2.1.4.4. Transboundary issues

Identification and analysis of trans-boundary issues are crucial for planning and decision-making in riparian governments. The following are five key trans-boundary issues identified for the Basin Development Planning of the 6C Sub-area.

2.1.4.4.1. Environmental degradation and contamination

Deforestation impacts on the environment beyond the boundaries of the concerned country. The most direct environmental consequences of deforestation are the depredation of the forest biota in the deforested area. Because forests are almost always more biologically diverse than the system with which they are replaced, this usually results in a local loss biodiversity, and potentially a reduction in global species diversity (MRC, 2003d).

An issue of great concern is the Lower Mekong Basin, and thus in the Kratie Sub-area, has been the consequences of forest clearance on hydrology and related processes, i.e. flooding, soil erosion and mass soil movement. When mature forest is cleared, the hydrological consequences depend on the subsequent use of the land.

Deforestation also impacts on society and economy. Progressive disappearance of the flooded forest in the downstream Tonle Sap Sub-area is a serious threat for fish reproduction and refuges where large numbers of people draw upon fishery resources for a high proportion of their subsistence and income needs. The agricultural encroachment that follows deforestation often causes the loss of traditional land use rights and traditional conservation mechanisms.

Water pollution by pesticides and chemical fertilisers under the development of intensive agriculture is another great concern. Even though persistent pesticides are banned in riparian countries, it is clear that residual and illegally imported stocks continue to be used because residues of DDT, Dieldrin, and similar chemicals have been found in fish across the Mekong basin.

Pesticides can also cause environmental problems through build-up in the soil, toxicity to humans and the development of resistance on the part of pests. Rapid development of hydropower projects in the upstream part of the Mekong River and its tributaries is negatively affecting the spawning and rearing of ecological systems of fish with the progressive destruction of deep pools in the provinces of Kratie and Stung Treng. When fish reproduction and migration are affected, so is the livelihood of people who rely on local resources their living.

2.1.4.4.2 Population migration

Migration is another trans-boundary issue in terms of social and geo-political implications. The search for employment is a major cause of migration. Seasonal and semi-permanent migration to urban areas provides important income for households in rural areas. Several different types of migration appear to be taking place at the same time, as suggested by national level data from Cambodia and Thailand. The largest movements are between rural areas. People relocate from densely populated rural areas to remote ones to seek new economic opportunities. Economic development in the Lower Mekong Basin, especially in urban centres, creates a strong attraction for rural people because jobs are more numerous, better paid and services are more developed.

Migration towards the Sub-area includes internal rural migrants and trans-boundary migrants for which statistics and legality remain a hot and controversial issue. Trans-boundary migrants are motivated by abundant fishery resources and the open business opportunities available after the liberalisation of the political system in 1989. There are few comprehensive and consistent data related to this migratory phenomenon.

The province of Mondulkiri accounts one of the highest rates of quite recent immigration in Cambodia, since five to ten percent of this population did not live in the province five years earlier. This phenomenon is comparable to the provinces of Banteay Meanchey and Oddar Meanchey. The provinces of Kratie and Stung Treng are also affected by a recent immigration flux at a lower rate of three to five percent, which is still significant given their geographical location in the Sub-area.

2.1.4.4.3. Fishery resources management

Fishery resources management is the perfect example of a trans-boundary issue that challenges every riparian country. Because fish reproduction and associated migration factors go beyond political, administrative and economic frontiers delimiting the States, the fishery issue is exacerbated by growing conflicts of interest between the governments. Rising waters, turbidity and/or the first rains trigger adults of many Mekong fish species to spawn (Poulsen, 2000). Long distance migratory fish species or "white" fish have adapted to spawn at the onset of the monsoon season (May to July), so that their fry and juveniles are ready to enter and feed when the plains become flooded from July to September. Short distance migratory or "black" fish species also migrate to spawn and feed in the inundated floodplains. Deep pools and channels in the mainstream of the Mekong near Kratie in Cambodia, in the Nam Theum, Nam Hinboun in Lao PDR, and in the Se San River in Cambodia are widely acknowledged as dry season refuges for fish, which re-colonize flooded areas during the following monsoon (Poulsen & Valbo, 2001). The long distance fish migrations within main river channels and their main tributaries are referred to as "longitudinal migrations." Such long distance migrations can cover distances of hundreds of kilometres from the Mekong Delta in Vietnam, through Cambodia, to Thailand or Lao PDR through the Mekong River mainstream, Lao PDR through the Se Kong River, or the central highlands in Vietnam through the Se San and Sre Pok Rivers (Coates et al., 2001).

