Within the context of climate change, the province of Phuket in Thailand is the only province in Thailand without any large rivers, which means that it is potentially at risk from problems associated with water scarcity in the future. Phuket Island is also the largest island in Thailand with an area of 543 km2 comprised of three districts (Thalang, Muang and Kathu); 77% of the island is mountainous and 23% consists of plains, primarily in the central and eastern regions. Most water is derived from rainfall, which is stored in reservoirs, mine shafts, and groundwater sources. Due to geography, Phuket is a popular tourist destination. Rates of development in the hotel industry and residential areas, as well as the population, have been rapid in recent decades. However, these developments have severely degraded watershed areas. Economic growth and increases in the number of tourists has resulted in an increase in demand for water, and in the year 2020 consumption exceeded 100,000 m3/day (Provincial Waterworks Authority 2020). Moreover, trends of water use in Phuket are expected to increase by 12% annually, and it is forecasted that the water demand for local consumption and tourism will rise to 103.07 million m3/year in 2032 (Patong Municipality 2020). As the water supply in the three major reservoirs (Bang Wad, Bang Niew Dam and Klong Katha) are limited due to long periods of a dry weather (Provincial Waterworks Authority 2020), there are problems of water scarcity in Phuket and other areas with public water systems in the province. The droughts in 2002 and 2019–2020 caused severe water scarcity in Phuket, and this has become an important issue that the province needs to address.

FormalPara Rainfall

Phuket typically experiences a tropical monsoon climate with a seven-month dry season (mid-October to mid-May) with occasional rain, and a five-month rainy season. A study of monthly rainfall in Phuket found that the rainfall was lowest in January–February (30–35 mm) and highest in August–October (303–385 mm). Monthly rainfall increases from March to October. Figure C7.1 shows monthly rainfall of the three districts and average monthly rainfall of Phuket. Annual rainfall of Phuket is in the range of 1882.7-2713.5 mm, with the average value of 2200 mm/year. The annual rainfall was below average in 1997, 2002, 2005, 2019–2020, which might be caused by the El Nino phenomenon (Golden Gate Weather Services 2020).

Fig. C7.1
figure 1

Monthly rainfall (mm) of Thalang, Muang, Kathu districts and average monthly rainfall in Phuket

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FormalPara Groundwater

Groundwater resources in Phuket can be classified into two types based on the degree of compaction and cementation, which are unconsolidated aquifers and consolidated aquifers (Department of Mineral Resources 2020). An evaluation of groundwater resources showed that 5.11 million m3 was extracted from 1024 groundwater wells.

FormalPara Surface Water

Surface water in Phuket consists of reservoirs, mine shafts, peat bogs, and canals (Irrigation Office 2020). The major source of water supply in Phuket is from the Bang Wad Watershed located in Kathu District (Fig. C7.2). The main canals are the Bangyai, Krang and Tha Yang canals, which have annual discharges of 49.02, 45.17 and 45.09 million m3, respectively. The average annual discharge is 153.29 million m3. Water storage capacity in the three main reservoirs of Phuket, i.e., Bang Wad, Bang Niew Dam and Klong Katha were 10.20, 7.20 and 4.32 million m3 respectively. In addition, the water storage capacity of 109 old tin mines was 21.02 million m3.

Fig. C7.2
figure 2

Bang Wad Watershed, Phuket

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FormalPara Water Resource Management

The problem of water shortage due to climate change and tourism development of Phuket requires good planning and management. The main issues related to water resource management in Phuket are as follows: (1) insufficient water supply for consumption by the local population and increasing inbound tourists; (2) incomplete area coverage by Phuket Provincial Water Works Authority; (3) lack of land to expand the main water lines; and (4) lack of budget for water resource development and service area expansion. To resolve the water supply problem, it is necessary to identify potential water sources, including feasibility studies in various fields that will resolve the problem of water shortages during the dry season. In conclusion, the solutions for mitigating water shortages in Phuket are as follows: (1) increase water storage: development of small irrigation projects, old tin mines and peat swamps; (2) improve the water retention capacity of main reservoirs; (3) provide more water to main reservoirs; (4) develop a water drainage system between main reservoirs; (5) develop groundwater pumping; and (6) transfer water from outside of Phuket (Phuket Provincial Administration Organization et al. 2020).