[Location and Area] Huizhou City is located in the southeast of Guangdong Province, and in the northeast of the Pearl River Delta and the middle & lower reaches of Dongjiang River. It lies between north latitude 22°24′-23°57′ and east longitude 113°51′-115°28′, with its west-east span of 152 km and south-north span of 128 km. It borders Shanwei City in the east, looks out to South China Sea in the south and connects Shenzhen City, adjoins Dongguan City in the southwest and Guangzhou City in the west, and neighbors Shaoguan City in the north and Heiyuan city in the northwest. Its administrative boundary bordering the surrounding 6 cities is 846.49 kilometers long. The City Government of Huizhou is located in Jiangbei Sub-district of Huicheng District.
Huizhou is located at the transportation hub of the eastern area of Guangdong, and there are Huizhou-Shenzhen, Huizhou-Heyuan and Huizhou-Guangzhou expressways connecting other cities; Guangzhou-Shantou Highway, Shenzhen-Shantou, Chaozhou-Dongguan and Xiamen-Shenzhen expressways, Guangzhou-Meizhou-Shantou Railway and Beijing-Kowloon Railway run through Huizhou City, and there are expressways running through each County (District) of the city. Huizhou Port connects to the ports both at home and abroad directly.
As one of the large coastal cities among Guangdong Province, its land area is 11,343 square kilometers, its sea area within the territorial sea baseline is 4,519 square kilometers, and its coastline is 281.4 km long. Alternating with peninsulas and bays, there are a number of good ports and 140 islands.
[Geology] The geotectonic unit where Huizhou is located belongs to the South China fold system. The lithology is diverse, mainly granite and other magmatic rocks, and tectonic folds and faults are developing. The spread of faults is mainly in the northeast direction, mainly including Luofu Mountain Fault Zone, Zijin - Boluo Fault Zone and Lianhua Mountain Fault Zone. Diverse lithology results in the formation of various soil types. Metamorphic rocks are mainly distributed in Lianhua Mountain Fault, north of Zijin - Boluo Fault and part of foothills of Luofu Mountain, and the soil layer of developed soil is generally more than 1 meter in thickness, with fine texture, high clay content, and abundant phosphorus and potassium. Red sand shale is mainly distributed in Boluo, Huidong and other places, composed of different sizes of gravel, sand and clay, and the soil layer is generally thin. River alluvium is widespread, and the soil layer is thick, with uniform texture, high clay content, abundant soil nutrients and wide adaptability. Beachfront deposits are mainly distributed in Huidong, Huiyang and other coastal areas, and the soil layer is thick, with abundant nutrient content and high fertility potential; however, its salt content is high, and some of them may be subject to acid and alkali damage.
[Landforms] Leaning on Jiulian Mountain in the north and looking out to the South China Sea in the south, Huizhou is the southwestern section of the paralleled ridge-valley of East Guangdong, with complex landforms. The relief is high in the northern and eastern areas and low in the central and western areas, the low mountains, hills, tablelands and plains alternate with each other in the central area, and alluvial terraces are around hills and tablelands and on both sides of rivers. In terms of the land area of the city, medium and low mountains account for 7.7%, hills account for 26%, tablelands account for 35%, and plain terraces account for 31.3%.
There are medium and low mountains and hills in the northern and eastern areas formed by Tiantang Mountain, Luofu Mountain, Baiyun Mountain and Lianhua Mountain, and most of them are medium and low mountains in the northeast-southwest direction and arranged in parallel. There are more than 30 peaks with an altitude of 1,000 meters or above in the city. Lianhua Mountain, with an altitude of 1,336 meters in Huidong County, has the highest peak in the city.
The central and western areas are mainly plains, tablelands or valleys formed through erosion and accumulation by Dongjiang River, Xizhi River and other tributaries, such as Huizhou Plain, Yangcun Plan and Xizhi River Valley.
Its south connects the South China Sea. With a mountainous coast, its coastline is twisted and curved, with a total length of 281.4 km. Headlands alternate with bays, forming a complex erosion-accumulation bedrock gulf coast. There are mangrove forests in Huangyuchong of Daya Bay and adjacent areas. The seabed topography is characterized by grooved bay bottom, flat bottom and great depth.
Karst topography develops in Pingling, Longjiang and Yonghan towns of Longmen County and Gongzhuang Town of Boluo County.
