Thematic studies and sector
Below, ultra-short summaries are given of the comprehensive thematic studies and sector studies that were made in connection with the Kok River Basin project.
The study lists the available hydrological data: Rainfall (22 stations, 22 years, data coverage 92 percent), streamflow (10 stations, up to 20 years), and climatological data (1 station, 30 years). On this basis, annual water balances are presented. Information about groundwater is minimal.
Present and planned irrigation schemes are described. Today, an area of 675,460 rai is irrigated by 227 schemes. Planned projects (excluding the Nam Kok scheme in Myanmar) will generate a potential irrigable area of 196,000 rai. This represents an expansion of 29 percent. The actual effect is larger, because the scarcity of water implies that not all the potentially irrigable area can actually be irrigated, particularly in the dry season. It is found that the actually irrigated areas will increase by 55 percent and 33 percent in the dry and the wet season, respectively (or 130,000 rai and 638,000 rai). The regulation will also reduce the flood risk in the wet season. The average flow (for the entire basin) is expected to decrease by 30 percent.
The demand of water is analysed in depth for irrigation, which is by far the predominant use. The analysis comprises crop water requirements, effective rainfall, and irrigation efficiencies. A representative cropping calendar for water demand is composed of paddy in the wet season (June through October) and shallot in the dry season (January through April).
The findings of the study are summarised in concluding chapters that evaluate the planned developments and the development potential as such. In general, the planned developments are found useful and technically and hydrologically feasible. Demand side management will be less effective, but will also require less investments and have much less environmental and social effects. Watershed management can improve the natural storage, and rehabilitation of irrigation schemes can improve their efficiency. There is also scope for non-structural development measures, like improvement of irrigation management and field application efficiencies.
Following a data review, 13 rainfall stations were applied, with an average data coverage of 90 percent. All the stations are located in the Thai part of the Basin. The rainfall in the Myanmar part has been estimated from Thai stations near the border.
The modelling was made by the NAM model, which is a conceptual distributed rainfall-runoff model. The model describes exchanges between (1) the atmosphere; (2) a snow cover (if any); (3) surface storage; (3) root zone storage; and (5) the groundwater. Among the transport mechanisms are rainfall, evaporation, evapotranspiration, overland flow, infiltration, capillary flux, groundwater flow and abstraction.
For the purpose of the analysis, the Basin was divided into 7 sub-basins. The model was calibrated against measured discharges covering 74 percent of the total area. The time increment was 1 day.
The analysis comprised the period 1976-1997 (22 years). Over this period, the water balance of the Basin changed visibly. In 1976-86, the surface runoff was 34 percent of the rainfall, while in 1987-97, the surface runoff had increased to 46 percent of the rainfall, presumably owing to catchment degradation. The latter period may be regarded as indicative for present conditions.
Two calibration periods were applied: 1976-87, and 1987-98. The former illustrates the base conditions of the basin, at a time when the basin was less affected by regulation and land use intervention than it is today. The latter represents present conditions and the present state of development. With this starting point, three scenarios have been examined: (1) planned conditions, representing the presently planned regulation and developments; (2) potential conditions, representing the ultimate sustainable development of water resources; and (3) Nam Kok Reservoir, representing the planned conditions including the 3,000 Mm3 Nam Kok Reservoir. Scenarios (1) and (3) include the Kok-Ing-Nan diversion.
Results are presented as time series of discharges at the Fang-Kok, Lao-Kok and Kok-Mekong confluences, and as predicted satisfaction (and abstraction) over the year of the demand for irrigation water at selected locations. More results are available as data files and graphical presentations.
Today, no part of the project area is sewered, and there are no treatment plants. The water consumption is estimated at 312 l/person/day in Chiang Rai municipality, and 200 l/person/day elsewhere.
In connection with the study, surface water samples were collected in April and November, 1999, at 9 locations on the main rivers in the project area. The samples have been analysed for 15 parameters as a basis for comparison with the NEB (1994) standard for 5 classes of surface water. Furthermore, older data (1991-98) are listed, as well as some analyses for heavy metals (from 1993 and 1995) are listed. In broad general, the water quality is characterised as fair or good.
The study describes present plans for sewage treatment, and recommends on practices and guidelines for management of sewage disposal from Chiang Rai, various districts, industry, livestock (the major source of pollutant loadings), and agriculture.
The study has produced estimates of the present and future pollution loads to rivers and streams in the Basin. The analyses comprise the area distribution and supply rates of BOD, nitrogen, phosphorus, and E. coli bacteria.
The results indicate that the surface water quality today is generally good, although there may be local and seasonal deteriorations that have not been resolved by the analysis. Disposal of untreated sewage from Chiang Rai is mentioned as a particular problem. Also, the predicted future water quality is characterised as good, although slightly below the present level. This is because the effects of increased loadings from a growing population and industrial expansion are not fully compensated by the improvements obtained by upland reforestation and water reclamation.
