Nature Environment
Terrain characteristic
into many small areas by springs and Tan Xa Lake.The lowest area is mainly in the southeast region with height level varying from 3.8m to 10 m. Direct slope of the terrain from northwest to southeast has gradient of 5%.
The hills in this area are not too high and rather flat with the average slope ranges from 10 to 20%. The highest hill is 22m high, average hills are about 17 m high and the average slope of hills varies from 3 to 7%.
The Northern area has an area of high hills with a height varying from 41 to 55m, with an average slope of 7% gradually declining from the Northwest to the Southeast. The average height in the remaining field land varies from 8 m to 11m. There are two small springs in the Southeast area.
Climate condition:
Located in the Northern area of Vietnam, the climate feature of HHTP area has typical specific characteristics of a tropical, monsoon and wet area. It is hot in the summer and cold in winter. The tropical monsoon climate normally leads to four specific seasons in a year. This includes two main seasons i.e. summer and winter and two transition seasons i.e. spring and autumn.
- Summer: from May to August; hot and heavy rain sometimes.
- Autumn: from September to November; dry and at ease.
- Winter: from November to January of the next year; cold and dry
- Spring: from February to April; cold, drizzling with high humidity
Air temperature
Average temperature
(Source: Statistic yearbook of Ha Tay province in 2006)
- Average temperature 23.4 ℃
- Highest Average temperature 28.7 ℃
- Lowest Average temperature 16.6 ℃
Radiation regime
The study area is located in the area, which has the average level of sunny hours as prevails in Vietnam. Total annually average sunny hours observed are 1595 hours. The longest sunny period is during rainy months; the average amount of sunny hours is about 168~205 hours. The least sunny month has about 43.3 hours.
- The yearly average total hours of sunshine: 1464 hours
- The yearly average total amount of radiation: 122Kcal/cm2.
Rainfall
This area has the high average volume of rain each year.
- Average rainfall: from 1,676mm to 1,839mm.
- Average rainy days/year: 144 days.
- The average evaporation: 989mm.
- numbers of days have drizzle rain/ year: 38.7 days.
Rainy regime of the area fluctuates immensely from year to another.
Humidity
Annually average air humidity is 84%. The highest humidity period in the year is from June to November. The driest periods in the year are February, March and April with the monthly average humidity below 77%.
Average relative humidity (%) of the air
(Source: Statistic yearbook of Ha Tay province in 2006)
Vapour degree
In the study area, the total amount of annually average vapour during the period of 2002- 2006 fluctuated from 864.4- 1122.2 mm, with a highest in 2003 and lowest in 2002.
The highest and lowest vapour degree in the year often happens during the period of May – July, and December-March, respectively.
The dates on which highest and lowest vapour amount were recorded are 2 October, 2004 (7.9 mm), and 9 April, 2003 (0.1 mm), respectively.
Wind
Mùa Hè:
- The average wind speed: 2.2m/s.
- The main wind direction: Southeast.
In the winter:
- The average wind speed: 2.8m/s.
- The main wind direction: Northeast.
- The average wind speed in all directions: 2.4m/s.
Storm
The storm often affects this area every year. The average speed of wind is low = 20 – 30m/s.
According to statistics of recent years as received from Lang stations hydrometeorology, the natural phenomena occurred between 100 to 200 days with drizzling rain, fog, thunder storm, mist. Fog and sleet took place with a low frequency.
Although the number of days with special natural phenomena is rather big, there’s no sign that hoarfrost and whirlwind would happen.
Statistic of special natural phenomena in the HHTP 2002-2006.
2002
2003
2004
2005
2006
(Source: National Institute hydrometeorology, 2007)
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Geological condition
The HHTP has some geological forms: Newly sediment and slope sediments are distributed on all hills. These hills are mainly occupied by block stone, and criss-crossed by literate with a high pressure capacity i.e. on average ≥ 2.5Kg/cm2. Slope sediment consist mainly of grit and clay. In addition, sand is distributed almost in all low hill slopes. Swamp sediment distributed in swamp and lakes consist of mixed mud with dark clay. This sediment has the low loading capacity i.e. ≤ 1.5Kg/cm2 on average. The alluvium composition of the Tich Delta comprises of alluvium, sand, grit, gravel and mixing clay. The loading capacity is 1.5 < R < 2.5 Kg/cm2. |
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Assessment on natural condition
This area has many favourable conditions for the construction of the project facilities:
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