nghiên cứu sử dụng hợp lý tài nguyên, bảo vệ môi trường lưu vực sông gâm (phần lãnh thổ việt nam) bản tóm tắt tiếng anh

Research objectives and purposes Research objectives: determine the use requirements and propose the use of three natural resources including land, forest, and surface water to contribu

INTRODUCTION

1 The rationale of research

Gam river is the largest tributary of the Lo river Its area in Vietnam's territory is 9.168/14.972km2 The human activities have a strong impact to the situation and evolution

of natural resources and environment in the basin It also contains the risk of natural resources degradation and ecological environment That situation requires a comprehensive research for the rational exploitation and use of natural resources and for basin environmental protection

2 Research objectives and purposes

Research objectives: determine the use requirements and propose the use of three natural resources including land, forest, and surface water to contribute in research, rational use of natural resources, environmental protection of Gam river basin and the sustainability

of Tuyen Quang hydropower plants

Rsearch assignment: review of research trends in rational use of natural resources and environmental protection in basin in the world and in Vietnam; establish a theoretical basis, approach and methodology proposed to rational use of natural resources and environmental protection in the Gam river basin in the context of Tuyen Quang hydropower projects; analyze the characteristics of nature and socio-economic conditions related to natural resources and environment issues, and mining and use problem of the Gam river territory; analyze the situation and transformation of resources and environmental under the impact of Tuyen Quang reservoir; determine the requirements, propose rational use of land resources, forest resources, water resources and protecting the environment of the Gam's watershed; propose mining orientation of Tuyen Quang lake based on the basis analysis of its potential natural

3 Research scope

The territory: the Gam river basin in Vietnam's territory has a total area 9.168km2, accounting for 61,23% of the total basin area According to the administrative boundaries, Gam river basin spreads in the area of 17 districts, 4 provinces of Ha Giang, Tuyen Quang, Cao Bang and Bac Kan

Content: analyze the characteristics of nature and socio-economic conditions related

to the situation and analyze the exploitation and use of the Gam river basin territory; determine the requirements and propose reasonable use of three main types of resources in the basin including land resources, forest resources and surface water resources; propose mining oriented and rational use of Tuyen Quang reservoir based upon the analysis of potential natural of reservoir

4 Research viewpoints

Thesis uses many key viewpoints in the research process, including: synthetic viewpoint, systematic viewpoint, historical and generating viewpoint, and ecological-economic viewpoint

5 Research methods

The thesis uses specific method including data collection, statistics, data analysis; synthetic analysis; map and geographical information system (GIS); monitoring, field work and experts

6 Theoretical argument

- Argument 1: Moutainous terrain occupies most of the area in Gam river basin Economic development has facilitated by the diverse distribution and complex of natural conditions, limited of socio-economic development, abundant of natural resources, advantage of forests, land, water, minerals and hydropower However, there is potential environment risk if it is lack of appropriate exploitation, use, and management in natural resources Along with the exploitation of natural resources in Gam river basin, the formation

of Tuyen Quang lake is an agent leading the change in the entire system of resources and environment in the basin especially land, forest, and surface water resources Therefore, analyzing the characteristics of nature, socio-economic conditions, their impacts to to the situation, the transformation of natural resources and environment, and mining and resource use issues, is a pre-condition to propose rational use of natural resources and environmental protection in Gam river basin The center assignment is to propose rational use of three main natural resources of basin

- Agurment 2: Study the rational use of natural resources and environmental protection in Gam river basin has accessed toward watershed/basin system analysis in the relationship between natural and human factors, between upper, middle, and down stream, and between level 2 watershed, to determine the percentage of forest cover, land use structure, rational exploitation and use of water resources and Tuyen Quang lake

7 Marks and contributions of the dissertation

1) The thesis has analyzed and clarified: the characteristics of natural, socio-economic conditions related to resources, environment and mining issues, the rational use of natural resources, environmental protection in Gam river basin; the situation and change of land resources, forest resources, surface water resources of the Gam river basin as a result of Tuyen Quang lake