It is obvious that any change of the eco-system occurring in the upstream region will affect and impact on the livelihood of hundred millions of people whose food supply and economic activities rely heavily on fishery resources in the downstream areas. Water quality, water availability, and preservation of the flooded forest are key conditions for the survival and sustainability of fishery resources in Cambodia.

The 1995 Agreement on the Cooperation for the Sustainable Development of the Mekong River Basin, means that attempts are being made to " Cooperate in all fields of sustainable development, utilization, management and conservation of the water and related resources of the Mekong River Basin, ...in a manner to optimize the multiple-use and mutual benefits of all riparian and to minimize the harmful effects that might result from natural occurrences and man-made activities" (Article 1).

However, among the weak-points, the Agreement does not set any strict upper limits on water use, except for trans-basin diversions in the dry season, but this is not where large potentials lie. Cambodia obtained an assurance that the reversed flow of the Tonle Sap River, following the annual flooding would be allowed. Cambodia, as a relatively small country, also benefits from the relative security of such an Agreement. More importantly, Cambodia received assurances about the protection of the water supply to the Tonle Sap Great Lake. This is perhaps the single most important factor for Cambodia. It will also benefit from improved information flow and a higher concern of overall environmental protection in the Basin. On the other hand, Cambodia is vulnerable vis a vis Thailand and Lao PDR when it comes to trans-basin diversions and other large-scale upstream water use, e.g. hydropower development. But Cambodia can expect strong support from Vietnam which has similar problems, and both have, consequently, a high interest in regional cooperation on this question. Flood control is an issue that deserves more attention in the Agreement.

To what extent does the Agreement represent a move toward a higher degree of regional cooperation or does it mean to move away from it? For instance, large-scale trans-basin diversions, the most unwanted and conflicting scenario for downstream countries, are allowed as long as the right amount of information is given and/or prior consultation is practiced, and that is done outside the critical dry season period. Even though the Agreement keeps a high profile on environmental sustainability in the Basin, it must be noted that there is yet no credible monitor mechanisms in place.

2.1.4.4.4. Fishery resource declines in figures

Table 10: Depredation of the eco-system supporting fishery resources

In the 1940s, the Tonle Sap Great Lake Region catch of 125,000 tons consisted mainly of large and medium size fish, while the 1995-96 catch of 235,000 tons contained hardly any large fish and was strongly dominated by small fish.

2.1.4.4.5. Transboundary factors impacting on fisheries resources

- Development of water resources, particularly dam and weir construction for hydroelectric power, resulting in increased water levels, increased turbidity and reduction in nutrient levels. Dams also impact on water quality, affecting downstream total suspended solids and nutrient levels, especially total phosphorus and dissolved oxygen levels. Oxygen-consuming decomposition of organic material mainly occurs at the bottom, and bottom water can become hypoxic or even anoxic if the reservoir is stratified. If oxygen-depleted bottom water is released from a dam, fish kills can occur downstream.

- The introduction of exotic fish species–if uncontrolled–represent a serious threat for biodiversity through hybridization, destruction of local species and competition for food and habitats. A good illustration of this is the mysterious introduction and banning of the freshwater species "Trey Chap" (Pirania sp.) from foreign countries for aquaculture purposes. Carnivorous and voracious, "Trey Chap" is feared because of damage to local species of fish.

- The increased and irrational use of chemical pesticides, herbicides and fertilisers in the agriculture sector is harming fish habitats and eco-systems through eutrophication and water pollution by aggressive chemical molecules, of which the use of some (e.g. DDT and Dieldrin) have been banned by the World Health Organization and other relevant international institutions, but not their production and commercialization.

2.1.4.4.6. Cambodia's demand for electrical power

The country's demand for electrical power is projected to increase from 251 MW to 746 MW between 2000 and 2016. Previous feasibility studies reveal potential hydropower sources in Pursat Province (3.5 MW) and Stung Sen (38 MW) (Bohneur, 2003).

The total potential for feasible hydropower projects in the four Lower Mekong Basin countries is approximately 30,000 MW including 13,000 MW on the Mekong's Mainstream, and the remaining tributaries' potential (13,000 MW in Lao PDR's tributaries, 2,200 MW in Cambodia and 2,000 MW in Vietnam). Only five percent (1,600 MW) of the Lower Mekong's hydropower potential have been developed, and all projects are on the tributaries, not on the mainstream. There is also huge hydro potential in the Upper Mekong Basin. In Yunnan Province of the People’s Republic of China, total hydro potential is an estimated 23,000 MW, and two projects, totalling 2,850 MW, have already begun operations.

