Application geographic information system in assessing flash flood, na ri district, bac kan province

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY NGUYEN NAM HAI APPLICATION GEOGRAPHIC INFORMATION SYSTEM IN ASSESSING FLASH FLOOD, NA RI DISTRICT, BAC KAN PROVINCE BACHELOR THESIS Study[.]

THAI NGUYEN UNIVERSITY

UNIVERSITY OF AGRICULTURAL AND FORESTRY

NGUYEN NAM HAI

APPLICATION GEOGRAPHIC INFORMATION SYSTEM IN ASSESSING FLASH FLOOD, NA RI DISTRICT, BAC KAN PROVINCE

BACHELOR THESIS

Study Mode: Full-time Major : Environmental Science and Management Faculty : Advanced Education Program

Batch : 2015 - 2019

Thai Nguyen, 09/2019

Thai Nguyen University of Agriculture and Forestry

Degree Program Bachelor of Environmental Science and Management

Student name Nguyen Nam Hai

Student ID DTN 11554290008

Thesis title Application geographic information system in assessing flash

flood, Na Ri district, Bac Kan provinceSupervisor Dr Nguyen Thanh Hai

Ri district

Na Ri is a hilly area with many rivers and soil being easily washed away due

to forest exploitation activities or forest felling as a residence, floods, and landslides have continued in recent years

Therefore, we need to develop maps that can warn the locals to help people pay attention to vulnerable areas and take precautions before the rainy season

Keywords Flash flood, Na Ridistrict, Geographic Information

System (GIS) Number of pages 39

Date of submission 07/09/2019

ACKNOWLEDGEMENT

I would like to express my gratitude to my supervisor Dr Nguyen Thanh

Hai, MsC Nguyen Van Hieu, for his invaluable useful comments, remarks,

encouragement and engagement through the learning process of this graduated

thesis I sincerely thank the lecturers who enthusiastically imparted useful

knowledge on flooding during the University program to all class attendants

I also thank the support of Thai Nguyen University of Agriculture and

Forestry, the coordinators and program managers for their support and assistance

Finally, I would like to express our gratitude to the family, relatives and

friends who have helped me during the internship

Thank you very much!

Nguyen Nam Hai

TABLE OF CONTENT

ACKNOWLEDGEMENT ii

TABLE OF CONTENT iii

LIST OF FIGURES 1

LIST OF TABLES 2

PART I INTRODUCTION 3

1.1 Research rationale 3

1.2 Research’s objectives 4

1.3 Research questions and hypotheses 4

1.4 Limitations 4

PART II LITERATURE REVIEW 5

2.1 Flash floods 5

2.1.1 Definition 5

2.1.2 Classify 5

2.1.3 Factors causing flash floods 5

2.1.4 Basic characteristics of flash floods 7

2.1.5 The basic criteria for determining flash floods 8

2.2 Situation of flood in Vietnam and in the world 9

2.2.1 Situation of flood in the world 9

2.2.2 Situation of flood in Vietnam 11

2.3 Geographic Information System 13

2.3.1 Definition 13

2.3.2 Main factor in GIS 13

2.3.3 Function of GIS 13

2.3.4 Ability to apply GIS in flash flood research and analysis 14

2.4 Na Ri district 15

2.4.1 Natural features 15

2.4.2 Topographic 16

2.4.3 Hydrological 17

PART III METHODS 20

3.1 Material 20

3.2 Methods 20

3.2.1 Most valuable of rainfall in a day 20

3.2.2 Map of surface slope 22

3.2.3 Map of land use 22

3.2.4 Map of distance on both sides of the river 23

3.2.5 Map of soil 23

3.3 Mapping process 24

PART IV RESULTS 27

4.1 Overlay the map layer 27

4.2 Commenting map 34

4.3 Proposing measures to prevent floods 34

PART V DISCUSSION AND CONCLUSION 36

5.1 Discussion 36

5.2 Conclusion 36

REFERENCE 38

LIST OF FIGURES

Figure 2.1: Map of Na Ri district 16

Figure 3.1: Steps of mapping process 25

Figure 4.1: Raster calculator tool in GIS application 27

Figure 4.2: Map of Rainfall in Na Ri district 28

Figure 4.3: Map of slope in Na Ri district 29

Figure 4.4: Map of land use in Na Ri district 30

Figure 4.5: Map of distain on both sides of rivers in Na Ri district 31

Figure 4.6: Level of soil in Na Ri district 32

Figure 4.7: Map of area at risk of flash flood in Na Ri district 33

LIST OF TABLES

Table 2.1 Rain threshold make flash flood 6

Table 3.1: Classify and give points for the factor 26

PART I INTRODUCTION 1.1 Research rationale

Flash floods is one of the natural disasters that happen unexpectedly,

quickly and complicatedly, with great devastation in the mountainous areas that

bring a lot of losses in people, economy and society.Climate change will cause

unusual weather events that will accelerate floods and landslides Special, this

phenomenon often occurs in the mountainous provinces, so losing due to natural

disasters in general and flash floods in particular will increase many times

compared to the delta regions.(Younis, J and J Thielen, 2008)

