Ruijin, a city under the jurisdiction of Jiangxi Province. It is located in the southeast of Jiangxi Province, at the west foot of the southern section of Wuyi Mountain, and at the upper reaches of Gongshui River in the east of Ganjiang River. Between 25 30' and 26 20' north latitude, east longitude115 42'-16 22', east longitude115 42. . It borders Changting County, Fujian Province (47 kilometers) in the east and Du Yu (85 kilometers) in the west. To the south of Huichang (48km) and Shicheng (76km); Ningdu (85km) in the north and Pishicheng County in the northeast.

The total area is 2448 square kilometers. In 20 12, the registered population was 674,600, of which 522,400 were agricultural. Hakka dialect (Ninglong film) is popular all over the city.

geology

Ruijin city is located in the middle of the first-order structural unit of Wuyishan uplift, and in the south-central part of the Neocathaysian structural belt from Xunwu to Guixi. The stratum is fully exposed, and the structure is developed in northeast and near east-west direction. The magmatic activity is weak, forming a mineral pattern dominated by nonmetal, fuel and precious metal minerals.

Except Triassic, all kinds of geological rocks are distributed in Ruijin City. The urban area is mainly built on the floodplain of Mianjiang River or the first and second terraces, surrounded by some low hills and hills. The strata are mainly Quaternary alluvial and diluvial deposits and Cretaceous semi-weathered red sandstone. The Quaternary surface has a typical "binary phase" structure, the upper part is clay and loam, and the local part is silt, with a thickness of about 3-4m, and the bearing capacity of the foundation is about 1.0-2.0 kg/cm2. The lower part is a layer of sand, gravel and pebbles with unclear bedding, with a thickness of about 5-6m and a bearing capacity of 2.0-3.0 kg/cm2.

zone

Ruijin is located on the west side of the southern end of Wuyi Mountain Range, with high terrain around and low middle. It is dominated by basins and belongs to one of the four great basin in Jiangxi. The highest peak is located in the three counties in the northeast border, with an altitude of 1232.9 meters, and the lowest point is at the angle of Mianjiang exit on the southwest edge, with an altitude of 162 meters.

According to the topographic features, the territory can be divided into erosion structure, low mountain and hilly terrain, erosion structure terrain, gully erosion accumulation terrain and erosion landform types. Among them, hilly terrain is dominant, with an area of 1967.85 square kilometers, accounting for 80.35% of the total land area, mountainous area of 243.89 square kilometers, accounting for 9.96% of the total land area, and hilly plain area of 237.26 square kilometers, accounting for 9.69% of the total land area. Gangdi Plain is a concentrated area of towns and villages in Ruijin. The urban area is located at the intersection of Mianjiang River and Gucheng River, which belongs to the valley erosion and accumulation terrain and is surrounded by mountains on three sides (open to the northeast).

land

Ruijin mountain area is dominated by red soil, and its parent materials are Quaternary red clay, metamorphic rock series, granite and red glutenite. Followed by purple soil and brown calcareous soil. The former parent material is purple sand shale and the latter is limestone; In addition, there is mountain yellow soil, mostly weathered by metamorphic rocks and granite. It is divided into 4 soil types, 6 subclasses, 1 1 soil genus, 18 soil species and 19 varieties. Weathered materials such as phyllite, sandstone and granite of metamorphic rock series develop into red soil, which is distributed in high mountains and hills. Weathered red glutenite develops into red soil, which is distributed in low mountains and hills; Laterite is distributed in gentle slopes and hilly areas; Purple soil and brown calcareous soil are widely distributed in low mountains and hills, and often mixed with lateritic red soil and red sandstone red soil; Mountain yellow soil is distributed in mountainous areas above 600 meters above sea level. Lateritic red soil is not strongly eroded and is suitable for farming. Purple soil and some red sandstone red soil are seriously eroded, so soil and water conservation is urgent; Metamorphic rocks and granite red soil are slightly eroded, mostly coniferous and broad-leaved forests, or covered by shrubs and grass. There are humus layers with different thickness on the surface of the soil, and the soil layer is deep, which is suitable for agriculture and forest.

