[Topography and landforms] Lin’an belongs to Jiangshan-Lin’an stratigraphic division in Jiangnan Stratum. From the Proterozoic Sinian Period to the Quaternary System of the Cenozoic, all strata have been developed except the Triassic of Mesozoic and the Tertiary System of the Cainozoic. The regional structure belongs to the Qiantang Platform Fold belt of Yangtze Quasi-platform. In the long geologic age, under the action of Indo-China movement and Yanshan movement, the topography and landforms in the region have presented diversity and singularity.

　　The terrain in the region tilts from northwest to southeast, and the north, west and south of the region are surrounded by the mountains, forming a southeast horseshoe barrier. The northwest is dominated by high mountains and lofty hills; the southeast mainly has hills and broad valleys, with flat terrains; the landform of the whole region is mainly governed by middle and lower mountains & hills. The average altitude of the northwest and southwestern mountainous areas is above 1,000 meters, and the altitude of the east valley and plain is below 50 meters; the altitude of Qingliangfeng in the west is 1,787 meters, and the altitude of Shiquan in the east is only 9, presenting an altitude difference of 1,778 meters between the east and west. This is quite rare in Zhejiang Province. In the region, low mountains and hills are arranged with basin valleys alternately, which can be divided into middle mountain – deep valleys, low hilly land – broad valley and valley plain. The area of the middle mountain (altitude above 1,000 meters) occupies 5.4%, the middle and lower mountain (altitude above 800 meters – 1,000 meters) takes up 8.8%, and the valley plain (altitude below 100 meters) occupies 10.4%.

[Climate] Lin’an is located in the northwest of Zhejiang Province. At the south edge of the Subtropical Monsoon Climate Zone, it belongs to the monsoon climate. It is warm and wet, with abundant sunlight and rainfall as well as four distinctive seasons. The average annual precipitation is 1,613.9 millimeters, there are 158 precipitation days, and the average annual frost-free period is 237 days; it is often influenced by disastrous weather like typhoon, cold wave and hail. It is dominated by hills and mountainous regions, and the terrain tilts from northwest to southeast. It has an obvious 3D climate. From Jincheng with the altitude of below 50 meters to the top of Tianmu Mountain with the altitude of 1,506 meters, the annual average temperature drops from 16 ℃ to 9 ℃, with an annual temperature difference of 7 ℃. It stretched across two climatic zones which are subtropical zone and temperate zone.

[Mountain range and river system – Tianmu Mountain] The mountain range in Lin’an can be divided into north branch and south branch: the north branch is Tianmu Mountain and the south branch is Yuling Mountain. Tianmu Mountain is the north branch of the trunk mountain of Zhejiang Province, Xianxia Ridge. It winds into the territory from Huaiyu Mountain in Jiangxi Province across Mount Huang in Anhui Province; it lies across the northwest part, from the northwest to the southeast. It rises from Zhejiang-Anhui Border, Qingliangfeng (altitude 1,787 meters) in the west, and goes to Lin’an-Yuhang Border, Yaotou Mountain (altitude 1,094 meters) in the east. Its main vein winds from Qingliangfeng to the northeast, including Longtang Mountain (altitude 1,586 meters), Changpingjian (altitude 1,226 meters), Maxiao Ridge (altitude 1,502 meters), Baizhang Ridge (altitude 1,334 meters), Xianling (altitude 1,014 meters), Qianqing Mountain (altitude 1,347 meters), and Zhaojun Rock (altitude 1,449 meters); besides, it has multiple vertical and horizontal branches, such as Liuling (altitude 730 meters), Lutang Ridge (altitude 885 meters), Jianshan Ridge (altitude 853 meters), Kangshan Ridge (altitude 948 meters), and Dishui Rock (altitude1,217 meters).

The terrain of the main vein drops after passing Daochangping (altitude 963 meters) to the northeast, including Tongguan Ridge (altitude 536 meters) and Qianqiu Pass (altitude 398 meters); its terrain rises in Laohuping, forming East and West Tianmu Mountains in the north. West Tianmu Mountain (altitude 1,506 meters) and East Tianmu Mountain (altitude 1,479 meters) is adjacent to Anji in the north of the two peaks. In the east, it has Longwang Mountain (altitude 1,587 meters), Yangtianping (altitude 1,248 meters), Pingding Mountain (altitude 1,109 meters), Chayeping (altitude 1,141 meters), Cao Mountain (altitude 1,122 meters), Dashan Ridge (altitude 988 meters), Mugong Mountain (altitude 1,059 meters), Hongtao Mountain (altitude 1,029 meters), and Yaotou Mountain (altitude 1,095 meters). The mountain goes low to the east. From the Jingshan Mountain at the border with Yuhang, the mountain forms a coccyx gradually, and disappears between Hangzhou Bay and Hangjiahu Plain.