2) The first time, the thesis proposed rational use of natural resources and environmental protection in the Gam river basin following basin analysis approach with specific findings include: proposed upstream decentralization protection, the direction used for different types of land use and land protection on the basis of the potential erosion classification of watershed; land capability assessment and classification of soil protection requirements; proposed reasonable use and forest restoration on the basis of assessment of imbalances cover and classification of forest resources in watersheds; proposed mining and rational use of surface water resources, hydrological flow changes, situation, demand and mining limitation, in Gam river basin based on analysis of potential surface water, the risks and causes of surface water resources degradation, shortcomings in the management of water resources in the basin; analyze natural conditions in Tuyen Quang lake for the purpose of aquaculture and tourism development

8 Dissertation structure

Besides the introduction and conclusion, the thesis includes 3 chapters, with 147 A4 pages,

44 tables, 14 maps, 12 drawings, charts, diagrams and 156 references and 16 appendices

Chapter 1 THEORETICAL BASIS AND RESEARCH METHODS OF REASONABLE USE OF RESOURCES, ENVIRONMENT PROTECTION IN GAM RIVER BASIN

(VIETNAM TERRITORY) 1.1 Overview of the research trends in reasonable use of natural resources and basin environment protection in the world and in Vietnam

Around the world and in Vietnam at present, research problems using appropriate resources, environmental protection is approached from the direction of future research: research landscape; assessment study soil erosion and protect soil from erosion; direction basin analysis study (including land-use planning based on an assessment of basin watershed decentralization, decentralization in the basin soil erosion); study integrated management of natural resources environmental and river basins studied the impact of hydropower, irrigation in the basin Several local authors have conducted research combined with landscape basin to the rational use of natural resources and environmental protection in the basin This is quite a new research direction

in Vietnam should have only been a handful of authors implemented

The research on the Gam river basin not only more focused and problem-solving impact

of Tuyen Quang hydropower to the natural environment and the economy - society On the access point system and basin analysis, the thesis studies the rational use of natural resources, environmental protection Gam river basin, which focuses primarily on three resources as land, forests and surface water The results of a number of works have deployed on the Gam river thesis used as input data sources and references of the research process

1.2 Theoretical basis of the study of the reasonable use of natural resources, environmental protection in Gam river basin

1.2.1 The basic concepts

Natural Resources: "natural resources are natural components of that at a certain level

of development of productive forces are used or can be used as means of production and objects Consumers "[113]

Environment: Environmental Protection Law in Vietnam in 2005: "Environmental factors, including natural and man-made physical factors related to each other, surrounded

by people, affecting their life, the survival, and development of human beings "

Between the environment and natural resources in general and natural resources in particular have a close relationship Therefore, protection of the environment always implies the exploitation and rational use of natural resources of the territory

Basin: a natural spatial territory includes all natural objects and artificial on it, which receive storm water and ground water provides natural flow system, which is limited by the the watershed The entire catchment area is a unity and fulfillment naturally On each river basin exists close relationship between the natural and human components work The relationship makes both watersheds is a geographical territory, both as a dynamic system to adjust to the level

of expression and different evolutions over time and space from the upstream to the mouth river Decentralized Watershed: the division of watershed area into different levels, reflecting the deterioration of soil erosion based on the geographical characteristics and their environment The most important objective of decentralization is to identify watershed areas need protection forests

for water regulation, flood protection, erosion and landslides, limited reservoir sedimentation also such as the protection of downstream areas and bring economic benefits, ensure social security

1.2.2 The impact of hydropower projects in natural resources and the environment in the river basin

Depending on the type and scale of development, hydropower projects have impacts

on the environment at different levels

For the natural environment, a system of dams - hydropower reservoirs are formed submerged part of the basin reservoirs The reservoir formation and operation of hydropower plants as well as changes in flow regimes, erosion and sedimentation of lakes, rivers, and change the appearance of new ecosystems, deforestation and loss biodiversity, water pollution, changing climate conditions of the reservoir

