Influence Of The Seabuckthorn Flexible Dam On Water Flow Characteristics Research Field Test

The arsenic sandstone areas that located in the border area of Jin, Shan and Meng is the core of our country more coarse sand sand area in the middle reaches of the Yellow River sand production, covers an area of about 12000 square kilometers, the region accounted for 7.6% of the more coarse sand sand area in the middle reaches of the Yellow River area, but its amount with abundant and coarse sediment yield is 20～30% of the total into the yellow coarse sand content, combined with the abnormal severe soil erosion area, become one of the main sources to the yellow coarse sand.Practice has proved that the plant is the basic measures to control soil erosion. Existing research shows that the seabuckthorn plant is governance arsenic channel of pioneer species, soil and water loss in the zone of the seabuckthorn flexible dam is governance arsenic sandstone channel an effective ecological measures of soil erosion, sediment in situ can be intercepted in the channel, to further reduce the coarse sediment deposition on the lower reaches of the Yellow River. In the July,2013, established the new seabuckthorn flexible dam field test site in Meixian,Shanxi Province. Carried out under the condition of constant flow the influence of the seabuckthorn flexible dam on water flow characteristics test in different growth periods(May and September).In order to further explore the seabuckthorn flexible dam block foundation and accumulated data, for the seabuckthorn flexible dam in arsenic sandstone areas widely planted within the branch channel to provide the theory and practice basis.In this paper, according to the basic theory of hydraulics and river dynamics, within the seabuckthorn flexible dam on water flow characteristics are analyzed, and the resistance characteristics of seabuckthorn plant has carried on the simple discussion. The test fixed field experiment of the seabuckthom flexible dam before some shortcomings, mainly displays in:perfecting the field test facilities, constructed of the five test bed, setting up four bed planting different parameters of the seabuckthorn flexible dam, a blank contrast test bed, replacing the previous blank contrast in the front of the dam section in field test bed; A rectangular measuring weir in above water inlet realizes the real-time observation of import flow; The success of the experiment instead of PIV velocity measuring method, using ZLY-type I combined intelligent velocity instrument and computer realizes the accurate measurement of hydraulic elements; realizes the control of constant flow’s test conditions in the field’s test site, makeing the constant water flow test from indoor to outdoor;Based on test data, this paper mainly discusses the seabuckthorn flexible dam dam plexus in depth and horizontal distribution of flow velocity and changes are analyzed. The results obtained with the main conclusions are as follows:(1)analysis of the seabuckthorn flexible dam planting distance, long dam, flexible dam bed surface slope and the influence on the depth of the water the plants growth, found long dam is a flexible dam water depth increases the major influence factors, through the comparison of the program, preliminary selected 4 # dam type.(2)Based on the analysis of the seabuckthom flexible dam under the condition of different water depth of vertical variation along the river, found within the test bed of seabuckthom flexible dam water depth compared with blank bed depth are obviously different, seabuckthorn flexible dam, dam, the first and the upstream area of backwater is quite obvious, suggests that the seabuckthorn flexible dam has significant effect of block water.(3)Under the condition of different working conditions, and different type of dam, analyzed the seabuckthorn flexible dam longitudinal and cross sectional velocity distribution along the change in velocity and change. Vertical flow velocity along the change for the seabuckthorn flexible dam dam upstream velocity decrease backwater area, the first and the water flow out of the seabuckthorn flexible dam, namely in the seabuckthorn flexible dam dam at the end, flow surge; Through the analysis of cross sectional velocity distribution and change, found the 1#～4# dam and 5# empty bed cross-sectional velocity distribution curves in different, the 1#～4# dam the flow regime, changes in the opposite direction, velocity curves in roughly the parabolic shape distribution, center of the river flow velocity less than the flow of the river bed wall, blocking effects of seabuckthorn flexible dam on water flow.(4)With the basic theory of river dynamics, on the basis of predecessors’ research, discusses the seabuckthorn plant resistance, resistance coefficient, total boundary resistance and roughness coefficient calculation formula. Drag coefficient formula shows that the flow resistance coefficient and the seabuckthorn flexible dam dam, dam width and slope is closely related to the long; Formula of roughness coefficient, seabuckthorn flexible dam is average roughness coefficient and gully bed planting density and hydraulic radius presents certain positive correlation, related to flood volume into the relationship.