近年來由於環保意識抬頭，對於任何構造物皆已不破壞自然生態為前提。對於水利工程師而言，構造物對於治水防洪之安全性與不破壞生態之間的評估，期許能營造出互利共生之境界是一門重要的學問。然而透水結構物被認為是比不透水透水結構物更具保護生態環境的效果，其因為可以允許水中生物的遷徙。從水質的觀點來說的話，在透水結構物中，細菌會生長在表面及內部來分解有機物，這種生化反應會促成河水淨化，而且會增加溶氧有助於需氧的有機物分解。本篇研究即是利用ADV流速儀來針對透水結構物與不透水結構物對於流場流動之差異性作一研究。
　　本文以實驗方法量測結構物前後一時序列中之垂向流速分佈，並藉由量測所得之瞬時速度變化來分析透水結構物與非透水結構物之紊流強度與紊流動量之差異。另外配合著水位之量測所得的水力坡降線與能量坡降線來探討結構物前方、上方及後方之能量損失。
　　由其分析之數據可看出對於不同孔隙率之結構物其流速分佈、紊流強度及能量損失等皆不相同，期許往後能藉由此研究對於水工結構物之設計能得到一最佳孔隙率，使其具有安全性且不破壞生態的功能。

　In recent years, environmental consciousness has gradually been an essential prerequisite for any hydraulic structures, which are not harmful to the surrounding ecology. It is important for hydraulic engineers to construct a coexistent state to the structure that it will sustain functions for flood-preventing, water-controlling and ecology-protecting. However, porous structure has much better effect on protecting environment than solid stuucture , because it allows the streamwise migration of aquatic life . From the viewpoint of water quality , inside the porous structure ,germs inhabiting the granular surface may decompose organic matter. The biochemical reaction contributes to the purification of river water.
　The purpose of this study is to find the difference in flow patterns of porous and solid structures when they are placed in channel. An Acoustic Doppler Velocimeter (ADV) is used for the flow measurements. The instantaneous velocities at selected verticals along the porous and solid structures are measured and mean values of them are obtained through time averaging. Besides, it probes into the energy loss of the structures in all sides in water, with the HGL and EGL measured by the water level.
　We got the different velocity distribution, the strength of the flow and the energy loss when we use different porosity of the structures. We expect to get a better-designed structure with the best porosity, which can be both safety and ecology-protecting, for hydraulic works through the study.

1. Chen X.W. and Y.M. Chiew,“ Velocity Distribution of Turbulent Open-Channel Flow with Bed Suction,”Journal of Hydraulic Engineering, Vol.130, No.2,pp.140-148, 2004.
2. Choi Y. and M.W. Peter,“ Momentum transport mechanism for water flow over porous media, ”Journal of Environment Engineering,Vol.123,No.8,pp.792-799, 1997.
3. Fang F.M. and D.Y. Wang,“ On the flow around a vertical porous fence, ” Journal of Wind Engineering and Industrial Aerodynamics,67&68,pp.415-425, 1997.
4. Fredrick W.B. and J. Davis,“Microflowregimes and the disturbution of macroimvertebrates around stream boulders, ”Freshwater Biology,Vol.40,pp.77-80, 1998.
5. Kohji M. and S. Maeno,“ Discharge through a Permeable Rubble Mound Weir, ”Journal of Hydraulic Engineering,Vol.131,No.1,pp1-10,2005.
6. Lee S.J. and H.B. Kim,“ Laboratory measurements of velocity and turbulence field behind porous fences, ”Journal of Wind Engineering and Industrial Aerodynamics,Vol.80,pp.311-326,1999.
7. Millar R.G.,“ Grain and form resistance in gravel-bed river, ”Journal of Hydralic Research,Vol.37,pp.303,1999.
8. Nezu and Nakagawa,“Turbulence in open-channel flows,” IAHR monograph, 1993.
9. Ranga R. and L.R. Sharma,“ Form drag of fences placed in Disturbed Turbulent boundary layers, ”Journal of Environment Engineering Mechanics, Vol.125, No.4,pp.419-425,1999 .
10. Snyder W.H. and I.P. Castro,“ Acoustic Doppler velocimeter evaluation in stratified towing tank, ”Journal of Hydraulic Engineering,Vol.125,No.6, pp.595-603, 1999.
11. Vito F. and B. Giorgio,“ Flow velocity profiles in gravel-bed rivers, ”Journal of Hydraulic Engineering,Vol.120,No.1, pp.60-69,1994.
12. 吳建民，「泥沙運移學」，中國土木水利工程學會，(1991)。
13. 易任，「渠道水力學」，國立編譯館，(1997)。
14. 張智凱，「壓力流況橋面下之流場與流量分析」，國立成功大學水利及海洋工程研究所碩士論文，(1999)。
15. 陳建文，「水流通過橋下保護工之流速分佈探討」，國立成功大學水利及海洋工程研究所碩士論文，(2001)。
16. 黃偉哲，「水流通過透水式橋墩保護工之流況分析」，國立成功大學水利及海洋工程研究所碩士論文，(2002)。
17. 楊清華，「防風柵透風間隙配置對防風功效之研究」，國立中興大學水土保持研究所碩士論文，(2003)。
18. 盧衍祺，「流體力學」，東華書局，（1992）。
19. 蕭慶章，「實用河川工程」，財團法人成大水利海洋發展文教基金會，(2003)。