For the economic environment - social area submerged by the reservoir may be the place

of residence, with the production of construction, aesthetic values, culture, and human sciences Therefore, the hydropower project also alter habitats and living conditions of a segment of the population, which may have a negative impact on the environment, such as deforestation, ecological housing for, cultivation, shifting cultivation, nomadic, erosion and desertification Space impact, including upstream and downstream reservoir dam, even estuaries Most of the impact is more long term, and could potentially manifest during operation of the project

1.2.3 Research approach

Firstly, analyze the current state of resources, Gam river basin environment as a result of the relationship agreement, closely natural conditions, economic - and social impact of Tuyen Quang reservoir to the entire system natural - basin ecological environment

Secondly, the proposed use of natural resources, environmental protection basin mainly focus on three types of resources as land resources, forest resources and surface water resources The approach of this project is to determine the required resources rational use of land, forest and water surface characteristics analysis based on natural conditions, economic

- social, sexual exploitation, and use of resources the status of resources and environment as the basis of proposed use of the resources of this kind

1.3 Research method proposed reasonable use of natural resources and environment protection in Gam river basin

1.3.1 Methods of assessment of potential soil erosion in the basin

Selecting assessment methods: These methods evaluate soil erosion mainly in the world are: classification, distribution territories on the extent of erosion on the basis of integrated assessment of the influence of natural conditions to and erosion modeling method based on empirical models erosion studies Due to widespread application of GIS tools with the advantages of the new technique in the process of erosion to study the thesis modeling methods used in studies evaluating the potential erosion of the basin

Choosing evaluation models: Thesis using USLE model of Wischmeier and Schmid (A = R×K×L×S×C×P) to assess the potential erosion of the Gam river, after the kind of off coefficient C and P The selection USLE model allows to meet research requirements hierarchy erosion potential as the basis for the proposed decentralized protection in the basin Many authors in the world and the country has confirmed USLE model can be successfully applied to watershed erosion The parameters of the USLE equation can be modified to suit the specific conditions and can be completely calculated using GIS tools

1.3.2 DPSIR analysis method

DPSIR (Driving forces-pressures - State - Impacts - Responses) is a cognitive model used to identify, analyze and evaluate the causal chain-result-response measures Thesis DPSIR methodology used to analyze general issues related to water resources of the Gam river basin, as a basis for determining the proposed solution to the rational use and protection of water resources basin

1.3.3 System analysis method

System analysis method was applied dissertation solving research tasks in sequence content (steps) the following:

Step 1: Analyze the characteristics of natural conditions and the status of natural resources and environment Gam river basin

Step 2: Mapping erosion potential decentralized Gam river basin as a basis for the proposed decentralized protection, rational use and restoration of forest use and protection of land resources Step 3 Assessment requires the use of water resources as a basis for proposing rational use of water resources of the Gam river basin

Step 4: Identify strategies for aquaculture development and tourism Tuyen Quang reservoir area based on the analysis and evaluation of the natural conditions, natural lake

Chapter 2 CHARACTERISTICS OF NATURAL, SOCIO-ECONOMIC CONDITIONS, AND SITUATION OF NATURAL RESOURCES AND ENVIRONMENT

IN GAM RIVER BASIN (THE TERRITORY OF VIETNAM) 2.1 The natural and socio-economic conditions and natural exploitation, environmental protection problems of Gam river basin

2.1.1 Geographical location

On the territory of Vietnam, Gam river has about 217km long and a catchment’s area of 9.168,02 km2 On the administrative boundaries, the Gam river basin is located on the territory

of 17 districts in the four provinces of Ha Giang, Cao Bang, Bac Kan and Tuyen Quang

Due to the distribution in the territory should the vast natural basin characteristics are varied and complex The local catchment area has good economic conditions - poor social development

in our country, especially in districts remote This is a major obstacle in the management of natural resources in general and land resources, forests, surface water in particular

