Now showing 1 - 10 of 51
  • Some of the metrics are blocked by your 
    Item type:Publication,
    The relationship between the climatic indices and the rainfall fluctuation in the lower central plain of Thailand
    (2019-02-01)
    Taweesin, Korrakoch
    ;
    Global climate changes are revealing the interconnections between natural conditions, natural resources, and regional climate variability that may affect the rain fluctuation. Rainfall plays an important role in the process of hydrology. This research presents an analysis of rainfall in the lower central plain of Thailand and the climate variability/oceanographic events in the wider geographical region, including the El Niño/Southern Oscillation (ENSO), Asian Summer Monsoon (ASM), and Indian Ocean Dipole (IOD). Data from 1980-2010 and 2011-2014 were collected for calibration and verification. Next, the frequency domains, spectra, and wavelet transforms were analyzed, together with the climate index and rainfall. The results revealed that rainfall occurs in seasons, yearly cycles, and off-seasons. The behavior of ASMs, for example, Indian Summer Monsoon Index (IMI) and Western North Pacific Monsoon Index (WNPMI), is the most similar to that of rainfall events, while the similarity of the other indices to rainfall events is not so strong. Cross-correlation analysis showed that there were delays between the climate indices and rainfall, so that multiple linear regression with lag time is required for further analysis. The results illustrate that the cross-correlation coefficients of IMI and WNPMI with rainfall are both approximately 0.6. The multiple regression with lag time shows that the average multiple coefficient correlation (R) is 0.64. The indicator of the summer monsoon index value is WNPMI, which is the most influential factor for rainfall. Finally, the proposed equations, based on the cross-correlation and multiple-linear regression with lag time techniques, can be used to predict precipitation and be applied to the development of rainfall forecasting in the future.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Evaluation of the SEdiment Delivery Distributed (SEDD) model in the Shihmen Reservoir watershed
    (2020-08-01)
    Thomas, Kent
    ;
    Chen, Walter
    ;
    Lin, Bor Shiun
    ;
    The sediment delivery ratio (SDR) connects the weight of sediments eroded and trans-ported from slopes of a watershed to the weight that eventually enters streams and rivers ending at the watershed outlet. For watershed management agencies, the estimation of annual sediment yield (SY) and the sediment delivery has been a top priority due to the influence that sedimentation has on the holding capacity of reservoirs and the annual economic cost of sediment-related disasters. This study establishes the SEdiment Delivery Distributed (SEDD) model for the Shihmen Reservoir watershed using watershed-wide SDRw and determines the geospatial distribution of individual SDRi and SY in its sub-watersheds. Furthermore, this research considers the statistical and geospa-tial distribution of SDRi across the two discretizations of sub-watersheds in the study area. It shows the probability density function (PDF) of the SDRi. The watershed-specific coefficient (β) of SDRi is 0.00515 for the Shihmen Reservoir watershed using the recursive method. The SY mean of the entire watershed was determined to be 42.08 t/ha/year. Moreover, maps of the mean SY by 25 and 93 sub-watersheds were proposed for watershed prioritization for future research and remedial works. The outcomes of this study can ameliorate future watershed remediation planning and sediment control by the implementation of geospatial SDRw/SDRi and the inclusion of the sub-watershed prioritiza-tion in decision-making. Finally, it is essential to note that the sediment yield modeling can be im-proved by increased on-site validation and the use of aerial photogrammetry to deliver more up-dated data to better understand the field situations.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    FLOOD AND DROUGHT PRELIMINARY ASSESSMENT IN THE BANG PAKONG RIVER BASIN USING THE WEIGHED FACTOR INDEX METHOD
    (2025-01-01) ;
    Jiao, Jinghan
    ;
    Sirikaew, Uba
    ;