Floods are formed by heavy rainfall, sweeping away everything on the

surface of the flow, with great destructive power and destroying everything

Floods are formed due to the synthesis of triggers such as topography,

geomorphology, rainfall, vegetation cover, soil structure Combined with

situation, that is increasing population and decreasing forest are due to

deforestation in which many forests are concentrated in the watershed where the

source of flash floods, from those areas to land for construction of houses, vacant

land or agricultural land potentially soil retention, poor water retention and the

construction of structures that prevent water flow

With the growing of GIS, This can be forecast the number of rainfall,

determine the actual state of coverage with data on topography, geomorphology,

land properties are aggregated and by GIS tools to predict the areas at risk of

natural disasters

From all demand and benefit, with an agreement of leader of Thai Nguyen

agriculture and forestry university, Geoinformatics research center, direct

instructions from Msc Nguyen Van Hieu, Dr Nguyen Thanh Hai, I make a

thesis: “Application geographic information system in assessing flash flood, Na

Ri district, Bac Kan province.”

1.2 Research’s objectives

- Using GIS for build map of damage of flood, rainfall, river or steam in

Na Ri district, Bac Kan city

- Assessment effect of flooding to nature and human

- Forecast, warning the cures and building prevention method

1.3 Research questions and hypotheses

- What is the overview of flooding in Na Ri district, Bac Kan city?

- How can we determine all damage from flood?

- How to use GIS application to build map?

1.4 Limitations

- Because of geographic, it is difficult to make out area which damaged by

flood

- The Limited of vehicle to go to the flood area

- There are too dangerous if we want to go to place that is flooding

PART II LITERATURE REVIEW 2.1 Flash floods

2.1.1 Definition

Flash floods are a large flood which is occurs unexpectedly and sustains

for a short time, it has fast flow and great devastation and it can take all obstacles

on the centralized flow of storage area.(Jonkman, 2005)

- Floods caused by heavy rains in the basins have been strongly affected

by human economic activities (change of cover, flow regime or basin

characteristics, )

- Flood caused by break dam or man-made lake

2.1.3 Factors causing flash floods

There are three main factors: Factors with less change, factors with slow

change and factors with fast change (Mai Thi Huyen, 2011)

Those factors interact with each other and the extent of this impact on the

type of basin to create different types of flash floods Therefore, determining the

criteria for forming flash floods is to analyze the impact of this relationship for

each specific basin

- Factors with less change: topography, geology, geomorphology, soil,

- Factors with slow change: Situation of land use, tectonic movements,

It seem to be that rain fall in the high land are always higher than delta

because flanks shield the wind and the valleys are take the humid from ocean

Rain is the decisive factor causing flash floods, usually concentrating for a few

hours with great intensity on small areas That explains why many flash floods

occur in some areas, which are uneven with floods on the big river Rain causes

flash floods that are often concentrated in an intensity of 1 hour or 2 hours;

Rain with high intensity is decisive in the formation of flash floods Heavy rain

is also the main driving force for erosion and landslide, creating a solid part of

the flash flood

Table 2.1 Rain threshold make flash flood

Nowadays, the major impacts of climate change on Na Ri include : The

impact of global warming; greenhouse gas emissions; impact of extreme weather

events; increase of natural disasters; increase flood, drought and soil degradation;

ecosystem and biodiversity are degradation

In recent years, with the global climate change, the calamity situation in

Bac Kan province has been complicated and increasingly serious year by year, it

greatly affecting the people's life, daily life and economy.According to the

statistics of natural disasters in 2017, there were 03 people died in the whole

province, 04 were injured; 877 houses were damaged; 29 schools, classrooms

and schools are affected; 966ha of crops and 109.7ha of small ponds were

damaged; 997 pets died; 172 irrigation works were damaged; over 770m3 of soil

and rock are eroded; 29 electric poles were broken; 05 works of drinking water

and environmental sanitation are damaged Total losses of crops and assets in

2017 caused by natural disasters were estimated at more than 167.7 billion VND,

3.7 times higher than 2016 In the first 4 months of 2018, natural disasters were

very complicated As of April 23, 2018, natural disasters caused an estimated

loss of over 69.6 billion dong (Bich Ngoc, 2018)(Jonkman, 2005)

