JOURNAL OF CLIMATE CHANGE SCIENCE NO 19 – 2021

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AN INTRODUCTION TO THE WORKING VERSION OF THE NINTH PHASE OF THE INTERGOVERNMENTAL HYDROLOGICAL PROGRAMME, 2022 – 2029

Tran Thuc

Chairman of Viet Nam National Committee for the UNESCO-IHP

Received: 03 August 2021; Accepted: 23 August 2021

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EFFECTIVENESS OF MEASURES TO IMPROVE WATER SECURITY IN QUANG NGAI PROVINCE IN THE CONTEXTOF CLIMATE CHANGE

Bui Duc Hieu⁽¹⁾, Ta Dinh Thi⁽²⁾, Nguyen Dang Huy Anh⁽³⁾, Nguyen Anh Tuan⁽⁴⁾

⁽¹⁾Office of the Ministry of Natural Resources and Environment

⁽²⁾Congressman of the 15th National Assembly, Viet Nam Administration of Seas and Islands

⁽³⁾Deparrtment of Climate change

⁽⁴⁾Viet Nam Institute of Meteorology, Hydrology and Climate change

Received: 12/8/2021; Accepted: 01/9/2021

Abstract: As one the countries most adversely affected by climate change and sea level rise, Viet Nam is facing many challenges threatening its water security. Currently, there have not been many studies assessing water security in the context of climate change, especially the quantification of the water security at national and provincial levels. The study used the method of developing a set of indicators to assess the water security in the context of climate change. On that basis, the study proposed measures to improve the water security in Quang Ngai province. The analysis results show that among the 17 proposed sub-indicators on water security, there are 5 sub-indicators that cannot be affected, namely: flood frequency; number of days of drought; ratio of flooded area; the average annual rainfall and the average annual temperature. The remaining 12 sub-indicators can be improved by measures and hence the study has selected prioritized measures to ensure water security in Quang Ngai in the direction of focusing on improving these 12 indicators.

Keywords: Water security; Climate Change; Set of indicators.

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IMPACT OF URBANIZATION ON FLOODING IN KHANH HOA PROVINCE

Luong Huu Dung, Doan Huy Phuong, Ngo Thi Thuy, Chu Nguyen Ngoc Son

Viet Nam Institute of Meteorology Hydrology and Climate Change

Received: 30 July 2021; Accepted: 20 August 2021

Abstract: Currently, natural disasters such as floods and inundation are increasing both in the quantity and degree of impact. The areas most heavily affected by flooding are low-lying areas such as coastal cities and countries. The characteristics of natural disasters such as floods and inundation are not only affected by changes in climate factors but also by urbanization and human activities. This paper uses the MIKE FLOOD (DHI) model to analyze the impact of urbanization on flood and inundation characteristics in the downstream areas of Cai river in Khanh Hoa province. The results show that the change of urban topography during the urbanization period has significant effects on the floodplain areas in terms of location and intensity, thereby changing the characteristics of flood and inundation distribution spatially.

Keywords: Urbanization, flooding, coastal areas, Khanh Hoa province, Viet Nam.

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STUDY ON FORECASTING TIDAL WATER LEVELS IN THE SAI GON DONG NAI RIVER FOR ASSESSMENT OF FLOOD IMPACTS IN HO CHI MINH CITY

Nguyen Van Hong, Nguyen Phuong Dong, Pham Thanh Long, Pham Anh Binh, Ho Cong Toan

Sub-Institute of HydroMeteorology and Climate Change

Received: 06 September 2021; Accepted: 20 September 2021

Abstract: In recent years, due to the impact of extreme weather, the evolution of rain and tides in Ho Chi Minh City (HCMC) has many changes. Particularly, rainfall and rainfall intensity have been increasing more and more, duration of rainfall has been longer and longer, the number of some heavy rains with a volume of 50 – 100 mm has been boosted, the high tide level on the river has also multipled in rencent year. As the result, the flooding situation of the city is heavily and seriously impacted, causing inevitable damage and challenges for the socio-economic activities of city people. Therefore, research on the impact of coastal water levels on flooding in the city is very necessary. In this paper, UTide software is applied to calculate and forecast tidal water levels along the coastal areas and inland stations of the Sai Gon River, thereby assessing the impacts of flooding due to high tides on HCMC with water level forecast results for 3 stations Nha B, Phu An and Vung Tau respectively 0.82, 0.83 and 0.97.

Keywords: UTide, flood, high tide, forecast, Ho Chi Minh City.

