The Physical and Geographical Environment of Dongying City

Dongying City is located in the Yellow River Delta in northern Shandong Province. The Yellow River, the mother river of the Chinese nation, flows into the Bohai Sea in Dongying City. The geographical location of Dongying City is 36 55' ~ 3810' north latitude and18 07' ~110' east longitude. It borders Bohai Sea in the east and north, Binzhou City in the west, Zibo City and Weifang City in the south. The maximum longitudinal distance from north to south is123km, and the maximum lateral distance from east to west is 74km, with a total area of 7923km2. Geological Dongying City is located at the eastern end of Jiyang Depression in North China Depression. The strata include Archaean Taishan Group, Paleozoic Cambrian, Ordovician, Carboniferous and Permian, Mesozoic Jurassic and Cretaceous, Cenozoic Tertiary and Quaternary. Proterozoic, Upper Ordovician, Silurian, Devonian, Lower Carboniferous and Mesozoic Triassic are missing. From north to south, the depressions and bulges mainly include Chengzikou bulge (east end), Chezhen sag (east), Yihezhuang bulge (east), Zhanhua sag (east), Chenjiazhuang bulge, Dongying sag (east half) and Guangrao bulge (part). The landform is mainly the plain landform in the urban area. Due to the frequent diversion and breach of the Yellow River in history, the surface has been washed and silted by floods many times, forming a complex micro-landform. The terrain inclines from southwest to northeast along the Yellow River. The highest elevation in the southwest is 28 meters (Dagu elevation, the same below), and the lowest elevation in the northeast is 1 meter, and the natural ratio is reduced to1/8000 ~112000. The highest altitude in the west is 1 1m, and the lowest altitude in the east is 1m, and the natural proportion is reduced to 1/7000. The Yellow River crosses the border, which is high near the river and low far away. The natural ratio of the river behind the river drops to 1/7000, and the floodplain is 2 ~ 4m higher than the river behind the river, forming a "suspended river on the ground". There are five types of micro-landforms in the city: ancient floodplain highlands, accounting for 4. 15% of the total area of the city, mainly distributed in the upper reaches of the Yellow River breach; Floodplain highlands, accounting for 3.58% of the city's total area, are mainly distributed between the Yellow River channel and the levee; Slightly inclined flat land, accounting for 54.54% of the city's total area, is a transitional zone between hills and depressions; Shallow depressions, accounting for 10.68% of the city's total area, are mainly distributed between the ancient floodplain highlands south of Xiaoqing River and the slightly inclined flat land between the gentle hills north of Xiaoqing River and the low-lying areas of the old Yellow River. Beach land accounts for 27.05% of the city's total area, which is distributed in a strip parallel to the coastline. Climate Dongying City is located in the middle latitude, with its back to the sea. Influenced by Eurasia and the Pacific Ocean, it has a warm temperate monsoon continental climate. The basic climate is characterized by Leng Xia heat in winter and distinct seasons. It is dry and windy in spring, and the temperature in early spring is changeable, often accompanied by spring cold, and it recovers quickly in late spring, often accompanied by spring drought; In summer, it is hot and rainy, hot and humid, and sometimes it is attacked by typhoons; In autumn, the temperature drops, the rain drops sharply, and the sky is crisp; In winter, the weather is dry and cold, the cold wind blows frequently, the rain and snow are scarce, and the north wind and northwest wind blow more. The main meteorological disasters are drought, hail, storm surge, strong wind and fog. There is no obvious climate difference between north and south in China. The annual average temperature is 12.8℃, the frost-free period is 206 days, and the accumulated temperature of ≥ 10℃ is about 4300℃, which can meet the needs of three crops in two years. The average annual precipitation is 6 13.6mm, mostly concentrated in summer, accounting for 65% of the annual precipitation. The annual precipitation changes greatly, which is prone to drought and flood disasters. In 2009, the annual average temperature of the whole city was 13.6℃, which was 0.8℃ higher than normal. The annual precipitation is 634. 1mm, slightly more than normal 14.5438+0%. The light hours are 25 16.0 hours, slightly less than normal. The general climatic characteristics are as follows: the temperature in winter is mainly high, with frequent alternation of cold and warm, and the precipitation is slightly less than normal; In spring, the temperature fluctuates obviously, with uneven heat and cold, abundant precipitation, more in the south and less in the north. At the beginning of May, there was a rainstorm and flood that was rare in history. In summer, the temperature is high, the number of high-temperature days is more than that in previous years, the extreme maximum temperature has exceeded the extreme value of nearly 40 years, the precipitation is close to normal, but the spatial and temporal distribution is uneven, and thunderstorms, hail and heavy rain occur from time to time; The temperature in autumn is close to normal, showing the characteristics of high in the early stage and low in the late stage. The precipitation is mainly less, and the precipitation