2.1.4 Basic characteristics of flash floods

Unexpectedness: According to Younis and Thielen (2008) and Jonkman

(2005) the period from when it appears to the peak of the flood is usually very

short Therefore, it is often difficult to forecast and warn flash floods effectively

at the current scientific and technical level in our country

Short-term and severe devastation: flash floods usually exist in a short

time, usually ending after 10-18 hours, rarely over 1 day, large flood water

erodes, wash away huge amounts of matter Snake from the steep slopes

Therefore, the speed of water flow in flash flood is very fast, different from

normal flood, there is a very high peak, much higher than flood peak (sometimes

2 - 5 times) in the same conditions due to the mechanism of formation and

movement Thus, in order to reduce or eliminate the short-term flash flood, the

measures must aim to prolong the flood time mainly and flood down and

basically to increase the concentration of flood flow in the basin and reducing the

severity of the flood (reducing the flood peak, the frequency of flooding up and

down, the flow of the river )

Concentration: Flash flood lines are different from regular flood currents

due to the very high ratio of solid matter In the process of formation and

mobilization, the rate of solid objects in flash flooding constantly increased,

increasing the most when moving from high mountains to valleys The amount of

solids usually accounts for 3% - 10%, even over 10% in flood currents to become

a mud-rock flood In order to reduce and limit the impact of this characteristic of

the flash flood, or to prevent the risk of flash flooding, measures should be taken

to reduce erosion, slipping, sliding, reducing the amount of solid material in the

flood, taking measures solution to cut down on solid objects in flash flood,

reduce the process of sliding motion

2.1.5 The basic criteria for determining flash floods

The basic criteria for determining flash floods are:

- Time of occurrence, time of flooding up, down and the whole battle,

flash flood process

- Flood peaks and time of occurrence, average amplitude, average and

maximum flow

- The intensity of flooding up, down medium and largest

- Total quantity and material composition in flood (liquid, solid),

characteristic of physical flow

- Flood concentration time, flood transmission time, transfer capacity of

flash flood flow

- Composition of solids, grain composition, particle distribution in flash

flood flow

- The momentum of the current and the impact of the current when

encountering an obstacle

- Hydrodynamic pressure when dam breaks (irrigation dams or dams are

newly formed due to movement of flow) and temporary congestion points when

flash floods occur

- Inertial velocity when flood increases and gradually decreases depending

on flash flood structure

2.2 Situation of flood in Vietnam and in the world

2.2.1 Situation of flood in the world

Flash floods occur in most countries around the world, especially in the

mountainous and subtropical river and basin basins Flash floods occur in the

south of France, Northern Italy, and Austria

The largest areas of flash flood risk in the United States are California

state, river basins in the mountains of Saint-Gabrient

In South America, along the slopes of Anda, frequent flash floods occur

Flash floods occur in many areas in Mexico, Columbia, Ecuador, Peru, and

Chile

Flash floods also occur in African countries, in Australia, in mountainous

catchments of the Pacific, Atlantic and Indian Oceans

In Asia, flash floods occur in many parts of the HimalayaMountains in

India, Pakistan and Nepal Flash floods occur in many places in China, Thailand,

Vietnam, Indonesia, Malaysia and Japan

Many areas in China have experienced flash floods For example, a flood

of 1,605 mm in 72 hours in LinZhuang in Ha Nam province had a flash flood on

the river branches in August 1975 Typhoons and floods in 1987 killed 2,300

people, destroyed 650,000 houses, causing losses of $ 2,400 million In early July

1992 in 6 southeastern provinces, floods killed 467 people, 5,000 were injured,

poured 25,000 houses, harmed 2 million hectares of crops Total losses were

estimated at 6.9 billion yuan, including many flash flooding places

In Malaysia, urbanized areas such as Penang, Kota Baharn, Ipoh and

Johor, the risk of flash floods is increasing In November 1986, a heavy rain

caused flash floods in the Kolantan River basin, causing 14 deaths and total

losses of 11.4 million dollars

The city of Kuala Lumpur is always threatened by flash floods from the

upper Klang River The heavy rain in 1971 created a flash flood that caused an

estimated loss of US $ 14 million over 13 years to prevent flash floods for this city

