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Item Open Access The reservoir inflow prediction of the Bhumibol and Sirikit dams using machine learning techniques(Mahidol University, 2022) Pheeranat Dornpunya; Areeya Rittima; Yutthana Phankamolsil; Jidapa KraisangkaThe recent research has been devoted to the machine learning (ML) technique to enhance the predictive performance of hydrological prediction models for a successful planning and water resources management. This study aims at applying ML... in the central region of Thailand. The precise and accurate prediction of both short–term and long–term time horizon of the reservoir inflows can lead to the proper management of water resources in coping with the anticipated hydrological events.Item Open Access Effects of changes in rainfall and land cover patterns on surface runoff in the Ayung watershed in Bali, Indonesia(Mahidol University, 2022) Dharamayasa, I Gusti Ngurah Putu, 1978 -; Ranjna Jindal; Kritsanat Surakit; Romanee ThongdaraClimate change is associated with changes in temperature, humidity, and rainfall patterns. While increased rainfall causes flooding in a watershed, a lack of enough rainfall leads to drought and water scarcity. Moreover, land conversions of forests and farmlands to residential and commercial zones, which are needed to deal with population growth, urbanization, and infrastructure development activities, cause increasing surface runoff that may also contribute to flooding. The Ayung River watershed, the largest watershed area on the island of Bali in Indonesia, has been experiencing environmental disasters of flash flooding caused by climate change induced rainfall coupled with increased surface runoff due to land cover changes. This study is aimed at evaluating the potential for flooding or drought in the Ayung watershed due to the effects of changes in rainfall and land cover. Firstly, future rainfall forecasts were generated using the global climate model (GCM)established by the National Center of Atmospheric Research in the United States for the most likely climate change scenario (NCAR). The Indonesian meteorological department provided rainfall data for the years 2006to 2018 from eight rainfall stations located across the Ayung watershed (Sading, Mambal, Tegalalang, Tampaksiring, Bedugul, Pengotan, Gitgit, and Kedisan). Simulated rainfall from the NCR model for the same time period was compared to observed rainfall for four climate change scenarios (RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5). Rainfall projections were made for the period of 2019-2030 using the most appropriate scenario(RCP 6.0) for the Ayung watershed. Future predictions indicate a decrease in rainfall, leading to the potential for insufficient water supply in the future. The land cover maps for the four categories, namely forest, agricultural land, settlements, and grasslands, were obtained for the period 2006-2019 by manually digitizing the maps given by Google Earth at a scale of 1:20,000 in order to examine the land cover changes in the Ayung watershed. Following that, two approaches were used to calculate runoff coefficients in the Ayung watershed: (1) Hassing method and (2)Cook method. According to the findings, agriculture and forest areas were reduced by 647.8 ha and 553.1 ha, respectively, due to conversion to fast-growing grasslands or unproductive land. Such changes in land cover have a detrimental impact since they raise the runoff coefficient in the area. The runoff coefficient was continuously greater than 0.6 during the study period (high-risk category). Flood risk maps could be created to pinpoint flood-prone locations. Several places in the Ayung watershed appear to be in high flood risk categories(runoff coefficient >0.6) based on runoff coefficient mapping between 2012 and 2019. The situation worsens as forests and farmlands are converted to grasslands and settlements, resulting in a higher runoff coefficient. Several portions of Denpasar, in particular, have seen a considerable increase in the runoff coefficient (>5%)from 2012 to 2019. As a result of the increased surface runoff, there is a high risk of flooding in the area. The heightened risk of floods in Denpasar, a densely populated city, could have a negative impact on its residents. Finally, flood modeling was carried out for several return periods including 5, 10, 25, 50, and100 years, using the HEC-RAS software, to determine the effect of flooding on settlements in the Ayun watershed. The modeling predicted water levels and changes in flood depths in four sections in the city of Denpasar, namely Penatih, Kesiman, Kesiman Petilan, and Kesiman