The Natural Environment |
1. Geographical Topography
The controlled area of The Ninth River Management
Office covers the whole Hualien County and partial areas of Che-Shan town and Hai-Ruey town. It is 140 kilometers long from the north to the south, approximately 27 to 43 kilometers wide from the east to the west. The Central Range is located at the west, high and precipitous. Many high mountains lie among it. The Coast Range is located at the east, 200 to 600 meters above the sea level. The valley plain, the finest area, lies among these two ranges and only covers 13% of the total area. Among which, the rivers covers 6% or so of the total area. Therefore, the mountain regulation and flood control are the two major tasks here in Hualien County.
There are two main rivers in area called Hualien River and Shiew-Gu-Luang River; Ji-An River, Mei-Loon River, Li-Wu River, and Ho-Ping River, four rivers as the secondary ones. All these originate from the Central Range and run to the Pacific Ocean.
Shiew-Gu-Luang River is located at the southern area, originates from Lun-Tien-Shan of the Central Range. After the valley, the river turns to north. It will merge with five branch rivers and turn to east at Ruey-Shuei town, pass through the Coast Range and run to the Pacific Ocean via the Big Harbor.
Hualien River located in the central area originates from Ba-Tse Mountain of the Central Range. It will turn to the north after the valley. After gathered with five branch rivers, it will run to the Pacific Ocean out of the southern end of Hualien.
Basic information of each main and secondary river :
| Category |
River Name |
Drainage Area
KM2 |
Length on the level ground
KM |
Gradient on
the level ground |
Planned Flood Amount
(Q100) |
| Secondary Rivers |
吉安溪 |
42.16 |
8.10 |
1:101 |
574 |
|
美崙溪 |
76.40 |
12.50 |
1:120 |
1,140 |
|
立霧溪 |
616.30 |
5.10 |
1:170 |
|
| Main Rivers |
秀姑巒溪本流 |
1,790.46 |
63.00 |
1:265 |
17,600 |
|
支流樂樂溪 |
628.40 |
7.00 |
1:265 |
8,270 |
|
支流卓 溪 |
25.40 |
3.90 |
1:45 |
324 |
|
支流豐坪溪 |
286.80 |
13.10 |
1:155 |
3,930 |
|
支流紅葉溪 |
65.30 |
7.60 |
1:57 |
713 |
|
支流富源溪 |
186.90 |
9.00 |
1:114 |
2,540 |
|
花蓮溪本流 |
1,507.09 |
36.00 |
1:337 |
16,900 |
|
支流光復溪 |
53.90 |
15.00 |
1:76 |
1,720 |
|
支流馬鞍溪 |
161.80 |
8.00 |
1:71 |
2,040 |
|
支流萬里溪 |
264.39 |
10.00 |
1:130 |
3,760 |
|
支流壽豐溪 |
275.92 |
9.00 |
1:65 |
2,920 |
|
支流木瓜溪 |
468.21 |
12.00 |
1:94 |
6,300 |
2. Meteorology
Taiwan is located at the sub-tropical area. The Tropic of Cancer passes through Ruey-Shuei town, southern Hulien. The monthly average temperature is about 17 – 28 degree centigrade. During the summer and the autumn, typhoons are formed in the northern Pacific Ocean and flew to Hualien area. Therefore, the rainfall concentrates from June to October. It will not bring much rainfall during the fall and the wintertime due to the strong northeast monsoon. Therefore, the annual rainfall is about 2000mm something. The rainfall in the summer and autumn occupies three quarters annually; only a quarter of rainfalls are in the autumn/winter time.
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