[Yuling Mountain] Yuling Mountain is located in the southwest of the region. Starting from Qingliangfeng, it stretches to the south along Zhejiang-Anhui Border, passing Shierjian (altitude 1,172 meters) and Guoyu Ridge (altitude 508 meters) to Gechuanjian (altitude 1,477 meters); to the east, it has Yusanjian (altitude 1,459 meters), Daling Tower (altitude 1,446 meters), and Qianniu Post (altitude 1,489 meters); in the north of the line from Daling Tower to Qianniu Post, it has Qianmutian of Daming Mountain, and the altitude of the main peak is 1,280 meters; Qifengjian is located in the north slope. From Daming Mountain to the east, the mountain descends slightly, with peaks below the altitude of 1,000 meters scattered. Between Hongling and Mashan Mountain, it has Heshangping (altitude 1,082 meters), Biandan Mountain (altitude 1,061 meters), and Liujian Mountain (altitude 1,135 meters); a banded uplift is presented from west to east, and the mountain becomes gentle after stretching for 4,000 meters, and it is the hill with the altitude of about 500 meters.

[Low mountains and hills] Low mountains and hills are in the middle, south and east of the region, and they are the extension of Tianmu Mountain and Yuling Mountain. A large area of low mountains and hills is formed under the cutting of South Tiaoxi Stream, Middle Tiaoxi Stream, Tianmu Stream and Changhua Stream. Drainage basin of South Tiaoxi Stream: It is the major are of low mountains and hills in the region. The trunk stream originates from Linmu, Yangqiao and Langkou in Taihuyaun Town; from Xiyuqiao of Linglong Sub-district, its branch Jinxi Stream has an open terrain and low & even hills. In addition, it also has rising mountains including Dawang Mountain (altitude 560 meters), Miji Mountain (altitude 407 meters), Jiuxian Mountain (altitude 392 meters), and Linglong Mountain (altitude 358 meters). From Hengxi Stream in Jincheng Sub-district and Hengtan to Qingshan Lake Sub-district, it is the largest valley and small plain. Along the stream, it has Huashi Rock (altitude 125 meters), Gongcheng Mountain (altitude 157 meters), Anguo Mountain, Shijing Mountain (altitude 92 meters), Qinshan Mountain (altitude 139 meters), Heshan Mountain (altitude 236 meters), Gongshan Mountain (altitude 311 meters), Mu (Lao) Mountain (altitude 171 meters), Qingshan Mountain (altitude 150 meters), and Dadi Mountain (altitude 299 meters).

Drainage basin of Middle Tiaoxi Stream: The region below Gaole and Hengfan also belongs to the area of low mountains and hills, and also has river valleys and small plains. Shuanglin Mountain (altitude 413 meters) exists between Gaohong Town and Jinbei Sub-district.

Drainage basin of Tianmu Stream: Various tributaries flows from West Tianmu, Zaoxi and Taiyang to Qianchuan and Leping by passing Yuqian Town, to form a large area of hills & broad valleys and river valleys & small plains, including Jiazi Mountain (altitude 419 meters) of Yuqian, Heshan Mountain (altitude 453 meters), Lvyunping (altitude 140 meters), Huangshan Mountain (altitude 298 meters), Difeng Mountain (altitude 261 meters), Wujin Mountain (altitude 368 meters) of Fangyuan, Xipu Mountain (called Xianren Rock, altitude 417 meters), and Baiyun Mountain (altitude 711 meters) of Leping.

Drainage basin of Changhua Stream: It flows from Longgang to Heqiao by passing Changhua. Both banks are broad, mainly dominated by low mountains and hills at the altitude of 200 m – 300 m. Wulong Mountain (altitude 340 meters) in the north of Changhua Town is famous; low mountains and hills in the south of the region and low mountains and hills of Qianli Post extending from Chun’an, Jiande and Tonglu are connected to form a large area, and the major lithology is sandstone, shale, limestone and quartzite. Owing to the corrosion effect of limestone, there are many miraculous peaks and caves.