Gam river basin is 38,77% of the area of China to the basin management will encounter difficulties to reach consensus and ensure the interests of both countries

2.1.2 Natural conditions

2.1.2.1 Characteristics of tectonics - geological

Gam river basin located mainly in tropical Gam structure, the North Vietnamese folded, form a graben in the Asian and enhanced meridional end Hecxini entirely Composition of tropical lava mainly terrigenous - carbonate Cambrian age - Ocdovic - Silua - Devon Magmatic activity is characterized by small intrusive bodies, penetrated the sediment

Due in active tectonic region with varying intensity should basins strong differentiation of structure and stratigraphy of lava composition in space Activity of the tectonic phase motor with magma intrusion has created much destruction tectonic area in the basin

On the Gam river basin includes the formation and lava groups are: the ancient lava (igneous, sedimentary and metamorphic), the lava Mezozoi (including Lang Son Formation, Song Hien and Na Khuat); Cenozoic sediments (Quaternary material)

Conditions geological tectonics is the primary basis of the continuous impact in the landscape basin crust, thereby controlling the direction and the extraction solution, using the territory for the purpose of economic development-society, especially for the use and protection of land resources

History long territory along the tectonic movement created complex for catchment mineral resources are quite diverse The movement is made up of well defined areas hilly nature, and make a strong differentiation of terrain structures The richness of the composition of the lava flow has defined the diversity of the nature and type of soil cover

2.1.2.2 Terrain

On the Gam river in the territory of Vietnam, it is possible to identify a level from low

to high are: 100m (3,8%) and 100-200m (7,8%); 200-300m (9,9%), 300-400m (11,4%), 400-500m (11,3%), 500-700m (18,6%) 700-1.000m (19,6%); 1.000-1.500m (1,8%) in the 2.000m (below 1%) The area has a height of 500-1.000m majority with 38,2% of the total catchment area 1,000 or more places from small areas as peaks in the watershed South of the basin, along the Gam river mainstream popularity as a level below 200m elevation Overall, the Gam river basin topography is mainly low hills, with the fragmentation and separation complex Lower elevation terrain from north (above 1.000 m) to the south and southeast (200-500m) along the Gam river flowing mainstream

Differentiation of terrain created by landscape diversity, and greatly influenced the direction exploitation and use of the territory Conditions mountainous terrain dominated resource extraction method primarily throughout history explored territory Farming practices have transformed the population structure of land use, exploitation of resources forms, form the system of shifting cultivation, terracing on slopes In the mountains upstream major advantage for forestry development with the protection of forests The model agroforestry farming, forestry and agriculture combined scale can only focus on the development of low hills and slopes In areas of low and flat terrain along the river were filled by new sediments should be very favorable for agriculture to help meet the demand for food, local food

The process of long-term development of the basin's natural made adaptations and relative stability of the natural environment The exploitation and use of sloping land fragmentation and the distribution of production space is subjective reasons appear to increase the risk of natural disasters have been happening throughout the basin

2.1.2.3 Climate

Climate of Gam river basin is nature tropical monsoon moisture, fertilizer complex, with cold winters and drier than other areas of the Lo river system - running warm and more humid than the Northeast The nature of the cold last winter due to the cold polar air masses due to the effects of tropical medium altitude terrain has made the annual average temperature is quite low (22-240C), but in a very large temperature range (12-140C)

Geographical location and topographic structure also create favorable conditions for frequent intrusions in summer, bringing significant rainfall, ranging from popular and time 1.200-2.500mm/nam rainy season prolonged, accounting for over 70% of the total annual rainfall

Temperature-humidity regime of the Gam river basin with the terrain and soil conditions arise, the development of the natural vegetation of the basin's rich This is one of the reasons that make the Gam river basin is home to the forest coverage rate much higher than the river basin and other localities of the country

As the season of heat-moisture distribution and diversity of structure and basin topography to facilitate diversification of crops and livestock in agriculture at the local level with the garden hill farms, gardens forest associated with livestock and poultry