[Hydrology] In 2013, Huizhou's average annual rainfall was 2288.0 mm, 20.6% higher than many years' average of 1897.0 mm (1956 - 2000), so it was a wet year. The rainfall was 2020.0 mm in the urban area, 23.0% higher than many years' average of 1641.8 mm (1956 - 2000), and there were 127 rain days. In terms of spatial distribution, the rainfall was gradually larger from the upstream areas to the downstream areas, and the number of rain days was gradually increasing from the downstream areas to the upstream areas. The rainfall is mainly concentrated in the flood season from March to August, accounting for 83.9% of the annual rainfall. The rainfall is largest in August, accounting for 25.5% of the year, followed by that in May, accounting for 18.1%. The rainfall was smallest in January in the year, that is, 2.7 mm. The distribution of high value area and low value area of rainfall was broadly consistent with that on the average annual contour chart. The high value area of annual rainfall was located in the area near Gaotan Station in Huidong County, and the rainfall was 3744.6 mm. The low value area was located in the area near Pingtan Station of Huidong County, and the rainfall was 1687.0 mm. There were fewest rain days in the area near Yuechang Station of Xinwei Town of Huiyang District, that is, 119 days.
During flood season, the water level measured by Huiyang Gauging Station of Huizhou reached 11.24 meters on August 18, which was the highest flood level in the urban area, and just 1.76 meters below the warning level of 13 meters. According to the measurement result of Boluo Hydrological Station - a control station in the lower reaches of Dongjiang River, the annual runoff was 28.4 billion cubic meters, the average annual discharge was 900 m3/s, the annual maximum discharge was 7900 m3/s, the annual minimum discharge was 1.93 m3/s, the annual sediment discharge was 1.68 million tons, the average annual sediment discharge rate was 53.2 kg/sec, the annual sediment discharge modulus was 66.3 tons/ km2, and the average annual sediment concentration was 0.059 kg/ m3.
In May and August, there were two obvious flood processes in Dongjiang River Basin. In May, the peak flow measured by Boluo Hydrological Station of the trunk stream of Dongjiang River was 6340 m3/s, less than the level encountered once every five years (7300 m3/s); in August, the peak flow measured by Boluo Hydrological Station was 7900 m3/s, close to the level encountered once every 10 years (8250 m3/s); during August 17 - 18, under the influence of heavy rainfall, flood broke out in some Dongjiang River tributaries, including Xizhi River, Andunshui River, Gongzhuang River, Danshui River and Zengjiang River. The flood-peak stage measured by Duozhu Station of Xizhijiang River was 28.93 meters, 0.70 meter higher than the actually measured maximum level in history. The flood-peak stage measured by Pingshan Station of Xizhijiang River was 20.75 meters, 0.75 meters higher than the warning level; the flood-peak stage measured by Dutou Station and Xiangxi Station of Zengjiang River was 90.59 meters and 40.11 meters respectively, 1.39 meters and 1.26 meters higher than the warning level respectively; the flood-peak stage measured by Danshui Station of Danshui River was 19.34 meters, 0.74 meters higher than the warning level; the flood-peak stage measured by Yangcun Station of Gongzhuang River was 22.91 meters, 0.09 meter lower than the warning level.
The water level measured by each station on the trunk stream of Dongjiang River rose significantly, but was below the warning level.
[Climate] Huizhou's climate characteristics in 2013: The temperature is generally normal, the sunshine is less than normal, and the rainfall is more than normal with uneven temporal and spatial distribution. At the beginning of the year, the rainfall is significantly less than normal, and severe drought occurred in most areas; the rainfall is more than normal in the first half of the flood season, appearing in phases, and hail, thunderstorms, short-time heavy rainfall and other local violent convective weather conditions occurred frequently; the rainfall is more than normal in the second half of the flood season, the influence of tropical cyclones was relatively severe, and the city was also affected by "Cimaron", "Utor", "Trami" and "Usagi"; the influence of cold air in autumn and winter was frequent.
Annual average temperature - The City's average temperature ranged from 21.0 to 22.7℃ according to the statistics of the Survey Stations, slightly lower than that in Longmen County and Huiyang District, basically the same as that in Huidong County, and 0.4℃ higher than that in Boluo County over the same period in history.
Annual extreme minimum temperature - Urban area (Huiyang District Survey Station): 4.7℃ on January 5; Huidong County: 4.1℃ on December 30; Boluo County: 4.7℃ on December 29; Longmen County: -0.5℃ on 28 December.
Annual extreme maximum temperature - Urban area (Huiyang District Survey Station): 36.7℃ on July 13; Huidong County: 36.3℃ on August 12; Boluo County: 37℃ on July 13; Longmen County: 36.3℃ on August 12.