[Overview of water system] Main streams in the region include East Tiaoxi Stream, primary source South Tiaoxi Stream, and main tributary Middle Tiaoxi Stream, belonging to Taihu Lake River System; the primary source of Fenshui River, Changhua Stream and the main tributary Tianmu Stream belong to Qiantang River System. All major streams originate from mountains with the altitude of above 1,000 meters; the upstream is dominated by gorges, characterized by steep slope, deep valleys and jet stream; the middle and lower reaches are located in low mountains and hills, with a relatively flat terrain, and there are many valley plains.

[South Tiaoxi Stream] Located in the east of the region, it is the primary source of East Tiaoxi Stream. It belongs to Taihu Lake River System, and originates from Linmu Majian Post of Taihuyuan Town. The altitude of the main peak is 1,271.4 meters, the total length is 63 kilometers, the drainage area is 720 square kilometers, and the gradient is 12.3‰. The length of the section in the region is 55 kilometers, and the drainage area is 620.8 square kilometers. According to the actual measurement at the Hydrometric Station of Qingshan Reservoir, the average annual discharge is 14.5 cubic meters/second. The primary source of South Tiaoxi Stream, Langkou Stream flows from the source Shuizhuwu to Shuangxikou, called Xikeng Stream (Xikeng Water); after it enters Dongkeng Stream from Shuangxikou, it is called Langkou Stream; in the south, it passes Lifan Reservoir, to Langkou, called South Tiaoxi Stream. The south stream flows into Nigou Stream in the west of Hulu Ridge, and joins Panxi Stream in Gantangyan; the east stream joins Maxi Stream in Changqiao, and enters Qingshan Reservoir after joining Jinxi Stream from Qinglongkou. Hengxi Stream and Lingxi Stream join in the south of Qingshan Reservoir, and Shuangling Stream joins in the north; Qingshan Reservoir flows into Youchetou and joins Yanxi Stream in the east; it joins Xieyang Stream in Baojiatan, and flows out by passing Wangjiabu in the east. After 1950, comprehensive treatment was conducted for South Tiaoxi Stream, and the large flood control project Qingshan Reservoir was completed in 1964; the medium-sized flood control and water storage project Lifan Reservoir was built in 1973, and expanded from 1993 to 1995; from 1975 to 1980, a flood bank of 34,738 meters was built for the stream bank of 24.5 kilometers from Lifan Reservoir to Changqiao. After 1995, the flood control capacity of South Tiaoxi Stream was improved from every 10 years to every 20 years.

South Tiaoxi Stream passes Jincheng

[Middle Tiaoxi Stream] Located in the northeast of the region, it is the main tributary of East Tiaoxi Stream, and belongs to Yangtze River System. It originates from Qingcaowan Post at the junction of Shimen of Gaohong Town and Anji County, and the altitude of its main peak is 1,073.9 meters. The stream originates from Meilingkeng, and passes Shimen, Gaohong and Hengfan in the southeast, and flows out in Xiatanglou; in the east, it passes Changle and Tangwandu, and joins East Tiaoxi Stream from the left bank. The total length is 47.8 kilometers, the gradient is 17.9‰, and the drainage area is 185.6 square kilometers. In December 1999, the upstream Shuitaozhaung Village started to build the medium-sized flood control project Shuitaozhaung Reservoir, and the total storage capacity is 28,880,000 cubic meters. The primary source of Middle Tiaoxi Stream, Youxi Stream passes Dashan Village, Shimen, Shuitaozhaung and Gaole from Meilingkeng to the southeast, and joins Chouxi Stream, called Middle Tiaoxi Stream. The length of Youxi Stream is 22.5 kilometers, and located in the middle & low mountains and deep valleys. From Dashan to Longtoushe, huge rocks are connected at the bottom of the stream; from Longtoushe to Baijie Temple, the stream width is about 30 meters, and cliff stones stand like a wall on both banks; from Baijie Temple to Daren Temple, the valley is narrow and winding, and only the river valley of Shuitaozhaung Section is wide, about 55 m – 200 m. In the lower part, it passes Ancun and Goushanjiao to join Baishui Stream; flows out from Xiatanglou in the east.

[Tianmu Stream] It runs through the middle of the region, and is the main tributary of Fenshui River, belonging to Qiantang River System. It originates from Tongkeng Post at the junction of the north of West Tianmu Mountain and Anji County, and the altitude of its main peak is 1,506 meters. Starting from Guniutang of Tianmushan Town, it passes West Tianmu Mountain, Shaolu, Yuqian, Yankou, Tashan and Zishui from north to south, joins Changhua Stream in Zixi, and enters Fenshui River in the south. The stream length is 58 kilometers, the drainage area is 761.5 square kilometers, and the gradient is 21.8‰.

