How Macau tripled its land by filling in the estuary

How much of Macau was built from the sea

The Macao Yearbook gives Macau's land area as 11.6 square kilometres in 1912, the year measurements were first taken, and 33.3 square kilometres in 2023. Almost all of the difference was reclaimed from the estuary. Portuguese Macau at the start of the twentieth century already included both islands: 3.4 square kilometres on the peninsula with Ilha Verde, 2.3 on Taipa and 5.9 on Coloane, according to Wikipedia's account of the colony.

Reclamation came in waves. Thomas Daniell, who headed the architecture department at the University of Saint Joseph from 2011 to 2018, told Macao News in 2024 that it divides into four stages: the Inner Harbour and the northern districts from the nineteenth century, when Ilha Verde, an island about a kilometre offshore, was joined to the peninsula by 1923; the Outer Harbour fill known as ZAPE in the 1920s and 1930s; NAPE in the 1980s; and Cotai, the strait between Taipa and Coloane, filled in the 1990s and 2000s. The street names of the Inner Harbour keep the old shore: Rua do Almirante Sérgio is New Riverside Street in Chinese and Rua do Guimarães New Seaside Street. Daniell put the reclaimed share of the territory at more than 50%.

The pace picked up after the handover. Macao News gives 23.8 square kilometres in 1999, 29.5 a decade later and 32.9 in 2019. The yearbook breaks down the 2023 figure as follows.

The ground is not always stable. Daniell noted that parts of ZAPE and NAPE are subsiding because the reclamation was not as solid as it should have been, damaging pavements and some buildings.

What the original hills of Macau look like

Under the fill are granite hills. The 2024 yearbook classifies 24.2 square kilometres, or 72.7% of the land, as flat, a figure that includes the reclaimed ground; granite hills cover 6 square kilometres, or 18%; and old terraces at 20 to 25 metres, along St Augustine, the Luís de Camões Garden and Russa Hill, cover 1.2 square kilometres. Reserves, monument sites and forest take up the remaining 1.9 square kilometres.

The land rises from north to south. Guia Hill, at 90 metres, is the high point of the peninsula. Taipa Grande reaches 158.2 metres, and Alto de Coloane, at 170.6 metres, is the highest point in the territory. The high-rise skyline now hides much of this relief. The peninsula itself began as an island: Wikipedia's geography of Macau describes a sandbar that grew into a narrow isthmus, which reclamation in the seventeenth century made into a peninsula. In the past the hills were quarried for granite, and Wikipedia records no other natural resource of note.

Coloane kept more of its original cover because it was colonised later. The peninsula has no arable land, pasture or woodland left, while Coloane still has forest and small farms around the villages of Coloane, Hac Sa and Ka Ho.

Where Macau's coastline is natural

The government fixed the coastline by Executive Order No. 2/2024, with 1 January 2023 as the baseline for the survey. It runs to 79.5 kilometres: 18.5 around the peninsula, 49.5 around Taipa, Cotai and Coloane, and the rest around New Urban Zones A and C and the bridge's artificial island. Artificial shore makes up 84.3% of it, mostly around the peninsula and the eastern and northern edges of Taipa. The natural 15.7% lies along western Taipa and the southern tip of Coloane.

Where Macau's boundaries run on land and water

Macau sits on the western side of the Pearl River estuary, 60 kilometres from Hong Kong, with Zhuhai in Guangdong to its north and west. In 2015 the central government drew the region's boundaries. State Council Order No. 665, published in Macau as Chief Executive Notice No. 128/2015 of 20 December 2015, gave it 85 square kilometres of sea in six sections, from the Inner Harbour to the eastern and southern waters, and fixed two land sections: the Border Gate checkpoint building and the Canal dos Patos. The land border moved to the middle of the Canal dos Patos. Macao News described the new waters as tripling the region's size, and quoted a pledge made that year that any reclamation in them would be reported to the central government and would carry no gaming venues.

Two pieces of Macau lie outside its old outline. The University of Macau campus, about one square kilometre, sits on Hengqin island under the region's jurisdiction, and the border crossing on the artificial island of the Hong Kong to Zhuhai to Macao Bridge is Macau ground. Beyond the campus fence the rest of Hengqin, about 106 square kilometres, is the Guangdong-Macao In-depth Cooperation Zone, defined in a general plan of 5 September 2021 as the customs area between a first line facing Macau and a second line facing the rest of China. The governments of Guangdong and Macau run it together through a joint Management Committee, and the plan sets goals for 2035 that include an improved system for integrating Hengqin with Macau.

How the monsoon and typhoons set Macau's weather

The yearbook describes a marine monsoon climate: northerly winds bring cold, dry weather in winter, and south-westerly winds bring heat and heavy rain in summer. Under the World Meteorological Organization normals for 1981 to 2010, average annual rainfall was more than 2,000 millimetres, most of it between April and September, with June the wettest month at 373.7 millimetres and December the driest at 31.3. The average annual temperature is 22.8°C and January, the coolest month, averages 15.2°C. The monthly mean is above 22°C in seven months of the year.

