Study of some characteristics of the cau river basin in bac kan province

The Cau river basin in Bac Kan province in the high mountain regions, the terrain is quite complex and special; steep slope and altitude, and the upstream of many rivers, so the concentr

THAI NGUYEN UNIVERSITY

UNIVERSITY OF AGRICULTURE AND FORESTRY

NGUYEN THI LAN TOPIC TITTLE:

STUDY OF SOME CHARACTERISTICS OF THE CAU

RIVER BASIN IN BAC KAN PROVINCE

BACHELOR THESIS

Study Mode : Full-time

Major : Environmental Science and Management

Faculty : International Training and Development Center

Instructor : Dr Pham Van Dien

Thai Nguyen, September 2015

DOCUMENTATION PAGE WITH ABSTRACT

Thai Nguyen University of Agriculture and Forestry

Degree Program Bachelor of environmental Science and Management

Student name Nguyen Thi Lan

Thesis Tittle

STUDY OF SOME CHARACTERISTICS OF THE CAU RIVER BASIN IN BAC KAN PROVINCE

Supervisor(s) Prof Dr Pham Van Dien, Viet Nam Forestry University

(VFU), Viet Nam

Abstract:

The development of the country towards industrialization - modernization, environmental problems have risen including the water environment problems in the river basin Therefore, the exploitation of the river, beyond the knowledge of the network of hydrological and geographical characteristics of its forms This study conducted in the stretch of the Cau river running through Bac Kan province Cau river basin in Bac Kan province includes Bac Kan town, Cho Don district (Ra Ban, Dong Vien and Phuong Vien commune), Bach Thong district and Cho Moi district Studying some characteristics such as topography, landforms, climate features, and hydrological and vegetation characteristics The Cau river basin in Bac Kan province in the high mountain regions, the terrain is quite complex and special; steep slope and altitude, and the upstream of many rivers, so the concentrating flow in the rainy season is very fast The climate there is a clear seasonal difference Winter is low temperatures, little rain and under the influence

of the northeast monsoon Summer has high temperatures with lots of rain so rainfall generated floods in highly concentrated areas, frequency of rain that created

flooding during the months of fairly uniform, concentrated mainly in the June, July and December Study of some characteristics of the Cau river basin will be addressed to assess the advantages and difficulty of watershed from which resources most effectively, as well as the protection and development of Cau river basin in a sustainable manner So study of some characteristics of the Cau river basin such as topographical land use, vegetation cover, hydrological and climate characteristics will be addressed to assess the advantages and difficulty of watershed from which resources most effectively, as well as the protection and development of Cau river basin in a sustainable manner

Keywords Cau river basin, topographical land use, vegetation cover,

hydrological and climate characteristics Number of

ACKNOWLEDGMENT

On the occasion of the thesis completion, I would like to express my appreciation

to the Department of Natural Resources and Environment, Department of flood protection, Department of Agriculture and Rural Development in Bac Kan Province for support and kind provision of necessary information concerning this study

In particular, I would like to express my gratitude to Dr Pham Van Dien who guided, instructed, coached me in the course as well as in implementation of this thesis Due to the time frame and my ability and experiences are limited, some shortcomings of the thesis should not be avoided I look forward to the comments by the teachers for improving my graduation thesis

I would like to sincerely thank you!