The Kok River Basin, like almost all Thai watersheds, has been gradually degraded. It is characterised by stressed ecosystems, distorted water yields caused by deforestation, soil erosion, landslides and downstream sedimentation, and, in turn, reduced soil fertility caused by soil erosion and leaching of nutrients. Visible effects are lack of water in the dry season, lowering of the groundwater table, and increased floods in the rainy season.
The study describes the present state of the watersheds, and the character and effects of human interventions. Upland areas and mountains are exposed to (i) population pressure by growth and migration; (ii) degradation caused by deforestation and excessive slash-and-burn agriculture; and (iii) forest fires, which can be either natural or set alight for various reasons. Different types of upland cultivation are described.
The causes and effects of soil erosion are described in relation to (i) physiographic factors; (ii) the climate; (iii) the soil; and (iv) the land use. The average soil erosion in the project area is estimated at 6.4 t/ha/year (which reflects a classification as 'moderate'). In 30 percent of the project area, the soil erosion is classified as 'severe', and nearly 1 percent is classified as 'very severe', applying the OEPP (1995) criteria for soil erosion severity.
Recommendations on watershed management practices comprise (i) reforestation; and (ii) soil and water conservation. Reforestation is divided into headwater protection, commercial plantation, fruit cultivation and agro-forestry. Soil and water conservation comprises agronomic measures (compost, cover crops, crop rotation, and mulching), and mechanical measures (for example bench terraces, contour tillage, hedgerows, minimum or zero tillage, soil barriers, and water harvesting). Principles are outlined for implementation of such practices, which should build on the needs of the farmers and their knowledge about options and attainable benefits.
As a separate activity, the study describes options for management and sustainable development of agro-forestry systems for mountainous lands.
The study has been based on topographic army maps, soil and land use maps compiled by Land Development Department in 1992, and satellite imagery from March 1998. The information has been analysed by a GIS tool.
The soil suitability has been classified into 5 categories, characterised by the topography (slope) and the soil composition. The land use has been classified into 14 zones, depending on the actual land use.
It was found that 65 percent of the Basin is unsuited for cultivation because of steep slopes. There is no potential for expansion of the paddy cultivation area. A part of the area that is now used for upland crops is threatened by soil erosion. There is a need of protecting the remaining forest areas from fires and encroachment. Certain steep headwater areas should be reforested.
The study describes present crops and cropping practices in each sub-basin. The following problems and constraints have been identified: (i) Low soil fertility (due to soil properties, poor management, or soil erosion); (ii) soil erosion in areas with steep slopes; (iii) use of land that is unsuited for cultivation; (iv) encroachment of forests causing soil erosion and high runoff; (v) lack of water; (vi) landholdings being too small, and lack of ownership; (vii) excessive use of fertilisers and pesticides; (viii) lack of knowledge about new technologies; (and (ix) top-down government policies that are not accepted by the target groups.
The following development options are suggested: (i) A partial replacement of paddy cultivation with cash crops; (ii) integrated farming; and (iii) development of fish ponds in areas that are suited for this purpose, such as the Lower Kok Basin.
The combined registrations from different surveys indicate the presence of 115 species in the Basin, belonging to 22 families of fishes and 1 family of freshwater prawn. There are several commercial species and exotic species, but no endemic, rare or endangered species. Several species migrate between the Kok Basin and the Mekong. The standing stock is estimated at 3-4 kg/rai, which is well below the 15 kg/rai found in productive rivers and reservoirs elsewhere in Thailand.
The study describes present fishing practices, which are simple and with a small yield. Capture fishery is typically practised as a side occupation, or for own consumption on a non-commercial basis. In the dry season, fishing is done by cast net, pole and line, and (illegally) by electro-fishing. In the wet season, bamboo traps are used as well. The non-commercial yield is 0.5 - 5 kg/person/day in the dry season and 5 - 6 kg/person/day in the wet season. The corresponding figures for commercial (side occupation) fishery are 2 - 6 and 10 - 15 kg/person/day.
The present trend is a degradation of the fish resource, possibly due to over-exploitation and pollution. Restoration requires targeted management and a number of regulatory measures, including prevention of over-exploitation and reduction of the pollution. There is scope for development of aquaculture, either as intensive or semi-intensive monocultures, or in connection with integrated farming.
Two sources of solid waste are considered: Hospitals and private households. There are 194 hospitals and 263 clinics in the project area, with an estimated waste production of 0.36 kg per bed per day, or a total of 230 t/year of infectious solid waste (1998 data). The household production is estimated at 0.9 kg per person per day for Chiang Rai Municipality, and 0.5 kg per person per day elsewhere (1992/96 data). This gives a waste production in 1998 of 33,000 t/year, 43 percent of which is from Chiang Rai Municipality. The projected growth is largely confined to Chiang Rai Municipality, where the waste production may possibly escalate by a factor 22 from 1998 to 2020.
