Estimation of breach outflow hydrograph using selected regression breach equations

Embankment dam is commonly built in Malaysia as it provides essential benefits to the local population, such as agricultural activity and flood control measures. However, the release of high potential energy by the impoundment imposes risk of catastrophic event during the dam failure. Therefore, estimation of flood arrival time under dam break event can be beneficial as primary information using numerical model to simulate the breaching process of the embankment dam. The purpose of this study is to establish dam breach profile of Temenggor Dam in predicting breach outflow hydrograph. A few selected regression equations for breach parameters will be tested namely Froehlich, Macdonald and Langridge-Monopolis and Von Thun and Gillete. One-dimensional dam break modelling were performed based on the calculated breach parameters for overtopping and piping failure. Hydrologic Engineering Center's River Analysis System (HEC-RAS) software is used for the dam break analysis. Results obtained from the study indicated that overtopping failure yields the highest peak breach flow of 202,099 m3/s, compared to piping failure's highest peak discharge of 201,126 m3/s