Thai Nguyen, Wednesday, 31 August, 2015

Student

Lan

Nguyen Thi Lan

TABLE OF CONTENTS

LIST OF TABLES 1

LIST OF FIGURES 2

INTRODUCTION 3

CHAPTER 1: LITERATURE REVIEW 4

1.1 Concept of river basin 4

1.2 The characteristics of a river basin 5

1.2.1 The geometrical characteristics of the river basin 5

1.2.2 Characteristics denote the flow 7

1.2.3 Climate factors 9

1.2.3 Buffer factor 9

1.3 The characteristic elements of river basin in Vietnam 10

1.3.1 The climate factors 10

1.3.2 Soils and lava 11

1.3.3 Topographic 11

1.3.4 Forest 12

CHAPTER 2: OBJECTIVES, OBJECTS AND LIMITATION, THE CONTENT AND RESEARCH METHODS 13

2.1 Objective 13

2.2 Scope of research 13

2.3 Research Content 13

2.4 Research Methods 13

CHAPTER 3: RESULTS AND DISCUSSION 15

3.1 Overview of the Cau river basin in Bac Kan Province 15

3.1.1 Natural characteristics 15

3.1.2 Characteristics of economy and society 18

3.2 Topographical, geomorphology features of the basin 20

3.2.1 The topographical zones 21

3.2.2 The slope of the terrain 22

3.2.3 The type of terrain 25

3.3 Geological characteristic 26

3.3.1 Geological structure 27

3.3.2 Features of stratigraphy 28

3.3.3 The intrusive magma rock 30

3.3.4 Overview of fault system 31

3.4 haracteristics of vegetation layer and coating plant 32

3.4.1 Vegetation Features 32

3.4.2 The major forest types 34

3.4.3 The percentage of forest cover 35

3.4.4 Assess the advantages and difficulties 37

3.5 Climate Characteristics 38

3.5.2 Climatic feature 39

3.6 Hydrological characteristics 48

3.6.1 The main characteristic of the rivers and streams of Cau the river basin 48

3.6.2 Hydrological station network 49

3.6.3 The characteristics of hydrological flow 49

3.6.4 Assess the advantages and disadvantages of water resources 54

CONCLUSIONS, RECOMMENDATIONSU 55

1 Conclusion 56

2 Recommendation 57

REFERENCES 58

LIST OF TABLES

Table 3.1 Decentralization of the slope of the Cau river basin in Bac Kan province 22

Table 3.2 Forest status in district of the Cau river basin in Bac Kan province in 2014 32

Table 3.3 The percentage of forest cover through the years from 2009 to 2014 35

Table 3.4 The percentage of forest cover in the districts and towns of Cau river basin 36

Table 3.5 A meteorological station and rainfall measuring station in Bac Kan province 38

Table 3.6 Air temperature characteristics 40

Table 3.7 Relative humidity of the air 41

Table 3.8 Total average sunshine hours in a month and year 41

Table 3.9 The average evaporation in the month and year piche tube 42

Table 3.10 Average wind speed of month and year 43

Table 3.11 The average total rainfall in the month and year 44

Table 3:12 Distributor average rainfall for the month and year 45

Table 3.13 yearly rainfall frequency 45

Table 3:14 The ratio of year rainfall is seasonal distribution 45

Table 3:15 statistically the highest rainfall of periods 1,3,5,7 days 46

Table 3:16 m coefficient calculated on the average for positions rainfall stations 47

Table 3:17 Percentage (%) of rainfall that generated floods appear during the rainy season in some regional stations 47

Table 3.18 hydrological station network, time factors and monitoring 49

Table 3:19 The annual average flow is measured on the stations 50

Table 3:20 Flow in the dry season in Cau river basin in Bac Kan province 51

Table 3.21 the frequency of runoff courses in some river basins of Cau stations in Bac Kan province 51

Table 3.22 The frequency of flood flow at several stations in Cau river basin 52

Table 3.23 Average turbidity in monitoring period 53

LIST OF FIGURES

Figure 3.1 Map of Cau river basin in Bac Kan province 16

Figure 3.2 The percentage of forest cover in the districts and towns of Cau river

basin in Bac Kan province 35

INTRODUCTION

Research rationale

Currently, along with the development of the country towards industrialization - modernization, environmental problems have risen including the water environment problems in the river basin Therefore, the exploitation of the river, beyond the knowledge of the network of hydrological and geographical characteristics of its forms, must also have the full understanding of the geographical factors affecting the flow, formation and evolution of river basin flow On that basis, we understand in detail the nature of the physical and hydrological characteristics

Cau river basin is one of the largest river basins in the country This is the most important watershed in the Thai Binh river system that the area is 6,030 km2 with main flow is Cau river of 288.5 km long which originates from the Van On mountains at an altitude of 1.175m and flowing into the Thai Binh river at Pha Lai district Cau river basin has 26 tributaries at levels I and 41 tributaries at levels II with a total length of 671km and 643 km, respectively, and hundreds of kilometers of branches at levels III,

IV and shorter ones, which its length is under 10km

Topic "Study of some characteristics of the Cau river basin", such as

topographical land use, vegetation cover, hydrological and climate characteristics will

be addressed to assess the advantages and difficulty of watershed from which resources most effectively, as well as the protection and development of Cau river basin in a sustainable manner

CHAPTER 1 LITERATURE REVIEW

1.1 Concept of river basin

River basin is the water area that water (including surface water and groundwater) will flow into the river The river is limited by watershed (watershed line) of the basin There are two kinds of watershed: the watershed line of surface and groundwater

- The source of the river is where the beginning of the river The big rivers are

often rooted in the high mountains, and dense forest In which having many ravines, crisscrossing small streams, and water flows all the year Sometimes the river originates from groundwater or a large lake

- The upper course of a river is often high areas with steep terrain, and is

complicated separation This is where the beginning of rivers, and surface often covered by forests which is like the "green water storage " that have a role in flow condition, reducing flows of flood peak and increase dry season flow for downstream

