Chao Phraya River Basin Research Articles

Effects of climate and land use changes on water balance in upstream in the Chao Phraya River basin, Thailand

A monthly water balance model was used to investigate the effects of climatic and land use changes on water resources upstream in the Chao Phraya River basin. The objective was to simulate and predict the hydrological processes under different climate change and land use change scenarios. The results showed that the climatic conditions and land development had an impact on changing the rainfall, evapotranspiration and streamflow. The simulated water balance for future climatic conditions and land use change scenarios showed increases during 2010–2099 in rainfall, temperature, evapotranspiration and streamflow. Under all land use conditions, the estimated evapotranspiration trends increased, especially for the worst case (12% forest area) which showed the highest evapotranspiration values in the A2 and B2 climate change scenarios. When discharge was calculated in the future, there was 27–40% of both A2 and B2 climate change scenarios under all land use conditions (12%, 20% and 40% forest area) when compared between 1970 and 1989 (calibration period) and 2090–2099 (prediction period). Increasing streamflow will be useful for human activities but it raises water resources issues such as the frequency of flood and drought events in the future.

Modification of DWCM-AgWU Model Applied to A Paddy-Dominant Basin with Large Dams

The Distributed Water Circulation Model incorporating Agricultural Water Use (DWCM-AgWU) was modified and the revised model was applied to assess water use in the Chao Phraya River basin in Thailand for the years 2008–2011, during which there were droughts and floods. A reservoir management model was introduced to incorporate two large dams (Bhumibol and Sirikit dams), with several remote irrigated areas in water allocation/management, and performed special treatments of flood peaks to account for agricultural practices. In the system, the two dams are the main sources of irrigation water during the dry season and they are used to control floods during the rainy season. Moreover, for the lower Chao Phraya River from Nakhon Sawan to the sea, another special water management was applied on rainy days to keep the release at the Chao Phraya Diversion Dam at or below a certain threshold. That is, when discharge exceeded the threshold, water was diverted to main irrigation canals on the western and eastern sides of the Greater Chao Phraya Irrigation Project. According to the simulation, the average relative error between the calculated and observed daily discharge was 21% at the Nakhon Sawan station, which is located below the confluences of the four main tributaries of the Chao Phraya River. The modified model will enable continuous calculations for mitigating the impacts of extreme events, such as the 2011 flood in Thailand, managing the use of irrigation water, and proposing adaptive countermeasures to climate change. Copyright © 2016 John Wiley & Sons, Ltd.

Skill of precipitation projectionin the Chao Phraya river Basinby multi-model ensemble CMIP3-CMIP5

Abstract Weather and climate extremes are of many types and they result in various physical and environmental impacts. The massive flooding and inundation in the Chao Phraya River basin, in Thailand, caused serious damage to various activities for a prolonged period of time. The consequence of 2011 great flood was a total of 815 deaths and has been recorded as the most economic damage (US$45.7 billion). The present study analyses the skill of the two generations of global climate model ensembles, CMIP3 and CMIP5, in projection of precipitation. We firstly examine the flood behavior in 2011 and perform statistical downscaling for 9 GCMs of CMIP3 and CMIP5. The observed precipitation data from 83 stations around the country were interpolated to grid data using various methods. The Inverse Distance Weighted (IDW), after performing cross-validation, is found to give the best statistical performance and is used for GCMs assessment. Both CMIP3 and CMIP5 models underestimate the mean precipitation in the southwestern and eastern regions for historical climatology (1980–1999). The CMIP3 and CMIP5 MME show similar pattern but different magnitudes (CMIP5 gives higher mean precipitation than CMIP3). The majority of CMIP3 and CMIP5 models overestimate the dry spell and the peak precipitation. The precipitation projection was downscaled by the distribution mapping for the near-future (2010–2039), the mid-future (2040–2069) and the far-future (2070–2099). Both model generations perform reasonably well in capturing the amplitude and phasing of past mean annual precipitation. The correlation coefficient from all models lies between 0.6 and 0.9, implying reasonable simulation. The summer monsoon precipitation has an increase trend (from low to high GHG emissions), of 7–32% in October, 6–28% in September, and 8–20% in September for Bhumibol reservoir, Sirikit reservoir, and Nakhon Sawan, respectively. A possibility of increase in hydrological extreme flood in the wet season may be indicated by these findings.

