Estimating Soil Organic Carbon Sequestration in Rice Paddies as Influenced by Climate Change under Scenario A2 and B2 of an i-EPIC model of Thailand

Carbon sequestration in soils constitutes an important option that can be used to reduce CO2 emissions to the atmosphere and reduce environmental impacts. Soil organic carbon (SOC) is both a source of carbon release and a sink for carbon sequestration. Our objectives in this study were to validate the interactive Environmental Policy Impact Calculator (i-EPIC) model version 0509, as well as to estimate SOC sequestration under climate change scenarios A2 and B2 SRES emission scenarios in Thailand. The SOC estimated by i-EPIC was compared with data from the Office of Soil Resources Survey and Research, Land Development Department. The results indicated that performance testing of i-EPIC is able to estimate SOC. Validation of SOC proved to be satisfactory with a resulting root mean square error (RMSE %) value of 34.60. The SOC content showed a decreasing trend under B2 and A2 climate scenarios (average 0.87% and 0.85%, respectively) compared to the reference from 2007 (average 0.92%). Stepwise regression analysis also revealed that carbon from residue decomposition, biomass pool carbon, and the total change of the carbon pool were directly correlated with the SOC (R2= 0.99, p< 0.01). Furthermore, the change from rain supplied water to irrigation also resulted in an increase of carbon inputs but a decrease in the SOC sequestered during the 2007-2017 period. Regression analyses indicated that soil carbon sequestration responds linearly to carbon input. Significant changes in carbon input as well as decreases in SOC levels were observed as temperature and precipitation increased. Based on the testing and analysis, we concluded that i-EPIC is capable of reliably simulating effects of climate change on SOC sequestration. Based on the results, this knowledge and information can increase effectiveness in the promotion of integrated rice management for rice production in Thailand

Teak Log Coffins in Northwest Thailand: Dated by Dendrochronology and 14Cwiggle Matching

Log coffins have been discovered in caves and rockshelters in the Pang Ma Pha district, Mae Hong Son province, Northwestern Thailand. Most are made of teak wood. Many researchers have used the 14C method to determine their age. However, 14C cannot provide as precise a calendar age as dendrochronology. In this paper, we therefore applied dendrochronology analysis to a number of teak log coffins at the Ban Rai Rockshelter to establish a floating chronology and to cross-date the coffins relative to each other. Then, wiggle matching was used for one log coffin to derive an approximate but absolute calendar age. The findings indicated that cutting of this teak tree occurred around AD 265. The analyses also revealed a close association between coffins of the same head style

Modelling Assessment of Sandy Beaches Erosion in Thailand

This paper focuses on the spatial and temporal aspects of rising sea levels and sandy beach erosion in Thailand. The major scientific challenge tackled in this paper was to distinguish the relevance and contribution of sea level rise (including storms) to beach erosion. The Simulator of Climate Change Risks and Adaptation Initiatives (SimCLIM) and its’ impact model (CoastCLIM) with two representative concentration pathway (RCP) scenarios (RCP2.6 and RCP8.5) was utilized to forecast changes in sea level and shoreline between the years 1940-2100. Input parameters underlying the modified Brunn Rule were applied (e.g., coastal and storm characteristics). Moreover, sand loss and forced people migration were estimated using fundamental equations. The sea level is predicted to rise by 147.90 cm and the coastline will be eroded around 517.09 m by 2100, compared to levels in 1995. This level of erosion could lead to a decrease of the coastal sandy area by about 2.69 km2 and a population of 873 people, over the same period. In scientific terms, this paper quantifies the contribution and relevance of sea-level rise (SLR) to sandy beach erosion compared to other factors, including ad-hoc short-term impacts from stochastic storminess. The results also showed that 8.02 and 23.26 percent of erosion was attributed to storms and sea-level rise, respectively. Nevertheless, limited multi-century data of residual movement in Thailand could create uncertainties in distinguishing relative contributions. These results could be beneficial to national-scale data and the adaptation planning processes in Thailand

Tree-ring stable carbon isotope-based June-September maximum temperature reconstruction since AD 1788, north-west Thailand

The first study of tree-ring stable carbon isotopes in Thailand has demonstrated that stable carbon isotope in northwestern Thailand represents a promising proxy for the temperature reconstruction of core-monsoon periods. A tree-ring delta C-13 chronology was constructed based on four cores covering the period of 1788-2013. After removing the long-term decreasing trend reflecting atmospheric CO2 concentrations, the Delta C-13 chronology was able to capture both temperature and hydro-climate signals Delta C-13 chronology showed particularly strong and significant negative correlation (r = -0.62, p &lt; 0.0001) with June-September maximum temperature (CRU TS 3.24). The maximum temperature was reconstructed, which explained 37.8% of the variance in the instrumental maximum temperatures over the period of 1901-2013. The maximum temperature reconstruction revealed that four cooler and three warmer periods, as well as a slightly increasing temperature trend, occurred during the late seventeenth to mid-eighteenth centuries, which were followed by severe temperature fluctuations during the twentieth century century. While the sea surface temperature anomaly in the Indian Ocean might not affect the maximum temperature, its unstable relationship with the El Nino-Southern Oscillation (ENSO) was detected. In addition, a close relationship was observed between the maximum temperature and ENSO during the negative phase of the Pacific Decadal Oscillation (PDO), but this relationship was lost during the positive phase of the PDO