- The middle course of a river is often mountainous or highland areas where

terrain is low, and is the intermediate zone which transfer water into a downstream area In the middle course, the rivers often have smaller slopes, riverbeds begin to expand out, and riverbed has many fine sandy The riverside often at risk of being inundated that forming dumps containing flood

- Lower course of a river is the lowest zone of the river basin that mostly

perennial alluvial can create the broad plains Generally, when the river flows to the river downstream, river section is expanded, and often divided into several branches to flow into the sea River in the lower course area usually has a small slope, and mud

flow at the bottom of the river is mostly fine sand and mud Since the river section is expanded so speed of water is small rate that leading to sedimentation process is primary, and erosion only occurs during floods in a certain number of points At the downstream near the sea, rivers are prone to be branched, riverbeds is deformed and meandering in sine form and often morphological change under the impact of process

of accretion and erosion constantly

- River mouth: river mouth is the place adjacent to the sea, lake, or another river

Determining watershed must be based on topographic maps with elevation contour drawing

1.2 The characteristics of a river basin

1.2.1 The geometrical characteristics of the river basin

a River basin area

The river basin area (F km2) is the area that is controlled by a regional distributor The basin area is determined from a map with scaling in approximately from 1/10,000

to 1/100,000 We can use the method of apportionment squares or the gauge for determining the area of the basin area

b The main river length (L) and the river basin length (L 1 )

The main river length of L (km) is the length that following the flow direction is measured from the river source to the river mouth basin Length of L1 (km) is calculated according to the center lines of the basin from the farthest point of the basin

of the river mouth In fact, it often takes river length as river basin length: L1≈L

c The average width of the basin B (km):

The average width of the basin B (km) is the ratio between the river basin area and length

(1)

d Basin shape coefficient

Basin shape coefficient (Kd) is the ratio between the width and length of the river basin Kd denotes the shape of the basin, usually with Kd ≤ 1 Basin shaped the more square, the Kd -> 1.0, whereas the more narrow and longer river basin is; the smaller

Kd is and the greater floodwaters get

(2)

e Average height of river basin:

The average height of the river basin is determined from the elevation contour map

(3)

In which: hi - Average elevation between two contours

Fi - The area between the contour elevations adjacent (km2)

N - Number of plots have area

f Average slope of river basin :

Average slope is the average slope of the basin

(4) Where: ∆H - The difference in height between the two contour lines

Fi - An area between two adjacent contour lines (km2)

li - The average distance between two adjacent contour lines

In case there are no elevation contour lines, we can use the following approximation formulas:

(5)

In which Hmax - The highest elevation point of the region

Hmin - The lowest elevation point of the basin

F - the basin area

This formula is only true when the basin slope changes little

g River mesh density D:

River mesh density (km/km2) is the total length of all rivers and streams in the basin dividing the river basin area

The thicker the streams are, the greater density grids of river are The region has abundant water resources, the D is often high value (Tuan, L.A, 2008)

1.2.2 Characteristics denote the flow

a The water flow

The water flow (water discharge) is the amount of water flowing through sections of the mouths of rivers that poured outside in a time unit is 1 second (m3 / s) The water flow at any one time is called the instantaneous flow

The process of change of water flow over time as an exit route called the water flow process, denoted by Q (t) or Q ~ t A graph of the change between the water flow and time is the water flow line

The average water flow over a period of time (t) randomly is the average value of the water flow in that period Average water flow is calculated by the following formula:

(6) where is the average value of the water flow, n is the number of computing time, Qi is the average flow at each initial interval

b The total amount of the flow W

The total amount of the flow W (m3 or km3) is the amount of water flowing through the section in river mouths over a period of time from t1 unit to t2,

(7) where is the average flow during the period t2-t1

c Flow depth (Y)

As the thickness of the average water layer is produced on the surface of river basin over a certain time period (mm)

(8) Where W - The total water volume (m3)

is, the greater flow losses and vice versa (Tuan, L.A, 2008)

1.2.3 Climate factors

Climate factors effect directly to runoff, which is rainfall and evaporation Rainfall is causing runoff and evaporation that reduces the flow, but rainfall and evaporation are also related to many other climate factors as temperature of buffer factors (the land surface, water suface), air temperature, humidity, and air pressure, wind, and storm, so before considering rainfall and evaporation, we need to research basic concepts of the above factors

1.2.3 Buffer factor

The characteristics of the location, soil, geology, vegetation cover, ponds in the river basin have a direct influence in the formation of the flow, and calling is generally buffering factor

Geological sites of river basin reflect the climatic conditions in the area Terrain, topography of the river basin are not only influence to evaporation and rainfall, but also affect directly to the flow concentration If the higher and the more sloped terrain have; the faster the flow is and vice versa

