Analysing potentials, advantages, disadvantages of natutal conditions, resources to make a basis to orient reasonable exploitation and use of Ba river basin

JOURNAL OF SCIENCE OF HNUE Natural Sci., 2008, Vol. 53, N ◦ . 5, pp. 149-160 ANALYSING POTENTIALS, ADVANTAGES, DISADVANTAGES OF NATUTAL CONDITIONS, RESOURCES TO MAKE A BASIS TO ORIENT REASONABLE EXPLOITATION AND USE OF BA RIVER BASIN Bui Thi Mai and Nguyen Van Cu Vietnamese Academy of Science and Technology Abstract. Ba River basin is of strategic importance site in economics, pol- itics, security & National Defence to the Highlands, Southern Central Viet- nam and the whole country. Protection and exploitation of potentials and advantages of the basin is very limited, natural resources are degrading, the rate of poor and hungry families is high, the cultural life of the people is low. To uphold potentials and advantages and overcome the above shortcom- ings, it is necessary to renew policies, mobilize at highest external sources to push up the economic development. Select sectors, fields of potentials and advantages as the breakthroughs for the development of each area. Increase the knowledge of ethnic groups and training of cadre staff. Especially, the Government should consider and give the decision to establish management units of the Ba River basin. 1. Introduction Vietnam's strategy for socio-economic development in the impending period, up to 2020 and the vision to 2050, assessing the natural resources for the sustainable development of the whole basin is important and of pressing significance. Ba River basin is the largest interland basin of the Southern Central Coast. The basin is rich with natural conditions and resources and ecologial environment, playing an imprortant location for the economy, polictics, security and defence of the country. However, there is the existance of natural disasters, unreasonably exploited by local people, which has caused the strong changes to natural resources. The economy of the Ba River basin is strongly and totally developing at the current time and in the future to intergrate into the economic development of the whole country. The natural resources explitation has appeared with a lot of prob- lems at different levels. Accordingly, it is necessary to provide concerns, solutions and preventative measures to these problems. Therefore, analysing advatanges and disadvantages of natural conditions and resources will become a foundation for ori- enting suitable exploitation and use of natural resources, environmental prevention and lightening natural disasters at the basin, which is of great significance both scientifically and practically. 149 Bui Thi Mai and Nguyen Van Cu 2. Content 2.1. Potentials and advantages of natural conditions and re- sources 2.1.1. Geographical location Ba River basin and the upstream of the Central Highlands together share the border with Cambodia. The region plays an important role in security, politics, de- fence and the ecological environment. It is considered to be a home roof of the Southern Central Coast with high potential for agricultural-forestal development and especially for industrial trees. This region is diversified of fauna and flora, wild animals listed in the Vietnamese, Southern Eastern Aisan and International Red Book. There is Highway No. 26, 27 and 14C connecting with the Central Highlands and the Southern Central Coast, the road 40 to Atopu (Laos), which forms good conditions to establish border gates to broaden international cooperation to the West. The downstream of the Southern Central Coast with a coastal line of 80 km in lengh, which will provide favourable conditions to develop a complex of coastal economy. In particular, this is the best location to build an Eastern and Western road, railway to Central Highlands along the Highway 25, with possibilities to con- struct a sea-port and an air-port, based on this information, Phu Yen Province will become an intersection to exchange economy and goods between the North - South and West - East of Vietnam. Besides the advantages, the basin of requently copes with natural disasters such as: storms, floods, drought etc, especially in the lower regions, which causes serious damage to property and the lives of local people. 2.1.2. Terrain The basin has a terrian with varied features of altitude layering that forms continous belt. According to the document [1,2,3], in the researched area exists several terrain layers as follows: - Layer I with an altitude greater than 1,500 m is the highest terrain layer in the basin. There still exists primeval forests in 5 layers in which there are 3 layers of wooden trees playing as a preventative layer. - Layer II with the altitude from 800 - 1,500 m popularly covers at upstream level. The fauna here is rich with a lot of big wooden trees, also playing as a pre- ventative layer. The flora here is diversified of wild and rare animals listed in the Vietnamese and International Red Book. - Layer III with the altitude from 400 - 800 m covers at upstream and middle stream levels. The forest at the terrain has 4 layers with a lot of specious woods playing preventative layers. Together with the annual average temperature of 21 o C; average rainfall from 1,500 - 2,000 mm and humidity coefficient 1.5, it creates a good condition to grow tropical trees (rubber, pepper) and subtropical trees (tea, coffee and mango). 