Isotope and REE Characterization of Groundwater Aquifers within the Aquifer Storage and Recovery Programme in Sukhothai (N.-Thailand)

Aquifer Storage and Recovery (ASR) was a pilot project for solving flood and drought problem in the northern part of Chao Phraya River basin, Thailand. This part of Thailand always faces flooding in rainy season and drought during dry season every year. The overexploitation of groundwater during dry season leads to continuously decline of water level in this area. In this project, the excessive surface water during rainy season was stored by injection of this treated surface water through recharge wells into the underground aquifers. This would serve to raise the water level, which can be extracted for use during the dry season. To assess the efficiency of the ASR process some tracers are required. The aim of this study is to prove the suitability of natural tracers to follow up the artificial recharge process; emphasis will be placed on Strontium (Sr) isotopic composition. The results showed that the change in 87Sr/86Sr ratios could be observed during an artificial recharge due to the different isotopic fingerprint of surface water and groundwater. However, the flow direction of the injected water cannot be clearly interpreted because of the limited number of monitoring wells, small distance between each monitoring well and the short duration of injection.

The 2011 Great Flood in Thailand: Climate Diagnostics and Implications from Climate Change

Abstract Severe flooding occurred in Thailand during the 2011 summer season, which resulted in more than 800 deaths and affected 13.6 million people. The unprecedented nature of this flood in the Chao Phraya River basin (CPRB) was examined and compared with historical flood years. Climate diagnostics were conducted to understand the meteorological conditions and climate forcing that led to the magnitude and duration of this flood. Neither the monsoon rainfall nor the tropical cyclone frequency anomalies alone was sufficient to cause the 2011 flooding event. Instead, a series of abnormal conditions collectively contributed to the intensity of the 2011 flood: anomalously high rainfall in the premonsoon season, especially during March; record-high soil moisture content throughout the year; elevated sea level height in the Gulf of Thailand, which constrained drainage; and other water management factors. In the context of climate change, the substantially increased premonsoon rainfall in CPRB after 1980 and the continual sea level rise in the river outlet have both played a role. The rainfall increase is associated with a strengthening of the premonsoon northeasterly winds that come from East Asia. Attribution analysis using phase 5 of the Coupled Model Intercomparison Project historical experiments pointed to anthropogenic greenhouse gases as the main external climate forcing leading to the rainfall increase. Together, these findings suggest increasing odds for potential flooding of similar intensity to that of the 2011 flood.

A Traditional Community in the Chao Phraya River Basin II: Influence of Water Circulation on the Traditional Living Culture according to the Settlement Pattern

<p class="1Body">The remaining traditional waterfront community in the Chao Phraya River Basin demonstrates human adaptability towards modern conditions. Everyday practice in the traditional community complex is about living in harmony with all other aspects of the system to which it belongs. However, the intensity and speed of such changes are challenging these complex urban environments in contemporary society. With high dynamicity, this important amphibious lifestyle is gradually disappearing.</p><p class="1Body">This study is based on a qualitative approach, to examine the general pattern of amphibious livelihoods from past to present, including changes and processes of adaptability to declination. Investigation was implemented by reviewing secondary data collection and oral history and collective memory by the interview method.</p><p class="1Body">The results found that water circulation patterns have exerted influence on traditional daily life over several decades: river overflows in paddy villages, irrigation network of ditches in orchard villages, brackish water circulation in estuarine agricultural villages, wetland fishery in coastal fishing villages, north-south corridor river trading in riverport towns, east-west canal network trading in canal trading villages, and surface water livelihoods in the raft community.</p>

Assessment on Hydrologic Response by Climate Change in the Chao Phraya River Basin, Thailand