In South Korea, coastal river basins are likely to have flash floods In 1987

in Chung Chang and Seoul Kuynggi, three heavy rains caused flash floods that

killed 243 people

In the Philippines, on October 3, 1981 flash floods occurred in a volcanic

basin, floodwaters followed rocky volcanic lava along the Amcon Creek River to

destroy many houses and trading centers, causing serious damage and killed 124

people, 12 people were missing The city of Manila has always been threatened

by flash floods

In Thailand, Typhoon Betty and Carry landed on August 15 and 27, 1987,

causing heavy rain causing flash floods in many river basins In 39 Northern

provinces and 5 southern provinces, Chiang Mai and Suchotnai suffered the most

damage A total of 16 people died, 8645 families were damaged and 77727 ha of

upland fields were flooded At 13:00 on September 25, 1994, at the Trakai Wang

waterfall in Nakhon Nayok Province, a flash flood occurred unnoticed,

maintaining for 20 minutes, causing 61 people to die and disappear

According to Michael Bonell (1993) flash floods are common in many

humid tropical cities, heavy rains cannot catch up Bang Kok, Kuala Lumpur and

Manila are often damaged by flash floods caused by high intensity floods in

Bang Kok cost up to US $ 50 million and flood losses in 1982 and US $ 330

million

2.2.2 Situation of flood in Vietnam

In recent years, the flash flood situation in the mountainous provinces of

Vietnam has become more and more complicated, flash floods happen

unexpectedly and quickly with devastating effects in small basins causing great

losses of people and property, and destroying environmental damage

Typical flash floods caused great losses of people and assets including:

- In 2000, the flood on July 15 in Sa Pa district, Lao Cai province caused

20 deaths, 25 injuries The flood on October 3 in Nam Coong village in Nam La

district at the end of Sin Ho district, Lai Chau province caused 39 deaths, 18

injuries

- In 2002, the flood on August 16 in Bac Quang and Xin Man districts of

Ha Giang province killed 21 people, 8 were injured The largest flash flood in

history in Huong Son, Huong Khe and Vu Quang districts of Ha Tinh province

has over 80% of communes in Huong Son, 50% of communes in Huong Khe and

Vu Quang districts in Ha Tinh province were flooded, where deep from 3.0 - 4.0

m and 83 people was dead or missing and 117 injured

- In 2004, the historic flood in 2 communes of Du Tien and Du Gia in Yen

Minh district, Ha Giang province, Ha Giang and Bao Lam district, Cao Bang

province, killed 56 people Mountain landslides in Lao Cai province have killed

and lost 48 people and 16 injured

- In 2005, landslides in Binh Lieu and Quang Ninh killed 11 people The

flash flood in Yen Bai on July 11 killed 5 people Flash floods in Nghe An on

August 12 killed 16 people The flash flood caused by the typhoon on September

28 caused 64 deaths, 17 injuries, particularly in Van Chan, Yen Bai province

died and lost 50 people

- In 2008, due to the effects of rain after the storm, it caused big floods,

flash floods, landslides in many places in the northern mountainous provinces

such as Lao Cai, Yen Bai, Son La, Lang Son, Ha Giang and Cao Bang, Quang

Ninh, Bac Giang; most of them are in Yen Bai, Lao Cai, upstream of Luc Nam

river in Bac Giang and Binh Lieu Quang Ninh Floods and flash floods in 2 flood

periods caused 246 people to die and disappear, more than 200 people were

injured, and the property damage was estimated at more than VND 3,229 billion,

of which the damage from flash floods and landslides was mainly

- In 2009, serious landslides occurred in Pac Nam commune, Bac Kan

made 13 people dead and missing, 5 injured Within 1 month from the end of

September to October, consecutive storms No 9 and No 11 landed in the Central

and Central Highlands provinces, causing serious damage to people and property,

including Quang Nam provinces , Quang Ngai, Binh Dinh, Phu Yen, Kon Tom,

Gia Lai, Dak Lak

2.3 Geographic Information System

2.3.1 Definition

A geographic information system (GIS) is a framework for gathering,

managing, and analyzing data Rooted in the science of geography, GIS can

integrate many types of data By using maps and 3D scenes it analyzes spatial

location and organizes layers of information into visualizations With this unique

capability, GIS reveals deeper insights into data, such as patterns, relationships,

and situations (Nguyen Kim Loi, 2007) (Nguyen Ngoc Quynh and Dao Van

Khuong, 2010)

