Geological conditions in Ningbo, please, thank you.

Ningbo is high in the southwest and low in the northeast. Dumped into the sea from southwest to northeast. In the hilly area of eastern Zhejiang in the southwest, there is a southwest-northeast Siming Mountain range, which originates from Tiantai and is distributed in Yuyao, Fenghua and Yinxian. Tiantai Mountain Branch enters from the southwest of Ninghai and extends to the southern mountainous area through Xiangshan Port. The northeast and middle parts are the Yongjiang river basin plain of Ningshao alluvial plain, with flat terrain and rivers. The urban area is 4-5.8 meters above sea level, and the suburban area is 3.6-4 meters above sea level. Geomorphology is divided into mountains, hills, terraces, valleys (basins) and plains. Mountains account for 24.9% of the land area, hills 25.2%, terraces 1.5%, valleys (basins) 8.65%, 438+0% and plains 40.3%. The geological structural unit of Ningbo belongs to Cathaysian fold belt of South China fold system, which is located in Dinghai fault uplift, a new field in Lishui-Ningbo trough uplift. The surface is Jurassic volcanic rocks, and the rock types are porphyry, rhyolite porphyry and crystalline tuff. The rock is hard, with dry compressive strength 1300-2500mpa, allowable bearing capacity of 300-400 kpa and ultimate bearing capacity of pile tip of 400-500 kpa. The ultimate side friction is 100— 120KPa. Climate introduction: Ningbo belongs to the north subtropical humid monsoon climate zone. The climate is mild and humid, with four distinct seasons, abundant rainfall and obvious alternation of winter and summer monsoon. The four seasons in Ningbo are long in winter and summer (about 4 months each) and short in spring and autumn (about 2 months each). If the average temperature 10-22℃ is taken as spring and autumn, > 22℃ as summer and < 10℃ as winter, it is generally the sixth spring in March, the first summer in June, the sixth autumn in September,165438+1the sixth winter in October. However, the winter in the western mountainous area is longer than that in the plain area 1 month, the summer is nearly 1 month, and the spring and autumn is slightly longer than that in the plain area 1 day. If spring comes late, autumn comes early. In winter, controlled by Mongolian high pressure, Siberian cold air continues to supplement the south, and the weather is dry and cold. At this time, the north wind prevailed. In summer, it is controlled by the Pacific subtropical high, prevailing southeast wind and continuous sunny and hot weather. In addition to local thunderstorms, there will be a large precipitation process affected by tropical weather systems such as typhoons or easterly waves. Spring is the transition season of winter wind direction and summer monsoon. Due to the frequent intersection of cold and warm air in the middle and lower reaches of the Yangtze River, the weather is changeable, sometimes cold and sometimes hot, and it is often rainy. Thunderstorms and strong winds often occur along the coast. Autumn is the transitional season when the wind direction in summer turns into the wind in winter. The climate is cooler, but sometimes there are autumn tigers. Because there is often a small cold air going south, frontal activities begin to increase, and rainy weather often occurs. Because Ningbo is surrounded by mountains and seas, the specific geographical location and natural environment make the climate difference obvious and the weather complex, but at the same time, it also forms a variety of climate types. For example, each island has the maritime climate characteristics of low temperature, warm winter and cool summer, humid climate, good lighting conditions and abundant wind resources throughout the year, but it is vulnerable to typhoons; The three-dimensional climate characteristics in the western mountainous areas are obvious, and the light, temperature and precipitation change obviously with height. The water resources are relatively rich, but it is also prone to floods or droughts. However, the vast plains are obviously affected by the monsoon. Ningbo's rich and diverse climate resources provide extremely favorable natural conditions for developing diversified economy. The annual average temperature in Ningbo is 16.3℃, which is the hottest in July, the coldest in L, and the extreme maximum temperature is 39℃. High temperature weather is more in the north, less in the south and less in inland and coastal areas. The extreme minimum temperature is-1 1. 1℃, and there are not many days of low temperature. The first day of stable passing through 10℃ is the end of March, lasting about 237 days, and the average accumulated temperature is 5 100℃. Compared with the plain, the accumulated temperature in mountainous area is less than 1000℃. The average annual precipitation is about 1400 mm, and the mountainous hills are generally about 30% more than the plains. The main rainy season occurs in March-June (that is, spring rain and plum rain, with monthly rainy days generally exceeding half a month) and August-September (that is, typhoon rain and autumn rain, with monthly rainy days nearly half a month). Ningbo is usually in mid-June, with the earliest history in the middle and late May and the latest at the end of June. Plum blossoms are in early July, the earliest in mid-June and the latest in early August. Ningbo is a humid and semi-humid area, that is, the income and expenditure (precipitation and evaporation) are basically balanced; In terms of regional distribution, the north is relatively drier than the south. The annual average sunshine 1900 hours or more. Due to the geographical span of nearly 1.5 latitude, the regional distribution is more in the north and less in the south; However, due to the fog in the western mountainous area, it is less than that in the plain 10% on average. In a year, due to the obvious alternation of monsoon, there are often low temperature and rainy days in spring and autumn; Rainstorm and flood in flood season; Drought, typhoon, hail and strong wind in summer and autumn; Disastrous weather such as frost and cold wave in winter directly affects agricultural production. The typhoons that affect Ningbo are mainly concentrated in July-September (process rainfall >; =50 mm or wind speed >; = 17m/s), with an average of 2.8 per year. The rainfall of typhoon process that can cause serious impact >: = 200mm) is 1 almost every few years. Since 1953, four typhoons have landed in Ningbo. The storm surge caused by typhoon is extremely harmful, such as the strong typhoon 56 12 (also known as typhoon in August 1), which caused heavy losses in Xiangshan; Another example is typhoon 97 1 1, and the loss of the whole city exceeds 4.5 billion yuan. The annual average rainfall of rainstorm (daily rainfall of 50 mm) is 2-5, which mainly occurs in plum rains in early June-July and typhoon rainstorm in August-September, with September as the majority. In terms of geographical distribution, Ninghai is the largest, and heavy rains often cause floods, such as the flood disaster caused by heavy rains in Ninghai1988 on July 30th. Drought usually occurs from July to September after plum blossom, especially in Ninghai, Xiangshan and Cixi hilly areas, and the utilization rate of precipitation is not high. Generally once every 2-3 years, and once every 4-5 years in other areas. However, droughts sometimes occur all year round. Some years are summer drought and autumn drought, while others are autumn drought and winter drought. The probability of hail and tornado in Ningbo is low. Hail generally appears in spring, summer and autumn from March to September, mostly from noon to evening. Hail in Ningbo is mainly distributed in Yuyao, Cixi, Yinxian and Zhenhai in the northern region, followed by Fenghua. Tornadoes mainly appear from June to September, with July being the most frequent. Most of Ningbo takes place in Yuyao and Cixi. 1983 September 16 At 3: 42 pm, a tornado occurred in Simian, Yuyao and Zhouxiang, Cixi, causing nearly 2,000 houses to collapse and 2/kloc-0 people were killed. Low temperature and rainy weather generally refers to the late spring cold in spring and the low temperature in spring and autumn. Late spring cold refers to the annual average daily temperature; = 0.0 mm, sunshine hours < 2 hours) rainy process. On average 1. 1 times per year; Low temperature in autumn refers to the appearance of daily average temperature.

/