150 Analysing potentials, advantages, disadvantages of natural conditions, resources... - Layer IV with the altitude from 250 - 400 m covers mostly at the middle stream and downstream. Annual average temperature is 22 o C, anual average rainfall from 1,500  2,000 mm, humidity coefficient of 1 - 1.5. The terrain is populated with local people and suitable to grow tropical and subtropical trees. - Layer V with the altitude from 50 - 250 m mainly covers downstream where most local people live and is a center of culture, ecnonomy, politics concerning the basin and a most favourable location to develop an economic complex. - Layer VI with the altitude less than 50 m locates near coastal lines. Annual average temperatures are greater than 26 o C, annual average rainfall from 1,500 - 2,000 mm. This location is a focus for most of population and suitable to grow tropical trees and specially to develop a complex of coastal economy. Generally, the Ba River basin includes some fairly plain areas which are suit- able for agricultural fortestal development. However, the deversified terrains with multi layers are also difficult to build infrastructures on transportation works, post offices and irrigation works. Seriuosly, with such terrain, it is a suitable condition for water discharging from the upstream to downstream which cause serious floods at downstream levels. 2.1.3. Mineral resources The mineral resources of the basin are fairly varied and diversified. According to the statistics [10], currently, there are 344 mines and mineral ore locations. Mineral resources exploiting and processing industry has brought out benefits and greatly contributed to the economic development of these coastal provinces in the past few years (Table 1). Table 1. Major mineral resources mines in the basin [3,10] Mines Quantity Locations Potentials and features Peat 5 Chu Se, Bien Ho, My Dien, Hao Son, Phuong Luu. Fairly good quality, low volume of toxic. Brown coal 5 Krong Pach, Chu Se, Buon Thoat, Phu Tuc, Xa Thu. Including conglomerate of clay, sand and pepple. Thickness from 0.2 to 3 m. Steel 9 Phong Hanh, Plei Kong Go, Thiet Dinh, Hon Gai, Nui Gai, Da Dang. At the length of 100 m, thickness from 0.4 - 13.5 m. Titan- Zircon 11 Tuy Hoa, Xuan Hai, Phu Duong, An My. Lengh greater than 10 km, width from 200 - 1,000 m. Thickness from 1.5 - 4.5 m. Aluminium Boxit 24 Dak Song, Bac Gia Nghia, Tuy Duc, Quang Son, Gia Nghia, Nhan Co. Thickness from 3 - 13 m, cover with 10 km 2 . 151 Bui Thi Mai and Nguyen Van Cu Tin 7 Krong Pach, Xlieng Dong, Chu Cam. Length up to 200 m, width from 30 - 40 m. Gold and Silver 80 Chop Vung, Suoi May, Keng Village, Le Diem Vil- lage, Ho Village, Ba River. Total estimated volume of gold at 24,000 kg and 53,000 kg silver. Black Molip 3 Northern West and North- ern East of Hon Lap. Thickness of ore stem esti- mated from 0.2 - 0.3 m. Lead and Zinc 1 Eanam. Thickness from 0.6 - 1.5 m, lenght greater than 100 m. sand, gravel 22 Located along the Ba River, ak Thong stream, Eahleo. Including quartz, fenspat. Paving stone 12 Chu Se, Tay Son, Ban Nham, Son Hoa, Deo Ca. Marble 6 Chu Se ak Lo, Kon Roi, South West of Kan Nak, South of Cong Lo Hem. clay, Brick 38 Located along the valley, small rivers and streams. With the lengh up to 10 km, width from 1 - 2 km, thickness from 2 - 4 m. Kaolin 11 Phong Hau, Chu Se, Eake- tan, Eaknop. At present, many kinds of mineral resources are being exploited at different levels and scales by individuals and organizations especially cement limestone, stone for construction, peat and sand. Many constructing stone mines have been estab- lished and met both quantity and quality requirements to serve construction works in the basin. However, almost of exploiting and processing activities have been not oriented from a master plan, which therefore leads to ineffective investment, unrea- sonable natural resources exploitation and environmental pollution. 