    This research is dedicated to forecasting flood and drought assessment in the Bang Pakong River Basin through a weighted factor index method. The study employed geographic information systems to prioritize and create hazard maps. The maps integrated both natural elements, for example, average annual rainfall, temperature, terrain slope, and forest area, as well as human-made elements such as land use, water body, and irrigation area. The Gumbel distribution method was used to generate the future rainfall and temperature. The study predicts future flood and drought assessment areas based on maximum average precipitation and temperature. The findings reveal a distributed spectrum of risk levels, ranging from no risk to very high risk. Currently, moderate risks of floods and droughts exist in certain areas. However, projections indicate a significant increase in flood-prone regions over 5-year, 10-year, and 15-year return periods, attributed to escalating average rainfall. Conversely, while drought-prone areas encompass approximately 27.5% of the watershed, there is a notable rise in high-risk zones alongside a decrease in moderate-risk areas due to rising temperatures. These insights underscore the imperative of proactive interventions to address the escalating threats posed by floods and droughts in the Bang Pakong River Basin.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Wavelet relationship between climate variability and deep groundwater fluctuation in Thailand’s Central Plains
    (2018-02-01)
    Groundwater is constantly under direct and indirect pressures from the anthropogenic effects, long-term climate change, and climate variability. This research investigates the association, in the time-frequency domain, between the groundwater fluctuations in Thailand’s Lower Chao Phraya Basin and specific climate variability forces: the El Nino/Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the Asian Summer Monsoons (ASM). The analysis was carried out using the wavelet method and the findings presented in the form of the complete, global, and local wavelet spectrums. In addition, the Pearson correlation was utilized to establish the linkages between the groundwater and the climate variability forces. The results indicated that the deep groundwater signals of the Lower Chao Phraya Basin were linked to the ENSO, IOD and ASM with the absolute correlation coefficients in excess of 0.5. Moreover, the recent climatic indices exerted greater influence on the groundwater than in the past, given the former’s correlation coefficients of 0.9 on average. By comparison, the deep groundwater was strongly associated with the recent ENSO and ASM but weakly linked to the IOD, with the absolute coefficients of around 0.5. The findings revealed the resilience of the deep groundwater under such high frequency signal conditions as the seasonal and tidal oscillations. Moreover, the results showed that the groundwater could be an alternative source of water supply during periods of droughts in the region.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    An empirical decomposition of deep groundwater time series and possible link to climate variability
    (2014-01-01)
    Deep groundwater data reflects hydrological processes, climate change and variability, as well as any anthropogenic influence. Decomposition of deep groundwater signal examines the history of the groundwater region. Detrending is a vital step in decomposition of groundwater time series because it is expected to remove anthropogenic effects and long-term cyclic patterns. Eight detrending methods were applied to long-term groundwater records monitored in the Lower Chao Phraya basin in Thailand. Detrended residuals and subsequently periodograms of the residuals were computed by applying the Fourier series analysis. The result from this study indicates that the 5<sup>th</sup> order polynomial interpolation provides the trendlines that significantly relate to the groundwater withdrawal background. The detrended residual function is imbedded with two major cyclic patterns, which can be the result from global climate variability, e.g. Indian Ocean Dipole and the El Niño Southern Oscillation. The magnitude of deep groundwater dynamics as the result from the anthropogenic effect, is much greater than that of the climate variability in this region. In addition, this study demonstrates that caution must be exercised when fitting groundwater time series with different detrending techniques can yield mistaken cyclic patterns and may infer to different climate variability phenomenon. © 2014 Global NEST Printed in Greece. All rights reserved.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Relationship between groundwater properties and soil salinity at the Lower Nam Kam River Basin in Thailand