Fractional importance of various moisture sources influencing precipitation in Iran using a comparative analysis of analytical hierarchy processes and machine learning techniques

Studying the moisture sources responsible for precipitation in Iran is highly important. In recent years, moisture sources that influence precipitation across Iran have been studied using various methods. In this study, moisture uptake rate from individual sources that influences precipitation across Iran has been determined using the (E − P) values obtained by the FLEXPART model for the 1981–2015 period. Then, moisture uptake rate from individual sources has been used as independent parameters to investigate the fractional importance of moisture sources that influence precipitation in Iran using analytical hierarchy process (AHP) as well as machine learning (ML) methods including artificial neural networks, Decision Tree, Random Forest, Gboost, and XGboost. Furthermore, the average annual precipitation in Iran was simulated using ML methods. The results showed that the Arabian Sea has a dominant fractional influence on precipitation in both wet (November to April) and dry (May to October) periods. Simulation of precipitation amounts using the ML methods presented accurate models during the wet period, whereas the developed models for the dry period were not adequate. Finally, validation of the accuracy of the ML models using RMSE and R2 values showed that the models developed using XGboost had the highest accuracy.Mahidol University | Ref. MU-PD-2021-13Xunta de Galicia | Ref. ED481B-2019/070Xunta de Galicia | Ref. ED431C 2021/4

Assessment of the Potential Climate Change on Rice Yield in Lower Ayeyarwady Delta of Myanmar Using EPIC Model

Climate 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

Assessment of the Sustainability of Accra Metropolitan Area, Ghana

Cities have become integral in the quest to achieving universal sustainable development. For example, the United Nations in 2015 as part of the 17 Sustainable Development Goals called for cities and human settlements to be inclusive, safe, resilient and sustainable (Goal 11). This was in line with the 2012 National Urban Policy of Ghana which seeks to promote a sustainable, spatially integrated and orderly development of urban settlements with adequate housing, infrastructure and services, efficient institutions, and a sound living and working environment for all people to support the rapid socioeconomic development of Ghana. Six years into the implementation of the National Urban Policy by the government, what is the sustainability status of the Ghanaian city? The aim of this study was to comprehensively evaluate the sustainability status of Accra Metropolitan Area, the capital city of Ghana. The study adopted a set of city sustainability indicators that revealed the weak and strong points of Accra metropolis. Forty-one Accra Sustainability Indicators were defined and classified into Economic, Environment, Social and Institutional (local governance) dimensions. The evaluation was for a period of 4 years, (2012 to 2015) during which the 2012 Urban Policy and its action plan were being implemented. Questionnaires were developed based on the indicators and administered to stakeholders. The quantitative data collected was analyzed using Statistical Package for Social Sciences (SPSS) and Microsoft Excel. The results showed Accra’s economic dimension approaching sustainability while environmental and institutional dimensions performed poorly. The social dimension, though performed below average, rose marginally over the period. Overall sustainability index of Accra was below average and showed a progression towards sustainability over the last 4 years, rising from 0.48 in 2012 to 0.51 in 2015. The findings of this study are helpful to local authorities for sustainable city planning and management

An Assessment of Climate Variability on Farmers’ Livelihoods Vulnerability in Ayeyarwady Delta of Myanmar

This study assesses the vulnerability of farm households in the Ayeyarwady Region, Myanmar. Fifty-nine farm households were purposively sampled to conduct a questionnaire survey, and secondary data were collected in 2016. In order to assess variability in household vulnerability, the Livelihood Vulnerability Index (LVI), based on five types of ‘capital’ as identified in the Sustainable Livelihoods Framework, was adopted and modified according to the local context. Vulnerability scores ranged from 0 (low vulnerability) to 1 (highly vulnerable), with an average LVI of 0.442, indicating moderate overall vulnerability across the study area. Regarding the five types of ‘capital’, households were most vulnerable in terms of financial capital with an average value of 0.530, followed by natural capital (0.515) and physical capital (0.418). Households were classified into three vulnerability groups (low, moderate, and high) to identify those households most likely to need special attention. The survey found that the vulnerability of each asset they suffered was different across the township. The results also revealed that the production area of households classed as highly financially vulnerable found in the flood-prone and saline intrusion areas. It is clear that in order to reduce the vulnerability of farm households, more interventions are needed to enhance access to agricultural credit, diversifying livelihoods, provision of farm technology, inputs and knowledge as well as upgrading of basic infrastructure

A 177 Years Extended of Teak Chronology Revealing to the Climate Variability in Phrae Province, Northern of Thailand

Teak ring-width is one of the promising paleoclimate proxies in the tropical region. Tree-ring chronology spanning from 1840 to 2016 (177 years) was derived from seventy-six trees from Phrae Province, northern Thailand. A total of 141 core samples were cross-dated, a standardized master was constructed, and the tree residual master chronology was developed by ARSTAN program. The tree-ring chronology has a significant positive correlation with the monthly rainfall and relative humidity during the monsoon season (May - June). In addition, the growth of tree-ring width also significantly inversely correlated with Niño 3, Niño 3.4, and Niño 4 indices during the second half of the dry season (January - March). We reconstructed summer monsoon season (May - June) rainfall based on a linear regression model which explained 21.95% of the actual rainfall variance. The trend of the reconstructed rainfall record shows a decrease of 0.6 mm per decade and substantially showed four wet periods and five dry periods. These results suggest that this teak chronology has a good potential to be a high-resolution proxy for reconstructing the past local climate in northern Thailand