Geographical environment of Zengcheng district

Zengcheng District is located in the east of Guangzhou City, Guangdong Province. Tommy Tam, Honghuadi, Xinshanxia, Litchi 'ao, Zhongguling and Danzhu Mountain in the east are connected with Boluo County in Huizhou City. Sifang Mountain, Modaoshi, Longtanpu, Tiexianguan, Niuzhangzhang and Zhengdingding bordering Longmen County, Huizhou City in the northeast. Dajianshan, Fenghuang Mountain, Dagushan and Zhanggu Aoding in the northwest are adjacent to Conghua District in Guangzhou. Sinopharm Farm, Yamaguchi, Guanshan and Shacun in the western province border on Huangpu District of Guangzhou. In the south, Dongjiang River faces Dongguan across the river. Licheng City is about 60 kilometers west of Guangzhou City, 60 kilometers east of Boluo County, 0/08 kilometers north of Longmen County, 5/0/km northwest of Conghua City and 40 kilometers south of Dongguan City. Zengcheng has been the main passage from Guangzhou to all parts of eastern Guangdong since ancient times, and it is also a military stronghold to defend Guangzhou.

Geographical coordinates are 23 5 north latitude? To 23 37 north latitude? ; E 1 13 32？ To east longitude 1 14 0? , with a total area of 16 16.47 square kilometers. Geomorphological features of Zengcheng: the terrain in the north is higher and the terrain in the south is lower. The mountainous area is dominated by low mountains, accounting for 8.3% of Zengcheng's area. It is an extension of Jiulian Mountain Range. The mountains run northeast and southwest, and the middle and low mountains are evenly arranged, forming Dongjiang River and Zengjiang River. Hilly land is mainly distributed in the south-central area, accounting for 35. 1% of Zengcheng District. Platforms are mostly located in the central and southern regions, accounting for 23.2% of Zengcheng District. The southern part is the delta plain, plus the valley plain, accounting for 35.4% of Zengcheng District.

Middle and low mountains: mainly distributed in Dajian Mountain and Niugu Mountain in the north (elevation 500 ~ 1000m). It consists of sandstone shale and medium-fine grained granite. The ridge is narrow and steep, generally 40 ~ 50, and the valley is cut deeply, often forming waterfalls and canyons.

Hills: The absolute height is below 500 meters, and the relative height is generally below 200 meters, with gentle shape, broken cutting and messy distribution. For example, in western Xiao Lou, northern Zhengguo and western Yonghe, it is mainly composed of granite. Generally, the hillside is gentle, the top of the mountain is round and muddy, the water system is dendritic, and the cutting power is strong.

Gentle slope hilly land: composed of granite and metamorphic rocks. The height is 200 ~ 400 meters, the top of the mountain is round and muddy, the slope is 20 ~ 30, and the water system is dendritic, mostly gentle slopes and valleys. Such as the southeastern part of China and the western part of Ningxia.

Terrace: a wide platform with steep slopes around it, called terrace. The height is below 150m, the slope is about 25, and there are no prominent hilltops, such as terraces composed of granite and metamorphic rocks. Carboniferous limestone scattered in Gaotan area mostly forms karst landforms such as karst residual hills, solitary peaks and peak forests beside river valleys. Most of the surface layer has weathered into red soil with vegetation. Poor water storage conditions often lead to rainwater loss. Spring water is exposed less, and it dries up in dry season.

The second terrace on the floodplain: it is distributed in the middle and upper reaches of Paitan River, 6 ~ 13m higher than the river surface, with a width of about 200 ~ 800m and an inclination of 2 ~ 4 to the river bed. It is composed of Quaternary modern alluvial deposits, with a thickness of 13m, flat terraces and deep soil layers, so it is an area with good agricultural production.

The first terrace of floodplain: distributed in the middle reaches of Zengjiang River, covering an area of 63 square kilometers. The terrace is 3 ~ 4 kilometers wide and 3.5 ~ 12 meters thick, which is higher than the river surface 1 ~ 6 meters. From Zhengguo to Xiao Lou, the terrain is flat, with only one terrace, which is asymmetric and 0.5 ~ 1.5km wide. ..

Valley Plain: distributed in Gaotan East Cave from Lingshan to Paitan, with an area of 4 1 km2. The valley plains around Zhengguo and Xiao Lou are characterized by flat terrain, 6-20m above sea level, curved rivers and numerous tributaries. There are low hills composed of granite and migmatite on the plain, covering an area of about 76 square kilometers.

River and sea accumulation: Xintang ~ Xiancun ~ Shitan ~ Sanjiang Delta Plain is the northeast plain of the Pearl River Delta. It is formed by the alluvial accumulation of Dongjiang and Zengjiang rivers and the deposition of ancient bays. The thickness is 20 ~ 30m, and the maximum thickness is 39.6m. Zengcheng water system belongs to Dongjiang water system, a tributary of the Pearl River. There are three rivers, such as Dongjiang River, Zengjiang River and Xifu River, with a drainage area of over 500 square kilometers, and six rivers with a drainage area of over 100 square kilometers. The average annual runoff in Zengcheng is more than1.900 million cubic meters, with tides advancing southward and abundant water resources.