hydrology

Domestic waters belong to Gongjiang waters. Ruijin is rich in surface water resources, but because all rivers in the territory belong to mountainous rivers, the ratio of runoff in high water year and low water year is very different, so it is difficult to develop and utilize them. The main rivers in China are Mianjiang River, Jiubao River, Wantianhe River, Meijiang River and Gucheng River, with a total basin area of 2,449 square kilometers and 36 tributaries. There are 0/7 reservoirs in China with a storage capacity of 0/980,000 cubic meters. The average annual runoff of surface water in China is 211560,000 cubic meters, and the water yield is 863,900 cubic meters/square kilometer, with the maximum annual runoff of 3.749 billion cubic meters and the minimum annual runoff of 952 cubic meters.

Ruijin city is located on the Quaternary alluvium, which is mainly composed of pore water of Quaternary gravel layer and karst fissure water of Cretaceous red sandstone. It belongs to diving and the water level is not deep. It is one of the water sources for the life and production of some enterprises and residents in this city.

climate

Ruijin is located in the transition zone between the climate zone in Central China and the climate zone in South China, and belongs to the humid climate in the middle subtropical zone. The territory has four distinct seasons, abundant sunshine, abundant heat, abundant rainfall and long frost-free period. Because of the different topography in the territory, the climate of the basin is slightly different from that of the mountainous area. Affected by monsoon, it is easy to produce weather and climate disasters such as water, drought, extreme heat and freezing damage. It shows the climatic characteristics of "spring rain, summer flood and summer drought, hot summer and warm winter, frost and freezing".

temperature

Ruijin has four distinct seasons: the average daily temperature is stable at 10-22℃ in spring and autumn, above 22℃ in summer and below 10℃ in winter. In Ruijin, the length of spring is 7 1 day, summer is 134 days, autumn is 6 1 day and winter is 100 days.

In the spring of Ruijin, the weather is changeable. As the saying goes, "children's faces change into spring every day." In spring, the temperature rises by leaps and bounds from mid-March. Before and after each cold air invasion, the daily temperature difference often reaches above 10℃, and there is a weather of "the south wind is exposed for three days a day, and the south wind dog drills the stove for three days". It is rainy in spring. The average rainy days in March-April are longer than 18 days, and the longest is 22 days (1969 February1August-March1day). In some years, there have been "peach blossoms flooding".

deposit

Ruijin has concentrated precipitation and many floods in summer. Summer begins in mid-May and ends in late September. April-June at the turn of spring and summer is the concentrated period of annual precipitation and the main flood season. Its rainfall often accounts for more than 50% of the annual rainfall, rainy days account for 56.6% of the annual rainfall, and rainstorm days (daily precipitation ≥50 mm) account for 65.5% of the annual rainfall. There was little precipitation from July to September, but there was high temperature and dry weather (summer drought), and the extreme maximum temperature reached 40.4℃, which appeared on July 23, 2003.

Ruijin has many droughts in autumn. The autumn of Ruijin is from the end of September to the end of 1 1 month every year. Under normal circumstances, the sky is high and the clouds are light in autumn, and it seldom rains. However, in some years, due to the influence of typhoon circulation, bad weather in autumn occurs from time to time.

The winter in Ruijin begins in late October of 165438+ and ends in early March of the following year. This quarter is mainly affected by the cold air from the north to the south, and its cycle is about one week. The temperature rises day by day before the influence of cold air, and decreases after the influence, which is often accompanied by rainy weather, but the amount of rain and snow is not large. In some years, after being affected by cold air, the weather turned fine, and the ground cooled strongly at night, resulting in ice frost. The extreme minimum value is -6.5℃, appearing on 199 1 year 65438+February 29th, and the deepest snow depth is 1 1 cm. [4]

illuminate

The annual average sunshine hours 1900 hours, sunshine rate of 43%, total solar radiation 1 1.87 kcal/cm2, light energy utilization rate of 2%, and average frost-free period of 269 days.

wind direction

The dominant wind direction in the urban area is north-northeast all year round and south-southwest in summer. Because the urban area belongs to the closed basin topography, the wind speed is low, the static wind frequency is high, and the atmosphere is relatively stable. The probability of inversion weather around winter is the highest in the whole year, and the gas pollutants in the atmosphere are not easy to spread and dilute under inversion weather.