Wikipedia's geography of Macau divides the year by the monsoon. March and April, when the north-east monsoon gives way to the south-west, are moist and foggy. Summer runs from May to September and is hot and rainy. The end of September and October are sunny and warm as the north-east monsoon returns, and winter, from November to February, is mainly dry, with occasional cold fronts. The extremes on record at the Meteorological and Geophysical Bureau are 38.9°C, reached on 2 and 6 July 1930, and minus 1.8°C on 26 January 1948.

Typhoons arrive from May to November, most often from July to September. Wikipedia's geography of Macau records a typhoon in September 1874 that drove high seas across the low-lying peninsula. Typhoon Hato in August 2017 killed 10 people and cut power and water across the city for at least a day; Hato and Mangkhut in 2018 together damaged the hill forests so badly that the Municipal Affairs Bureau began a replanting programme in the fourth quarter of 2018, aiming to restore 120 hectares of woodland. The first phase replanted or transplanted 35,000 saplings along 11 trails and was finished in September 2019, with more than 98% of the saplings surviving.

What one recent year looked like

In 2023 the yearbook recorded an average temperature of 23.4°C, 0.6°C above the normal, and 2,176.8 millimetres of rain. The hottest day was 15 July at 36.6°C and the coldest 22 December at 6.4°C. Five tropical cyclones affected Macau that year, from Typhoon Talim in July to Typhoon Koinu in October, and the No. 10 typhoon signal was raised once. Talim caused the worst flooding of the year, 0.33 metres in the south of the Inner Harbour on 17 July. The Meteorological and Geophysical Bureau issued 38 rainstorm warnings.

How Macau watches for storm surge

Low-lying streets around the Inner Harbour are where the sea comes in, and the bureau's monitoring is built around them. It runs 17 automatic weather stations and a Water Level and Tide Monitoring Network of 20 land stations at flooding black spots, 18 of them reporting to the public in real time, and two tide stations on the coast. Storm Surge Alert labels showing expected flood heights are posted on 132 civil protection camera poles in low-lying areas, at more than 20 public car park entrances and outside more than 40 social service buildings. Because the territory is small and the weather arrives from outside it, the bureau worked with the Zhuhai Meteorological Bureau to install four phased array weather radars in Zhuhai, and it exchanges data with the Guangdong bureau and the Hong Kong Observatory.

Where Macau's green land survives

Coloane holds most of what is not built. More than 1,500 species of vascular plants have been identified in the territory, according to the yearbook, mainly evergreen broad-leaf woodland, shrub and coastal bush. Seac Pai Van, on the west of Coloane, was set aside by law as a reserved zone in 1981 and became the first country park in 1984. Three more followed: Taipa Grande Nature Park and the Hac Sa and Ka Ho reservoir parks.

The Taipa-Coloane Wetland Reserve, next to the Lotus Flower Bridge, covers 55 hectares: a 40-hectare foraging area and a 15-hectare bird habitat. By the end of 2023 the Cotai reserve had recorded 197 bird species, among them the Black-faced Spoonbill, and 116 species of fish. More than 290 bird species have been recorded across Macau since 2006. The commonest wild mammals are bats, rats and the Red-bellied Tree Squirrel, an introduced species now established in the wild.

Where the people of Macau live

The 2021 census put population density at 20,620 people per square kilometre, up from 18,454 in 2011. The densest statistical districts were Areia Preta and Iao Hon at 153,104 per square kilometre, Doca do Lamau at 144,424 and Barca at 141,621, all on the northern peninsula. The most populous district had become Baixa da Taipa, on the island.

New land is where the growth went. Between the 2011 and 2021 censuses the population of the Coloane district rose by 753.7% and that of Ilha Verde by 143.9%, as public housing estates were completed there. At the end of 2023 the yearbook gave a resident population of 683,700, with 75,100 in Baixa da Taipa. Of that total, 86,500 were foreign employees living in Macau. Wikipedia's article on Macau notes that rising living costs have pushed many non-resident workers to live across the border in Zhuhai.

Density shows in the air. The yearbook attributes Macau's air quality to population density, scarce land, narrow streets and heavy traffic, offset by low industrial discharge, and it is worst in winter. In 2023 the high-density residential districts of the peninsula had good air on 51.5% of days and poor air on nine days. Ambient stations on Taipa recorded poor air on 32 days and very poor air on one.

Fresh water comes from the mainland. Macau draws its supply from the West River, and in the dry season of 2006, in late winter and early spring, it suffered a crisis of salinity in that supply. Three pipelines had been built to the territory by 2018, with a fourth planned for 2019, according to Wikipedia's geography of Macau.