Study On The Navigable Water Level In The Confluence Of Yangtze River And Tuo River

What makes the water condition complicated is that the Mountain Rivers change a lot and have many tributary steams, and it changes the former nature of the channel, and brings inconvenience to the navigation. The design navigable water level of inland channel is an important design parameter in the design of inland channel regulation engineering, which is the important indicator in evaluating the channel and shipping efficiency. it is very important to make a reasonable navigable water level of the confluence of main steam and tributary steam.The methods of the design navigable water level are the synthetic duration curve method, the frequency method and the duration-frequency method. They are common in hydrology, and correspond to the synthetic duration curve, the frequency curve and the duration-frequency curve. The three curves are important to make the level (discharge).Now the evaluation of hydrological processes-lines is by the peak and average values, and it can not make a reasonable assessment of the overall. Luckily Hydrological system is a complex and large nonlinear system, and also has a large number of self-similarity behaviors, these are precisely the premise of using fractal theory. Estimating the lowest designed navigable level, the synthetic duration curve, annual the lowest water level frequency curve and the duration-frequency curve are plotted and fractal dimension D and the flat rate of curves"a"are calculated by box counting method, And gives a reasonable evaluation of the curves. Fractal dimension D reflects the complexity of the curve and"a"reflects the flat Level of curves. Compared with three groups of D and a, the lowest designed navigable level is the water level of the duration-frequency curve with moderate values of D and"a", because of water levels of curves with the oversized values of D and"a"do not match with the actual data, in other words, they are distortions.The highest design navigable water level is affected by the navigation flow condition and it is one of the indicators of evaluating the channel efficiency. The highest design navigable water level is discussed by the frequency method and duration method, and the reasonable method of making the highest design navigable water level according to the actual situation is to change the frequency indicators into duration indicators, and appropriately reduce the value depending on actual channel conditions, so this will not only meet the navigation requirements, while increasing the number of days suspended is not much, but also meet the shipping needs.