The Chao Phraya River in Thailand has been greatly affected by climate change and the occurrence of extreme flood events, hindering its economic development. This study assessed the hydrological responses of the Chao Phraya River basin under several climate sensitivity and greenhouse gas emission scenarios. The Soil and Water Assessment Tool (SWAT) model was applied to simulate the streamflow using meteorological and observed data over a nine-year period from 2003 to 2011. The SWAT model produced an acceptable performance for calibration and validation, yielding Nash-Sutcliffe efficiency (NSE) values greater than 0.5. Precipitation scenarios yielded streamflow variations that corresponded to the change of rainfall intensity and amount of rainfall, while scenarios with increased air temperatures predicted future water shortages. High CO2 concentration scenarios incorporated plant responses that led to a dramatic increase in streamflow. The greenhouse gas emission scenarios increased the streamflow variations to 6.8%, 41.9%, and 38.4% from the reference period (2003–2011). This study also provided a framework upon which the peak flow can be managed to control the nonpoint sources during wet season. We hope that the future climate scenarios presented in this study could provide predictive information for the river basin.

The effects of Thailand׳s Great Flood of 2011 on river sediment discharge in the upper Chao Phraya River basin, Thailand

Severe flooding that occurred during the 2011 monsoon season in Thailand was the heaviest flooding in the past 50yr. The rainfall over the northern part of Thailand, especially during July–August 2011, was 150% higher than average. During the flooding period, river flows of the four major Chao Phraya River tributaries (Ping, Wang, Yom, and Nan rivers) increased in the range of 1.4–5 times the average discharge. This study examined the river sediment discharge of the four major rivers in the upper Chao Phraya River basin in Thailand. The four rivers are considered the main sources of sediment supply to the Chao Phraya Estuary. River surveys of the Ping, Wang, Yom, and Nan rivers were carried out in October 2011 (during the Great Flood) and October 2012 (one year after the flood). Survey data included river cross sections, flow velocities, suspended sediment concentrations, and bed load transport in each river. Analyses of these data indicated that total sediment transport rates for the four main rivers during the flooding of 2011 were 2.3–5.6 times higher than the average sediment discharge over 60yr. The flood of 2011 significantly affected the sediment characteristics including the proportions of suspended and bed sediment loads in each river though in different ways. The rates of sediment transport per unit discharge for the Ping and Wang rivers dramatically increased during the 2011 flood, but the flooding had minimal effects on the sediment characteristics in the Yom and Nan rivers. The amount of total sediment discharge in each river caused by the 2011 flooding varied between 0.3 and 1.6Mt. Additionally, the bed load transport in these rivers varied between ~0% and 26% of the suspended sediment discharge.

Impacts of urbanization on the prevalence of antibiotic-resistant Escherichia coli in the Chaophraya River and its tributaries.

River water samples were taken from 32 locations around the basin of Chaophraya River and its four major tributaries in Thailand to investigate resistance ratios of Escherichia coli isolates to eight antibiotic agents of amoxicillin, sulfamethoxazole/trimethoprim, tetracycline, doxytetracycline, ciprofloxacin, levofloxacin, norfloxacin and ofloxacin. Principal component analysis was performed to characterize resistance patterns of the samples. Relevancy of the obtained principal components with urban land use and fecal contamination of the river were examined. The ratio of antibiotic-resistant bacteria is likely to increase when urban land use near the sampling site exceeds a certain ratio. The resistance ratio to fluoroquinolones tends to be high in a highly populated area. Meanwhile, no significant contribution of fecal contamination was found to increase the resistance ratio. These results suggest that an antibiotic-resistance ratio is dependent on conditions of local urbanization rather than the upstream conditions, and that the major sources of antibiotic-resistant bacteria in the Chaophraya River basin are possibly point sources located in the urban area which contains a high ratio of resistant bacteria.

