Modelling climate change impacts on the seasonality of water resources in the Upper Ca River Watershed in Southeast Asia

New function of Hypoxia-responsive unknown protein in enhanced resistance to biotic stress

Submergence and waterlogging lead to significant reductions in crop productivity and trigger dramatic changes in gene expression of plant biotic/abiotic stress response. Several of the host factors are involved in low-oxygen stress that is induced by endogenous reactive oxygen species (ROS) accumulation. Hypoxia-response unknown protein (HUP) has been found as a host factor of hypoxia screening but HUPs function largely is unknown. In this study, we found the Arabidopsis HUP26 gene which was conserved in different plant species and responded to various oxidative stress. HUP26 promoter analysis showed GUS activity in root and leaf tissues was significantly responsive to oxidative stress. HUP26-GFP is predominantly located in the cytoplasmic region. HUP26 overexpression results in altered enhanced pathogenesis-related gene 1 gene expression and reduced ion leakage levels compared with hup26 knockout and WT plants after inoculation with Pst DC3000. HUP26 overexpression transgenic plants showed improved resistance to Pst DC3000, but hup26 knockout plants exhibited increased susceptibility. Collectively, these results indicate that HUP26 plays important role in responses to various oxidative stress and confers biotic stress resistance. Engineering of HUP26 gene expression may represent a strategy to enhance biotic stress resistance of crops.

A Modeling Approach to Diagnose the Impacts of Global Changes on Discharge and Suspended Sediment Concentration within the Red River Basin

The Red River basin is a typical Asian river system affected by climate and anthropogenic changes. The purpose of this study is to build a tool to separate the effect of climate variability and anthropogenic influences on hydrology and suspended sediments. A modeling method combining in situ and climatic satellite data was used to analyze the discharge (Q) and suspended sediment concentration (SSC) at a daily time scale from 2000 to 2014. Scenarios of natural and actual conditions were implemented to quantify the impacts of climate variability and dams. The modeling gained satisfactory simulation results of water regime and SSC compared to the observations. Under natural conditions, the Q and SSC show decreasing tendencies, and climate variability is the main influence factor reducing the Q. Under actual conditions, SSC is mainly reduced by dams. At the outlet, annual mean Q got reduced by 13% (9% by climate and 4% by dams), and annual mean SSC got reduced to 89% (13% due to climate and 76% due to dams) of that under natural conditions. The climate tendencies are mainly explained by a decrease of 9% on precipitation and 5% on evapotranspiration, which results in a 13% decrease of available water for the whole basin.

A Review of SWAT Studies in Southeast Asia: Applications, Challenges and Future Directions

The Soil and Water Assessment Tool (SWAT) model is recognized as one of the top hydrological models applied for addressing hydrologic and environmental issues. This is the first review on the SWAT model studies in Southeast Asia, with an emphasis on its applications, current challenges and future research directions. A total of 126 articles were identified since 2006; roughly 50% of these studies were conducted in Vietnam or Thailand. About 16% of the studies were performed at a transnational scale, which included Cambodia, Lao PDR, Thailand, and Vietnam. Model capability assessment, land use, and climate change assessment are the main SWAT applications that have been reported for the region. Most of the SWAT calibration and validation results for these studies were classified as satisfactory to very good results based on widely recognized performance indicators. However, the parameterization, calibration and validation procedures are not well reported in some articles. Availability of reliable data is one of the main problems that SWAT users are confronted with, as these data are either not freely available or restricted from public access in some countries. Hence, future studies should be considered on identification and development of reliable input data for SWAT modeling. SWAT model modification based on the SEA climate, geographical and land use conditions is another research direction to be considered in the future. Moreover, application of SWAT for extreme events simulation requires more attention in this region.

Assessing Climate Change Impacts on River Flows in the Tonle Sap Lake Basin, Cambodia

The Tonle Sap is the most fertile and diverse freshwater ecosystem in Southeast Asia, receiving nurturing water flows from the Mekong and its immediate basin. In addition to rapid development in the Tonle Sap basin, climate change may threaten natural flow patterns that sustain its diversity. The impacts of climate change on river flows in 11 sub-basins contributing to the Tonle Sap Lake were assessed using the Soil and Water Assessment Tool (SWAT) model to quantify the potential magnitude of future hydrological alterations. Projected river flows from three General Circulation Models (GFDL-CM3, GISS-E2-R-CC and IPSL-CM5A-MR) for three time horizons (2030s, 2060s and 2090s) indicate a likely decrease in both the wet and dry season flows. The mean annual projected flow reductions range from 9 to 29%, 10 to 35% and 7 to 41% for the 2030s, 2060s and 2090s projections, respectively. Moreover, a decrease in extreme river flows (Q5 and Q95) was also found, which implies there could be a decline in flood magnitudes and an increase in drought occurrences throughout the basin. The results of this study provide insight for water resources planning and adaptation strategies for the river ecosystems during the dry season, when water flows are projected to decrease.