Study On The Regulation Measures Of The Long Straight Narrow Deep Rapids Of Xi Tan

Since entering the new century, with the rapid development of economy along theriver, the Yangtze river has become our country important industry concentrated belt,80%of the iron ore,40%of the crude oil and83%of the coal, which the largeenterprises required to produce are relying on the Yangtze river water transportation toguarantee, so its navigation benefit is very significant. With the rapid development ofnational economy, the party central committee, the state council and the localgovernment has attached great importance to the construction of the Yangtze rivergolden waterway, on December14,2007, premier Wen Jiabao has made importantinstructions about the Yangtze river waterway construction should be strengthened. Thenavigation condition of the river between the two Dams is extremely dangerous becauseof its narrow and deep channel, steep vally wall, rapid flow and so on. Xi Tan is thefamous flood rapids in Yangtze river, and it is also one of the most classical longstraight narrow deep rapids. To ensure the unimpeded transportation of the Xi Tan andto improve the ability of navigation, it is great important to study the flowcharacteristics and the regulation measures of Xi Tan.With the two-dimensional flow simulation technology, this paper preliminarilystudies the flow characteristics and the regulation measures of Xi Tan, the main contentsand results are as follows:(1)To build the two-dimensional flow mathematical model of Xi Tan and tocarefully validate the two-dimensional flow mathematical model with the concretehydrological data of Xi Tan, to get the right calculation parameters such as roughnessand mesh density to better simulate the flow field.(2) Use the two-dimensional flow mathematical model to calculate the flow fieldof Xi Tan under eight levels flood flow, analyze its flow condition in detail. The resultsshow that Xi Tan is bedrock flood rapids whose main flow condition is rapid flow. Thevalley is narrow, river width is from tapering to sudden expansion, the growth rate ofdischarge and cross section area is unbalanced. These are the main reasons of shoalformation.(3)To study the measure of enlarging discharge area shows that this regulationeffect on the long straight narrow deep rapids is not obvious only by expandingdischarge area. It’s difficult to reach the remediation goal.(4) Based on the hydraulic tunnel and water pumping, proposed the method of water diversion from the upper reaches of Xi Tan, namely by reducing the rate of streamflow thereby reducing stream velocity. The results show that relying on this method cansignificantly improve flow condition, but through economic analysis the cost is huge,and the construction is full of difficulty. So this method does not have the actualfeasibility.(5) To propose an unconventional rapids method based on the flow condition ofsmall velocity in shallow water, it is named submerged and straight dam. To calculatethe tests combined with different parameters of dam’s width, dam’s length and dam’sheight. The results show that relying on submerged and straight dam can significantlyimprove Xi Tan’s flow condition, this method provides a new idea for the study onregulation measures of the long straight narrow deep rapids.