A Traditional Community in the Chao Phraya River Basin: Classification and Characteristics of a Waterfront Community Complex

<p class="1Body">Traditional waterfront communities are extremely significant in understanding the role and influence of the daily lives of an indigenous amphibious culture and are considered to be a counterpart of the contemporary community that would have existed in the past. This study gives a systematic overview of the traditional waterfront community complex in the Chao Phraya River Basin to identify the phenomenology and salient features characterizing the waterfront community through the analysis of the following: 1) features of geography and waterbodies; 2) cultural landscapes and agricultural activities; 3) urban components; and 4) architectural features. A total of 138 traditional waterfront communities were selected using the purposive sampling method.</p> <p class="1Body">Quantitative data collection was conducted using field investigation to collect and evaluate the validity of properties in actual conditions. The data were analyzed using a statistical analysis program to examine the similarity and correlation of the data set. To identify characteristics, hierarchical clustering and decision-tree analysis were used to group similar communities together and classify the complexity of a traditional waterfront community. Principal component analysis was then used to detect the true association between the relevant variables. In addition, qualitative assessment of secondary document collection, legislation, previous and present public policies, research, and criticisms were used to support the argument for statistical analysis.</p> <p class="1Body">The results provided seven clusters based on common preferences consisting of a market town, paddy village, raft community, waterfront market, comprehensive estuarine agricultural village, orchard village, and fishing village. These clusters show diversity in the cultural landscape, with agricultural activities exerting influence on the community complex, creating both direct and indirect association, with several significant variables.</p>

Flood control and loss estimation for paddy field at midstream of Chao Phraya River Basin, Thailand

2011 Thailand flood has brought serious impact to downstream of Chao Phraya River Basin. The flood peak period started from August, 2011 to the end of October, 2011. This research focuses on midstream of Chao Phraya River Basin, which is Nakhon Sawan area includes confluence of Nan River and Yom River, also confluence of Ping River and Nan River. The main purpose of this research is to understand the flood generation, estimate the flood volume and loss of paddy field, also recommends applicable flood counter measurement to ease the flood condition at downstream of Chao Phraya River Basin. In order to understand the flood condition, post-analysis is conducted at Nakhon Sawan. The post-analysis consists of field survey to measure the flood marks remained and interview with residents to understand living condition during flood. The 2011 Thailand flood generation at midstream is simulated using coupling of 1D and 2D hydrodynamic model to understand the flood generation during flood peak period. It is calibrated and validated using flood marks measured and streamflow data received from Royal Irrigation Department (RID). Validation of results shows good agreement between simulated result and actual condition. Subsequently, 3 scenarios of flood control are simulated and Geographic Information System (GIS) is used to assess the spatial distribution of flood extent and reduction of loss estimation at paddy field. In addition, loss estimation for paddy field at midstream is evaluated using GIS with the calculated inundation depth. Results show the proposed flood control at midstream able to minimize 5% of the loss of paddy field in 26 provinces.

Hydrologic sensitivity of flood runoff and inundation: 2011 Thailand floods in the Chao Phraya River basin

Abstract. The Thailand floods in 2011 caused unprecedented economic damage in the Chao Phraya River basin. To diagnose the flood hazard characteristics, this study analyses the hydrologic sensitivity of flood runoff and inundation to rainfall. The motivation is to address why the seemingly insignificant monsoon rainfall, or 1.2 times more rainfall than for past large floods, including the ones in 1995 and 2006, resulted in such devastating flooding. To quantify the hydrologic sensitivity, this study simulated long-term rainfall–runoff and inundation for the entire river basin (160 000 km2). The simulation suggested that the flood inundation volume was 1.6 times more in 2011 than for the past flood events. Furthermore, the elasticity index suggested that a 1 % increase in rainfall causes a 2.3 % increase in runoff and a 4.2 % increase in flood inundation. This study highlights the importance of sensitivity quantification for a better understanding of flood hazard characteristics; the presented basin-wide rainfall–runoff–inundation simulation was an effective approach to analyse the sensitivity of flood runoff and inundation at the river basin scale.

Dry season water allocation in the Chao Phraya River basin, Thailand

This study examines the recent quantitative characteristics of dry season water allocation in the Chao Phraya River basin, Thailand. Previous studies have focused on inequitable allocation, where the highest priority is given to the domestic water sector and uneven irrigation water variability exists among projects in the delta. This study uses a statistical test and panel data analysis to confirm that the characteristics highlighted in previous studies remain accurate, and it discusses the source of these characteristics in order to understand the issues in water allocation in the Chao Phraya River delta.