2.1.4. Climate Resources Due to the basin location at both the two eastern and western coastal lines of the Truong Son mountain chain, the climate is clearly divided on space and time. a. Upstream of the Ba River. The upstream of Ba River is mainly at an altitude greater than 500 m in Konplong, Kon Ha Nung Highlands and a part of Pleiku Highlands, the climate is divided into cases as follows: - The climate at altitude greater than 800 m: The base temperature is lower than tropical standards (less than 8,000 o C), some locations less than 6,000 o C, no month at which the average temperature is greater than 25 o C, the highest tempera- 152 Analysing potentials, advantages, disadvantages of natural conditions, resources... ture does not exceed 37 o C, the lowest temperature may reach below 6 - 7 o C. Annual average rainfall is from 1,500 - 2,000 mm, the rainy season is from April to October. Annual humidity coefficient is from 1.5 to 2.5 [2]. This location is suitable to grow subtropical trees (coffee, tea,. . . ). - The climate at the altitude from 500 - 800 m: The base temperature reaches tropical standards (from 7,500 - 8,500 o C), the average temperature is more than 25 o C during 1 to 3 months, the highest temperature reaches from 39 - 40 o C, the lowest temperature is from 10 - 11 o C in the cold season which appears in December and January. Annual average rainfall is from 1,800 - 2,000 mm. Annual humidity factor is from 1.5 - 2.0 [4]. The climate here is suitable to grow tropical trees (mango, tea, coffee,. . . ). b. Middle stream of Ba River. Segments of middle stream extends from Cheo Reo - Phu Tuc to Dong Cam dam, with the terrain altitude varying from 400 - 1,000 m and the climate is divided as follows: - The climate at altitude greater than 800 m: This terrain covers a small area. The base temperature is lower than tropical standard values (less than 8,000 o C), the average temperature is more than 25 o C, the highest temperature does not exceed 37 o C, the lowest temperature is less than 7 o C. Annual average rainfall is from 1,500 - 1,800 mm. Annual wet humidity factor is from 1.5 to 2.0 [4]. The rainy season is mainly from May to November. The climate here is suitable for planting subtropical trees (mango, coffee, tea,. . . ). - The climate at altitude less than 800 m: The base temperature here is higher than tropical standard values (8,000 - 9,000 o C), there are only 1 - 2 months at which the average temperature is lower than 25 o C, the highest temperature reaches from 39 - 40 o C, the lowest temperature is down to 9 - 10 o C. Annual average rainfall is from 1,600 - 1,700 mm, somewhere less than 1,400 mm. Annual wet humidity factor is from 1 - 1.5 in some locations, it is lower than 1.0 similarly as Ayunpa [4]. This area is suitable for growing tropical trees. c. Downsteam of Ba River. The downstream of Ba River has a high base temperature, average temperature is greater than 26 o C equivalent to annual temperature total of 9,500 o C, sunny season prolongs from 8 - 9 months, the highest temperature is greater than 40 o C, the lowest temperature rarely drops down to 12 o C. Usual average annual rainfall is in the range from 1,500 - 1,800 mm, however the rainy season is within 3 - 4 months leading to heavy rain intensity. Annual wet humidity factor varies from 1 - 1.5 [4]. This area is suitable to grow typical tropical trees, xerophyte and allows for planting 3 crops of rice per year. Generally, the basin of Ba River has a neutral temperature in upstream and middle stream areas therefore it is suitable to grow subtropical and temperate trees at terrain altitude greater than 800 m and tropical trees at an altitude lower than 153 Bui Thi Mai and Nguyen Van Cu 800 m. The downstream of Ba River that has various temperature resources is a good area to plant typical tropical trees and xerophyte. Humidity resources are diversified but not dispersed regularly on space and time hence the dry season is severe and lasts a long time, plus particularity of a terrain area difficult to reserve water resulting in droughts in this season. In the downstream area, rainfall in the rainy season is high but appears in short spurts, especially this area each year is usually effected by thunderstorms resulting in massive flooding. 2.1.5. Water resources a. Water sources. - Network of river, stream. Total rainfall in Ba River valley is 24.05.10 9 m 3 , the same with rainwater layers are 1,730 mm [3]. In Ba River valley, the part of Hinh River with the most profuse water source and rainfall layer is 2,760 mm. Ba River valley has over 100 estuaries with the length of over 10 km, in which the rivers are affected strongly to the main stream flow are 04 estuaries (Table 2). Table 2. The rivers, streams in Ba River valley [3,9] River Flv Xo Yo Qo Mo Wo ∞ (km 2 ) (mm) (mm) (m 3 /s) (l/skm 2 ) (106 m 3 ) Ayun 2,950 1,580 597 55.8 18.9 1,760 0.38 Krong H'nang 1,840 1,700 684 39.9 21.7 1.260 0.4 Hinh 1,040 2,760 1,859 61.3 58.9 1,930 0.67 Ba 13,900 1,730 743 328 23.6 10,332 0.43 - Annual flow varies. The flow in Ba River valley changes complexly. In the upstream that are affected by climate of West Truong Son so that summer and the flood season comes and finishes sooner in comparison with the lower section affected by the climate of Eastern Truong Son. Out of that feature of natural geography also strongly affects the change of