JOURNAL OF CLIMATE CHANGE SCIENCE No.3-2017

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UNESCO’S INTERNATIONAL HYDROLOGICAL PROGRAMME
AND CONTRIBUTION OF VIET NAM TO THE PROGRAMME

Tran Thuc
Chairman of Viet Nam National Committee for the UNESCO-IHP

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HYDROLOGY AND WATER RESOURCES PHD PROGRAM AT VIET NAM INSTITUTE OF METEOROLOGY, HYDROLOGY AND CLIMATE CHANGE

Nguyen Van Thang
Director General of Viet Nam Institute of Meteorology, Hydrology and Climate Change

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GROUNDWATER RESOURCES IN VIET NAM: POTENTIAL AND CHALLENGES

Pham Quy Nhan⁽¹⁾, Tae Yoon Park^(2)
(1)Ha Noi University of Natural Resources and Environment, Viet Nam
⁽²⁾Yonsei University, R.P. Korea

Abstract: Groundwater is a precious resource in Viet Nam, especially in areas with a lack of other available water resources. Intensive investigation of groundwater resources has been undertaken over the past five decades and identified 26 water-bearing units in 7 regions. Groundwater resources are represented by potential reserves, classified by hydrogeological regions. The total groundwater potential reserves in the country reach nearly 133 million m³/day, which equals 48.5 billion m³/year. Groundwater resources are exploited for many purposes such as drinking, manufacturing, irrigating, aquacultural cultivation in Red river/aquacultural cultivation plain, in Southern plain and in the Central Highlands. During groundwater extraction, some challenges have been arise such as groundwater contamination of Nitrogen, Arsenic etc., Land subsidence as a result of overuse for example in Ha Noi, Ho Chi Minh City, Ca Mau peninsular and groundwater salinization in coastal aquifers where there is about 3,260 km coastal line with developing areas and impacts of climate change and sea level rise.

Keywords: groundwater resource, potential, reserve, contamination, climate change.

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WATER RESOURCE SECURITY
IN THE CONTEXT OF CLIMATE CHANGE IN VIET NAM

Ta Dinh Thi, Ta Van Trung, Bui Duc Hieu
Ministry of Natural Resources and Environment

Abstract: Nowadays, there is an alarming fact about the shortage of national water resource which is not known by the public. According to statistics, with the population of about 95 million, on average each Vietnamese can receive only 3,200 m³/person/year from the internal water source. On the other hand, the assessment criteria of the International Association of Water Resource indicates that if a country cannot reach 4,000 m³/person/year, it is regarded as a water shortage country.

Viet Nam is one of the countries that are most severely affected by climate change. With the global impact of climate change, many issues about water resources in Viet Nam, which used to be a potential threat, have now become a reality.

Keywords: climate change, water resource security, national security.

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ASSESSMENT OF DROUGHT CONDITIONS IN THE RED RIVER DELTA

Nguyen Van Thang, Mai Van Khiem, Truong Thi Thanh Thuy,
Ha Truong Minh, Pham Thi Hai Yen, Nguyen Dang Mau
Viet Nam Institute of Meteorology, Hydrology and Climate Change

Abstract: The standardized precipitation index (SPI) is used to analyse drought conditions in the past 54 years (1961-2014) and to assess possible drought conditions in the 21^st century under the RCP4.5 and RCP8.5 scenarios for the Red River Delta. The results show that with different timescales, the drought conditions of the Red River Delta tended to increase during the period of 1961-2014. Compared to the baseline period (1986-2005), the number of drought spells are likely to decrease in the future under both scenarios. The projected drought changes of the 1-, 3-month timescales are smaller than those of the 6-, 12-month timescales. Remarkably, the drought intensity of 1-, 3-month timescales is likely to be more extreme by the end-21^st century under both RCP4.5 and RCP8.5.

Keywords: SPI, drought, Red River Delta.

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MULTI RISK: A NEW APPROACH FOR DISASTER RISK MANAGEMENT

Huynh Thi Lan Huong, Tran Thanh Thuy
Viet Nam Institute of Meteorology, Hydrology and Climate Change

Abstract: Natural disaster risk assessment is a critical part of a risk management system. Single risk assessment which addresses different natural hazards and their associated risks separately is a popular one used in risk management in Viet Nam. Single risk assessment deals with only one source of disaster ignoring all the possible risk interactions. A multi-risk approach therefore has currently been developed and tested by a number of scholars. This paper introduces a multi-hazard and multi-risk assessment methodology adopted from literature review, which combines single risk assessment and a three-level risk assessment. Multi-risk approaches takes into account the interactions and relations among hazards and among vulnerabilities. It can bring benefits but also challenges to both end-users and scientists.

Keywords: Multi-risk, Multi-hazard, Disaster risk reduction.

