Investigation of Current Status in Jhong-gang River System (The 2th River Management Office, WRA, MOEA. June, 2007)
Due to the fact that exploitation and use of land in Taiwan usually have strong connections with rivers, related river management bureaus tended to put emphasis on facilities for water regulation, water utilization and flood control when they faced river development and management. They paid less attention to environment and ecology, to consider the issues entirely. The fact that human being’s use of river is getting diverse and that the need for space is increasing has caused the unbalance of ecological environment in river basins, and even the deterioration of environmental quality. Nowadays, because environmental protection has caught more and more attention, Water Resource Agency, the Second River Management Office and other affiliated agencies have made efforts not only to maintain regular functions of rivers, prevent disasters from happening, but also to actively consider and execute protection, conservation and planning of rivers’ ecological environment. In order to promote business, management and habitat protection of Jhonggang River, and to provide water resources engineering agencies with useful references for their planning, designs of ecological engineering, the Second River Management Office delegated investigation of Jhonggang River to Chung Hua University Department of Landscape Architecture.
This project is a two year continuing plan. In the first year, the investigation area includes Jhonggang River mainstream and its south and east branches. In the second year, the investigation areas cover Jhonggang River’s breaches, including Nangang River, Emei River, and Daping River. The main goals are conducting investigation of Jhonggang River system and establishing GIS ecological database about Jhonggang River based on the information collected. In addition, it is expected, by using documentation and investigation results, to provide proper suggestion and necessary information about ecological engineering planning of this river system.
The investigation in 2005 discovered fishes from 20 families, 45 species, a total number of 1125 times; Shrimps and crabs from 6 families, 21 species, a total number of 834 times; benthos from 5 phylum, including insects from 9 orders, 46 families, Attached algae from 126 species, and phytoplankton from 110 species; birds from 38 families, 104 species, a total number of 5099 times; amphibious animals from 5 families, 17 species, a total number of 715 times; reptilians from 8 families, 20 species, a total number of 64 times; mammals from 8 families, 17 species, a total number of 79 times; butterflies from 5 families, 62 species, a total number of 5238 times; and land-flora from 115 families, 306 genera, 421 species.
The investigation in 2006 discovered fishes from 23 families, 45 species, a total number of 5304 times; Shrimps and crabs from 12 species, a total number of 585 times; benthos from 5 phylum, 51 families, a total number of 5146 times, including insects from 9 orders, 42 families, Attached algae from 69 species, and phytoplankton from 100 species; birds from 39 families, 81 species, a total
number of 3583 times; amphibious animals from 5 families, 17 species, a total number of 572 times; reptilians from 12 families, 37 species, a total number of 296 times; mammals from 12 families, 27 species, a total number of 250 times; butterflies from 5 families, 104 species, a total number of 2343 times; and land-flora, Vascular plants from 48 families, 118 species.
According to the analysis of ecological investigations, a part of Jhonggang River, between Nangang River Bridge and its outlet, is Tidal river. Because of pollution, the most adaptable fish is Mugilidae, which can endure polluted environment. Freshwater fishes are clearly found to be more adaptable in the area near Emei Bridge, especially Cyprinidae, which have better ability to bear pollution. Allochthonous fishes are commonly found here. Between Ping-an Bridge and Jhonggang River Bridge, this region is greatly affected by waste water from Sanwang City, so the changes of the fish’s Similar quantity in the 4 seasons are more apparent, and the compositions are stable. Pseudobagrus brevianalis brevianalis is more likely to appear in winter. Hemiculter leucisculus conversely is more likely to appear in summer and fall. Fishes discovered between Tian-Mei Weir and convergence of Da-Dong River are evidently different from that in downstream. Acrossocheilus paradoxus, Hemimyzon formosanum and Rhinogobius candidianus tend to have more advantage to survive.
Even though Peng-La River is very short, it is well maintained as a
freshwater fish habitat. The effect of fish protection is that Peng-La
protected areas has the most variety. Even if destroyed by typhoons,
it is able to recover in a short period of time. However, although
it has various kinds of fishes and clean water, the fact that there
are noticeable large amount of Acrossocheilus paradoxus, Crossostoma
lacustre and Candidia barbata shows that the water has been lightly
polluted. The research on Attached algae also shows similar
conclusion. Fishes found between the east breach and Daping River
are all primary division freshwater fishes. So far no allochthonous
species is found in this area. Below Luo-La and Shi-Bi, because the
water course has been disturbed for a long time and used for
dredging and building construction pavements, the density of fishes
is very low. On the other hand, below Nangang River Bridge, the
water has been polluted by waste water for a long time, the density
of fishes is low, even affecting Upstream Migration Populations of