Table 11: List of completed hydropower projects (10MW)

Negative impacts occurring from hydropower dams are as follows:

- adverse impacts on the ecosystem (aquatic life, animals, birds, vegetation);
- blocking the flow of sediment;
- negative impacts due to changing river flow patterns;
- negative social impacts (resettlement, loss of livelihood);
- loss of scenic landscapes (tourism potential);
- negative impacts on water quality due to storage of water (eutrophication, lower temperatures for discharged water);
- negative impacts to other users of water (navigation, fisheries);
- problems during the construction period (noise, vibration, dust, traffic problems), and;
- when associated with irrigation, land salinization and water logging.

The second type of risk is geo-political, i.e. the inevitable dependence of countries who do not possess hydropower upon those who develop hydropower projects. Cambodia is particularly vulnerable because it will depend on Thailand, Lao and Vietnam for power supply. A cut-off of power supply by power producers would seriously impede any possibility for Cambodia to achieve its development goals and strategies, alleviate poverty, and improve the population livelihoods, etc.

A. Geo-hydraulic conflicts:

Hydropower involves dam building which requires water diversions. Conflict may arise between upstream countries and downstream countries because of water scarcity and/or unequal allocation. The most crucial is perhaps where a basically agricultural country risks losing access to water sources and thereby is robbed of the chance to achieve food security, poverty alleviation, and possible economic growth (Öjendal, 2000). Furthermore, aggressive and hostile capture could lead to tensions and conflicts through population movements, group identity conflicts, economic deprivation and/or civil strife (Ibid).

B. Progress generated by hydropower projects:

Quite a number of positive impacts of hydro projects deserve to be highlighted:

– harnessing of a renewable natural resource;
– reducing the negative impacts that power generation has on the global environment (e.g. use of fossil fuels reduced, thus will lessen air and water pollution);
– increasing the river's flow in the dry season, and reducing peak flow during the flood season;
– increasing the availability of electrical power to stimulate economic development and improve people's living standards, and;
– revenues will be earned from the sale of power.

References

• - Ahmed et al.1996.
• - Ahmed et al.1998
• - Basin Development Planning of the Mekong River Commission, Regional Sector Overview (2002),
• - Bohneur.2003
• -Cambodia National Mekong Committee. 2003
• - Cambodian Center for Study and Development in Agriculture (CEDAC). 2004.
• - CNMC.2003
• - Coates et al.2001.
• - Colm .1997.
• - Department of Fisheries.
• - Diep et al.1998.
• - FAO.1992.
• - FAO.1994.
• - FAO.2001.
• - Hart.2001
• - Hasselskog. 2000.
• - Himel, J & Nhem, S., 1997
• - Ibid. 2001
• - International Rice Research Institute (IRRI).1997.
• - JICA.1997.
• - Nielsen. 2004.(What is the title of artcicle?)
• - Mc.Kenny & Tola.2002.
• - Mekong River Commission. 2003. State of Basin Report
• - Mekong River Commission.2003. Basin Development Plan.
• - Mekong River Commission 2003d
• - Mekong River Commission. 2003c
• - Mekong River Commission. 2003e
• - Mekong River Commission. 2002g.
• - Ministry of Environment. 1994.
• - Monirith et al. 1999. Mc.Kenny & Tola.2002.
• - Öjendal, 2000
• - Öjendal J. et al, 2001
• - Population Census. 1998.
• - Poulsen. 2000.
• - Royal Government of Cambodia. 2001.
• - T.S. Touch. 1996.
• - Van Zalinge et al.1998.
• - Van Zalinge and Nao.1999
• - Water Utilization Program- JICA.2004

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Table of contents > 2. River Basins > 2.1. The Mekong River System (Basin)

2.1.1. Introduction

2.1.2. Mekong River tributaries and Rainfall

2.1.3. Detailed survey of rainfall and surface water in the Mekong catchment

2.1.4. Water environment in the Mekong River systems

2.1.4.1. Human activities threatening to water quantity

2.1.4.2. Human activities threatening to water quality

2.1.4.3. Case study on human factors threatening to the water environment

2.1.4.4. Transboundary issues