The study gives a summary of disposal practices and various related problems in each district. In many cases, it is difficult to locate suitable sites for waste disposal. In several cases, inappropriate operation causes pollution, or annoyances to people living nearby.
Since 1996, the garbage from Chiang Rai Municipality has been disposed on a controlled site, with a plastic membrane, geotextile, a drainage layer and drainage pipes for leachate collection. The waste is continuously covered by topsoil. Leachate is removed by evaporation or by overflow to a pond with an impermeable membrane. The disposal site will require expansion within a few years. A pilot project for waste separation was initiated in early 1999, but was discontinued due to lack of funds.
The study presents recommendations on the short-term and long-term management of domestic waste and infectious waste, respectively. The recommendations comprise structural as well as non-structural measures. Among several other measures, the public should be encouraged to Reduce, Reuse, Recycle and Repair the waste.
During the surveys, samples were collected of plankton, benthic fauna, and aquatic weeds. The results are presented and discussed.
The study provides an outline of an aquatic management plan. The potential for development of reservoir fisheries is mentioned. Among other targets, it is suggested that a minimum depth of 1 m should be maintained throughout the year in the rivers and their tributaries. Also, obviously, an appropriate water quality should be aimed at.
A separate chapter deals with wetland conservation. There are two particular wetlands in the project area, both of which are located in Chiang Rai Province: Nong Luang and Nong Wiang. Neither is in a pure natural state, but they serve as habitats for a variety of plants, fish species and other animals. Their ecosystems are not known in detail. No conservation measures have been imposed officially, but the local communities have regulated hunting and fisheries on a voluntary basis.
The general economic growth in 1990-1995 was concentrated on manufacturing, construction, transport and communication, and wholesale and retail trade. Agriculture was stagnant, as well as the service sector. Industry is not visible in the statistics.
In 1997, the population in the project area was 206,848 persons in the Chiang Mai Province part, 36,974 persons in the Chiang Rai Municipality part, and 436,428 persons in the Chiang Rai Province part outside the Municipality. A projection based on 1993-97 data points at a strong growth in Chiang Rai Municipality, and a slight growth elsewhere in the project area.
The following social indicators have been analysed: Population and households, education, labour migration (type of work, place and period), domestic supply of water (source and adequacy) and electricity, durability of house, and use of toilet. The following economic indicators have been analysed: Land holding, land use, rice cultivation area, dry season cropping, livestock/fishery/cottage industry, farmers' organisation and farmers' credit, and household income.
Areas of concern are (i) low education by national standards; (ii) poor health service by national standards; (iii) problems related to drugs, HIV and crime; and excessive migration, including cross-border migration.
A discussion is made of the implications of a water fee and a wastewater treatment charge.
Furthermore, the study describes the development of the tourism sector on the basis of data from TAT. In 1997, tourism generated an income of 5.4 bio. baht in Chiang Rai Province, and 20.9 bio. baht in Chiang Mai Province. There is a strong potential for a continued growth of this sector.
The study points at a potential for industrial development within fruit juice, processing of vegetables, orchids, ceramics, electronic parts, artificial flowers, jewellery, antiques, and milk and milk products. A recommendation is given on establishment of a university in Chiang Rai Province, and upgrading of the communication network.
A distinction is made between governmental administrative institutions and local self-governing bodies (or municipalities). The governmental administrative levels are province (changwat); district (amphoe); sub-district (tambon); and village (muban). The self-governing bodies are (1) the provincial capitals, which are classified as metropoles (nakhon) (like Chiang Mai) or towns (muang) (like Chiang Rai); and (2) the sub-districts (tambon). The provincial administrations are linked with the central administration in various ways, including administrative officers, who are employed under the provincial governor, but who serve as counterparts to the different ministries. The tambon administrations are new and are not yet consolidated. There are two types of informal, participatory institutions: The well-functioning people's irrigation systems, and the labour exchange system, which is now on a decline.
A total of 21 NGOs operate in Chiang Rai province (1999). They are involved in community development, including support to ethnic minorities, health promotion and AIDS alleviation, environmental preservation, and general social work.
In Chiang Rai province, there are somewhere around 145,000 hilltribe people and around 20,000 minority people (or 11 and 1.6 percent of the population, respectively) (1998 data). These people live mostly in the highlands.
The study gives an outline of mechanisms behind public awareness and attitudes, and types of conflicts of interest. It is evaluated that a positive attitude can be relied on towards integrated management of water resources and the environment. Recommendations are made on public consultations and institutional strengthening.