Climatic conditions also brings significant difficulties for the natural environment and economic - social activities of the basin Summer is usually the weather disturbance that causes widespread heavy rain Rainfall and unpredictable fluctuations in the rainy season are important factors leading to floods, landslides, rock succession occurs in many parts of the basin

2.1.2.4 Hydrology

Gam river basin have long and narrow shape The small tributaries, but as feather structure is very convenient for the country to focus on the main line Low density of rivers (0.5-1km/km2), especially in the upland areas and paint the limestone On the territory of our country's territory, with 2 Gam river is the largest tributary river and Nho Que river Energy Flood season in the Gam river basin extends from May to October, accounts for 70-80% of the total annual flow Dry season lasts from November to April next year The seasonal distribution of basin flow regime increases the risk of water shortage, production in the dry season and the natural disasters of flooding The space division of the flow give rise

to a conflict between the needs and potential of local water between the basin The construction of hydropower dams in the basin in recent years raises the conflict between water demand for irrigation and power generation However, the formation of Tuyen Quang lake also has facilitated the development of tourism and aquaculture, contributing to job creation and increased incomes for labours

2.1.2.5 Soils

Covering of Gam river basin soil is formed under conditions of tropical monsoon climate mountains Therefore, yellow red soil on clay feralit and metamorphism (Fs) accounted for over 50% of tropical land basin Rule elevation and soil geomorphology is characterized by non-zonal soil mantle basin So, from a height of over 900m, and the weakening feralit appearance of the mulch, mulch Alit red loam soils with brown, yellowish red loam appear quite common, especially in the 1.500-1.800m Customary land from mining long pattern shown in the classic land-use and backward Method exploiting irrational slopes have accelerated erosion, leaching to the bare rocks in many places

Soil structure coating the Gam river basin is quite diverse and rich The abundance, diversity of land resources to allow local catchment planning in the agro-forestry development towards product diversification, combining agriculture - forestry with tourism development eco tourism community

Of the total land, soil feralit occupied the largest area, with nearly 70% of the total catchment area This is the kind of land capable of cultivation agroforestry and reforestation Groups gathered in upland watersheds Gam although small footprint but is valuable in agriculture to provide food, local food

Most of the Gam river catchment area is hilly terrain with steep slopes to erosion, washout occurred powerful Each unit of land contained in the basin are at risk of

developing the degenerative process The causes of land degradation can be caused by natural processes or by human impacts such as land use unreasonable, shifting cultivation, monoculture, deforestation, mining products Intensity erosion, runoff, soil degradation is enhanced by human activities Status monoculture, intensive burst structure and discolored soil, nutrient poor This is a very common situation in the district upstream Gam

Coating structure and soil diversity basin but fragmented distribution, retail Meanwhile, agro-forestry farming is mainly based on the production of natural difficult to create focus and specialization Most of the agricultural products obtained from the extraction, land use is ultimately self-reliant

Tuyen Quang Hydropower Project is built on the Gam river has flooded an area of arable land is quite large, mainly lowland soils capable river for farming already occupies the area very little of the total land area of the basin groups The process of migration and resettlement in the reservoirs to increase pressure on the resource type, the natural environment and the economy - society, especially for land resources The management of the State for land resources in time independent nature of each industry and in each locality should approach alone, and not inconsistent with the close coordination This raises the need to explore solutions, rational use of land resources and protect the environment in the basin

2.1.2.6 Creatures

- The vegetation: Vegetation structure of the Gam river basin are quite diverse On most of the basin and sub-types of vegetation typical of the mountains in the North and North East In particular, the secondary vegetation of the area is mainly occupied, reflecting the strong human impact in the territory of the mining process

- On the species composition of plant: Among 3.551 species of vascular plants of the Gam river, Tuyen Quang Lake area, about 1.159 plant species in 5 sectors In the flora of about 470 species of plants, 75 species of trees and natural values of 50 species of wild crops Gam river basin has an area of significant SUF This is where the richness in species composition and biological reserves, including many rare species have scientific value Across the basin was initially counted 47 rare plant species listed in the Vietnam Red Book

