variations in temperatures due to maritime influences. Most of the country receives a mean annual rainfall of . However, certain areas on the windward sides of mountains such as Ranong Province on the west coast of southern Thailand and eastern parts of Trat Province receive more than of rainfall per year. The driest areas are the leeward sides of the central valleys and the northernmost portion of south Thailand where mean annual rainfall is less than . Most of Thailand (north, northeast, central, and east) is characterized by dry weather during the northeast monsoon and abundant rainfall during the southwest monsoon. In the southern parts of Thailand, abundant rainfall occurs in both the northeast and southwest monsoon seasons with a peak in September for the western coast and a peak in November–January on the eastern coast. Resources and land use Natural resources Tin, rubber, natural gas, tungsten, tantalum, timber, lead, fish, gypsum, lignite, fluorite, arable land. Land use Arable land: 30.7% Permanent crops: 8.8% Other: 60.5% (2011) Land ownership Pattamawadee Pochanukul, a lecturer from the Faculty of Economics at Thammasat University, estimates that about 59% of all arable land in Thailand belongs to the state. the Treasury Department owned 176,467 plots of land, consisting of about 9.9 million rai (15,769.6 km2). The Ministry of Defence owns about 2.6 million rai (4,230 km2) or about 21.2% of total public land. Information from the Office of the National Anti-Corruption Commission (NACC) shows that members of the house of representatives in 2013 owned a total of 35,786 rai of land (about 57.3 km2). Irrigated land Total: 64,150 km² (2007) Total renewable water resources Total: 438.6 km3 (2011) Environmental concerns Natural hazards: Land subsidence in Bangkok, resulting from the depletion of the water table; droughts (see also 2004 Indian Ocean earthquake and 2011 Thai floods). Thailand is highly exposed to the effects of climate change such as the rising sea levels and extreme weather events. Drought: Droughts are a persistent feature of Thailand's climate. Droughts appear to be worsening: the drought of 2020 is expected to be the worst in four decades, according to the Thai Meteorological Department. and drought hazard mapping. Air pollution Water pollution from organic and factory wastes Deforestation Soil erosion Wildlife populations threatened by illegal hunting International environmental agreements Party to: biodiversity, climate change, climate change-Kyoto Protocol, desertification, endangered species, hazardous wastes, marine life conservation, Ozone layer protection, tropical timber