Kertalangu, were predicted to experience fairly serious flooding in the future. Changes in land cover patterns have increased the possibility of floods in the Ayung watershed, according to this study. Such data could be valuable in predicting future floods and avoiding losses for the administrations of Denpasar City and Bali Province.Publication Open Access Impact of Climate Change on Reservoir Reliability: A Case of Bhumibol Dam in Ping River Basin, Thailand(2561) Allan Sriratana Tabucanon; Areeya Rittima; Detchasit Raveephinit; Yutthana Phankamolsil; Wudhichart Sawangphol; Jidapa Kraisangka; Yutthana Talaluxmana; Varawoot Vudhivanich; Wenchao Xue; Mahidol University. Faculty of Environment and Resource Studies; Mahidol University. Faculty of Engineering; Mahidol University. Faculty of Information and Communication Technology; Kasetsart University. Faculty of Engineering; Kasetsart University. Faculty of Engineering at Kamphaeng; Asian Institute of Technology. Department of Energy Environment and Climate ChangeBhumibol Dam is the largest dam in the central region of Thailand and it serves as an important water resource. The dam’s operation relies on reservoir operating rules that were developed on the basis of the relationships among rainfall-inflow, water balance, and downstream water demand. However, due to climate change, changing rainfall variability is expected to render the reliability of the rule curves insecure. Therefore, this study investigated the impact of climate change on the reliability of the current reservoir operation rules of Bhumibol Dam. The future scenarios from 2000 to 2099 are based on EC-EARTH under RCP4.5 and RCP8.5 scenarios downscaled by RegCM4. MIKE11 HD was developed for the inflow simulation. The model generates the inflow well (R2=0.70). Generally, the trend of increasing inflow amounts is expected to continue in the dry seasons from 2000-2099, while large fluctuations of inflow are expected to be found in the wet seasons, reflecting high uncertainties. In the case of standard deviations, a larger deviation is predicted under the RCP8.5 scenario. For the reservoir’s operation in a climate change study, standard operating procedures were applied using historical release records to estimate daily reservoir release needed to serve downstream water demand in the future. It can be concluded that there is high risk of current reservoir operating rules towards the operation reliability under RCP4.5 (80% reliability), but the risk is lower under RCP8.5 (87% reliability) due to increased inflow amounts. The unmanageability occurs in the wet season, cautioning the need to redesign the rules.Publication Open Access Revision of Vajiralongkorn Dam’s Reservoir Characteristic Curves Using NDWI Derived from Landsat 8 Data(2020) Yutthana Phankamolsil; Ekasit Kositsakulchai; Mahidol University. Kanchanaburi Campus. Environmental Engineering and Disaster Management Program; Kasetsart University. Faculty of Engineering at Kamphaeng Saen. Department of Irrigation EngineeringReservoir characteristics are the essential information for water management planning and reservoir operation. Regular monitoring and assessment of the reservoir characteristics can reduce risks associated with the reservoir operation. This research assessed the reservoir characteristics (water surface, volume) of Vajiralongkorn Dam using remote sensing. Reservoir water surface was classified using the Normalized Difference Water Index (NDWI) derived from the Landsat 8 data, and validated using the streamline matching rate (SMR) and the streamline matching error (SME) techniques for shoreline accuracy assessment. The volume between two water levels was calculated using the prismatic equation. The storage capacity curve was constructed from the reservoir water level and cumulative volume. The accuracy of NDWI technique was satisfactory in identifying reservoir water surface with a good accuracy of shoreline delineation (SMR>95% and SME=11.7 m). The water surface has decreased on the average of 8.2 km2 (2.8%) compared with the original data in 1980. The storage capacity has decreased 495.3 million m3 (MCM) over 38 years from 1980 to 2018, an annual capacity loss of 13 MCM. Finally, sustainable service of the reservoir needs better knowledge of the effects of storage loss, the erosion and sediment-transport processes, and conservation measures.Publication Open Access Organic Carbon in Wetland Soil: Seasonal Flooded Forest, Northeastern Thailand(2021) Piyakarn Teartisup; Prapeut Kerdsueb; Suwalee Worakhunpiset; ปิยะกาญจน์ เที้ยธิทรัพย์; ประพฤติ เกิดสืบ; สุวลีย์ วรคุณพิเศษ; Mahidol University. Faculty of Environment