Rainfall estimation for real time flood monitoring using geostationary meteorological satellite data

Rainfall estimation by geostationary meteorological satellite data provides good spatial and temporal resolutions. This is advantageous for real time flood monitoring and warning systems. However, a rainfall estimation algorithm developed in one region needs to be adjusted for another climatic region. This work proposes computationally-efficient rainfall estimation algorithms based on an Infrared Threshold Rainfall (ITR) method calibrated with regional ground truth. Hourly rain gauge data collected from 70 stations around the Chao-Phraya river basin were used for calibration and validation of the algorithms. The algorithm inputs were derived from FY-2E satellite observations consisting of infrared and water vapor imagery. The results were compared with the Global Satellite Mapping of Precipitation (GSMaP) near real time product (GSMaP_NRT) using the probability of detection (POD), root mean square error (RMSE) and linear correlation coefficient (CC) as performance indices. Comparison with the GSMaP_NRT product for real time monitoring purpose shows that hourly rain estimates from the proposed algorithm with the error adjustment technique (ITR_EA) offers higher POD and approximately the same RMSE and CC with less data latency.

The effect on river discharge estimation by considering an interaction between land surface process and river routing process

Abstract. There is much research assessing the impact of climate change on the hydrologic cycle. However, it has often focused on a specific hydrologic process, without considering the interaction among hydrologic processes. In this study, a distributed hydrologic model considering the interaction between flow routing and land surface processes was developed, and its effect on river discharge estimation was investigated. The model enables consideration of flow routing, irrigation withdrawal from rivers at paddy fields, crop growth depending on water and energy status, and evapotranspiration based on meteorological, soil water and vegetation status. To examine the effects of hydrologic process interaction on river discharge estimation, a developed model was applied to the Chao Phraya river basin using near surface meteorological data collected by the Japanese Meteorological Research Institute's Atmospheric General Circulation Model (MRI-AGCM3.2S) with TL959 spatial resolution as forcing data. Also, a flow routing model, which was part of the developed model, was applied independently, using surface and subsurface runoff data from the same GCM. In the results, the developed model tended to estimate a smaller river discharge than was estimated by the river routing model, because of the irrigation effect. In contrast, the annual maximum daily discharge calculated by the developed model was 24% greater than that by the flow routing model. It is assumed that surface runoff in the developed model was greater than that in the flow routing model because the soil water content was maintained at a high level through irrigation withdrawal. As for drought discharge, which is defined as the 355th largest daily discharge, the developed model gave a discharge 2.7-fold greater than the flow routing model. It seems that subsurface runoff in the developed model was greater than that in the flow routing model. The results of this study suggest that considering hydrologic interaction in a numerical model could affect both flood and drought estimation.

Assessing potential flood vulnerability to climate change by CMIP3 and CMIP5 models: case study of the 2011 Thailand great flood

The 2011 monsoon season was exceptionally heavy, leading to extensive and long-lasting flooding in the Chao Phraya river basin. Flooding was exacerbated by rapid expansion of urban areas into flood plains and was the costliest natural disaster in the country's history, with direct damages estimated at US$ 45 billion. The present study examines the flood behavior in 2011 and flood impact from changing climate. Two generations of the global climate model (GCM), ensembles CMIP3 and CMIP5, are statistically downscaled through historical 20th century and future projections. The majority of GCMs overestimate the dry spell (in June and July) and underestimate the peak precipitation (in May and September). However, they can simulate the mean precipitation reasonably well. Use of the Multi Model Mean shows continuously increased precipitation from near-future to far-future, while the Multi Model Median shows increased precipitation only for the far-future. These findings in changing precipitation are assessed by flood simulation. With several adaptation measures, flood in the lower Chao Phraya river basin cannot be completely avoided. One of the best practices for a high flood risk community is to raise the house with open space in the first floor. This is promoted as one resilient approach in Thailand.