- On the composition of animals: According to incomplete statistics, there are about 840 species of Gam river basin higher animals Of these 163 species, 42 species of amphibians, 86 reptiles, 411 birds and 138 mammals In addition, the basin has 64 species of zooplankton, 44 species and 33 benthic taxa Tuyen Quang lake area alone, an estimated 344 species of wild animals in 4 classes, including 48 mammals, 226 birds, 50 reptiles and 20 amphibians

General biological resources, forest resources in particular have a huge role for both ecological and economic development - the local society of the Gam river basin

Naturally, most of the Gam river basin area is hilly and plateau with large split level quite popular these sensitive ecosystems, easily degraded and difficult to exploit and protect In such conditions, forest resources have an important role in regulating the flow and soil protection, limiting natural disasters, contribute to stabilizing the basin ecological environment, especially in the local area upstream

In economic terms - society, in general, biological resources have contributed to the development of certain economic - social Basin Production value of agriculture, forestry and often reaches 35 to 40% of the total production value of the sector in the local economy

Biological resources are the basis for the development of industries such as wood processing, food processing, food

Since 2008 Tuyen Quang reservoirs in operation has facilitated the development of aquaculture and fisheries and eco-tourism zone of the lake due to the predominance of natural conditions

However, so far, the extraction and use of biological resources in the basin is not really reasonable The forest exploitation and indiscriminate deforestation less strict management took place in many places for many years to increase the area of bare soil and risk of natural disasters due to deforestation From 2000 to present, the forest cover has increased, but mainly forest regeneration, recovery and upland forest

The main reason degrade biological resources Gam river basin is affected by the increasingly powerful and diverse forms of community residents living in the basin In addition, the management and protection are neglected for a long time The education, raise awareness and mobilize people to participate in forest protection and forest resources are not really effective

2.1.3 The socio-economic conditions

2.1.3.1 Population and labor

Gam river basin area of residence of many ethnics with a population of nearly 730.000 people (2010) Population structure by sex in recent years quite stable The population is not evenly distributed On the basin is 15 ethnic communities living in which people account for the largest number is Tay Number of employees in agriculture, forestry large proportion of the labor structure Population, labor and economic development - social Basin Gam relationship always closely linked By its manufacturing operations, human impact on the land, to transform it in the direction of positive or negative in order to serve

Gam river basin is an ecological and cultural diversity The communities living together

in conditions of strong natural division, with the customs and practices unique History of residence and production has long provided farmers with large capital experience in the production and exploitation of natural resources The mix of resident space, the production of the nation has created the interference of customs and production experience, creating knowledge systems of indigenous communities and ethnic minorities At a certain level, this is considered to be one of the advantages of implementing measures, advanced production model

in accordance with the natural conditions in each local residents and practices, cultivation of particular ethnic groups The exploitation of cultural values from the traditional rituals associated with spiritual tourism, eco-tourism is one of the advantages to attract more tourists to the local basin However, the restrictions on the level of awareness of the people, which is the majority ethnic minorities in several years ago had a major influence on the selection method

exploiting natural resources and protect environment

2.1.3.4 The impact of the Tuyen Quang hydropower resources, environment to the basin

Tuyen Quang hydropower dam system has a major impact on both positive and negative directions to resource, environment Gam river basin The main positive impact of

Tuyen Quang Hydropower is: power supply, improve infrastructure, enhance cultural life and facilitate the development of local industries, and flood control irrigation water as well

as to limit the damage caused by flooding downstream These negative effects are mainly: the life of a disturbed residents in parts of the project area, agricultural land - forest

submerged large; ecological environment changes etc

2.2 The situation of natural resources and environment in Gam river basin

2.2.1 The situation of soil resources in Gam river basin

2.2.1.1 The structure and distribution of soil cover

Total area of natural watersheds is 916.802,1 ha Gam, including rocky area is 130.896,5 ha and is divided into 12 major soil types Properties, soil type Gam river basin is quite diverse and dispersed Land feralit gold on red clay and metamorphism (Fs) is the largest area of 494.104,0 ha (equivalent to 53,9% of Gam river basin), followed by yellow red loam over clay and metamorphic rocks (FHs) and land on the yellow sandstone feralit (Fq) has an area corresponding proportion was 8,5% and 8,4% of the total catchment area Smallest basin is gray with yellow loam where goods are potzon (Ha) and slope convergence (D) with both types of area less than 1% of the total area Gam river basin

