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Abstract

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Climate change intensified rainfall extremes in central Vietnam: A case study of Da Nang city

Tran Dinh Hoa
Vietnam Academy for Water Resources

Do Hoai Nam,
Tran Phuong Anh,
Nguyen Thi Thu Thao,
Nguyen Thuy Tien
Center for Training and International Cooperation
Vietnam Academy for Water Resources

Nguyen Vinh Long
Da Nang Flood Management and Operation Center

Climate change has intensified rainfall extremes. It was well demonstrated during the invasion of Storm Son Ca over Central Vietnam in mid-October 2022. This paper presents the analysis of rainfall extremes in Da Nang City based on climatological observation in the present climate (1983-2022). Conventional trend and frequency analyses were employed to detect the pattern of changes. Results show that rainfall extremes tend to be increasing over the entire period, but they have been further intensified in the last decades in line with the simulation by climate models. These research results are good references to support water engineers and policy-makers in urban planning and development for the promotion of climate resilient infrastructure.

Keywords: Climate Change, Rainfall Extreme, Frequency, Da Nang

7

Water use efficiency in irrigation systems of Vietnam

Nguyen Tung Phong
Vietnam Academy for Water Resources

Vu Hai Nam,
Tran Minh Chinh
Center for Training and International Cooperation
Vietnam Academy for Water Resources

Nguyen Van Kien,
Nguyen Xuan Thinh
Center for Participatory Irrigation Management
Vietnam Academy for Water Resources

Water use efficiency in irrigation system is mainly determined based on irrigation efficiency and water productivity. According to the World Bank, water productivity in Vietnam attains at $2.57/m3, approximately one-tenth of the global average of $19.42/m3. The agricultural sector consumes over 80% of the total water demand, however, its contribution to the national gross domestic product is merely 13.96%. Therefore, improved water use efficiency in the agriculture sector will increase the value of water to the economy. This paper addresses water use efficiency in different irrigation schemes as well as evaluates the aspects that affects the water use efficiency. Results from this research are considered fundamental inputs for proposing solutions to promote the water use efficiency in Vietnam.

Keywords: Water Use Efficiency, Irrigation Efficiency, Water Productivity.

16

Landslide hazard mapping using ensemble machine learning algorithm in Ba Be lake basin

Le Van Thin,
Dao Anh Tuan,
Nguyen Dang Giap
Key Laboratory of River and Coastal Engineering
Vietnam Academy for Water Resources

Nguyen Thi Thuy Quynh
Academy of Finance

The paper presents landslide hazard mapping for Ba Be lake basin using four machine learning models namely: Logistic Regression (LR), Random Forest (RF), Gradient Boosting (GBC) and Xgboost (XGB). Based on field surveys, literature review and available data, ten indicators were used to derive the landslide hazard, including: slope, soil, plan curvature, normalized difference vegetation index (NDVI), topography, geomorphons, distance from roads, distance from rivers, density of streams and rainfall accumulation. These indicators were arranged in grid cells. The Receiver Operating Curves (ROC) and Area Under Curve (AUC) were used to validate the modes. The results of the analysis showed that the RF and GBC models had the highest predictive ability (AUC = 0.88), followed by the XGB models with AUC = 0.86 and the last one is LR with AUC = 0.78. The results could be useful for planners in general land use planning and management.

Keywords: Landslide, hazard mapping, machine learning

28

Climate change and impacts on sustainable socio-economic development in the coastal area of Ca Mau province

Pham Chi Trung,
Nguyen Duc Anh,
Le Quang Thanh,
Nguyen Linh Giang,
Nguyen Tien Phu,
Truong Thi Lan Anh
Center for Training and International Cooperation
Vietnam Academy for Water Resources

The Mekong Delta has seven coastal provinces, including Tien Giang, Ben Tre, Tra Vinh, Soc Trang, Bac Lieu, Ca Mau and Kien Giang. Typically, Ca Mau province has a coastline of 254 km along both the East and West sea. In the recent years, the province has been severely influenced by climate change. Nearly 10,000 ha of land and coastal forests, infrastructure and properties of local people have been eroded and seriously damaged. Production activities are vulnerable to sea level rise and other hydro-meteorological hazards. The life of coastal communities mainly depends on agricultural production. Main incomes are from rice, forestry, aquaculture, and fishing. This paper demonstrates a situational analysis on how climate change and natural disasters affect the livelihoods of the coastal communities in Ca Mau province and a case study is conducted for Phu Tan district. Study results are considered valuable inputs to propose urgent measures for sustainable socio-economic development in the province, adapting to climate change in the future.