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IMPACT OF CLIMATE CHANGE ON INTENSITY-DURATION-FREQUENCY CURVES
IN HO CHI MINH CITY

Mai Van Khiem, Ha Truong Minh, Luu Nhat Linh
Viet Nam Institute of Meteorology, Hydrology and Climate Change

Abstract: Viet Nam is considered as one of the countries most affected by climate change. The magnitude and frequency of extreme events (such as high-intensity rainfall, flooding, severe droughts) are expected to increase in future due to climate change. The evaluation of the possible climate change influence on extreme precipitation is very interesting in megacities city due to the usual and characteristic high intensities of its rainfall pattern. This study aims at developing Intensity-Duration-Frequency (IDF) curves for Ho Chi Minh City, Viet Nam for the present as well as future climatic scenarios. The rainfall projections for future periods based on ensemble regional climate modeling approach are used to calculate IDF curves and their plausible changes in the middle of the 21^st century (2050s), and at the end of 21^st century (2090s). The results suggest that intensities of extreme rainfall events versus various durations with different return periods are all likely to increase over time in comparison with baseline period (1986-2005): [11, 60]% in 2050s, and [15, 69]% in 2090s under most likely case; and [38, 141]% in 2050s, and [28, 105]% in 2090s under high impact case. Such a consistent increase in the exceedance values of rainfall intensity of extreme events, implying that intense rainfall events are likely to occur more frequently in the future under climate change. The results presented in this paper are important for the design and construction of different hydrological structures in water management in Ho Chi Minh City.

Keywords: IDF curve projection, climate change, Ho Chi Minh City.

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THE USE OF COMBINED TOP-DOWN AND BOTTOM-UP CLIMATE CHANGE IMPACT
ASSESSMENT IN HYDROLOGICAL SYSTEMS

Tran Van Tra⁽¹⁾, Nguyen Xuan Thinh^(2)
(1)Viet Nam Institute of Meteorology, Hydrology and Climate Change;
Doctoral Student, TU Dortmund University
⁽²⁾University Professor, Faculty of Spatial Planning, TU Dortmund University

Abstract: Climate change impact assessment in hydrological systems in the past is of a top-down nature. In particular, future climate states are predicted using scenarios and climate models. Although the approach could provide optimal adaptation measures for the intended future, its applications may be increasingly limited as there are large uncertainties. The top-down approach provide too much of the wrong information for policy makers. Bottom-up approaches in climate change impact assessment have also been used in the past as an alternative. The strength of the approach lies in its ability to provide robust adaptation options since the focus is on the vulnerability space, not the prediction of future climate space. Nonetheless, without the information from a top-down approach, the bottom-up approach would lack a basis for selecting the range of climate states to test the vulnerability of the system. The vulnerability exploration would be imprecise and unbounded, and of limited decision-making value. For this reason, a more recent development of a combined top-down and bottom-up approach has been advocated. The combined top-down and bottom-up approach uses top-down information such as climate model outputs while still focuses on the vulnerability space of the system. Through the approach, relevant climate conditions that poses threat to the system could be identified. This paper provides a summary of the top-down and bottom-up approach and introduces more recent development in the combined top-down and bottom-up climate change impact assessment approach.

Keywords: climate change, impact assessment, top-down, bottom-up, combined.

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FLASH FLOOD EVENTS IN MU CANG CHAI AND MUONG LA ON AUGUST 3, 2017 – CAUSES AND PREVENTION MEASURES

Hoang Minh Tuyen, Luong Huu Dung, Le Tuan Nghia
Viet Nam Institute of Meteorology, Hydrology and Climate Change

Abstract: In the early morning of August 3, 2017, the two flash flood events occurred in Kim Noi and Nam Pam watersheds in Mu Cang Chai and Muong La districts, respectively. The analysis of rainfall data and field surveys shows that the severe events related to extreme local rainfall (>100 mm in 6 hours) accompanying with steep topography (>40% slope) and low vegetation cover. Therefore, flood is formed fast with short concentration time. Furthermore, narrowing cross-sections on stream by 25-80% cause flow clog and temporarily generate small dams. When the amount of floodwater exceeded the capacity of these small dams, water from dam break generates flash flood and sweep everything in downstream. The paper aims to provide short- and long-term measures to prevent and reduce flash flood damages.

Keywords: flash flood, flow clogging, flash flood causes.

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CALCULATING AND BUILDING INUNDATION MAPS CORRESPONDING
TO FLOOD FREQUENCIES IN GIANH RIVER BASIN

Vu Van Thang⁽¹⁾, Tran Dinh Trong⁽¹⁾, Phung Duc Chinh⁽¹⁾, Jerome Faucet^(2)
(1)Viet Nam Institute of Meteorology, Hydrology and Climate change
⁽²⁾German Red Cross in Viet Nam

Abstract: Gianh is the largest river basin in Quang Binh province with the flood season lasts about four months, from August to November. The number of floods and their magnitude vary widely by the years and from upstream to downstream of the river. This article presents a set of inundation maps corresponding to flood frequencies of 1%, 2%, 5%, 10%, 20% in the Gianh river basin. The results show that flooding happens more frequent in both river banks and downstream areas of Gianh river basin. As Gianh River runs mainly along Tuyen Hoa District, the communes along the river banks of the district are seriously affected by floods. The article also presents a calculated inundation area and inundation rate of the area of districts in the Gianh river basin, corresponding to flood frequencies of 1%, 2%, 5%, 10%, 20%.
Keywords: Flood, flood frequency, inundation maps, inundation area.

