1、Discussion about transformation of curve conduit of Yellow river Tie xie projectLiu you zhan( western he nan Yellow River Affairs Bureau)Abstract: Tie xie project was passively built due to rush to deal with emergency, it is separated to two up-down bend in north gate dam (number 10 dam). Until last

2、 70 centuries, stuff and descend projects were respectively built in up and down the dam. Though the building of projects cannt transport downstream the 10 dam, it was suited to temporal water-sediment conditions, the river was in a perfect condition. After the “96.8 flooding, the Tie xie projects i

3、nflow point ascend continually, since the project didnt develop a integrate smooth bend and water-sediment conditions are changing, the disadvantage river conditions that Lu cun project is near river began to appear. To settle Tie xie project transport effectively, the emphases of project bend is ho

4、w to improve 入溜 conditions ,make stuff project complete, make project a intact smooth bend and use riverbed dredge up to improve inflow, stream guidance and outflow conditions of riverbed project.Key words: Tie xie project; bend; fluctuating river; river regulation; Yellow river1 the questions put f

5、orward Yellow river Tie xie project is between Bai he and Hui meng country ,Meng jin county, 24km downstream xiaolangdi dam, south bank of Yellow river, it is up to Bai po project and down to Lu cun project, 7.45km total lengths. Tie xie project is in initial sections downstream Yellow river, it pla

6、ys a important role in controlling flood and river circumstances. In a long time, because Tie xie projects plane condition is not smooth, outlet flow is unsteady, often swings in about 2 km near Lu cun project, this make the river circumstances by Lu cun project is very unsteady and only its downsec

7、tion is near river after 1996. the long time unsteady of Lu cun project must disturb river conditions downstream and make the results of river improvement fail. Since complex river boundaries of Tie xie project, river is restricted to bridge and beach and cannt adjust itself. Meanwhile, with the con

8、struction of xiaolangdi, qixiayuan reservoir,taiao high speed yellow river road and so on, river regime have some new things and problems. So speeding at constructing river regulation, rebuildingTie xie project, building smooth and plan flow guidance bend to make them suited to new water-sediment bo

9、undary conditons are keys of this river reach regulation and emergent needs of downstream wandering river regulation.2 .basic conditions of river way2.1 characteristics of river wayThe reach of Yellow river Tie xie project is reach that is transited from mountain areas river to fluvial plain. In mou

10、ntain areas, water flow diffuses and velocity is slow, sand-cobble bed load which are brought from upper ravine river bed can be deposited in river section, so sand-cobble river island that has several flow branches distributary is developed upper Yellow river road bridge, Luo Yang. River island is

11、constituted of scree and rude sand, it is in the north center of river bed and is1m-5m taller than river bed, its top is sandy roam and bottom is round gravel and scree. Generally, river bed is covered by sand-cobble, grain diameter from 20 to 200 mm, the width of river is 2500m, width of main river

12、 channel is 500-700m, slope of river bed is 0.50.7, the depth of scree down Luo Yang bridge is gradually increased, its riverbed is consist of rude sand, beach is unsteady and slope of river way is 0.265.2.2 characteristic of water-sedimentAccording to Xiaolang di hydraulic station datum, the averag

13、e annual discharge of the river regime is 378.38 hundred million m3 from 1956 to 1995, the sediment discharge is 11.4 hundred million tons. Average discharge is 200 hundred million m3 in flood seasons, is 53% of total discharges, mean annual discharge is 1300 m3 /s. the virtual changes of sediment a

14、mounts are high, 30 hundred million tons if the sand are much and 10 hundred million if it is little, average sediment concentration is 33.9kg/ m3. there were high sediment concentration flood in 1996, the most high sediment concentration is 941 kg/ m3. Until sluice in Xiaolangdi reservoir October,1

15、999, downstream water-sediment changed obviously in the affluence of the reservoir. The main features are: the flux is obviously slower, the scope of flux fluctuation decreased, discharge is nearly equal in flood and unflood seasons, runoff amount decreased more obvious in flood seasons; sediment am

16、ounts decreased obviously, mean annual sediment concentration is 1.97 kg/m3 from 1999 to 2002, sediment runoff is 10615 ten thousand tons. Mean sediment concentration is 0.292 kg/m3 in 2000, annual sediment runoff is 442 ten thousand tons; mean sediment concentration is 1.43kg/m3 in 2001, annual sed

17、iment runoff is 2213 ten thousand tons, mean sediment concentration is 4.18 kg/ m3, annual sediment runoff is 7960 ten thousand tons.2.3 erosion and deposition of river bed In natural condition, the erosion and deposition of Tie xie river regime is high. According to measurement data, section of Tie

18、 xie deposited 7000 m2 from 1934 to 1952 and 4290 m2 from 1952 to 1960. After Sanmenxia Reservior worked, river regime eroded obviously. Tie xie sections water level decreased obviously from 1960 to 1965, it decreased 3.36m when the flux is 3000m3/s. Tie xie river section continued to erode after 19

