懸浮沉積物與侵蝕之相關性研究，絕大部份都集中於探討極端降雨與懸浮沉積物之關係；極少會深入探討低水位時之相關性。傳統上在估算全年度的懸浮沉積物總量時，經常將低水位時之懸浮沉積物濃度直接認定為零。經長時間野外工作，我們認為台灣低水位時之懸浮沉積物濃度雖然不高但也不至於為零。既使懸浮沉積物濃度很低，若考慮台灣中南部乾季低水位時間很長，把全年度的低水位之懸浮沉積物總量精算後加入全年懸浮沉積物總量的估算；這很可能會對長久以來所認知的全年懸浮沉積物總量的估算造成相當大的影響。於是、本計劃主要是透過精準量測低水位時河川中懸浮沉積物濃度來回答下列問題: 1. 將台灣河川低水位時之懸浮沉積物濃度直接認定為零是否合理? 2. 當懸浮沉積物的搬運不再直接與降雨相關時，台灣河川低水位時之懸浮沉積物的搬運機制為何? 我們選擇鹿野溪與旗山溪來做對比。一方面收集低水位時之懸浮沉積物也同時持續收集懸浮沉積物在時間上與空間上的分布而且著重在豪大雨下之特性，更會測試地質岩性與地體構造活動下之懸浮沉積物之時空變化與意義。本研究區域之上下游正好有構造邊緣因此、當區域降雨機制改變時其懸浮沉積物的傳輸也無可避免的將隨之改變。為了更清楚了解懸浮沉積物在本區域傳輸之機制，本計劃將密集採集極端事件及夏季降雨前到降雨後之水樣分析其懸浮沉積物濃度、顆粒分析及礦物岩性分析。本系已採購了一部雷射粒徑分析儀且已測試完成的雷射粒徑分析儀正好可以輔助本計劃之順利進行，這樣野外採集樣本就可以在本系直接量測不必像往年要到處排時間做實驗。臺灣不但具有活躍大地構造運動、相似之水文條件及短距離下豐富之地質變化使得臺灣成為研究懸浮沉積物之傳輸的理想地方。懸浮沉積物之傳輸研究不但與侵蝕有關，可以幫助釐清板塊運動的機制；更會影響海岸線之消長，對國土保安有一定之重要性。
Most previous studies on suspended sediments have concentrated on extreme events such as typhoons or heavy precipitation periods to examine the relationship between discharge and suspended sediment dynamics. However, such studies have so far had limited success on a completed spectrum, from extreme high flows to low flows. We are proposing a new collaborate project to measure the suspended sediment concentration at low flow periods especially during the winter times where little precipitation to provide extra inputs except from the channel itself. We are particularly interested in estimating the suspended sediment load at low flows because that it occupies more than 80 % of the winter in the southern Taiwan. Given the time span, even with a small amount suspended sediment load can be projected to a substantial total annual load. This project is set out to test by addressing the following questions: 1. Is it reasonable to assume that suspended sediment concentrations (SSC) in Taiwan be zero during low flow periods? 2. Are SSC in Taiwan a function of discharge capacity or is it a function of in-channel supply at low flow periods? We are proposing to evaluate the effect in two watersheds, Luyeh Chi and Chishan Chi watersheds for the major reason that these two watersheds can provide comparative base for the study under the similar weather condition, particularly the duration of low flow periods. Moreover, we have just newly acquired a Leaser Particle Analyzer from school fund, which would be just perfect for the project. This instrument can be used to measure suspended sediment taken from the field. Taiwan provides a unique opportunity to complete the spectrum relationship between hydrological inputs and active tectonic bedrock regions. This project will allow us to understand the processes better on the response of suspended sediments to hydrological inputs at different bedrock regions in Taiwan.
