花蓮南濱公園土堤設施對風速及飄鹽之影響

Influence of Wind Velocity and Salt Spray through the Mound Facilities at Nanbin Park, Hualien, Taiwan

陳財輝(Tsai-Huei Chen) ； 黃隆明(Long-Ming Huang) ； 賴振墉(Zhen-Yong Lai)

《台灣林業科學》 21卷4期 (2006/12) Pp. 395-407

https://doi.org/10.7075/TJFS.200612.0395

摘要

南濱公園原為低漥海岸林地，經由掩埋垃圾及廢棄土而墊高，再經過景觀規劃植栽，成為多功能之海濱公園。為瞭解公園前線土堤設施實際功效，本研究以多層風速計觀測不同型態土堤迎風面與背風面之風速及飄鹽量分布，研究結果顯示，由於土堤走向與風向幾近平行（夾角僅5°）因此，迎風面氣流受地形抬升與流場擠壓之效應，並不顯著，導致氣流越過土堤後，能量衰減有限，減風效果不彰；經分析得知，圓形土堤平均減風效果僅有32%，而細長形土堤平均減風效果也只有38%，兩種土堤設施減風效果都不盡理想；至於圓形與細長形土堤中間之風口處，由於土堤並未造成流場擠壓效應，反而成為風口之遮蔽屏障，在背風面156m範圍內之平均減風效果高達約25%。在減鹽效果方面，圓形與細長形土堤背風面平均減鹽效果達50至60%，兩者之減鹽效果皆優於減風效果；再者，圓形與細長形土堤中間之風口處，鹽分量隨距離增加而遞減，然而差異並不明顯。綜合而言，土堤設置應與風向垂直，才能發揮其減風與減鹽效果，由於南濱公園土堤規劃僅考慮景觀因素，而忽略對氣流之消能設計，致使土堤走向與風向幾近平行，使得南濱公園整體區域之減風與減鹽效果不佳，導致栽植林木生長不良。

關鍵字

花蓮 ； 南濱公園 ； 土堤設施 ； 風速 ； 飄鹽

並列摘要

Nanbin Park was originally formed from a low seacoast windbreak along the Hualien County coast with a pad of deposited waste soil and garbage, and was later developed through landscape planting practices into a multifunctional seashore park. In order to understand the physical benefits of the mound facilities of Nanbin Park, a multi-layer anemometer was used in this study to investigate changes in wind velocity and salinity occurring at varying distances for 2 types of mounds located in areas with different topographic characteristics. The wind velocity survey showed that owing to the mound alignment being nearly parallel to the wind direction (the included angle was only 5º), the wind reduction was not substantial because of the insignificance of the flow compression effect caused by topographic lifting. The wind velocity at the windward side of the mound decreased an average of about 32% and 38% for rounded and slender mounds, respectively. The wind velocity on the leeward side of the mound was reduced by up to 25% on average within 156m. Results of the salinity reduction survey showed that, on average, the salinity reduction on the leeward side of the round mound reached 50%, and was 60% for the leeward side of the slender mound. Therefore, salt reduction showed better performance compared with wind velocity reduction. The salinity observed at the wind gap decreased with the increasing of distance from wind gap, but between round and slender mounds, no significant difference was detected. In summary, the wind velocity and salinity reduction functions can be achieved only if the alignment of the mound is perpendicular to the wind direction. As the park mound was constructed principally with the landscape in mind (i.e., parallel to wind direction) and without considering airflow reduction, the ability to reduce the wind velocity was degraded, which therefore, accounts for the poor growth of the planted trees.

並列關鍵字

Hualien ； Nanbin Park ； mound facility ； wind velocity ； salt spray