The length of the primary source of Tianmu Stream, Dongguan Stream is 36 kilometers, the gradient is 33.7‰, and the catchment area is 173.3 square kilometers. It passes Pingxi, Houyuan and Zhongjia Village from Guniutang, to join Xiguan Stream, and joins Zhengqing Stream in Baihe Village; joins Fengling Stream in Shuangxikou by passing Jiaokou and Shaolu, called Tianmu Stream. It joins Zaoxi in Yaocheqiao by passing Yuqian Town, joins Taiyang Stream (Jiaoxi) in Nanshanwu, joins Guzhu Stream in Longtoufan, joins Zhulingshui in Yicun, joins Zhuxi in Xiaoxikou, joins Zhongtangshui in Machebu, and enters Fenshui River after joining Changhua Stream in Zixi.

[Changhua Stream] Located in the northwest of the region, it is the primary source of Fenshui River, and belongs to Qiantang River System. It originates from Bijia Mountain of Jixi County in Anhui Province, and the altitude of its main peak is 1,385 meters. It enters the region from Xishewu of Daoshi Town. Its trunk stream passes Xinqiao, Daoshi, Daxiagu, Longgang, Changhua, Heqiao, Qianchuan and Zixi, and flows to Qikeng Section after taking Tianmu Stream, called Fenshui River (known as Tianmu Stream before). The total length of Changhua Stream is 106.9 kilometers, the gradient is 8.6‰, and the drainage area is 1,440.2 square kilometers, in which the length in the region is 93 kilometers, and the drainage area is 1,376.7 square kilometers. According to the actual measurement at the Hydrometric Station of Qingshandian, the average annual discharge is 45.4 cubic meters/second.

New look of Changhua Stream

The primary source Changbei Stream (called Houxi or Juxi before) originates from Shanzhi Ridge of Anhui Province and enters the region from Xishewu of Daoshi Town; it is called Houxi in Daolongshan, and known as Changbei Stream after joining Renli Stream. It joins Yinkeng Stream in Huritang, and joins Shangxi slightly below Tuchuan; it flows to Taipingqiao and joins Taohua Stream in the southeast, joins Zhelinkeng Stream at the foot of Qiaomai Ridge, and joins Hexi of Dita Village in the southeast; joins Changxi Stream in Tangjiawan, called Changhua Stream below. The total length of Changbei Stream is 67.9 kilometers (the length in the region is 54 kilometers), the gradient is 12.3‰, and the catchment area is 385.5 square kilometers (the area in the region is 330.5 square kilometers).

　　In the southeast of Tangjiawan, it joins Longtankeng Stream in Jiukengqiao, and joins Lixi in Bainiuqiao; joins Huanggan Stream in Qiliqiao, and joins Pingdu Stream in Youcheli; joins Yuxi when passing the east of Changhua Town, and joins Jinkeng Stream below Yunlang; Chang’nan Stream joins in Baixia, and it joins Xishanshui in Kengkou in the southeast, joins Mashan Stream in Yinshan of Qingshandian, and joins Tianmu Stream in Zixi, called Fenshui River. From 1957 to 1995, According to the actual measurement at the Hydrometric Station of Qingshandian, the maximum discharge was 7,200 cubic meters/second (July 5, 1969), the minimum discharge was 0.95 cubic meters/second (September 8, 1978), the highest water level was 64.51 meters (July 5, 1969, Wusong Elevation System, formation level 52 meters), and the lowest water level was 52.11 meters (July 29, 1971). The source is Changhua Stream, and the tributary is Tianmu Stream. The intersection of Changhua Stream and Tianmu Stream flows to Qikeng of Leping, belonging to the reach of Fenshui River. Zixi flows to Daoshuiwu in the southeast, and receives Zifangshui; receives Shenjia and Liwushui below Leping, and receives Qikengshui above Qikeng; it flows out in the southeast. The total length is 8 kilometers. The watercourse is flat and broad, and the drop is 2 meters. The watercourse width of the intersection of Changhua Stream and Tianmu Stream is 171 meters. The catchment area above Qikeng (including Changhua Stream and Tianmu Stream) is 2,275 square kilometers. The tributaries include Zifangshui, Liwushui, Shenjiashui, and Qikengshui.