19、65 and reach the biggest value 20000 m2 in 1968. Sanmenxia Reservior discharged sediment to open bottom holes in 1970, Tie xie river section quickly deposited and reach its biggest 5000m2 in 1973. Sanmenxia Reservior sluiced and discharged sediment in 1974, Tie xie section began to erode, the accumu

20、lated erosion exceeded 10000m2 from 1976. later, from 1977 to 1999, with the changes of water-sediment, Tie xie section eroded and deposited regulations, but the extent is little, Tie xie section is eroded about 9000m2 contrasted to before Sanmenxia Reservior worked from Xiaolangdi reservoir worked

21、in October,1999. After Xiaolangdi reservoir worked, riverbeds erosion is obvious, average erosion depth is about 2.53.0m, the main channel of Tie xie section depth decreased.3 project construction and river evolvement 3.1 historical river The river way that Tie xie project is in has 4000 years old,

22、its left bank is Qing feng ling and the right is Mang mountain, the wander is restricted to the regions. The main changes of river section is in big flood time, in history, flood brought a great deal scree bed load out of gorges and deposited suddenly, that made branch river eroded or deposited fier

23、cely and changed the river regime. Sand-cobble river bed is steady when the flow is medium or little and the river regime is not changed acutely. Between 1933 and 1958, the river was separated south and north branches after it outflowed Bai po. The south and north branches river could be streamed du

24、ring many years, the main stream flowed the north river way between Bai he and Bai po, and the river regime dinnt change much compared with that in 1933, after the flood in 1958, north river disappeared, the river outflowed Tie xie and went into Zhao gou wan near Lu cun and Tie hu, forming the curre

25、nt river regime . The translation extent of main flow positions was was bigger in Bai he and Bai po projects, so Tie xie project was instable that made downstream river regime disordered.Between 1960 and 1964, Tie xie project inflowed and the conditions near river improved a little, but Tie xie coul

26、dnt flow well. To block up the bunch channel between Bai po and Zhi shu town, Bai po bunch channel project was built up in 1969, north river went south and the stream decreased gradually, this limited the problems that the Yellow river north bank collapsed continually. Later, Bai he and Bai pos infl

27、ows were regulated more , Tie xie project standed by river and the inflow condition was improved intensively, the Lu cun began to go incurvate during several years and each embayment descend and collapsed. Lu cun project was began to built in 1971. high sediment concentration flood block up the rive

28、r in 1973, Tie xie outflowed and the north branch deposited, south branch increased to 80%, 21-31 dam of Lun cun standed by river.3.2 Tie xie block up embayment and descend Because Tie xie project was built to deal with the emergencies, the whole vulnerable spot was not developed a full embayment, t

29、he north dam could be separated up and down embayments looked from the plane. River regime descended when the big flood came, the outflow was smooth by the north dam and was suited with the down Lun cun and Hua yuan zheng project. River regime went up when the flood was small, small embayment reache

30、d river up north dam and streamed to Tao wan up the Lun cun project. The rebuildment of Tie xie project was made to block up embayment up 1200m north dam, that comprised down north dam vulnerable spot a smooth embayment, controlling the water consistent with the river regime . Number 1-5 dam were bl

31、ocked up and down extended between 1973 and 1986. number 1-5 dam head was in the line with the 31battlement and the north dam head, the down project head was in the with the guidance line, the extension line of dam head was face to the number 10 dam head. After number 1and 2 the blocked embayment wa

32、s built in the spring of 1974, due to the embayments top flow widely, number 10 dam streamed badly, and Lu cun project flowed down, Hua yuan town project went out of river in 1975.Tie xie projects inflow condition was stable,the river regime changed little, up embayment and down river regime had the

33、 chances of adjusting itself, Lu cun projects flow lengths gradually increased, due to water and sediment were rich this period of time. The river regime gradually tended to smooth, at the most time main stream made a trajectory bucket type energy dissipation to the river channel north side of Tie x

34、ie project, by the influence of cobble island, the river was separated to two branches ,the 80% main stream went the north, from up Lu cun project to embayment of lu cun project, lu cun project was nearly by the river. Down of 21dam Hua yuan town project began to go by river and the river regime gra

35、dually went stable. Until the flood time in 1996, the river section was in a healthy condition.3.3 appearance and development of disadvantage river regime After the 96.8 flood came, Tie xie projects flow point went up, the flow angle was partially big, the main flow went up blocked dams upstream sur

36、face at a big flow angle due to the number 1 dam s stream guidance, the project bended and the flow point ascended, this made the main stream bended on the opposite of number 12 dam, the main channel of Tie xie section nearby shifted south, though Tie xie project was by the river the entire year, th

37、e river went out of vulnerable spot and extended number 5dam, the outflow went south center or glissaded, this made the south branch river developed down Luo yang road bridge, north branch river shrunk, this made Lu cun project descended continually, the flow dam section diminished quickly, river re