The terrain and pedological characteristics of the basin It decides the water amount that penetrates into the soil and the amount of water stored in the river basin that are two factors which influence obviously to the flow In addition, because of the geological structure properties of the river basin generally lead to the watershed line in the surface and groundwater in river basin which aren’t overlap, making the hydrological analysis become more complicated

Vegetation cover increases the absorbed level on the surface, making the soil porous layers discrete, increasing water infiltration, greater groundwater flow and flow

distribution in the year were more harmonious Vegetation cover increases roughness

on the surface that leading to disturbances of air flow increases, resulting in increasing rainfall in part Vegetation cover prevents quickly erosion on the ground, which reduces the small amount of sand in rivers

1.3 The characteristic elements of river basin in Vietnam

1.3.1 The climate factors

1.3.1.1 Rainfall

Features of humid tropical climate in our country, monsoon have shown very markedly the average rainfall in many years and the relationship between annual rainfall and evaporation Considering the whole territory of our country, the average rainfall of about 1960mm in some years In comparison with average rainfall the same latitude (100-200 in the north) in our country, there is abundant rainfall, about 2.4 times Only areas are hidden wind, annual average rainfall fall below 1000 mm

The distribution rule of average rainfall amount in many years is irregular in space, and depending on the terrain elevation and direction of the slopes which get wind Rain factor affects surface runoff distributing in space and time

The amount of the flow and its distribution on the territory of our country depends primarily on the distribution of rainfall Features have nature of rule which is reflected very clearly in practice and on contour line maps and the average flow in many years

1.3.1.2 Water evaporation

Besides the rainfall factor, the evaporation factor from surface of river basin also participated directly in the water balance of rivers, significantly influence the flow formation In our country, there are high temperatures that made the process of

evaporation on river basin from north to south are quite large Average annual evaporation is 953 mm in the entire territory, compared with average annual rainfall, the evaporation coefficient is 0.48, less than about 35% compared to the same latitude

In conclusion, rain and evaporation are the two most important factors affecting the flow, it determines the potential flow of rivers in our country Climatic factors have

a decisive influence on the flow distribution in space and time

1.3.2 Soils and lava

The river basin is composed of soil and lava Soils and lava are important factors influencing the flow The fact shows that the river basin has a large rainfall that don't still creates enough produce a rich surface flow, because the flow depends on the water permeability of the soil and geological architecture of the river basin

Impact of soil and lava on flow in two directions river: it may increase or reducing the amount of flow, conditioning or erratic flow regime In whole territory of the country, there are two kinds of soil and lava clearly influence and the most important for the river flow and its regime is limestone and basalt soils

1.3.3 Topographic

The whole territory of our country, increasing the absolute height of the terrain is often manifested in the increase of rainfall, and basin slope, decreasing the temperature, increasing river density In such conditions, the amount of flow increases with altitude quite well

The amount of flow and rainfall increases with elevation The largest increase occurs in the range from 300-600 m elevation and elevation limit that rainfall rule increases with defunct elevation which often estimated from the height of 2000 meters

or more

In addition, the elevation increase rule of precipitation and the amount of annual flow, we also see that the influence of the terrain is quite apparent to the quantity and flow distribution due to the direction and slope characteristics of the terrain Under this rule, the slopes get wind, which has precipitation greater flow in comparing to the lee This difference is quite obvious, especially in the south of northeast and southwest of

Dong Trieu mountain; between two stations in Cam Binh Lieu and Cam Dan where the amount of flow differ to 35% Thus, elevation and direction of getting winded 1.3.4 Forest

In fact, in our country the influence of the forest on the streams depend on many factors, including forest coverage rate and type of forest are the most important factors According Winliam and Nikhitsin, the woods transformed soil very strong, so when forest cover change that is often accompanied by changes in forest type and flow regime of the river In our country, the changing process often changes from the primitive forest to regrow forest, bamboo forest, reeds, bushes and finally the barren hills The change direction is the contrary, even though, there is very little and very slowly Particularly, the surface flow on slopes of forest have the effect greatly reduced Experiment document of flow proved that the amount of flow close to surface slopes which occupy a significant proportion of the formation of flood flow

Effects of forest on runoff courses through the results of experimental studies in foreign countries and in our country have confirmed that forest increase runoff courses with a considerable amount In many areas, forest are still large that runoff courses can

be increased by 30-100% Module value of the average minimum flow in many years

in having forest area is much greater significantly forest than no forest areas

(Forest Protection Department of Bac Kan Province, 2014)