December is the coldest month of the year - The city's monthly average temperature was 12.5℃, 2.4℃ lower than the average temperature over the same period of previous years. Urban area (Huiyang District Survey Station): 13.3℃, 2.2℃ lower than the average temperature over the same period of previous years.
August is the hottest month of the year - The city's monthly average temperature was 27.9℃, 0.3℃ lower than that over the same period of previous years. Urban area (Huiyang District Survey Station): 27.7℃, 0.7℃ lower than that over the same period of previous years.
Annual rainfall - The city's average annual rainfall was 2,270 mm, 17.5% higher than that of previous years. The annual rainfall of the urban area (Huiyang District Survey Station) was 2,193.6 mm, 23.9% above the average; the annual rainfall of Huidong County was 2,129 mm, 12.8% above the average; the annual rainfall of Boluo County was 2,401.6 mm, 24.2% above the average; the annual rainfall of Longmen County was 2,355.8 mm, 9% above the average.
Annual sunshine hours - The number of annual sunshine hours of the urban area (Huiyang District Survey Station) was 1,561.8, 14.1% less than the average annual sunshine hours in previous years; the number of annual sunshine hours of Huidong County was 1,610.8, 21.4% below the average; the number of annual sunshine hours of Boluo County was 1,560.6, 15% below the average; the number of annual sunshine hours of Longmen County was 1,627.5, 1.7% below the average. The annual percentage of sunshine of each County (District) ranged from 35% to 37%; the maximum percentage of sunshine was in October, that is, 55% - 70%, the minimum percentage of sunshine was in April, that is, 5% - 14%.
Cryogenic freezing - From the late stage of mid-December to the late stage of late December, the temperature was low for a long time due to increasing cold air, temperature rise was slow, and the weather was cold; most of the city was subject to wide-range low temperature and frosting (freezing).
Cold, overcast and rainy weather - In early January, under the influence of cold air, cold, overcast and rainy weather continued for 3 - 5 days; from the end of November to early December, Longmen County sustained 3 - 5 days of cold, overcast and rainy weather; from mid-December to late December, the City sustained long-time coldness, overcast and rainy weather, in which Longmen County sustained up to 16 days, and the rest of the City sustained 10 - 15 days (Definition of cold, overcast and rainy weather: daily average temperature≤12℃, continuing for more than three days).
Thunderstorm - On March 19, thunder occurred in each County (District) of the city. The annual average number of thunderstorm days was 73 days in the city, the annual number of thunderstorm days was 77 days in the urban area (Huiyang District Survey Station), 58 days in Huidong County, 81 days in Boluo County, and 76 days in Longmen County. On April 30, 17 people were injured due to lightning strike incident in Luofu Mountain of Boluo County caused.
Flood season - On March 28, the food season started all over the city. The city's average rainfall in the flood season was 2036.9 mm, accounting for 89.7% of the annual average rainfall, and 25.7% higher than the average over the same period of previous years; the rainfall in the in the first half of the flood season was 1050.4 mm, 17.4% higher than the average over the same period of previous years, and the rainfall in the in the second half of the flood season was 986.5 mm, 35.8% higher than the average over the same period of previous years. The city's rainfall in the flood season is more than normal, with uneven temporal and spatial distribution. The rainfall of each County (District) in the flood season was as follows: 1979.2 mm in the flood season in the urban area (Huiyang District Survey Station), 32.3% above normal, including 908.1 mm in the first half of the flood season, 16.4% above normal, and 1071.1 mm in the second half of the flood season, 49.7% above normal; 1938.8 mm in the flood season in Huidong County, 20% above normal, including 919.8 mm in the first half of the flood season, 12.8% above normal, and 1019 mm in the second half of the flood season, 27.4% above normal; 2203.1 mm in the flood season in Boluo County, 34.9% above normal, including 1130.8 mm in the first half of the flood season, 28.4% above normal, and 1072.3 mm in the second half of the flood season, 42.6% above normal; 2026.6 mm in the flood season in Longmen County, 16.5% above normal, including 1243 mm in the first half of the flood season, 12.8% above normal, and 783.69 mm in the second half of the flood season, 22.8% above normal. The city's precipitation of "dragon boat rain" was less than normal; the influence of tropical cyclones was relatively severe.
