Taipei City Government

Taipei City is situated in the northern part of Taiwan Island, and the northeastern tip of the Taipei Basin. It borders New Taipei City on all sides. The city's easternmost point is Jiuzhuang Ward in Nangang District; westernmost point, Guandu Estuary of Guandu Ward in Beitou District; southernmost tip, Zhinan Ward in Wenshan District; northernmost tip, Hutian Ward in Beitou District.

The city covers a total area of 271.7997 square km; and it is divided into 12 administrative districts. Geologically speaking, Xindian, Taipei and Kanjiao are the three great faults that span the city. The city's strata is made up of sedimentary terranes and igneous rock. According to the geological map released by Central Geological Survey, other than Datun Volcanoes, which consist of igneous rock, the remainder of the exposed strata is made up of sedimentary terranes. Further, Taipei City’s terrains are divided roughly into three types of landform: Taipei Basin, the over-thrust fault ridges, and Datun Volcanoes. Taipei Basin is a basin area formed by fault displacement; and erosion activities by Tamsui River and its tributaries contribute to the way it looks today.
 

Taipei City sits in the northeastern region of the basin. The bottom of the basin is low and flat, and slopes northwesterly from the southeast. Tamsui, Xindian and Keelung Rivers snake across the basin. Between the three, Keelung River has the most prominent meandering river course; the geomorphological shifts of the course over the years have also been the most noticeable. Taipei has a subtropical monsoon climate, with scorchingly hot summers and mild winters. The city enjoys plentiful rainfall throughout the seasons, with typhoons in the summer and autumn.

During winter, the island experiences continental high pressure systems from Mongolia and Siberia, and is influenced primarily by the northeastern monsoon climate. In summer, the island's weather is controlled by the marine high-pressure system formed above the Pacific Ocean, with a humid, southwestern monsoon climate. Meanwhile, the island's high mountains and the surrounding oceans contribute to the city's strong seasonal differences. Spring lasts from March through May; summer, June through August; autumn, September through November; and winter, December through February of the following year.

Other than Beihuang Creek that runs along the city's northern border, rivers in Taipei City consist primarily of Tamsui River, Xindian and Keelung Rivers. Tamsui River is made up of Dahan Creek (its main tributary), plus Xindian Creek and Keelung River (two minor tributaries). The stretch where Xindian and Dahan Creeks converge is known as Tamsui River, in a narrow sense. Jingmei River is Xindian Creek's tributary, while Shuangxi is Keelung River's tributary. The stretch along downstream Tamsui River - the section that is nearing sea levels - is susceptible to tidal highs and lows.

The area, scope of the tidal fluctuation (tidal reach), the interaction of the river and the sea, and the effects of tidal reach are dynamically defined by the discharge of the river, the tides, and the nature of the river. The discharge of the river is most affected by the tidal reach. Keelung River's tidal reach is more predictable than that of Tamsui River, Dahan Creek, and Xindian Creek. Tidal fluctuations in the headwaters and downstream areas are also more noticeable.