CHAPTER 2 OBJECTIVES, OBJECTS AND LIMITATION, THE CONTENT AND

RESEARCH METHODS 2.1 Objective

- Identifying some characteristics of the Cau river basin

- Proposing some recommendations for the conservation of the Cau river basin

2.2 Scope of research

- The scope of space: Studying conducted in the stretch of the Cau river running through Bac Kan province Cau river basin in Bac Kan province includes Bac Kan town, Cho Don district (Ra Ban, Dong Vien and Phuong Vien commune), Bach Thong district and Cho Moi district

- Scope of time: Implementation of 6 months (from January to June 2015)

- The scope of content: Studying some characteristics such as topography, landforms, climate features, and hydrological and vegetation characteristics

2.3 Research Content

- Overview of the Cau river basin in Bac Kan province

- The characteristics of topography, geomorphology of the river basin

Methods of gathering documents and secondary data

- Collecting data on natural and economic - social conditions in Bac Kan province The secondary data collected from the Department of Natural Resources and

Environment of Bac Kan province, the Department of Agriculture and Rural Development, Department of flood prevention in Bac Kan province, Department of Forestry in 2014

- In addition, the report also uses secondary materials such as reports, results of the ministerial level, the legal documents related and other documents in order to obtain specialized information, particularly differences in soils, geology, and minerals

- Finally, the electronic website of the province, district, and also used as a reference material otherwise

- Based on the nature of the data, the report uses both qualitative information (the description, quotations, and comments) and quantitative information (statistics) in the analysis process

CHAPTER 3 RESULTS AND DISCUSSION

3.1 Overview of the Cau river basin in Bac Kan Province

3.1.1 Natural characteristics

a Geographic location

Cau river basin belongs to the Thai Binh river system in the range 105027 -

106018 east longitude; 21007 - 22020 north latitude, the basin is mostly located in Bac Kan and Thai Nguyen province Cau river basin in Bac Kan province begins Cau river basin upstream that originates from Tam Tao mountain with 1600 meters altitude and across Cho Don, Bach Thong districts, and Bac Kan town

The terrain is mainly mountainous with an average altitude of 500-600 meters, the northwest is the Gam river bow that begins from Chu Cho district,

The northwest is Gam River bow running from Bac Me Cho Chu In the east, the Bac Son mountain range runs west, which extend from the Ngan Son district to Yen Lac district The basin topography is rugged with steep mountain ranges The main direction of the basin is north - south, then turning to the East - West The area is approximately 1100 km2, forest covers area accounts for approximately 56%, the average slope of the basin is about 24%0

Cau river basin runs through in Bac Kan province that is the upstream area of the Cau River basin In Bac Kan province, the Cau river basin is located in 4 districts and towns like Cho Don district, Bach Thong district, Bac Kan town, Cho Moi district, and having location as follows

- The East adjacent to Na Ri district, Bac Kan province

- West adjacent to Cho Don district, Bac Kan province

- Southern adjacent to Dinh Hoa district, Phu Luong district, Vo Nhai district, Thai Nguyen province

- North and northwest adjacent to Ba Be District, Ngan Son district, Bac Kan province

Figure 3.1.Map of Cau river basin in Bac Kan province

b Climate Characteristics

Cau river basin has the common characteristic of Vietnam northeastern climate,

is influenced by the northeast monsoon and the physical activity of the weather: tropical convergence zone, the low trench, and typhoon fall in the basin due climate divides into many small regions with different climates The cause of the difference is due to the terrain which was divided sharply, and forming narrow valleys

Thac Rieng basin is located in the opposite side that facilitate to get wind as a Cho Don valley of Bac Kan province, so it has centers of heavy rain as a Cho Don district and Bac Kan town, with average annual water volume from 1500mm to 2000mm

The rainfall regime in the basin is divided into two distinct seasons, the rainy season usually starts from May to October, which accounts for about 80% of the total annual rainfall, rainy months are usually in July or August with the month rain amount may account for 40% of total annual rainfall The dry season usually lasts from November to April of the next year, rainfall amount of this season is only about 20% of the total annual rainfall, the driest month of the year usually falls in January or February, rainfall in this month usually negligible Prevailing wind direction is the southeast, but due to the terrain should be deflected into the southwest, in the winter, the prevailing wind direction is the northeast The annual average temperature is 21,50C, and tends to increase from upstream to downstream, typically the hottest month in June, usually the coldest month is January The evaporation in the basin ranges from 650-800mm, and transformation increases from upstream to downstream

c Hydrological situation in the Cau river basin

Small river network Cau river basin is relatively thick, the main river is twist, and there are many local flowing directions, but main direction is the east-west to Bac Kan town and then this flow transfer to the north-south The mainstream is combined by two tributaries flow, which is the hot river (the main branch) is derived from Tam Tao mount

of Cho Don district, cold tributaries are rooted in the Bach Thong district The river bed

is in deep steep and many waterfalls Fan shaped basin with river length is L = 64 km

