Pingding Channel has been maintained of original look, in Channel and tunnel, since the excavation in Qing Dynasty, with the exception for necessary maintenance. The environment surrounding the Channel has not been destroyed and the ecology is quite abundant. Hence Chi-Sing Irrigation Association takes consideration of irrigation water, ecological environment and various factors in the improvement on the Channel by conducting a series of planning and design. The Association applies rock stacking in U-shaped ditches to build porous environment with irregular cross-sections in depth and width to conserve irrigation water, produce changes in depth and create an environment for the habitat of fish, shrimp and insects in the water. The engineering of Channel is further divided into the following types:

• U-shaped Ecological Engineering

This is the most traditional but also the best engineering for maintenance. This engineering applies mold for fixed shape, then apply concrete similar to the average drainage construction in cities. Such construction method is easy but also has the most flaws mainly because of its impact on the ecology of Channels. It is quite destructive for frogs or insects relying on water. For example, dragonfly nymph and firefly larva would have no place for pupation. For frogs, it could cause impact on the breeding quantity due to the reduction of moss attaching to the wall and planktons in water.(b)

• Porous Concrete Engineering

Porous concrete engineering is applied to reach balance with nature after the implementation of U-shaped engineering. In view of impact of U-shaped engineering to the environment, porous concrete engineering emphasizes on building a survival space in favor of benthos. The engineering crisscross rocks of different sizes to produce small apertures and apply concrete on the hills after stacking. The advantage of such engineering is that organisms can habitat in dark apertures while more plants and moss will grow from the apertures, providing certain level of protection for frogs or insects and shrimps relying on water for survival.(b)

• Simulated Ecological Engineering

This engineering digs pits of different depth from flat aqueduct in order to simulate the real situations in the creek and river, causing water flow speed to result in drift currents and torrents. It is also integrated with porous concrete engineering to provide apertures for the survival and hiding of benthos. Such engineering takes consideration of both the environment and aesthetics. The massive use of such ecological engineering aims to reach balance between the ecological environment of the region and artificial construction. However this is not easy task.

In sum of all abovementioned engineering, simulated ecological engineering has become an inevitable trend as time evolves. It is believed that there will be better engineering that can more closely connect with the nature, and that is the biggest wish for people who love and care about the nature.(b)

Reference material：

(a)Taipei City Chi-Sing Irrigation Association Journal, September 2012
(b)Ancient Channel, June 2002
(e)Praise Channel