period is concentrated. From the end of September to the middle of 10 and 1 10, there was a continuous lack of rain. 2009 is a general year to comprehensively evaluate the impact of climate conditions on various industries in Dongying City. Soil Urban soils are divided into five categories: cinnamon soil, Jiang Sha black soil, fluvo-aquic soil, saline soil and paddy soil. Cinnamon soil is mainly distributed in the south of Xiaoqing River, accounting for about 4% of the city's soil area, which is the high and stable yield area of grain, cotton and vegetables in the city. Black soil in Jiang Sha is mainly distributed in the low-lying areas of cinnamon soil area in the south of Xiaoqing River, accounting for 0.6% of the total soil area in the city. This kind of soil is suitable for planting shallow-rooted crops such as wheat, corn and sorghum, and it is a potential soil type in agriculture. Tidal soil is the largest soil type in the city, accounting for 59% of the city's soil area. Widely distributed in cities, it is the main cultivated soil in cities. After cultivation, it is suitable for planting crops such as wheat, corn and cotton. Saline soil is distributed in the coastal zone, accounting for 36% of the total soil area in the city. Natural vegetation includes reeds, yellow clover, thatch, wormwood and so on. This kind of soil is difficult to be used for planting without major transformation. At present, it is mainly used to develop water conservancy and animal husbandry (planting). Paddy soil accounts for 0.2% of the total soil area, mainly distributed in Lijin and Kenli old rice areas. After more than 20 years of hydroponics, it has initially possessed the characteristics of young paddy soil. The Yellow River runs through Dongying City from southwest to northeast and joins the Bohai Sea in the northeast of Kenli County, with a total length of 138 km. The runoff of the Yellow River varies greatly from year to year, with uneven distribution and large sediment concentration during the year. According to the measured data of Lijin Hydrological Station 1950 ~ 200 1 year, the average annual runoff of the Yellow River is 33.26 billion cubic meters, with the maximum of 97.3 1 100 million cubic meters (1964) and the minimum of10.8 billion cubic meters (/kloc). Maximum discharge10400 m3/s (1July, 958), minimum discharge and main flow interruption; The average annual sediment discharge is 836 million tons, with the maximum of 265,438+tons (1.958) and the minimum of1.500 million tons (1.997). Since the 1990s, the annual runoff of the Yellow River has decreased and the flow has been cut off frequently. After 1999, the Yellow River Conservancy Commission strengthened the management of water transfer along the Yellow River, and the phenomenon of water cut-off slowed down, achieving ten-year continuous flow from 2000 to 2009. From 2005 to 2009, the annual runoff of the Yellow River was 65.438+0.982 billion cubic meters, 65.438+0.965438+0.88 billion cubic meters, 20.2 billion cubic meters (reported flood value), 65.438+0.47 billion cubic meters (reported flood value) and 65.438+0.36 billion cubic meters respectively. Besides the Yellow River, there are 30 backbone water systems in the city. Taking the Yellow River as the dividing line, the south of the Yellow River belongs to the Huaihe River basin, and the river system of the basin is mostly east-west. From south to north, there are Xiaoqing River and its tributaries Zi River, Yang River, Nihezi, Prepare River, Branch River and its tributaries Xiaohezi, Wujiadagou, Guangpu River and Wugan Pai, Guangli River and its tributaries, Dongying River, Laoguangpu River, Wuliu River and Pai, and Yongfeng River and its tributaries. The north of the Yellow River belongs to the Haihe River basin, and the drainage system of the basin is mostly north-south trend. There are 10 rivers from west to east, namely Chaohe and its tributaries, Chuguan River, Taiping River, Maxin River, Lizhan River, Caoqiaogou, the east main stream of Caoqiaogou, Tiao River, Shenxiangou and its tributaries, and Dong Xinwei River. The coastline of Dongying City in the sea area starts from Shunjianggoukou in the north and reaches Zimaigoukou in the south, with a total length of 4 12.67 km, accounting for more than 1/7 of the coastline of Shandong Province. The beach area is 6.5438+0.52 million mu, and the shallow sea area within the isobath of minus 654.38+00 meters is 4,800 square kilometers. The seabed along the coast is relatively flat, and the transparency of seawater is 32 ~ 55 cm. The temperature and salinity of seawater are greatly influenced by continental climate and runoff of the Yellow River. Dongying sea area is semi-closed, and most of the sea areas are irregular semidiurnal tides, with an average tidal range of 0.8 ~ 1.2m and a maximum tidal level of over 5m, which is prone to storm surge disasters. More than 5 million mu of land reserve resources in the city are also mainly distributed in coastal areas. The Yellow River Delta National Nature Reserve is the most complete, broadest and youngest wetland ecosystem in the warm temperate zone of China, with unique tourism resources. Under the influence of the Yellow River and other rivers, the coastal waters are low in salinity, high in oxygen content, rich in organic matter and rich in bait, which is suitable for many kinds of fish and shrimp to find bait, reproduce and migrate. The coastal areas are rich in mineral resources such as oil, natural gas and brine.