The average width of the basin is B = 9.25 km Allocation of basin on both sides is asymmetric and skewed to the left of the river

The main direction of the river runs north-south direction and come to Phuong Vien district, the river is east-west navigation When coming to Bac Kan town, the river moved to the north-south direction with river mesh density is 1.30km / km2 The flow in the river is mainly caused by rainwater, partly formed surface flow, the rest provides groundwater system The flow in the year also divides two distinct seasons, the rainy season with flooding often occurs from May to October, which is usually around 80% of total annual flow, and usually the driest months are March and April

Flood flow carries many characteristics of the flow of mountainous areas Floodwaters is often up and down very quickly and often causing widespread flash floods Usually high flood time is from 9 to 12 hours, and low flood time is from 20 to

30 hours (Department of Flood Protection in Bac Kan province, 2014)

3.1.2 Characteristics of economy and society

a Economic development

In 2011, GDP increased by 13% in comparison with 2010 (plan is 13.5%) including: the agriculture, forestry, and fisheries increased by 11.36% (planning is 7.5%) Industrial sector, capital construction rose to 2.64% (planned 23%): industry and construction decreased to 14.7% and 21.4%, respectively The service sector increased

to 20.29% (planned 14%) Per capita income reached 14.6 million, and an increase of 2.7 million compared to 2010

Economic growth already has a huge impact on the social life and the environment in the province On the one hand, helping the material and moral life is improved and increasingly advance The cultural, society, science - technology sectors

continue to develop, on the basis having conditions invested back to protect the environment

b Social characteristics

- Population and Labor

According to the Statistical Yearbook of Bac Kan province in 2011, the Cau river basin in Bac Kan province has an area is 1372.78 km2, including 44 communes, wards, and towns The population in the area is 153 096 people The proportion of relatively high population growth is 0.63%, the population of urban areas tends to increase every year The inhabitants of the province are not distributed evenly among regions The majority of people live in rural areas Labor structure is primarily in the fields of agriculture, forestry, fisheries and services; in the industrial sector in which construction accounted 6.3% Labor in rural areas is mainly associated with livestock farming, horticulture and services in households

The increase in population will lead to an increase in the exploitation of environmental resources and this means that depleting resources, making environmental issues become increasingly pressing and intractable The migration from rural areas to urban areas and the disparities in population growth between the regions leads to poverty in rural areas and the excess spending in urban areas that generate source waste that focus beyond environmental biodegradable lead to environmental pollution

- Infrastructure

+ Transportation: The road network in the system, including highways, provincial roads, district roads, urban roads, communal roads and village roads To ensure the road network convenient to serve the economy and national security effectively Many roads have been renovated and upgraded as 257 roads from Bac Kan

town to Cho Don district, and 279 roads from the junction of Thac Gieng to Na Ri district

+ Electric system: Bac Kan province has the electricity grid system, which is on the rise in association with the national grid system Voltage grid in Cau river basin development in the areas of communes, the medium and high voltage lines basically provide production activities and daily life of people in the river basin

+ Health system: Currently, the areas in the Cau river basin have one of the provincial general hospitals with 320 beds, 3 district hospitals with 150 beds and 44 wards commune health stations In addition, there are 50 private clinics In 2010, there

is starting construction of Bac Kan hospital with 500 bed sizes, to meet the health care needs of people in Bac Kan town

+ Educational system: Currently in the areas of the Cau river basin having 116 schools at all levels of education from kindergarten to high school level in which including 42 kindergartens in the communes; 40 primary schools, 20 secondary

schools and four school junior high school There are also community colleges,

political school and continuing education center of Bac Kan province (Report Water Environment Status River in Bac Kan province, 2014)

3.2 Topographical, geomorphology features of the basin

After the climate factor, soil and lava are two factors that directly affect the amount of flow and the distribution in space with the flow regime, topographic factors also influence has been clearly flowing and its regime Influence of terrain has certain effects to flow through the enhanced zonal climate The increase in absolute elevation

of the terrain is often manifested in the increase of rainfall, the slope of the basin, the

decrease of temperature and the increase of river density In such conditions, the amount of flow increases with height quite clear

In addition the rule that increasing with elevation of precipitation and annual flow, we also see the influence of the terrain quite apparent to the quantity and distribution of the flow due to the characteristics of the direction and the slopes of the terrain The mountain sides receive wind, the flow and rainfall is greater than that in the absence of wind

