Kaiyuan topography, geology, earthquake, climate and hydrology

Kaiyuan City is located in the southeast of Yunnan Province and belongs to Honghe Hani and Yi Autonomous Prefecture. Yanshan in the east, Qiubei, Mengzi and Gejiu in the south, Jianshui in the west and Maitreya in the north. It is a traffic fortress and a central city in southeastern Yunnan.

Kaiyuan is located in the south of Yunnan Plateau, adjacent to the Yunnan-Kang axis in the west, adjacent to the edge of Guizhou-Guangxi platform in the east, and between the Wutong layers in the two major cities of Honghe and Nanpanjiang. Affected by the geological tectonic movement, the complex landforms of folds, faults, fault basins, karst mountains and mountains are formed, and the Zhongshan Canyon formed by Nanpanjiang River and its tributaries is a moderately shallow mountain plateau landform. The mountains are north-south, high in the southeast and low in the northwest, with undulating terrain. The highest point is 2775.6 meters above sea level and the lowest point is 950 meters above sea level. Relative height difference1825.6m, with outstanding three-dimensional terrain features.

There are five landforms in the whole territory: fault basin, impact fan group, low hills, Zhongshan Canyon and karst mountain area. The mountains in the territory belong to the Yunling branch of Hengduan Mountains, bounded by Kaiyuan Dam, and juxtaposed with the east and west. The eastern part is the branch of Liuzhaoshan in Yunnan Plateau, and the western part is the residual vein of Ailao Mountain. The main peaks are Peinichong Peak, the main peak of Daheishan, Xiamishan Mountain, Shucheng Mountain, Liuziqingpo, Zhuqingpo, Chuangtian Liangzi, Liufengshan and Matoupo.

Kaiyuan City belongs to the Nanpanjiang River Basin of Xijiang River (a tributary of the Pearl River), with 12 rivers such as Nanpanjiang River, Lujiang River, Nandongjiang River, Dazhuang River and Zhongheying River, and more than 60 natural lakes, triangular seas and spring pools.

Nanpanjiang River, which originated in Zhanyi County, Qujing region, enters from the vicinity of Denglongshan Station in the northwest of the urban area, reaches Datuzhai in the south, turns to the boundary of Kaimi and Mi in the north, goes east along the boundary of Bai Le Road, Mazheshao and Zhongheying, and leaves at the junction of the northeast of the urban area and Qiubei. Nanpanjiang River is 82 kilometers long and has a drainage area of 882 square kilometers. Average discharge is 2 17.5 m3/s, maximum discharge is 1440 m3/s, and sediment concentration is 1.09kg/m3.

Lujiang River, which originates from the northwest foothills of Chirui Lake in Shiping County, passes through Yilong Lake and Jianshui to Ruodian Lanpanzhai. Enter from the southwest of the city, cross Kaiyuan Dam in the north, and join Nanpanjiang River near Village Nine. The section of Kaiyuan Dam on Lujiang River was called Meng Le in ancient times, and the section below Muhuaguo Village was called Donghe in ancient times. The flow of Lujiang River is 25 kilometers long, the drainage area is 33 1 km2, the average flow is 10.64 m3/s, the maximum flow is 573 m3/s, the minimum flow is 0.87 m3/s, the annual average runoff is 39 1 100 million m3, and the sediment concentration is 0.97 kg/m3.

The South Dongjiang River, an underground undercurrent, gushed out from the South Cave and flowed into Lujiang River from south to north, which was called Qingshui River in ancient times. The original length of Nandong River is 6.6 km, and it is 5.3 km after the reconstruction of 1978, with an average flow of 8. 18 m3/s, a maximum flow of 86.5 m3/s, a minimum flow of 2.97 m3/s, an annual average runoff of 294 million m3 and a sediment concentration of 0.97kg/m3. Accumulated water area 160 km2.

Dazhuang River, which originates from Shiping Village at the foot of Dazhuang Daheishan, flows through Dazhuangbazi from east to west and flows into the Triangle Sea. The total length of Dazhuang River is 13.8km, the maximum discharge is 156 m3/s, the minimum discharge is 1.6m 3/s, the annual average runoff is 58 million cubic meters, and the sediment concentration is 1.09kg/ cubic meter. Water accumulation area 13 1 km2.

Zhongheying River, which originates from Longtan of Zhongheying Shucheng, flows through Zhongheying Dam from west to east, flows through Xiangshui Dam to north, and flows into Nanpanjiang River through Feiyuze Power Station. The maximum discharge of Zhongheying River is 40 m3/s, the minimum discharge is 0.4 m3/s, the annual average runoff is102 million m3, and the sediment concentration is10.09kg/m3. The accumulated water area is 3 19 square kilometers.

The triangle sea covers an area of 4.33 square kilometers, with the deepest point 10 meter. It is a man-made reservoir with a storage capacity of 27 million cubic meters.

Kaiyuan belongs to subtropical plateau monsoon climate. Due to the influence of low latitude, high altitude and monsoon activities, the following characteristics have been formed:

Summer is long without winter, and autumn and spring are connected, with large daily temperature difference and small annual temperature difference. The annual average temperature in Kaiyuan dam area is 19.8℃, the extreme maximum temperature is 38.2℃, and the extreme minimum temperature is -2.4℃. The accumulated temperature of 10℃ is as long as 326 days, reaching 6729.8℃, and the frost-free period is 34 1 day. The hottest month is July, the average temperature is 24.2℃, the Leng Yue is 1, the average temperature is 12.8℃, and the annual temperature difference is 1 1.4℃. The average temperature in the coldest month of 65438+ 10 is still above 12℃, so summer is long without winter, and autumn and winter are connected.

The dry and wet seasons are distinct, and there are many droughts all the year round. Kaiyuan is located in the leeward slope of warm and humid airflow in the southeast and warm and humid airflow in the southwest, and it is not easy to form clouds to rain under the action of sinking and burning wind, so it belongs to one of the three rainless areas in the province. The annual average rainfall is 800 mm, the water surface evaporation power reaches 1466 mm, and the annual dryness is 1.8. It belongs to subtropical semi-arid monsoon climate, with distinct dry and wet seasons and frequent droughts all year round.