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CHARACTERIZING EFFECTS OF DIFFERENT ENSO PHASES ON SEA SURFACE TEMPERATURE IN THE VIET NAM EAST SEA

Le Quoc Huy⁽¹⁾, Pham Tien Dat⁽²⁾, Tran Van My⁽¹⁾, Nguyen Hong Hanh⁽¹⁾, Nguyen Thi Lan⁽¹⁾, Dang Linh Chi⁽¹⁾

⁽¹⁾Viet Nam Institute of Meteorology, Hydrology and Climate change

⁽²⁾VNU University of Science

Received: 13 September 2021; Accepted: 29 September 2021

Abstract: The effect of different ENSO phases on Sea Surface Temperature (SST) has been an intensive effort to find the link between this basin-scale climate pattern and one of the most critical marine parameters. This issue, however, has not been well-studied in the Viet Nam East Sea (VES). This study examined the effect of different ENSO phases on SST in the VES by applying a series of statistical techniques on both satellite data and observed data from coastal stations. We find a significant correlation between ENSO and satellite-based SST data in the winter season (r = 0.56). We recognize a stronger relationship of ENSO-SST in the southern stations (with r varies from 0.47 – 0.83). We then compared the impact of different ENSO phases for the period of 1990 – 2019. Our results reveal that the extreme El Nino event 1997/98 had impacted SST strongly than any other event. In addition, we find that the response of SST to ENSO phases does not depend on intensity. The outcomes of this work may significantly contribute to the understanding of the effects of ENSO on marine parameters in the VES.

Keywords: ENSO, SST, EEMD, EOF.

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DETERMINATION OF EVAPOTRANSPIRATION USING SOLAR RADIATION AND METEOROLOGICAL DATA APPLYING DIFFERENT METHODS: A CASE STUDY HOA BINH PROVINCE

Le Hung Chien⁽¹⁾, Doan Ha Phong⁽²⁾, Tran Xuan Truong⁽³⁾, Ngo Thi Dinh⁽¹⁾

⁽¹⁾ Viet Nam National University of Forestry

⁽²⁾ Viet Nam Institute of Meteorology, Hydrology and Climate Changer

⁽³⁾ Ha Noi University of Mining and Geology

Received: 19 August 2021; Accepted: 08 September 2021

Abstract: Evapotranspiration (ET) is a significant parameter that needs to be determined and accurately estimated in many practical applications such as the management and use of water domestic, agricultural production, and forestry. The content of the article presents four methods that include the Makkink method (1957), Abtew method (1996), Priestley & Taylor method (1972), Hargreaves & Samani method (1982, 1985) to calculate evapotranspiration from meteorological data at monitoring stations in Hoa Binh province. The results of evapotranspiration calculated from the methods are compared and evaluated for accuracy with direct measurement data at the province’s hydro-meteorological stations, attend to the management, forecasting water demand in agriculture and forestry, and design of irrigation works with climate conditions of Hoa Binh province. The results indicate that the average evapotranspiration values at the hydro-meteorological stations of Makkink method (1957), Abtew method (1996), Priestley & Taylor method (1972), Hargreaves & Samani method (1982, 1985) to calculate evapotranspiration from meteorological data at monitoring stations in Hoa Binh province. The results of evapotranspiration calculated from the methods are compared and evaluated for accuracy with direct measurement data at the province’s hydro- meteorological stations, attend to the management, forecasting water demand in agriculture and forestry, and design of irrigation works with climate conditions of Hoa Binh province. The results indicate that the average evapotranspiration values at the hydro-meteorological stations of Makkink method (1957), Abtew method (1996), Priestley & Taylor method (1972), Hargreaves & Samani method (1982, 1985) on 04th June 2017 were 8.1 mm, 5.8 mm, 7.8 mm and 11.3 mm, respectively. The average error of evapotranspiration at meteorological stations calculated according to the methods compared with the average evapotranspiration at meteorological stations measured directly is 5.2%, 24.7%, 1.3%, 46.7%, respectively. Calculating evapotranspiration by the Makkink method with coefficients a = 0.9 and b = 0 gives the most accurate results with the highest correlation coefficients R2 = 0.969 and RMSE = 0.346. According to the results, the Priestley- Taylor and Makkink method is proposed to calculate the evapotranspiration for the Hoa Binh area.

Keywords: Evapotranspiration, Makkink method, Priestley – Taylor method, , Hoa Binh Meteorological station.