The Cau river basin is an upstream area with different terrains, mostly high hills surround the valley, and is surrounded by 2 bow, which are the Gam river bow in the west and Ngan Son bow in the east

Flows in the Cau river basin strongly dominated terrain of the area should the majority of the rivers and streams that flow from the Northwest - Southeast, meandering flow, narrow and steep riverbed, many waterfalls and rapids Upstream of Cau river flow through the mountains to the north - south, the average high is 300-400 m

3.2.1 The topographical zones

Cau River terrain is divided into four categories as follows:

* The terrain of the high mountains: Topography forms a strip that runs along

the west and to the north of Cho Don district, which interjected that the high mountain ranges form the border between BachThong districts and the northern area of the Cho don district In this area, granite block intrusions are often with steep slopes, sharp peaks and the highest region The sandstone and clay shale mountain has softer forms, and watersheds have the sharply and clearly with little flat or wavy places Overall, this is a dangerous terrain, and traffic is disadvantageous

* The terrain with low hills and mountains: Going along 3 Highway and routes

in other districts, the topography of this region is less complex, the slope is lower than 700m, and the slope is lower than the slope in the high mountains with poor natural vegetation and mostly secondary and plantation forests Due to reducing of forest cover and located in rainy areas, so erosion on sloping land happen quite strong

* Terrain of limestone mountain: Limestone mountain is in Bac Kan province

belongs to Ngan Son bow Views of the majestic limestone mountains, steep cliffs, jagged peaks, sharp serrated In karst, appearance underground streams (phenomenon Kazasto) should normally lead to dehydration in the dry season

* Valleys tectonic – Erosion terrain: Topography occupies one small area, but

has many advantages for the agricultural exploitation Alternating between the mountain ranges is relatively land stretch to grow rice in Nam Cuong, Phuong Vien, Dong Vien commune (Cho Don district); Luc Binh, My Thanh commune (Bach Thong district)

3.2.2 The slope of the terrain

Most of the land area of Cau river basin in Bac Kan provinces is steep slopes, especially those where there are limestone mountains which contains more than 73%

of the natural area with slope over 150, an area with a slope under 80 account for only 15% of the natural area of the province The results determine the slope on topographic that base on maps at rate 1 / 100,000 of the province are as follows:

Table 3.1 Decentralization of the slope of the Cau river basin in Bac Kan province

natural area (%)

(Source: Bac Kan Department Of Environmental Protection)

The Cau river basin in Bac Kan province has high mountain terrain, dominated

by mountains bow extends from north to south in the west and east of the province; topography surface has been eroded, fragmented

The mountain system of Gam river bow runs along the west of the province Mainly lava here is schists - quartz, sandstone, and limestone Topography in the north-northwest is high with peaks over 1000m, descending southward into the low hills, with a few hundred meters elevation Overall, the mountains here have pretty soft contours with relatively equal peaks and slopes There are interspersed the craggy limestone blocks, layered thick, cacxto ongoing process strongly, creating interesting shapes, majestic scenery

Belonging to the Gam river bow located in Bac Kan province remarkably that having Bjooc Phja range is high over 1000m as a wall "stretching from Pac Nam and

Ba Be district through Cho Don district, Bach Thong district, with Tam Tao mount is granite intrusion with the metamorphic rocks The north-west of Pac Nam district has the highest mountain peak of the province: Phja Gia peaks adjacent to Ha Giang and Tuyen Quang provices that is l.640m in high On Phja Bjooc range, much higher than 1300m peaks as tops Phja Ieng (l.527m), Phja Bjooc (l.502m), Pu Binh (l.404m), Khau

Tang (l.359m) mounts Tam Tao mountains have elevation up to 1.328m The end of Bjooc Phja sequence of Bach Thong district remain peaks on l000m as Khau Mo (1104 m) The Gam River bow in the south of Cho Don district, and in the northwest

of Cho Moi district where the terrain is lower down, shape is soft with low hills and having bowl shape, little more rugged

Ngan Son bow runs from north of Ngan Son district (bordering Cao Bang province) along the eastern site of Bac Kan to Lang Hit the mountains (Thai Nguyen province) that form the bow according to north-south direction Ngan Son bow clearly indicates as watershed between the basins of the rivers that run into Lang Son, Cao Bang basin with rivers flowing down Thai Nguyen province; simultaneously forming the boundaries that divide the important climate areas: the eastern mountainside gets wind, winter become drier and colder than the western mountainside; mountainside in the western part is no wind but getting southwest winds and more rain