Keyword: Risk, climate change, livelihood, coastal community, Ca Mau province

43

Research and propose a model of aforestation combining medicinal plants suitable for the natural and social conditions of Ba Be district, Bac Kan province

Duong Thi Kim Thu,
Nguyen Gia Vuong,
Hoang Thi Na
Institute for Water and Environment
Vietnam Academy for Water Resources

Tran Manh Truong
Vietnam Academy for Water Resources

Nguyen Thi Phong
Center of Policy and Technology for Water Resources Directorate of Water Resources

Ha Thi Quyen
University of Engineering and Technology
Vietnam National University, Hanoi

Nguyen Huong Quynh
Hanoi University of Pharmacy

The agro-forestry system is a farming model that brings many social and economic benefits and has been implemented effectively in many forested areas of Vietnam. Bac Kan province (including Ba Be district) has a lot of potential for developing this farming system because of having the largest forested cover in Vietnam and favorable natural conditions for cultivating of many types of precious medicinal plant. The results of this investigation about models of afforestation combining medicinal plants in Bac Kan as well as in Ba Be district showed that many forestry lands have not been exploited effectively. Areas growing medicinal herbs are still small; this does not commensurate with the development potential of local and have not yet brought the maximum benefits of the agro-forestry system. On the basis of actual investigation, the current research proposed a model of growing medicinal plant (Camellia chrysantha) combination with afforestation (Tram tree and De van tree) in Ba Be district. These plants have been suitable for farming practices in mountainous regions and bring more incomes for the local people

52

Safe water supply for pepper community in Dak Nong province in the context of climate change

Nguyen Thi Nguyet
Institute for Water and Environment
Vietnam Academy for Water Resources

Nguyen Thi Yen
CARE International in Vietnam

Dak Nong is one of the provinces with a large pepper growing area of ​​the Central Highlands of Viet Nam where the pepper is considered as a major crop. The sources of water for irrigation are mainly from groundwater extraction and partly from surface water in the ponds, lakes, rivers and streams. However, these water sources are exposure to potential unsustainable factors due to water scarcity, water pollution, and inefficient operation of irrigation schemes. This paper introduces research results on safe water supply for pepper producing communities in the context of climate change in Dak Nong province considering gender role in water supply in order to make recommendations to relevant agencies to ensure safe water supply in Dak Nong in particular and the Central Highlands in general, contributing to the achievement of the sustainable development goals in Vietnam.

Keywords: Safe water supply, climate change, gender, pepper

65

Some research results using the cement, fly ash, ground blast furnace slag and magnesium oxide to improve the mechanical characteristics of the dredging mud in Ca Mau province

Ngo Anh Quan,
Do Viet Thang,
Nguyen Tien Trung,
Tran Chi Thanh
Hydraulic Construction Institute
Vietnam Academy for Water Resources

Tran Van Quan
University of Transport Technology

The article presents a study of stabilized dredged mud in brackish water in Ca Mau province. A method using a mixture of cement, finely crushed blast furnace slag, fly ash and magnesium oxide to improve the mechanical and physical properties of the dredged mud material. The dredged mud is used to replace sand leveling materials, embankment structures surrounding irrigation works. The results also show that using magnesium oxide in different proportions in the mixture of cement, finely crushed blast furnace slag and fly ash significantly improves the mechanical and mechanical properties of the hardened sludge, especially the compressive strength. This is a useful solution to reuse the dredged mud besides other solutions being used.

Keywords: Cement; Ground blast furnace slag; Fly ash; Magnesium oxide; Hardened mud soil.

73

Prediction of pile capacity using artificial neural network with two hidden

Nguyen Quang Hung
Thuyloi University

Giap Van Loi,
Nguyen Huu Nam,
Tran Van Quan
University of Transport Technology

The bearing capacity of the pile is an important factor in the design of the pile foundation. Determining the bearing capacity of piles through in situ load testing is costly and time consuming. The purpose of this study is to show the applicability of artificial neural network (ANN) to predict the axial load capacity of piles. The data set used to build and verify the ANN simulation tool includes 100 data of test results of pile load testing in Dong Van industrial zone - Ha Nam. After conducting trial and error, the structure of the selected ANN includes 10 input parameters, two hidden layers with the number of neurons in the two layers of 12 and 10 neurons, respectively. Programmed and run in the Python platform, the authors use the ANN model to predict the axial load capacity of the pile. The results show that ANN has good potential to be used as a pile bearing capacity prediction tool to help design engineers predict pile load capacity for minimizing the time experimental and expensive.

