調節池水力沖淤影響之評估-以大潮州地下水人工補注工程為例

本研究目的是進行應用調節池引水期間，透過調整水尾閘門開度以流體力學的概念產生水力流場，將調節池內淤積土壤帶出。本研究以實際高程量測比較水力沖淤後調節池淤積土方量之變化，借此來驗證「大潮州地下水人工補注湖實施計畫」中的調節池利用水力沖淤之可行性，其實驗數據可為操作清淤及提供類似工程計畫設計規劃參考。根據計算結果，沖淤效果最佳的範圍，入口端往西北側的動線到卧箕堰頂的位置，由X軸方向(東西向)平均沖淤可達到31公分，以北測沖淤效果最佳。Y軸方向(南北向)靠近堰堤北側附近沖淤深度達36公分，沖淤效果是最佳的位置。由整個分佈情形研判，主要在調節池中間段土壤回淤變化相當顯著，淤積回升高度最高約為110公分。由於降雨期間引水補注，河川含砂量高，土壤回淤非常明顯，主要以靠近堰堤附近回淤高度最顯著平均高度約58~64公分。土壤粒徑分析結果研判，調節池主要的沉澱的土壤顆粒屬於細顆粒土壤。以平均含砂量2,000 mg/L來計算，試驗期間從2018/8/21日至2018/09/23總引水量為1250萬立方公尺，產生約2.5萬立方公尺的沉泥(砂)淤積，主要的沉積將發生在調節池，調節池必須進行經常性的清淤。

關鍵字

調節池；大潮州地下水人工湖；水力沖淤

並列摘要

The purpose of this study is to introduce the soil sandstone of the Linbian River water using the natural hydraulic force to adjust the water tail gate opening degree to carry out the siltation adjustment pool. The measurement records and compare the changes of the amount of silt soil in the adjustment tank before and after the flushing. According to the calculation results, the best range of scouring and silting effect, the moving line from the inlet end to the northwest side to the position of the lying dome, the average scouring and silting from the X-axis direction (East-west direction) can reach 31 cm, and the effect of scouring and silting in the north. optimal. The Y-axis direction (north-south direction) is close to the north side of the dike, and the depth of erosion is 36 cm. The effect of erosion and siltation is the best position. Judging from the whole distribution situation, the change of soil back-sludge in the middle section of the adjustment tank is quite significant, and the sedimentation height rise is about 110 cm. Due to the re-injection of water during the rainfall period, the sand content of the river is high, and the soil back-sludge is very obvious. The most significant average height is about 58-64 cm near the back of the embankment. The results of soil particle size analysis showed that the main precipitated soil particles in the adjustment tank belonged to fine-grained soil. Calculated with an average sand content of 2,000 mg/L, the total water intake during the test period was 12.5 million tons, resulting in about 25,000 tons of sediment (sand) siltation. The main sedimentation will occur in the regulation tank, and the adjustment tank must be carried out frequently.