There are areas in due the process of tectonic plates which raised, descend uneven monoclinic terrain forming (e.g Na Phac slopes of Deo Gio - Ngan Son) In Ngan Son bow with limestone Kim Hy, Yeu Lac limestone range is kacxto young kacxto terrain with rugged peaks, precipice deep pools, and rivers have very dangerous undercurrents The mountain ranges are located in Ngan Son bow with height over 1000m as Khau Xiem (1147m), Phja Khao (l 061m), Pha Ngoem (l.263m) Ngan Son district; and the 1000m peak at the bottom of Bach Thong district is lower down Cho Moi district

Topographic depression runs north - south direction in the provincial territory, one side is Gam river bow in the west, one side is Ngan Son bow is in the east The terrain here is mostly low mountains (400- 500m), hills (100 - 200m) interleaved or

extended by the river valley or foothill valley Lava is commonly schists, clay and a little lime old limestone, soil deposition or rocks along the river at the foot of the mountain

3.2.3 The type of terrain

The terrain is varied that including many types of terrain: Valley, high hills and low mountain, limestone highest peak is the Nam Khieu Thuong (1.640m) in the north

of the province, the lowest peak in Quang Chu commune, Cho Moi district have an elevation is above 40m in comparison to the sea

- In the west of the Bac Kan province, an elevation is lower from the northeast to southeast, with many peaks above 1000m, fragmented terrain, average slope 26-30o, and many huge rocks in the north of the Cho don district interspersed with mountain land to form the narrow valley

- In the East, the terrain is located in the last section of the Ngan Son-Yen Lac bow, with Kim Hi limestone mountains which is a huge stone blocks, sparsely populated

- Average mountain topography type (700 - 1700m) occupied 12.43% of the natural area of the province The distribution is concentrated in the districts of Ngan Son, the northwest of Cho Don district Average slope is from 30 to 380, thick and porous soil

- In the south of the province is a low mountain as a transition from the midlands

to the mountains, the average elevation of 300 - 400m compare to the ocean surface, this is the final part of the Gam river bow, Ngan Son - Yen Lac bow However, there is

not great altitude, average slope 26o but the terrain is fragmented, creating valleys is wider which is typical valleys next to Cau river basin

- Low mountain terrain type (300- <700m) occupies 64.31% of the natural area

in the whole province The distribution is concentrated in the district, which is the southern of Bach Thong and Cho Moi districts Average slope is from 28 - 350 Where average slope is lower than 300, the ground floor is quite thick, suitable for forestry production development Interspersing with this type of terrain is terraced areas that situated in the narrow valley

- Cacxto topography: Cacxto height is mainly smaller than 700 meter accounting for 7.29% of the natural area in the whole province, and more concentrated distribution

in Vu Muon communes (Bach Thong district); On this type of terrain with many caves, the fauna and flora in rocky mountain with many rare species

- Topography valley and basin account for 6.41% of the natural area in the whole province, which are interspersed with the type of low mountain terrain and bowl shape hills Land was formed from the runoff of mountains, fertile soil, favorable for agricultural development

3.3 Geological characteristic

Bac Kan province is located on the four zones of metallogenic belong to " Viet Bac metallogenic" that were Lo Gam metallogenic zone, Phu Ngu metallogenic zone, Bac Son metallogenic zone, Hien river metallogenic zone Bac Kan geological structure is complicated In terms of geological structure, most of the Bac Kan territory belongs to the Northeast tectonic region in Vietnam

Bac Kan province has stratigraphy structure that is quite complex, with many different origins The richness of the stratigraphic kingdom has a very large decision to quality and richness of the minerals of Bac Kan province But the province's mineral reserves are not big, but at a limited level

3.3.1 Geological structure

Bac Kan province is located in the geological structure of the Northeast, according metallogenic zoning map of Nguyen Nghiem Minh in 1984, the area of Bac Kan province located on four metallogenic zone "belonging to "metallogenic domain belongs to the north of Hanoi city"

Phu Ngu metallogeny zone: This zone lengthen has arcs shape and convex

towards the East from Pac Nam and Ba Be, Bac Kan Town, Cho Moi districts, the western adjacents to Lo Gam block, the eastern boundary adjacents to Bac Thai - Bac Son block by deep faults along Highway 3 and extends from the Nang River - Cho Moi district This Phu Ngu zone brings complex l ong syncline, syncline cores clearly observed along the 257 road from Duong Phong to Dong Vien district Related minerals include building materials (clay, clay cement), iron, lead, zinc, gold

Bac Son metallogenic zone: The zone extends along the east side of Highway 3

from Ngan Son district to Cho Moi district West boundary of the zone is deep faults along Highway 3, the eastern boundary adjacent to Hien river through the system of faults stairs BacThai - Bac Son block in the territory of the province shows Ngan Son anticlinal structures and Khau Au anticline part that related minerals, including iron, lead, zinc, gold and limestone building