Keywords: Artificial Intelligence (AI), Artificial Neural Network (ANN), bearing capacity; pile foundation

81

A model for simulation of acid water in canals and linkage to acid sulphate soil model

Nguyen Tat Dac
Ho Chi Minh City Association for Science
 and Engineering of Water Resources

Tran Ky
Ho Chi Minh City University of Natural Resources and Environment

It is given in this paper an attempt to consider the problem of canal acid water in linkage to  the ground acid  water  with the presence of the alunite and jurbanite  in the soil. 1D model is applied for canals while 2D depth-average model is used to simulate the processes occurred in the soil. Data of 1995 collected at Tan Thanh farm, in the Plain of Reeds of the Mekong Delta in Vietnam, are used as a case study.

Keywords: Acid water in soil and canal, modeling, spreading of acid water

89

Calculation of flood discharge and storage capacity by climate change scenarios in Rach Bau Ha, Tuy Hoa city using the Mike model

Vu Thu Hien,
Dao Duc Bang,
Tran Vu Long,
Duong Thi Thanh Thuy,
Kieu Thi Van Anh
Hanoi University of Mining and Geology

Dinh Anh Tuan,
Nguyen Thi Binh Minh
Power Engineering Consulting Joint Stock Company 1

Pham Minh Hoa
Institute of Energy

The climate and topography characteristics of Tuy Hoa city, Phu Yen province are quite complicated and being affected by most types of natural disasters, in which storms and floods frequently occur in the downstream of rivers. Huge amount of water from upstream in combination with local downpour have caused numerous flash floods. Rach Bau Ha, the main flood-discharge of the city, is a low-lying area and often being submerged during rainstorms. This article aims to apply MIKE model in forecasting the flood discharge and storage capacity of Rach Bau Ha response to climate change scenarios and proposing appropriate alternatives for the purpose of minimizing flood in the research area. Collected hydro-meteorological, topographical and geological data, previous research results, synthesis, analysis and calculation of designed hydro-meteorological characteristics will be used as input for the MIKE model. The results show that the cross-sectional area and lake area of Rach Bau Ha according to a scenario (lake surface area F = 12.50 ha) completely ensure the flood discharge and storage of Rach Bau Ha, without much increase of the maximum water level and inundation duration, ensure that the water levels of the canal shall not affect inhabitants and infrastructure of the vicinity.

Keywords: MIKE model, flood discharge, climate change.

96

Studying into solutions for flood and inundation control in bui basin and its vicinity

Le Viet Son,
Nguyen Van Tuan,
Bui Tuan Hai,
Nguyen Duy Quang,
Bui The Van
Institute of Water Resources Planning

Bui river is a tributary of the Day river that flows in the territory of Hanoi city and Hoa Binh province. The downstream part of the Bui river, located in the districts of Chuong My and Quoc Oai of Hanoi, is where heavy rains often occur, causing serious impacts on people, especially the floods in 2008, 2017, and 2018. This study used the MIKE hydraulic model, ArcGIS software, and Google Earth to build inundation maps and evaluate effectiveness of flood defense solutions. Options have been proposed to prevent and control flooding and inundation for the Bui river basin and its vicinity, including Restoration of the Tich, Bui and Day rivers; Upgrading and building new reservoirs; Building channels to isolate mountain floods; Upgrading and building new dikes; Upgrading and building new drainage pumping stations, detention basins, and relocation in vulnerable areas. In addition, the study also estimated the number of households to be relocated and the required costs to implement these solutions.

Keywords: Bui basin and its vicinity, Flood prevention solutions, MIKE model

106

Simulation methododlogy of sediment imbalance in calculation and forecast morphological changes at downstream of Thai Binh river

Nguyen Manh Linh,
Nguyen Ngoc Dang,
Nguyen Ngoc Quynh
Key Laboratory of River and Coastal Engineering

Hydraulic regime and morphology of a river section is in equilibrium if there is no human impact. However, under the human action impacts, the hydraulic regime and morphology of a river section have changed. The sediment imbalance in the river is usually caused by two factors, including the decline of sediment discharge from upstream when reservoirs were built and the sand mining. In particular, the sand mining process has a significant influence on the internal morphological changes as well as the river morphology at downstream section. In this article, a method of simulating the sand mining process on a mathematical model is presented and some results of morphological river prediction for the Thai Binh river are also shown in case of existing sand mining activities at the river upstream parts.

Keywords: Simulation methods, sediment imbalance, sand mining, morphology, Thai Binh river