Dongjiang originated in Xunwu County, Jiangxi Province, and flows through the south of Zengcheng through Longchuan, Heyuan, Huiyang and Boluo, which is the boundary river between Zengcheng and Dongguan. It starts at the junction of Boluo in the southeast of the city and ends at the junction of Huangpu District in the southwest of Guangzhou, with a flow of 30 kilometers, all of which are alluvial plains, with a river bed gradient of 0.08‰, vertical and horizontal river networks and numerous tributaries. Then it flows southwest into the Lion Ocean in the Pearl River Estuary, which is a rare river flowing from east to west in China. The river reaches within the territory are 400-500m wide and 800m wide at most. The water depth and gradient are gentle, and it can be navigable for 300-ton ships, and navigable for 1000-ton ships below Xintang.

Zengjiang River is the most important river in China. Originally it flowed directly into the Pearl River Estuary, and the Pearl River Delta Plain became a tributary of Dongjiang after its formation. Zengjiang River originates from Qixingling in Xinfeng County, flows through the northeast of Conghua County, turns to the northwest of Longmen County, and then flows south. It is the boundary river between Zengcheng and Longmen. After Modaokeng flows to Longtanpu in the northeast corner of Zhengguo, the flow increases, and it flows into Dongjiang River at Guanhai via Zhengguo, Licheng and Shitan, with a total length of 203 kilometers and a drainage area of 3 160 square kilometers. The average annual runoff is 3.59 billion cubic meters, with an average gradient of 0.74‰. The Zengjiang River in Zengcheng is 66 kilometers long and 90-220 meters wide, with a drainage area of 97 1 km2, accounting for 60% of the Zengcheng area, with a slope of 0. 17‰.

Paitan River originates from Makengzhang, Nankun Mountain, and consists of five small rivers: Gaotan Water, Lingshan Water, Gaopu Water, Chedong Water and Trail Water. It flows through Paitanxu, flows into Xiaolou Town and Er'long River, and flows into Zengjiang River. The river is 36 kilometers long with a slope of 5.5‰. The basin covers an area of 357.5 square kilometers with an annual runoff of 500 million cubic meters.

Er'long River, formerly known as Chengxi River, originated from Jiya Mountain in Xiaolou Town. It flows through Erlongwei and Lapu villages and flows into Zengjiang River in Dalou village. The river is 22.5 kilometers long with a gradient of 2.8‰. Watershed area 122.7 square kilometers, annual runoff1500,000 cubic meters.

Heping water, also known as Jiuqu water, originated in Mabiling, Zhengguo, and flowed into Zengjiang River through the cold water pit of Baihu Lake. The length of the river is18.7km, and the drainage area is 48km2.

Xifu River, formerly known as Suifu River, is the largest river in western China. Originated in Dagu Mountain, it flows through Fuhe and Xiancun and flows into Dongjiang River in Xiangtou Village. The river is 58 kilometers long with a slope of 65438 0.6 ‰. The basin area is 580 square kilometers, and Zengcheng area is 457.7 square kilometers. The average annual runoff is 5 1 100 million cubic meters. In the early 1950s, navigation was possible below Fuhe River. After the end of 1950s, due to soil erosion, the riverbed silted shallowly, and a sluice was built along the river, so only a few kilometers south of the railway could be navigable. Zengcheng belongs to the south subtropical maritime monsoon climate, and the Tropic of Cancer runs through the north of Zengcheng, which is characterized by high temperature, abundant rainfall, few frosty days and sufficient sunshine, and crops can be planted all year round. But the climate is changeable because the monsoon alternates in the morning and evening with different intensity. Affected by topography, the climate in the northern mountainous area is different from that in the southern plain.

Climatic characteristics throughout the year: It starts from beginning of spring in spring, with rainy and humid weather and relatively low temperature, generally between 12.7 ~ 2 1.7℃. In summer, from mid-April, the temperature rises, with the highest temperature of 28.5℃. The weather is often controlled by subtropical high, and the air is sultry. There is much frontal rainfall in April-June and heavy rain in July-September; Flood disasters often occur. In autumn, from 10, due to the influence of dry and cold air from the north to the south, the temperature dropped, and it was dry and rainy, but the weather was cool. From June 12 to June 1, there are often cold waves and occasionally frosty days. In winter, there is no climatological winter in China, but people still call the month with low temperature 1 1 ~ 1 as winter.

The annual average air pressure is 10 12.2 mbar, which is quite different between winter and summer. In winter, controlled by the polar high, the air pressure is relatively high, with an average of about12 ~ 1020 mbar in10. Affected by tropical cyclones in summer, the air pressure is relatively low, with an average of about 1003 mbar in July and August.

According to statistics from1994 to 2005, the annual average temperature is 22.2℃ (historical value is 2 1.8℃), and the annual maximum temperature difference is 1.5℃. The average temperature in July was 28.3℃, the highest temperature appeared on July 2, 2004 and July 18, 2005, and the extreme highest temperature was 38.6℃. The longest continuous high temperature days is 9 days (high temperature is defined as temperature ≥35.0℃), which occurred from July 13 to July 2 1 day in 2005. 65438+ 10 monthly average temperature 13.6℃, extreme minimum temperature 0℃( 1999).