2.2.1.2 Change in land area by the construction of hydroelectric lakes in Tuyen Quang

Tuyen Quang lake has an area of 81,94 km2, formed by the expansion of water when the river bed The formation of the reservoir has 7.978 ha of land were flooded and converted to other uses when building the hydroelectric project items as well as changes in the nature and system of exploitation, land use after lake water Because the reservoir is characterized by steep slopes, narrow lake, the area submerged completely submerged area is big but small

The submerged a large area of flat land along the river (over 60% of the total land area flooded) has lost agricultural land by residents This is one of the big changes of the natural environment and the economic environment - social sector, requires effective measures for the protection of the natural environment and especially in the resettlement planning for local residents Flooded land slopes up 38,28% of the land flooded, mainly red and yellow soils feralit Much of this land is forest land cover and land high above the rice terraces

In addition, the construction of Tuyen Quang Hydropower also lost 440ha of land for the construction items A small portion of this area have been restored or converted to other uses after the completion of construction works

2.2.1.3 Land and rock slides in the lake and in the river bank in downstream of the dam

Landslides occurred across much of the study area, but concentrated along the roads, along rivers and streams In recent years, the phenomenon of erosion is related to the operating performance of lake water and Tuyen Quang In the upstream dam, the water level rise and groundwater to increase the volume of soil while reducing the coherence of the material increased the slope processes on the slopes The volume of rock slides are mainly engaged in the process of sedimentation of the lake, taking part in the sandy mud flow downstream Corresponding to the sliding material, the lake will be deposited at a faster rate during the first 10 years of water then slowly due to reduced supply of raw materials However, reservoir sedimentation rate over time depending on changes in the rate of vegetation cover in the basin In the downstream of the dam, regional erosion process variation early and most powerful river from the dam to the town of Na Hang

Due to time and volume of the reservoir operation of Tuyen Quang Hydropower often should not impact the Tuyen Quang hydropower to the river bed erosion and riverbank erosion and sedimentation of lakes and should be followed continue to monitor and study the longer time to complete the assessment and accurate

2.2.1.4 Land use situation of Gam river basin

The status of land use in 2010 Gam river basin is divided into 6 groups as agricultural land, forest land, residential land use land, unused land and not rocky woods Farmland Gam river basin has an area of small (91.101,1 ha), accounting for 9,63% of the total natural area of the basin Due to topographical conditions, to land the Gam river basin has an area

of forest land is very large (743.823,8 ha), including production forests, protection forests and special-use forests, accounting for over 80% of the total catchment area Group land and use land in an area of 30.000ha, accounting for 3,3% of the catchment area Unused land is 38.218,8 ha, accounting for 4,2% of the catchment area The whole basin to 13.833,6 ha non-forest mountains, accounting for 1,5% of the basin, most concentrated in Dong Van (5.550,3 ha), Meo Vac (3.558,2 ha) and Yen Minh (2.310,8 ha)

2.2.2 The situation of forest resources in Gam river basin

2.2.2.1 Forest cover situation

Gam river basin coverage is relatively high compared to other river basins of North and North East As of 2011, the entire region 338.169,3 ha are forest land forest coverage rate reached 36,9% natural catchment area In particular, the natural forest area is 322.644,0

ha, equivalent to 95% of forest area and 35,2% of the total land area of the basin

