Chihshang Townshipn is located on the south section of Taitung Longitudinal Valley. It is geographically a part of the Longitudinal Valley. Its west sees the towering and wide Central Range, and east the relatively shorter but still steep Coastal Range. Chihshang Plain lies between the two massive ranges and at the suture zone between where the structural soil is the Eurasian Plate and Philippine Sea Plate. The ranges and longitudinal valley are roughly parallel to each other and run in the northeast-southwest direction.
The horizontally widest distance of Chihshang Plain is 6 km and no major river runs through it and its geography is neat and wide. The west of the plain sees the 2,000-meter hills above sea level of the Central Range and the steep precipice connects with Chihshang Plan. Its east is the Coastal Range and the top of which is 900 to 1,000-meter-high neat ridge. The steep and straight cliffs of the ridge connect with hills with an elevation of 500 meters, the scenery of two marked levels. The north of the plain is the Funan River Terrace, closely linked to the Central Range in its west. The width of the longitudinal valley in this place is only 1 km, making Chihshang Plain like a semi-enclosed valley in the mountain. The south of it is of uninterrupted view and sees the Peinan Mountain standing in the longitudinal valley starting from Luyeh River.
The development of drainage system decides the geography of Chihshang Plain. The height of Hsinwulu River Alluvial Fan is between 265 to 335 meters. The two major rivers on the south section of Taitung Longitudinal Valley, Hsiukuluan River and Peinan River, form a opposite direction of running in the valley. The origin of the name of this town comes from Dapo Pool located on the east of the plain. The water of the pool runs northwards into Hsiukuluan River through an artificially controlled drainage ditch.
The geography of Chihshang Plain is the main part of this town and also the space where local residents live in. The area of the plain includes Lungchuan River and Dapo River, the north end of it, to Peinan River, the south end of it, slightly with the shape of a trapezium. The widest distance is between Jinping Community and Dapo Primary School. In respect of longitudinal length, the east side is 9 km long, and the west side is 5 km long. The west side of the plain (335 m.) is higher than the east side (275 m.), with the lowest place being the longitudinal line of Dapo Pool.
Chihshang Plain is composed of the Hsinwulu River Alluvial Fan, Lungchuan River Alluvial Fan, Dapo River Alluvial Fan, Chinyuan Alluvial Fan, Wanan Alluvial Fan and Fuhsing River Terrace, with an area of 36.52 square kilometers. Due to the different rock types of the two eastern and western ranges and the varied rock debris that rivers carry, the topography of the plain in this town is not a one of the same quality despite its unity and completeness, meaning that the soil properties of the plains on both sides vary.
North-west mountainous region
The west of this township is the eastern sloping side of Central Range, made up by more than 2,000-meter-high Luntien Mountain, West Luntien Mountain and others. Underneath the mountain sees Lungchuan Precipice, the wall of which is steep and all the way down to Chihshang Plain, being a part of the eastern great precipice of Central Range. Lungchuan Precipice is surrounded by the separated hills that Luntien Mountain and West Luntien Mountain develop towards Chihshang Plain, forming a small triangular pocket in which the catchment area of Lungchuan River locates. The source of Lungchuan River is connected by waterfalls of different sizes in the precipice. Lungchuan River appears in subsurface flow in the plain and gushes out from the ground into Hsiukuluan River at the fan end.
The separated hills stretching from Luntien Mountain (2155 m.) and West Luntien Mountain (1977 m.) towards Chihshang Plain slightly protrude towards the plain. There are a great many dwelling places at the passage through the separated hills. Hsuehtien and Kuangyuan are on the north side of Lungchuan River, and Lungchuan, Wanchao, Luan and Jinping are between Lungchuan River and Hsinwulu River. These dwelling places are situated near the piedmont and most of them are shelters with the exception of Hsuehtien Village in Fuli Township.
Coastal Range is located on the east side of us and is a flat and straight hill that reaches 1,000 meters in elevation. The range can roughly be divided into two parts. The upper part is the steep mountain walls from 1,000 meters down to 500 meters in height, and the lower part is the river terrace from 500 meters down to 300 meters in elevation.
Coastal Range is the range elevated by the arc-continent collision of the west brink of the Philippine Sea Plate. From Oligocene Epoch to Miocene Epoch, South China Sea Plate submerged beneath the Philippine Sea Plate, resulting in the eruption of Coastal Range from the bottom of the sea. Certainly, the location of the eruption is nowhere near the Costal Range today but is at the bottom of the sea hundreds of kilometers away from its south-east. It took five million years for it to come to where it is today, during which there were a number of eruptions and non-equal ascending and descending movements to achieve the towering shape of what it is today. The shove of Coastal Range makes the Central Range move backwards and elevate.
The river terraces on the west side of Coastal Range are the sediments of forearc basin. The thing elevating after the push and amassing beneath the Coastal Range is the river terrace in the east of the plain.
The north of the Coastal Range in the east of Chihshang Township is cut through by the running of Pie River, and south of it hides in the Lichi mélange in the south-east of Guanshan Township, with a total length of 27 km. In this part of the Coastal Range, there are numerous peaks and its geographical display is steep with Tukaipu Mountain, 989 meters, Fuhsing Mountain, 1,022 meters, and Litung Peak, 1,023 meters, standing in the order from the north to the south. The rivers in the east of this township start here.
Chihshang Township of Taitung County lies between the Central Range and Coastal Range and is an alluvial fan plain. Its temperature differences between day and night are great. Its soil is heavy textured soil with plenty of micro-organisms. Moreover, Hsinwulu River in the south and Hsiukuluan River in the north, both unpolluted, are the irrigation source. Also, the Dapo Pool is here to control the water level. This gives Chihshang the capability to produce quality rice.