    (2013-07-01)
    The Lower Nam Kam River Basin lies in the vicinity of the Mekong River and is located in the eastern section of the Nakhon Panom Province in northeastern Thailand. Drought, particularly in the winter and summer seasons, is the main environmental challenge in this area. In addition, soil becomes saline and groundwater is brackish in some locations. This problem worsens the drought crisis in the area. Groundwater is known to closely relate to the soil salinity distribution. To successfully manage highly saline areas, saline groundwater and soil properties must be evaluated together. Therefore, the main objective was to study the shallow groundwater physical and chemical properties in conjunction with surface soil salinity. Soil samples were collected and measured for physical and chemical properties. Shallow groundwater was measured for depth from ground surface and sampled from the sites in the study area. The water samples were measured for pH, total dissolved solids, electrical conductivity, and salinity. Results were interpolated and displayed via a geographic information system and further analyzed by simple linear regressions between surface soil salinity and the other factors. The results show that the topsoil contaminated with salinity is typically situated in relatively low areas with shallow groundwater levels and low head gradient of groundwater. This is due to the characteristics of the soil profile and groundwater depth. © 2012 Springer-Verlag Berlin Heidelberg.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Physico-chemical characterization of saline subsurface system near small endorheic ponds in Thailand
    (2014-04-01)
    The problem of salt-ravaged lands is reported in many parts of the world and could be exacerbated by the presence of an endorheic pond normally associated with a saline low-lying area. An endorheic or playa pond accumulates dissolved salts which can be carried primarily by groundwater before discharging into the pond; then, intense evaporation produces salt residues which can wreak havoc on the adjacent areas. The objective of this study is to investigate the subsurface conditions and groundwater interactions beneath two endorheic saline ponds of Thailand's Great Mekong Basin to have a better understanding and thereby efficiently manage the resources. A comprehensive analysis of the physical and geochemical properties (limited to pH, specific conductance and salinity) of the subsurface system was performed to determine the processes that regulated the migration of dissolved salt. The data collected from the deep and shallow groundwater of the basin were analyzed to determine their physical and chemical properties. Soil samples of various depths were examined to determine their respective geologic, chemical and unsaturated properties. The groundwater near the salt ponds was different from that of other areas in that its groundwater table was closer to the surface soil and its deep groundwater, which is of high pressure, was more saline than its shallow groundwater. As the capillary rise influences the topsoil, particularly in the saline pond areas, the vertical upward flow and the capillary force are thus the additional mechanisms of salt transportation to the endorheic ponds. Since these surface water bodies are the discharge sites for saline groundwater and are not perennial, a practical solution is to localize the saline groundwater. © 2014 Springer-Verlag Berlin Heidelberg.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Estimation of Soil Erosion and Enhancing Sediment Retention in the Lam Phra Phloeng Watershed: Insights from RUSLE and InVEST Modelling
    (2025-12-01) ;
    Mandadi, Ranadheer
    ;
    Thammaboribal, Prapas
    ;
    Gonzales, Arlene L.
    ;
    Bharadwaz, Ganni S.V.S.A.
