Conveyance Loss of Irrigation Canal System－A Case Study for Ailiao Canal

• Main Authors: Wu Chang-Cheng, 吳昌成
• Other Authors: Wang Yu-Min
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/57887273935568113092

碩士 === 國立屏東科技大學 === 土木工程系碩士班 === 93 === In this study,a fied survey along the Ailiao Canal has been conducted for flow data collection. Flow velocity at water levels of 50cm, 60cm, 74cm and 84cm were measured with a current meter, and the flows were calculated. Then, the total conveyance loss between channels was calculated with percentage method, unit-distance flow method, and unit-distance loss percentage method. Moreover, using the empirical formula for canal seepage suggested by E. A. Moritz and T. Ingham, calculation was made on the theoretical conveyance loss of the channel, thereby separating the theoretical and management losses from the total conveyance loss. Finally, this study uses HEC-RAS to simulate the conveyance loss of the channel during high water level. The results are as follows: 1. With the total conveyance loss of R1, R2, R3 and R4 of the Ailiao Canal, unit-distance conveyance loss is used for showing its high relevance with the water depth . The relationship for unit-distance conveyance loss (y) and water depth (x) of each channel section (Ri) are: R1: y=0.5311x1.9697, R2: y=0.4186x1.2661, R3: y=0.6186x1.8116, R4: y=0.6637x1.8702, and R1~R4: y=0.5661x1.7718. 2. The theoretical conveyance loss merely accounts for 5% of the total loss, whereas the management factor makes up over 95% of the total loss. The main reason might be the private pumping behavior along the channel. Besides, if it can be addressed through government decrees or management means, the conveyance loss might be reduced significantly. In addition, damage and seepage at the bottom of the channel can be repaired and improved on a regular basis. 3. According to the result from the simulation of the conveyance loss, the unit-distance conveyance loss increases with rises in water levels. In terms of percentage, R1 and R4 are within 1.5 percent, R2 and R3 are 3.5 and 4 percent accordingly.