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CLIMATE CHANGE VULNERABILITY ASSESSMENT
FOR AGRICULTURE SECTOR IN TUYEN QUANG PROVINCE

Nguyen Xuan Hien⁽¹⁾, Pham Tien Đat⁽¹⁾, Doan Thi Thu Ha^{(1, 2)},
Nguyen Thi Phuong⁽¹⁾, Dang Linh Chi^(1)
(1)Viet Nam Institute of Meteorology Hydrology and Climate Change
⁽²⁾Sejong University, Korea

Abstract: Climate Change (CC) has significant impacts to socio-economic development in Viet Nam and agricultural is one of the most affected sectors. The most impacted provinces are those where economic activities are highly dependent on ecosystem services such as Tuyen Quang. This study applies vulnerability assessment framework proposed by Allison et al (2009) and the unequal weights methodology developed by Iyengar and Sudarshan (1982) to assess climate change vulnerability for agriculture sector in Tuyen Quang province. The results show that, in the 21^st century, Son Duong and Na Hang districts are highly vulnerable to climate change while Tuyen Quang city is less vulnerable than other districts. This study presents useful results to help local governments and communities to respond to climate change impacts in the future.

Keywords: climate change, agricultural, impact, vulnerability assessment.

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POLICIES TO PROMOTE SUSTAINABE WATER RESOUCES
MANAGEMENT IN VIET NAM – AN IN-DEPTH ANALYSIS

Le Ngoc Cau
Viet Nam Institute of Meteorology, Hydrology and Climate change

Abstract: The importance of water for sustaining country’s growth while improving public health and the environment cannot be understated. While Viet Nam uses only about 10% of the volume of available water on a national basis, regional and especially seasonal shortages are major limiting factors for industrial and agricultural development. Vulnerable ecosystems such as the Mekong River Delta and Red River Delta are seeing lower flows, causing shortages of water supply and saline water intrusion, disrupting fisheries and impacting the quality of irrigation supplies. The delicate balance of upland ecosystems and crops is being affected to a greater extent by more severe weather patterns and flooding. These factors are clearly unfavorable for rural development and poverty reduction. The Government of Viet Nam (GoV) is committed to address these complex water sector issues. A series of water resources management related legal policies and documents have been promulgated and implemented in the past decade. This paper presents an overview of legal frameworks and policies promulgated and implemented by GoV to promote sustainable water resources management in Viet Nam. An in-depth analysis of the water resources management related legal framework and policies was conducted to get an insight into the coherence of the policies and impacts brought by the implementation of the promulgated policies.

Keywords: sustainable water resources management, water saving and efficiency, climate change resilience, Viet Nam.

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APPLICATION OF AIRLIFT MEMBRANE BIOREACTOR
FOR SLAUGHTERHOUSE WASTEWATER TREATMENT:
20 M³/DAY PILOT STUDY IN HA NOI, VIET NAM

Do Tien Anh⁽¹⁾, Huynh Thi Lan Huong⁽¹⁾, Pham Hai Bang^(2)
(1)Viet Nam Institute of Meteorology, Hydrology and Climate Change
⁽²⁾Ministry of Natural Resources and Environment

Abstract: Untreated wastewater from slaughterhouses has been contributing to the contamination of Day River due to its high concentration of COD, BOD, total nitrate (TN) and total phosphate (TP). Centralized wastewater treatment is not a good option at present due to lack of wastewater conveyance infrastructure and finance. On-site wastewater treatment has been emerging a better choice. This study evaluates an onsite wastewater treatment system using an airlift membrane bioreactor for a slaughterhouse in a suburb of Ha Noi. The system was designed to treat 20 m³/day slaughterhouse wastewater. Wastewater from the Slaughterhouse contains 1060 ± 458 mg/L COD, 1060 ± 458 mg/L BOD and 451 ± 133 mg/L TN. Anaerobic and anoxic tanks were operated at the mixed liquor volatile suspended solid (MLVSS) of 1,500 mg/L. Cross-flow velocity, airlift flow rate and the transmembrane pressure (TMP) were maintained at 2 bar. The removal efficiencies of COD, TN were 89.1±4% and 85±8.7%, respectively. The results proved that AL-MBR could work well at pilot scale and be promising for upscaling along Nhue – Day River in future.

Keywords: wastewater, slaughterhouse, Nhue – Day River, membrane, airlift.

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