Rainstorm - Eight wide-range rainstorms occurred in the city during the year. In the early and medium stages of early April, under the combined effect of southwest jet, shear line and cold air, rainstorm occurred in each area and heavy rainstorm occurred in some areas, and the maximum process rainfall was 136.5 mm; in the medium stage of late April, under the influence of weak cold air and shear line, heavy rain to rainstorm occurred in each area and heavy rainstorm occurred in some areas, and the maximum process rainfall was 119 mm; in the medium stage of mid-May, under the influence of the high-level trough and southwest monsoon, rainstorm to heavy rainstorm occurred in each area, and the maximum process rainfall was 195.2 mm; from the end of mid-May to the beginning of late May, under the influence of the south branch trough and shear line, heavy rainstorm occurred in each area and extraordinary rainstorm occurred in some areas, and the maximum process rainfall was 217.7 mm; from the end of early June to the beginning of mid-June, under the influence of the high-level trough, weak cold air and shear line, heavy rain to rainstorm occurred in each area, and the maximum process rainfall was 124.2 mm; in the medium and late stages of mid-August, under the influence of the super typhoon "Utor" and southwest monsoon successively, rainstorm to heavy rainstorm occurred in each area and extraordinary rainstorm occurred in some areas, the maximum process rainfall was 1145.6 mm, and the daily maximum rainfall reached 924.3 mm in Gaotan Town of Huidong County, hitting the record high according to the meteorological records and refreshing the historical record of the province; In the early and medium stages of late August, under the influence of the peripheral circulation of "Trami" and the southwesterly airstream, heavy rain to rainstorm occurred in each area and heavy rainstorm occurred in some areas, and the maximum rainfall was 112.6 mm; in the early stage of late September, under the influence of the super typhoon "Usagi", rainstorm to heavy rainstorm occurred in each area, and the maximum process rainfall was 166.8 mm.
Tropical cyclone - There were 4 tropical cyclones affecting the city in the year: No. 1308 tropical storm "Cimaron", No. 1311 super typhoon "Utor", No. 1312 typhoon "Trami", No. 1319 super typhoon "Usagi", in particular, "Utor" and "Usagi" caused a serious impact on the city. During August 13-18, under the influence of the peripheral circulation of "Utor" and the southwest monsoon successively, scale 8 - 9 instantaneous wind blew in the south of the city, rainstorm to heavy rainstorm occurred in each area and extraordinary rainstorm occurred in some areas, the cumulative process rainfall was over 200 mm in the most of the city's townships and towns, the general cumulative process rainfall was over 400 mm in Longmen County, Boluo County, Huidong County and other eastern mountainous areas with the largest rainfall, the daily maximum rainfall reached 924.3 mm in Gaotan Town of Huidong County, hitting the record high according to the meteorological records of the province, and the maximum cumulative process rainfall was 1145.6 mm; severe flood disaster caused by rainstorm occurred in the city, and the direct economic loss reached RMB 960,725,720; the typhoon "Usagi" landed on the coastal area in Shanwei City at 19:40 on September 22, then moved to Huidong County at about 22:00 and crossed the county, scale 11-13 strong wind blew, and Duozhu Town of Huidong County recorded the greatest gust of 45.4 m/sec in the city; rainstorm to heavy rainstorm occurred in the city, and wild waves and significant water increase appeared in the coastal waters of the city; the city's total direct economic loss was over RMB 1.5 billion.
Drought - From December 2012 to the early stage of late March 2013, the rainfall was seriously below normal in the city, and drought continued and reached the severe drought level; on March 28, the city's flood season came, and drought conditions alleviated. From the late stage of late September to the beginning of mid-December, drought recurred in different places, and reached the severe drought level; during December 13 - 17, heavy rain to rainstorm occurred in different places, which alleviated the drought conditions to some extent.
High temperature - The number of high-temperature days averages 15 in the city each year, it is 15 days in the urban area (Huiyang District Survey Station), 7 days in Huidong County, 24 days in Boluo County, and 15 days in Longmen County (definition of high-temperature day: daily maximum temperature ≥ 35℃). High-temperature weather mainly appeared in the following periods: late May to early June, end of mid-June to the beginning of late June, early stage of early July, early stage of mid-July, middle and late stages of early August to the early stage of mid-August, beginning and late stage of late August, and beginning of late September.
Cold wave - Cold air came earlier than normal, with frequent influence. In early September, weak cold air affected the city. There were 10 cold air influence processes in the second half of the year, of which two had a strong degree of influence: In the late stage of late November, cold air of moderate intensity came, with a temperature drop of 3.6℃ - 4.6℃ in each County (District), and the lowest temperature was 2.5℃; from the middle stage of mid- December to the early stage of late December, strong cold air came, with a temperature drop of 5.6℃ - 7.4℃, and the lowest temperature was 0.8℃.
Source: Huizhou Office of Local Chronicles "Huizhou Annals (2014)".