    The increasing rate of land use change, particularly deforestation and agricultural expansion, has intensified soil degradation, leading to reduced sediment retention and accelerated soil erosion. This study aims to analyze soil erosion and sediment retention in the Lam Phra Phloeng (LPP) watershed, Thailand, using a coupled modelling approach integrating the Revised Universal Soil Loss Equation (RUSLE) and the Sediment Delivery Ratio (SDR) model from the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) suite. Six land use classes (forest, cropland, rangeland, flooded vegetation, built-up areas, and water bodies) were identified using Sentinel-2 MSI satellite data, with a Random Forest (RF) classification algorithm achieving an overall accuracy of 91.3% (Kappa coefficient = 0.89). The results indicate that forested areas exhibit the highest sediment retention, whereas croplands and rangelands experience the most significant soil loss due to erosion. The RUSLE model estimated an average annual soil loss ranging between 50 and 90 tons/ha/year, with the highest erosion rates observed in agricultural lands with steep slopes and minimal vegetation cover. The InVEST SDR model further corroborates these findings, showing that sediment retention is predominantly concentrated in densely vegetated areas, reinforcing the crucial role of natural forests in preventing soil displacement. This complementary modelling approach identifies priority areas for soil conservation practices. This study is the first study to integrate the RUSLE and InVEST models for the Lam Phra Phloeng watershed, providing a coupled assessment of erosion risk and sediment retention capacity and offering a novel and transferable framework for watershed-scale conservation planning and soil management in tropical monsoonal environments.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Geographic information system-based impact assessment for illegal dumping in borrow pits in Chachoengsao Province, Thailand
    (2016-01-01)
    Rapid industrial development along Thailand's eastern seaboard has increased pollution and environmental degradation in this densely populated region of the country. A growing problem is illegal disposal of industrial waste in abandoned borrow pits in many locations, especially in the capital Bangkok and its neighboring provinces. Previous work has identifi ed the most likely illegal dumping sites in Chachoengsao Province. The focus of this work was to establish an impact assessment of potential dumping sites using a geographic information system (GIS) in order to create a patrolling and monitoring program for areas at highest risk. The impact assessment is based upon exposure and sensitivity factors of the illegal dumping sites. The exposure factor attempts to quantify the likelihood of illegal dumping; it includes distances from borrow pits to the nearest villages and highways, as well as the areas of the borrow pits. The sensitivity factor assesses the probability of environmental contamination; it includes site topography, ground permeability, aquifer characteristics, and distances to the nearest rivers. GIS was used to compute distances and to overlay other site characteristics. Variables within exposure and sensitivity factors were weighted based upon previous studies and recent expert analysis to compute exposure and sensitivity indices. Maps were then created in GIS for particular exposure and sensitivity factors, and overall impact assessment maps were constructed to indicate zones with low, medium, and high risk. These assessment maps could be adopted by local and regional governmental agencies, as well as local citizens, as part of preventive measures to conserve the local community and environment. Identifi cation of high-risk areas can contribute to the initiation of a monitoring and patrolling program to prevent illegal dumping and preserve environmental and natural resources.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    The influence of climate variability effects on groundwater time series in the lower central plains of Thailand
    (2018-03-08)
    Taweesin, Korrakoch
    ;
    ;
    Saraphirom, Phayom
    This research studies the relationship between the climate index and the groundwater level of the lower Chao Phraya basin, in order to forecast the groundwater level in the studied area by using Autoregressive IntegratedMoving Average with Explanatory (ARIMAX). The combination of 6 climate indices-Dipole Mode Index, Indian Summer Monsoon Index, Multivariate ENSO Index, Sea Surface Temperature NINO4, Southern Oscillation Index and theWestern North PacificMonsoon Index-were used, along with the groundwater level data from 14 stations during the period 1980-2011 to develop the forecastmodel and verify itwith the data of 2012.The first stepwas correlation of the ARIMAmodel with Autocorrelation Function and Partial Autocorrelation Function. The possible model was then selected using BIC statistics. Diagnostic Checking was done to consider the white noise characteristic of estimated residuals by using the statistics of Box and Ljung (Q-statistic). If the selected models were found to be proper, then the Granger Causality Test of the leading parameters or the climate index would be performed as the next step. The results show that there is a relationship between the groundwater level and the climate index. The model could be used to forecast effectively the average RMSE value at 0.6. The last step was to develop theMODFLOWfor a conceptualmodel and synthesize groundwater levels in the study area, which covers around 43,000 km<sup>2</sup> and has 8 layers of groundwater, with Bangkok clay on the top. All other boundary values were set to be steady. The calibration was done using the data of 325 observed wells. The normalized RMS value was 9.705%. The results were verified by the data using ARIMAX over the same time periods. To conclude, the simulated results of the monthly groundwater level in 2012 of the wells have a confidence interval of around 95%, which is near the result from the ARIMAX model. The advantages of the ARIMAX model include high accuracy, no requirement for a large amount of data and inexpensive implementation. It is one of the effective tools for the groundwater prediction.