2.3.2 Main factor in GIS

There are five main factors in GIS include: Human, hardware, software,

methods and databases

2.3.3 Function of GIS

GIS has four main functions: data entry, data management, geographic

data analysis and display

2.3.4 Ability to apply GIS in flash flood research and analysis

GIS software is built to create surfaces: Characteristics of surfaces need to

be studied and analyzed, such as slope, slope direction, shadow and special

objects of the surface such as valleys, hills, hydrological networks, to study

natural phenomena such as water flow research, pollution research

mathematical models can often relate to software conversions The basic

functions of the software are: the method of expressing the digital form (or

measuring data), creating surfaces, calculating surface values (Younis and

Thielen, 2008)

Multi-layer information control: understood as operating vertically

(vertical operation) with the basis of relying on the relationship between the

information layers

It allows controlling data in separate layers while checking the

relationship between different objects This control can separate the material of a

class into multiple layers with the aim of analyzing any relationship between

elements of natural phenomena In contrast, multiple layers of information of a

region can also be aggregated to create a single layer for ease of processing and

modeling

The study also made use of GIS data and functions for flood simulation

and flood risk mapping They were able to obtain the flood risk map by map

multiplication in ArcGIS environment of flood hazard and flood vulnerability

maps By overlaying vulnerability and flood values with the polygon map of the

area, Samarasinghea et al (2010) (Younis, J and J Thielen, 2008) were able to

map out zones with low, moderate and high flood risk

2.4 Na Ri district

2.4.1 Natural features

Na Ri district is a mountainous district, located in the northeast of Bac

Kan province, with a natural area of 85, 300, 00 ha, accounting for 17.54% of the

natural area of Bac Kan province, including 21 communes and 01 town with 233

villages and hamlets; located in the geographical coordinates from about 210 55

’to 220 30’ North latitude, 1050 58 ’to 106018’ East longitude

The North or Na Ri district borders Ngan Son district, the South borders

Cho Moi district and Thai Nguyen province, bordering Binh Gia and Trang Dinh

districts (Lang Son province) to the East and the last, it is border with Bach

Thong district to the West.(Luong Thanh Loc, 2010)

Yen Lac town is the economic - political - cultural center of the district, 72

km from Bac Kan town and 130 km from Thai Nguyen city along National Road

3B and National Highway 3 The people's economic life is still abundant, low

educational level, infrastructure such as roads, schools, national electricity grids,

commune health stations, despite being invested by the State, are still facing

many difficulties

Figure 2.1: Map of Na Ri district

2.4.2 Topographic

Na Ri district has complex terrain, mainly hills and mountains with many

limestone mountains and large slopes The average height of the whole district is

500m, the highest is Phyia Ngoam mountain (in Cu Le commune) with the height

of 1,193m, the lowest in Kim Lu commune with the height of 250m above sea

level In general, the topography of the district tends to lower from the Southwest

to the Northeast, divided into the following two types of terrain:

- Terrain of rocky mountains: The rocky mountain ranges stretching over

most areas of the district are the communes of Kim Hy, An Tinh, Lang San, Lam

Son, Hao Nghia, and Cu Le with the slope of more than 200 In many places, the

rocky mountain has a slope of up to 600 with altitude varies from 300m to 500m

Kim Hy limestone block is considered as a kind of young karst terrain with cliffs,

abyss, and many rivers flowing underground, extremely dangerous

- Terrain of mountainous areas: Distributed in most communes in the

district, including the successive mountain ranges with elevations varying

between 300m and 700m The topography of this region is complex, most of the

mountain ranges are formed on magmatic, metamorphic, sedimentary rocks with

sharp peaks and large slopes Alternating between mountain ranges running

along the large rivers and streams, narrow valleys have been mostly exploited for

growing crops In this region, the plants grow very diverse and plentiful, where

there is still good soil forest, thick soil layer In some places, due to unreasonable

exploitation, reduced vegetation cover, soil erosion, leaching, the concentration

of nutrients is greatly reduced

The terrain of Na Ri district has a direct influence on soil formation,

namely leaching and accumulation processes The leaching process takes place

strongly in the rainy season in the divided, steeply sloping rocky area, in the low

hills with relatively flat valleys, adapting to food crops and short-day crops in the

tropics

2.4.3 Hydrological

In Na Ri district, there are 2 big rivers flowing through them, namely Bac

Giang and Na Ri