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RADAR EXTRAPOLATION IN VERY SHORT-RANGE RAINFALL FORECASTING IN HO CHI MINH CITY

Truong Ba Kien⁽¹⁾, Tran Duy Thuc⁽¹⁾, Nguyen Quang Trung⁽¹⁾, Nguyen Binh Phong⁽²⁾, Vu Van Thang⁽¹⁾

⁽¹⁾Viet Nam Institute of Meteorology Hydrology and Climate Change

⁽²⁾Ha Noi University of Natural Resources & Environment

Received: 29 July 2021; Accepted: 18 August 2021

Abstract: This article presents the study results of TITAN and SWIRLS tools for extrapolating radar data to forecast rainfall (1 – 6 hours) in Ho Chi Minh City region. The SWIRLS and TITAN are optional tools to extrapolate radar data. The validation results implemented by comparing with GSMAP data (gridded rainfall data) and observation measured at 219 stations at Southern Viet Nam (SVN). The study results show that TITAN and SWIRLS tools can forecast well the place n, direction and speed of rain as well as place of thunderstorm. Especially, the error index calculations showed the better results in SWIRLS than TITAN. However, the better moving trend forecast in the case of Typhoon Usagi is found by TITAN than by SWIRLS.

Keywords: Short-range rainfall forecast, TITAN, SWIRLS, Extrapolation, WRF.

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THE ABILITY OF RCA4 REGIONAL CLIMATE MODEL TO SIMULATE AND PROJECT SURFACE SOLAR IRRADIATION OVER VIET NAM

Vu Thanh Hang⁽¹⁾, Pham Thi Thanh Nga⁽²⁾, Doan Thi The⁽²⁾, Pham Thanh Ha⁽¹⁾, Nguyen Thi Phuong Hao⁽³⁾, Nguyen Tien Cong⁽³⁾

⁽¹⁾Ha Noi University of Science

⁽²⁾Viet Nam Institute of Meteorology, Hydrology and Climate change

⁽³⁾Viet Nam National Space Center, Viet Nam Academy of Science and Technology

Received: 09 August 2021; Accepted: 30 August 2021

Abstract: Currently, the application of numerical models in simulating, forecasting, and predicting meteorological factors and features of the atmosphere, including solar radiation combined using satellite data, is widely used. Therefore, comparing the difference between the parameters calculated from the model with the satellite is extremely necessary, thereby evaluating the quality of the model as well as the quality of the satellite products compared to the value of the satellite with monitoring or re-analysis, is the basis for making accurate forecasts/forecasts in the future.

This study aims to assess the regional climate model RCA4 (RCP4.5 and RCP8.5) to simulate surface solar irradiation (SSI) based on estimated radiation data from the Himawari-8 satellite for Viet Nam using statistical indicators.

The results showed that the radiation values estimated from model correlated well with estimates from the satellite, which has been validated very close to the observation at the surface. In the spring and winter, the general correlation trend shows that the radiation at the stations in the North tend to be higher than the stations in the South of Viet Nam. Based on the assessment of the RCA4 model compared to satellites in the period (2016 – 2018), the results of model are used to analyze the progress of solar radiation during the year in 7 climate zones of Viet Nam between different versions. It can be seen that the maximum/minimum values of the month do not change much between versions. Comparing to the period 1976 – 2005, the estimated short-wave radiation at the surface in the period 2020 – 2050 decreases in most of Viet Nam for both scenarios RCP4.5 and RCP8.5. In contrast, the Central Highlands region shows an increase in short-wave radiation.

Keywords: surface solar irradiation, satellite data, RCA4 regional climate model, solar radiation projection.

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DEVELOPING TROPICAL CYCLONE RISK WARNING SYSTEM FOR NORTH CENTRAL VIET NAM

Nguyen Xuan Hien⁽¹⁾, Nguyen Thi Thanh⁽²⁾, Ngo Thi Thuy⁽²⁾, Du Duc Tien⁽³⁾

⁽¹⁾Centre for Oceanography, Viet Nam Administration of Sea and Islands

⁽²⁾Viet Nam Institute of Meteorology Hydrology and Climate change

⁽³⁾National Centre for Hydro-Meteorological Forecasting

Received: 10 September 2021; Accepted: 30 September 2021

Abstract: Viet Nam is one of the most impacted countries by climate natural disasters especially tropical cyclone and tropical depression. Under climate change context, the natural disasters in prone areas have becoming more extreme. With the supporting of advance technology, warning systems are considered as effective measures to prevent and mitigate damages of natural disasters, in particular, tropical cyclone and tropical depression. Locating in the middle of Viet Nam and Gulf of Tonkin, the North Central region is directly affected by one to two tropical cyclones every year, one of the most tropical cyclone – impacted regions in Viet Nam. Developing an effective tropical cyclone risk warning system would be helpful to protect local people in tropical cyclone seasons. This paper proposes a methodology to assess tropical cyclone risk and introduce a practical risk warning system to apply to local hydrometeorological stations.