and Resource Studies; Mahidol University. Faculty of Tropical Medicineshortage. Therefore, vegetation and hydrology management have to be implemented practically to retain the existing organic carbon in wetlands and allow the soil to sequester additional carbon.Publication Open Access Investigation on Impact of Changes in Land Cover Patterns on Surface Runoff in Ayung Watershed, Bali, Indonesia Using Geographic Information System(2022) Dharmayasa, I Gusti Ngurah Putu; Kritsanat Surakit; Jindal, Ranjna; Romanee Thongdara; Mahidol University. Faculty of Engineering. Department of Civil and Environmental EngineeringPopulation growth, urbanization, and infrastructure development activities have resulted in the land conversion of forests and farmlands to residential and commercial zones. Such land conversion causes changes in the land cover, as experienced in the Ayung Watershed, in the island of Bali, Indonesia. Here, the land cover undergoes rapid changes due to the growing tourism sector, affecting the runoff coefficient. This study evaluated the changing land cover patterns and surface runoff in the Ayung Watershed between 2012 and 2019. An increase in the surface runoff during the high rainfall events may lead to flooding in the area. The identification of land change patterns in the Ayung Watershed was carried out by a manual digitizing process on Google Earth maps. The runoff coefficient was calculated by Cook’s method using the four physical characteristics of the watershed: land cover, infiltration rate, land slope and drainage density; showing significant changes in the land cover in the study area. Farmlands and forests were reduced by 647.8 ha and 553.1 ha respectively, converted into fast growing grasslands or unproductive land. Such land cover changes have a negative impact by increasing the runoff coefficient in the area. During the study period, the runoff coefficient was consistently found to be more than 0.6 (high-risk category). Several sections in the city of Denpasar experienced an increase in the runoff coefficient by more than 5%. Consequently, there was a high-risk of flooding in the area because of the increasing surface runoff.Publication Open Access Stakeholder engagement practice: An experience in IWRM-Based Mekong River basin development plan forum(2010-08) Weng Tan, Kok; Jongdee Toim; Bin Mokhtar, Mazlin; Jongdee Toim; Mahidol University. Faculty of Environment and Natural Resource StudiesExtensive population growth and usage have led to increasing unplanned development pressures within the basin and these have caused many direct threats to valuable ecosystems in the region. This poses a significant threat to biodiversity and environmental sustainability, and thereby to the livelihoods of the Mekong communities. Stakeholder participation is an integral part of integrated approach on water resources management, which the Mekong River Commission (MRC) adopted in its Strategic Plan 2006-2010. Likewise, stakeholder participation is particularly important for the Basin Development Plan (BDP), the umbrella programme of the MRC to promote the joint planning function as an inter-governmental river basin organisation for sustainable development of the Lower Mekong Basin (LMB). This paper aims to provide overview of lesson learned for the BDP practice which was held during 15-16 October 2009 in Chiang Rai, Thailand. Mekong River Basin is international trans-boundary basin and has spanned up to six countries. The development issues have international implications and can only be resolved through the effective regional coordination and cooperation framework. MRC has demonstrated a series of stakeholder engagement activities for the region such as forum, special meeting and online forum. Nevertheless, it should not become the symbolic activities to fulfill the engagement and participation process.Publication Open Access Assessment of the Potential Climate Change on Rice Yield in Lower Ayeyarwady Delta of Myanmar Using EPIC Model(2018) Naw Mar Lar; Noppol Arunrat; Soe Tint; Nathsuda Pumijumnong; Mahidol University. Faculty of Environment and Resource StudiesClimate change has been occurring and its consequences are a threat to rice production and hence food security. In this study, the effect of climate change on rice yield has been assessed by using the Environmental Policy Integrated Climate model under climate change scenarios RCP4.5 (medium emissions) and RCP8.5 (high emissions) and to propose alternative adaptive measures for farmers’ livelihoods in the lower Ayeyarwady Delta. The results show that the average yield increase of early rice are 11.84% and 7.56% and the average