Urban Green Areas – their functions under a changing lifestyle of ...

1.1 Hanoi – the city under study
Vietnam, with its capital Hanoi is located in south-east Asia on the Indochina peninsula
(see Figure1.2). Hanoi is the largest city in Vietnam in terms of area and the second largest
in terms of population. The population of the city was around 6.5 million inhabitants in
2010 (GSO: 2010).
Since the beginning of Vietnam’s history Hanoi has been a centre of economic, cultural and
political life. The capital is known by three different names: Thang Long, Dong Do, Dong
Quan, Dong Kinh and Hanoi. The name Hanoi have been called since 1831 till now (see
PHUC 1994:31).
1.1.1 Location and topography
Hanoi is located in the northwest of the Red River Delta. The city is 5m to 20m above sea
level and the topography drops slightly low from north to south and from west to east. This
topography is clearly reflected in the natural direction of flow of major rivers running
through the city.
The study area is within the alluvial plain of the Red river system. In addition to the high
alluvial zone, there are also traces of ancient riverbeds surviving as low lands, la es and
pools (for example, the y u la e in Thong hat par and la es in the otanic ar
and Hoan Kiem Lake). Lenin park once had a natural pool, but this was filled in long ago.
1.1.2. Climate
Climate factors have a strong influence on par s’ utilization, in terms of frequency, density,
and diversity of activities. Climate also determines and limits the botanical composition of
green areas.
The dominating features of Hanoi’s climate are clear and distinct seasonal changes: From
May to September the weather is hot and rainy, while from November to March it is cold
and dry. Between these two main seasons lie two transitional periods (April and October)
and thus the climate can be divided into four seasons: spring, summer, autumn and winter.
Average annual air temperature is 23.5 0 C. Influenced by the high terrain toward the
northeast and the wind carrying moisture from the South Sea, Hanoi has both high humidity
and precipitation. Relative humidity in most months is over 80%, with an annual average of
81%. Average annual rainfall is 1676 mm, and rain falls on acerage on 114 days per year.
However, the weather in Hanoi can change erratically, mainly due to the influence of the
two monsoons and El Niño and La Niña phenomena. The precise onset of the cold weather
period is therefore hard to predict accurately.
Variations in the climate parameters can be considerable. The highest temperature recorded
was 42.8 0 C (May 1925) and the lowest was 2.7 0 C (January 1955). In some years there has
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