Keywords: tropical cyclone, risk assessment, warning system, North Central region.

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ASSESSING CLIMATE CHANGE RISK AND VULNERABILITY FOR AGRICULTURAL SECTOR IN HOA BINH PROVINCE

Le Ngoc Cau, Pham Van Sy, Ngo Thi Van Anh,
Le Van Quy, Mai Trong Hoang

Viet Nam Institute of Meteorology, Hydrology and Climate change

Received: 02 August 2021; Accepted: 24 August 2021

Abstract: Hoa Binh is the Northern mountainous province of Viet Nam, with the economy still depends on agriculture. Hoa Binh province in general and the province’s agricultural sector in particular have been affected by climate change. Under the climate change scenario, 2016, temperature and precipitation are increasing. This will put more pressure on the province’s agricultural sector. This study, using climate change scenario information and documents and local data, assesses the vulnerability and risks of the provincial agricultural sector to climate change to 2030. The results show that some poor mountainous districts, dependent on agriculture, have high sensitivity and high risk, such as Luong Son, Lac Son, and Kimboi district. While Hoa Binh city has low vulnerability and low level of risk because of its small area of agricultural land, small proportion of agriculture in the economy, and high adaptability. In addition, the study also proposes some major solutions on planning, technology, capacity building and economy to minimize the impacts of climate change on districts with high vulnerability and risk.

Keywords: Hoa Binh province, climate change, vulnerability, risk.

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REVIEW OF ASSESSMENT OF AGRICULTURAL METEOROLOGY IN VIET NAM CROPS 2020

Doan Thi The⁽¹⁾, Duong Hai Yen⁽¹⁾, Nguyen Van Son⁽¹⁾, Le Thi Thu(2), Nguyen Hong Son⁽¹⁾, Le Thi Thu Ha⁽¹⁾

⁽¹⁾Viet Nam Institute of Meteorology, Hydrology and Climate change

⁽²⁾Tokyo University, Japan

Received: 12 September 2021; Accepted: 29 September 2021

Abstract: Assessment of the agricultural meteorology has a critical role in agriculture production, especially in Viet Nam, where the agricultural products play a majority part in its economy. In addition to that, more frequent and intense changes in climate patterns as a result of the global warming have been recently increasing. This study therefore attempts to provide an assessment as an input for sustainable solutions to cultivation, improvement and protection of climate resources that facilitate the crop production.

The climatic impacts on each cropping pattern vary by the growth cycles of different crops. In this study, the authors generally review agricultural meteorology in Viet Nam by applying the comprehensive methodology of the seasonal characteristics of climate factors, based on the meteorological and statistical data of the General Department of Meteorology and Hydrology of Viet Nam (MONRE), in order to determine the changes and characteristics. The characteristics of climate factors according to each season throughout the territory of Viet Nam in 2020, are the basis for assessing the agro-climate for the next production crops.

Keywords: Agricultural meteorology, Viet Nam crops 2020, crops season, climate factors.

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CHANGES IN AIR QUALITY DURING COVID-19 SOCIAL DISTANCING IN HA NOI CITY

Ngo Thi Thuy(1), Tran Van Tra(2), Cung Hong Viet(1), Nguyen Đinh Hoang(1)

(1)Viet Nam Institute of Meteorology Hydrology and Climate Change

(2)Water Resources Institute

Received: 15 July 2021; Accepted: 11 August 2021

Abstract: The COVID-19 pandemic has changed people’s lives in many ways. Under the impact of COVID-19, the economy and society face challenges to recover. To control the spread of the COVID-19 epidemic, Viet Nam and countries around the world have restricted unnecessary travelling and transportations. The regulations on social distancing have significantly changed people’s habits, activities, living and working styles. Many studies have shown that social distancing has significantly changed air quality. This study was conducted to assess the change of air quality in Ha Noi during the social distancing period. The evaluation is built based on measurements at air monitoring stations in the period before and after social distancing in 2021. The results show a significant improvement of air quality compared to its situation before social distancing at most of the air monitoring stations. The average daily VN_AQI index at Nguyen Van Cu station (Long Bien district), Kim Lien (Dong Da district), Tan Mai (Hoang Mai district) and Tay Mo (Nam Tu Liem district) and Minh Khai (Bac Tu Liem district) in the first 8 months of 2021 dropped from 97 (near unhealthy grade for sensitive groups) to 52 (near good) in averaged. The concentration of other pollutants (PM₁₀, PM2.5,) at other stations also show a significant decrease compared to the previous time.

Keywords: Air quality, monitoring stations, COVID-19, social distancing.