yield reduction of late rice are 37.37% and 50.89% under both scenarios. The study found that rice yield reduction will be significantly higher under the RCP8.5 than that of RCP4.5 for both rice. Yield reductions are attributed to increases in mean maximum and minimum temperatures and variation in rainfall pattern. The model result suggests that changing the sowing date is a good option for compensating the future rice yield reduction. The other adaptations that offset the rice yield response to climate change include providing farming machines, irrigation facilities, improving infrastructure, improvement in cultivars that resist disease, pest and drought, better weather forecast and extension systems.Publication Open Access Geographic information system for flood hazard area delineation and estimation of at-risk households at the community level: a case study of salaya sub-district, Nakhon Pathom Province(2015-07) Teeranong Sakulsri; Supavan Phlainoi; Sura Pattanakiat; Sureeporn Punpuing; Mahidol University. Faculty of Social Sciences and Humanities; Mahidol University. Faculty of Environment and Resource Studies; Mahidol University. Institute for Population and Social ResearchEvery year, Thailand faces flooding, the greatest natural disaster threat for the country. It is at the household level where risk outcomes first materialize. This study delineates flood-hazard areas in Salaya sub-district and provides estimates of at-risk households located in this area by using geographic information system (GIS) technology with Potential Surface Analysis (PSA) and Overlay Analysis. The analysis classifies areas into different levels of hazard, hazard zones and at-risk households. The results show that 41.6% of the sub-district is an area of “moderate” flood hazard, comprising 10.45 square kilometers. “High” flood-hazard areas account for 8.98 square kilometers (35.9%), “low” hazard areas represent 4.28 square kilometers (17%) and “very low” hazard areas account for 1.38 square kilometers (5.5%). As or the number of households in the hazard area, it was estimated that the highest percentage—1,160 households or 50%—are located in moderate flood-risk areas, followed by low flood-risk areas (560 households or 24%), high flood-risk areas (521 households or 23%), and very low flood-risk areas (70 households or 3%). All results are shown on a map of the study area with a 1:50,000 scale.Publication Open Access Geographic information system for risk area assessment on natural gas pipeline construction in Nakhon Nayok Province(2010-04) Ponson Chernkwansri; Sura Pattanakiat; Charlie Navanugraha; Mahidol University. Faculty of Environment and Natural Resource StudiesThe objective of this study is to identify potential risk areas caused by the pipeline construction project in Nakhon Nayok province. The potential surface analysis was employed for the manipulation process using critical factors including soil drainage, clay minerals, soil texture, slope, relative humidity, air quality index, distances from bodies of water, roads, and the pipeline. The evaluation of weighting and rating scores has been proposed by experts using 2 main methods, including scaling and hierarchical methods. The risk areas have been divided into high, moderate and low levels. The outputs of these two methods are compared. It was found that the risk areas identified by the scaling method consist of high risk areas of 316.69 square kilometers (14.77%), moderate risk area of 1,523.05 square kilometers (71.04%), and low risk areas of 304.12 square kilometers (14.19%). Meanwhile, the risk areas evaluated by the hierarchical method consist of high risk areas of 219.47 square kilometers (10.24%), moderate risk areas of 1,839.05 square kilometers (85.78%), and low risk areas of 85.34 square kilometers (3.9%). The comparison of those two methods using the Kappa index has shown the value of 0.66. Thus, those two methods were only in the relation of 66 %. The assessment on land utilization within the high risk areas was analyzed based on the output of the scaling method with larger high risk areas. The land use patterns found in the high risk area include the following areas agriculture of 200.50 square kilometers (63.31%), urban of 74.71square kilometers (23.59%), forest of 5.35 square kilometers (1.69%), water bodies 20.71 square kilometers (6.54%), and others 15.42 square kilometers (4.87%). The purpose of this study was to apply the Geographic Information System for to identify potential risk areas. Geographic Information System (GIS) are a set of computer tools for collecting, storing, transforming and displaying spatial data from the real world.