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6.1.2 Muang Chiang Rai
During the monsoon periods, heavy rainfall trigger every year flooding of various intensity within Muang Chiang Rai. The capacity of the river and associated canal network is not
sufficient to cope up with the sudden inflow of water due to intense rainfall. The water level thereby rises rapidly, leading to flooding and erosion. In July 2000 massive floods occurred
and overwhelmed the city, destroying the surrounding agricultural fields and farm land, affecting livelihoods and leading to business interruption for several days. In 2006, flash
floods occurred and affected the built-up areas and environment as well as the utility facility network within the city. Transportation system was blocked and tourist activities ceased to be
active for several days. Loss of crop and economic breakdown led to migration wave of rural population to Bangkok and other cities.
Water run-off is constantly increasing due to inadequate land-use planning coupled up with increasing climate variability. Landslide and mudslide are becoming substantial issues to
urban as well as rural population. Muang Chiang Rai has to face over the past decade several significant destructions due to slope destabilization during extreme weather events. The
topography of the Muang Chiang Rai area associated with heavy rainfall events and unplanned human settlements increase the landslide risk. Reported damages and losses to
livelihoods, infrastructure and property due to landslide disaster events over the past shows rapid trend in increase. In fact, each year several events of landslide occur in the high
gradient zone of topography. For instance, in 2005, seven events have been reported in Chiang Rai province, affecting a total area of 800 square meters; and in 2007, four landslide
events occurred, affecting 300 square meters.
Tropical storms are highly frequent in Muang Chiang Rai. Since the beginning of the eighties, the cyclone frequency trends have been accelerated. Strong winds, comprised between 63
kmh and 118 kmh and associated heavy rainfall events are often reported during cyclone period. When storms bring ice rain the situation becomes devastating as it was reported in
year 2008 which has created loss of farm land and heavy destructions to shelter in several communities.
Drought is also a main concern of the province. In April 2008, a period of extreme drought hit the province. The water level of the Mekong River was very low, impeding the boat tours
and creating difficulties to work force usually commuting from rural areas. According to TNA, 314,000 families in 18 districts have been heavily affected by water shortages. The
lack of options for irrigation of agricultural areas has led to the loss of harvest and crops. In fact, more than 68,000 rai 27,700 acres of agricultural lands have had severe impact due to
drought. The provincial authorities have declared the 18 districts of Chiang Rai as a drought ravaged area in order to provide relief measures.
Environmental degradation is also of concern to Muang Chiang Rai due to reported levels of water pollution as much as air pollution. Many communities within Muang Chiang Rai use
the Mekong river water for domestic purposes such as dinking, cooking etc. The pollution level of the river as well as more frequent events of drought, influence the concentration of
bacteria in river water in a considerable way, and currently have significant impact on daily life of lot of people as they are heavily dependent on Mekong river being the only source of
82 water. Health hazard is thus increasing, especially to the water related diseases. The
concerned pollutants in the Kok River running through the city are Dissolved Oxygen DO and Total Coliform Bacteria TCB. The city, resulted due to expansion of its commercial
activities, is one of the sources of pollution. As per the records City area is also a place where the rate of TCB increase is highest within Muang Chiang Rai. On the other hand up stream
sources of Mekong River and its drainage network, highly contribute to the pollution state in Muang Chiang Rai. Spills from ships, industrial waste, domestic sewage, drainage water from
solid waste deposits and landfills are some of the sources of pollution of Mekong River and believed to be added in upstream areas such as China .The municipality which is located
downstream also contribute to further increase in pollutant levels through the Kok River which is a part of the catchment. Concerning air quality, with higher number of days
exceeding standards of ozone indicator, show an increasing trend, even with limited data as the station used for measurements is only three years old. The direct consequence of high rate
of low-level of ozone is the formation of smog. Furthermore, the number of days of PM10 exceeding standards is also increasing within Muang Chiang Rai and this trend has a
possibility for deepening the risk of respiratory diseases development such as lung cancer.
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Figure 6.3. Damages and destruction in Chiang Rai province Source: DDPM provincial office, Municipality
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6.1.3 Muang Hat Yai
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