flow in the year. The Document [3,9] shows that: in the year of heavy water, increasing 1.5 - 2 times of numeric value in many years, in the year with heavy water it can increase from 3 - 6 times in comparison with the year with lower water, in which the change of rainfall is not much. Coefficient of annual flow change in Ba River valley changes from 0.35 - 0.45 [3]. - Annual flow distribution. According to document [3], the flood season in Ba River valley as follows: + Ba River upstream; the flood season extends to about 5 months, from July to November, as 70 - 75% annual flow. The months with the biggest flow are August 154 Analysing potentials, advantages, disadvantages of natural conditions, resources... to October, as 17 - 24% of annual flow. Dry season extends 7 months, from December to June of the next year, as 25 - 30% of annual flow. March, April are the months with the lowest, as 1.3 - 3.3% of annual flow. The small steam branches do not have water in March and April. + Middle stream of Ba River: This area includes area along to Ba River valley extending to the upstream of the Krong Ana River. The flood season extends from September to December, as 70 - 75% of annual flow. November has the largest flow as 22 - 27% of annual flow. The dry season extends 8 months from January to August as 25 - 30% of annual flow. March and April has the smallest flow around 1.7 - 2.0% of annual flow. There is a crest of a flood caused by early rainfall annually in June. + Lower of Ba River: The area of Eastern Truong Son includes the whole of the lower region of Ba River. The flood season lasts about 3 months, from October to December, as 65 - 75% of annual flow. November has the largest flow, as 30 - 35% of annual flow. The dry season extends about 8 - 9 months, from January to August, as 25 - 35% of annual flow. On annual equation of flow there are 2 dry periods in April and August. The largest flow reaches about 2% of annual water flow normally in August. At present in Ba River valley have been built 332 irrigation works with various types: 153 water reservoirs, 119 dams, 60 pump stations [9]. In the whole year the water source in Ba River valley can meet requirements. However, calculating balance of water source for each period we can see a shortage of water source in the dry season. If the water source in the dry season is used to meet the demand of using water, the flow of river does not meet the demand of maintained flow. Demand for using water in the dry season is over 33% of potentiality of incoming water source. At present, demand for using water in the dry water on Ba River valley as 33.2%; up to 2010 is 59.4%; up to 2020 is 75.3% [3]. Therefore, natural water source and demand of using water in Ba River valley show that the importance of work resolutions to adjust the flow to recover the shortage of water in the dry season and adjust water in flood seasons. b. Water environment. Documents [3,11] show that surface water source in upstream is clean, the con- tent of substances is still in permitted standards, excluding some polluted areas due to nutriment, organic substances. Surface water source in middle and lower sections affected by riverside residential areas, towns, operations of industrial manufacturing companies so that they are polluted by nutriment, organic substances, the content of chemical elements of Cu +2 , Zn +2 , Pb +2 ,... are over permitted standards and in- creasing in the coastal areas. The areas affected by tide is salty contamination areas, especially in the dry season when the water from upstream is low. Salinity of Ba River water in the coastal areas changes from 0.02 - 6%0. At Tuy Hoa station, the largest salinity is 5.52%0, the smallest salinity is 0.017%0. Largest salinity of river water often occurs in the dry season and by June reaches 1.01%0 [3]. 155 Bui Thi Mai and Nguyen Van Cu 2.1.6. Land resources Land resources in Ba River valley are much diversified and found in many different terrains, belonging to 9 groups as follows (Table 3): Table 3. Land groups in Ba River valley [6] No Name Area (ha) Ratio (%) 1 Sandy soil group 5,320 1.04 2 Alkaline soil group 608 0.11 3 Alluvial soil group 45,999 9.0 4 Stagnate sloping soil group 611 0.12 5 Infertile soils group 81,649 15.97 6 Black soil group 26,612 5.2 7 Yellow-red soil group 308,156 60.3 8 Humus soil in mountain 18,924 3.7 9 Gravel eroding soil 23,321 4.56 Total 511,200 100.0 Table 4. The area of form of using lands of whole valley [3,7] Whole valley Total Fish-breeding, agricultural dedicated lands Agricultural, forestry and changed lands Production forestry lands Protecting forestry lands Area (ha) 1,390,000 343,793.7 454,840.6 326,650.5 264,715.2 % in com- parison with total areas 100.00 24.73 32.72 23.50 19.5 Among 9 groups of land above (Table 3), the groups having the best conditions for socioeconomic development of the valley are alluvial soil;