2.2.2.2 Change of forest resources due to the impact of Tuyen Quang reservoir

- On the positive side: rising water level increases the natural water supply for natural forest vegetation along the lake Ensure irrigation water also facilitates the expansion of plantation areas

in the local reservoir area Rising water levels have enriched ecosystems and habitats

- On the negative side: the construction, the entire forest area of the reservoir area to a height of 120m with artisanal mining This activity also facilitates illegal logging, as the Biodiversity and living space for many species decline When the lake water has submerged 7.987ha soil types In particular, forest land covers a large area with over 58% When the lake water has increased the risk of forest loss due to favorable mining conditions The relocation and resettlement of people in the lake as well as forest loss due to conversion purposes

2.2.3 Situation of water resources in Gam river basin

2.2.3.1 Surface flow

As of Tuyen Quang Dam Gam total water year was 10.0 billion m3, with Qo = 319m3/s Due to the impact of the structure and topography climate Gam flow should be strong differentiation in space The seasonal climate classification did flow regime of the river Gam divided into two distinct seasons The flood season lasts from May to October, accounting for over 70% of the annual flow During the flood season, due to the combined effects of the floods caused morphology, structure and topography on a network of rivers to flood Gam usually fast and pulled up slowly, causing severe flooding across the downstream, especially the city of Tuyen Quang Dry season from November to April next year In the dry season, due to the relatively large amount of rain and the possibility of regulating the flow of the buffer should flow remained approximately 130m3/s corresponds

to the flow module is 8,63 l/s/km2

Overall, the potential for surface water basin Gam large contribution to the Red river (accounting for 10,4% of the Red river in Shanxi) However, due to the higher flows in the river during the flood season should Gam often flooding downstream Therefore, the Gam river flood control will reduce the pressure of flood flows on the Red river in North Delta

2.2.3.2 River and reservoirs water quality

Water quality is assessed by the major targets, including the mineralization, nutrient content, and trace ions, organic compounds, pH, coliforms bacteria Most indicators of chemical and biological water Gam general, Tuyen Quang lake in particular have changed markedly after Tuyen Quang reservoir is formed but still within the permissible limits of regulation Vietnam 08: 2008 (B1) However, a number of indicators of nutrients, organic compounds in the reservoirs tend to increase These are signs confirming the worse evolution of water channels, related to the human activities in the basin

2.2.3.3 Change the water flow in the Gam river in Tuyen Quang reservoir conditions

Gam plays an important role in the appearance of large floods downstream Lo river The formation of the Gam river in Tuyen Quang lake has changed big flood situation downstream, reducing flood levels for Tuyen Quang town than before the dam The appearance of Tuyen Quang lake is an important agent makes the water level difference, and mode Gam flow upstream and downstream of the dam In the upstream dam, water level and water level fluctuation amplitude increases than in the absence of a reservoir In the downstream, the flood flow restriction and increased dry season flow, contributing to flood control, to ensure ecological balance and water resources in agriculture Role of lakes for flood control Tuyen Quang has been confirmed as participants and storing flood water for irrigation during the dry season from 2008 to present

In summary, the natural conditions and economic - social characteristics of the Gam river basin has the dominant characteristics, evolution and current status of the resource, environmental and mining issues, resource use, Environmental Protection basin

Chapter 3 PROPOSED REASONABLE USE OF THE NATURAL RESOURCES AND

ENVIRONMENT PROTECTION IN GAM RIVER BASIN

(THE TERRITORY OF VIETNAM) 3.1 Proposed reasonable use of land resources in Gam river basin

3.1.1 Define requirements and the rational use of land resources protection

3.1.1.1 Basin potential erosion assessment

a Classification of potential erosion for the basin

Potential erosion map of the Gam river basin is built on the model of Wischmeier and Schmid USLE based on the following components map: map rain erosion coefficient R; map of soil erosion resistance coefficient K, DEM digital elevation model; map slope coefficient length L, the slope coefficient map S

Potential soil erossion model of watershed land Gam established by Wischmeier and Schmid's formula: A=R×K×L×S Thesis conducted hierarchical level of erosion potential