Simulation of Modeling Approach for Flood Condition and Proposed Flood Protection at Midstream of Chao Phraya River Basin, Thailand

2011 Thailand flood has resulted in serious impact to downstream of Chao Phraya River. Study on midstream of Chao Phraya River Basin has rarely been conducted. This research focuses on midstream of Chao Phraya RiverBasin, which includes confluence of Nan River and Yom River, also confluence of Ping River and Nan River. Flood condition at midstream is simulated using coupling of 1D and 2D hydrodynamic model, MIKE FLOOD to understand the flood generation. The model is calibrated and validated using flood marks measured at study area and streamflow data received from Royal Irrigation Department (RID). Furthermore, scenarios of flood control at 3 rivers are simulated and Geographic Information System (GIS) is used to calculate the flood distribution area and flood volume. Subsequently, 2 kinds of suitable flood control measurements are proposed. Results shows flood control at midstream helps reduce the risk of reflooding or flood return from small streams and flood plain into starting of Chao Phraya River. However, flood volume before confluence of Ping River and Nan River, which is Bung Boraphet area will be increased. Therefore, the land use planning and regulation at area nearby Bung Boraphet need to be considered.

An emergency response‐type rainfall‐runoff‐inundation simulation for 2011 Thailand floods

AbstractA devastating flood disaster occurred in Thailand in 2011. In case of such large‐scale flooding, it is important to predict the dynamics of inundation on a near real‐time basis for safe evacuation. To predict widespread inundation, where both rainfall‐runoff from surrounding mountains and rainfall on floodplains contribute to the event, this paper applied a rainfall‐runoff‐inundation (RRI) model to the entire Chao Phraya River basin (160 000 km2). Near real‐time simulation was conducted for emergency responses with globally available dataset including satellite‐based topography (HydroSHEDS derived from SRTM) and rainfall (TRMM 3B42RT) during the disaster. Post‐flood simulation was also carried out with more local information. The RRI model was found capable of representing the peak inundation extent with an acceptable accuracy and correctly predicting a 1‐month lasting inundation in the lower part of the basin. On the other hand, the prediction overestimated the river discharge by 40% and the inundation water level by 2 m mainly due to the neglect of the evapotranspiration effect. The post‐flood simulation improved its accuracy by up to 10% for river discharges and 1 m for peak inundation water levels, but it did not lead to better agreement of flood extents with those based on the remote sensing. Further study is recommended to improve accuracy for modelling of spatial extent of flooding. Furthermore, sensitivity analysis with different input suggested what information should be prioritised for emergency response‐type flood simulations.

Performance Assessment for Irrigation Water Management: Case Study of the Great Chao Phraya Irrigation Scheme

AbstractThe objective of this study is to assess the performance of irrigation water management of the Great Chao Phraya Irrigation Scheme consisting of 25 operation and maintenance irrigation projects (OMPs) in the Chao Phraya River Basin, central Thailand. Benchmarking is used to evaluate irrigation performance amongst the schemes. The eight performance indicators are crop yield ratio, output per unit area, operation and maintenance (O&M) cost, total financial viability, efficiency of infrastructure, sufficiency of irrigation staff, irrigation ratio and cropped area ratio. The results provide a feasible mechanism for performance improvement in the irrigation and drainage sector, but need strong support from key stakeholders. Though there are some uncertainties concerning the quality of secondary data, experience and insight gained from this study could provide valuable information for other schemes and will be a good starting point for benchmarking the performance of irrigation in Thailand. Copyright © 2015 John Wiley & Sons, Ltd.

Opportunities and constraints in adapting to flood and drought conditions in the Upper Chao Phraya River basin in Thailand

ABSTRACTTo assess alterations of the rice-growing season as a sustainable option to overcome temporary groundwater storage shortages resulting from flood and drought conditions in the Upper Chao Phraya River basin in Thailand, rice was planted in May (1.5 months earlier) to harvest before seasonal flooding occurred (normally in October). The assessment showed that a cropping intensity (CI) of approximately 1.4 (100% and 40% of the total agricultural area for the wet and dry seasons, respectively) could be supported by the total available water (surface runoff and renewable groundwater storage). Shifting the growing season did not have a negative impact in terms of rice production area, but it did ensure that the area of rice cultivation avoided flooding or surface water shortage conditions. Expanding the rice production area was also assessed; however, this required the implementation of artificial groundwater recharge (AGR). For example, 1.0 km3 of AGR annually was enough to support CI equal to 1.5 without experiencing groundwater depletion.