38、gimes disadvantage conditions.After the 96.8 flood, since the Yellow rivers downstream did not flow inundation, in the condition of small flow low sediment concentration, small flow river regime was influenced seriously by sand-cobble marginal and channel bar. The river regime transformed very slowl

39、y, the disadvantage river regime lasted for long. The most serious condition was the length was only 400m by the river, 90% of stream guidance went out of river from number 32 dam in 1999. the river collapsed and shaped concave to Wen men bank immigrant settlement protection embankment after the riv

40、er went out Lu cun, this threatened protection embankment and influenced river regime down Lu cun. Though number 5 and 15 submerged dam were built down Tie xie project in 2000 and 2003, dam by the river of Lu cun ascended gradually, Lu cun project that was near the river was all along in 24-36 dam,

41、the disadvantage river regime was hold back temporally.4 the reason why changes of river regime4.1 the direct reason of changes of river regime was upper bends early over flowAnalysing historical and current Tie xie regime data, the change of upper bend over flow position was the direct reasons of T

42、ie xie project river regime. From the1970s on, Tie xie project was upper bend overflow at the most time, outflow reached to upper and medium head when the upper bend was overflowed by blocked bend and number 10 dam, the river regime was in a favorable condition. When the upper bend was overflowed by

43、 number 1-3 dam, the number 12dam was to face bank and the cobble of depth of burial was superficial, that lead to the outflow could not reached the Lu cun project and went bend here, the river regime was in a unhealthy condition. The disadvantage river regime was caused by blocked projects upper on

44、es when blocked project 1 and 2 were constructed in the spring of 1974 and the disadvantage river regime after the flood in 1996. the differences were upper outflow was changed by men by building the blocked project 1-2 dam, and the upper outflow did not changed much, in additionally to rich water a

45、nd sediment, the river regime had chanced to adjust itself.4.2 Tie xie project did not develop a complete smooth bendBlocked bend and down extend project that were rebuilt through Tie xie project could not make the whole vulnerable spot a smooth bend , it was hard to arrange the river regime. Then,

46、because upper inflow condition was stable, the emphasis was how to make dam 10 a smooth bend and the upper ones of project was omitted. The first battlement lay crossly, the space between each battlement and the angle of dam flow were different, viewing from in a plane, dam 1 protruded into the rive

47、r, was bounded to dam 1.when the outflow point was vary, the influence to the backward river regime was different. The initial flow point of vulnerable spot was dam 1-2, blocked bay 1-4 streamed smoothly, the upper bend of several dam flow smoothly, flowed through blocked bay project and dam 10, the

48、 dam of Lu cun project was long, the degrees of flow increased gradually and the flow guidance was ideal. The initial flow spot of vulnerable spot ascended to revetment 4,Bai he inflow went to revetment 4 before bank stand bend, the main stream guided to Tie xie channel bar through dam 1 and then we

49、nt up to blocked bays face at a big angel, the dam sent flow out and the outflow went south to the end of Lu cun project.4.3 the influence of “96.8 flood and water-sediment of upriverAfter the “96.8flood, tie xie projects flow point ascended, inflow angle went partially bigger, the big one was sent

50、to southeast by dam 1-3, blocked dam 5 did not stream that lead to the disadvantage of the lu cun project was stand by the river. After the “96.8flood, water and sediment that were from upriver decreased obviously, and the were not big flood in the flood season especially after the Xiao lang di proj

51、ect worked that made rinsing discharged, but long term condition that small river regime make Tie xie project flow point ascend did not change, and gradually intensify, revetment bank gradually collapsed and retreated. Tie xie flow condition were not improved and the disadvantage river regime lasted

52、.4.4 influence analysis of sand and cobble river bed to river regime The upper of Tie xie project had a channel bar, under the center there were not flood plain, the beach head was erode when big inundation and the effect was not obvious. Meanwhile, the river channel existed small cobble beach, and

53、the influence to the river regime was in the variety with the flux. After the 96.8 flood, especially Xiao lang di reservoir worked, water diminished from upriver, Tie xie channel bar cobble restricted Bai po outflow and Tie xie project went on ascended, the changes of river regime did not enhance th

54、e capability of vulnerable spot flow.After the steam went out of Luo yang road bridge, the river way extended quickly and the slope of river minished quickly, the beach between Tie xie and Lu cun transformed at a unregular rule, there were several branches river in the channel. Before 1996, the upri

55、vers water was rich and was influenced little by sand-cobble beach, the river regime was normal at a global view. After the 96.8 flood, the disadvantage river regime was developed. Though two submerged dam were built in 2000 and 2003 at the end of Tie xie project, sand-cobble riverbed, especially th

56、e appearance of cobble beach and the riverbeds general down-cutting between Tie xie and Lu cun, main stream was blocked off by cobble beach after submerged dam, it still steamed in the down south river and did not influence the whole river regime, Lu cun project that was near river was not improved

57、fundamentally.5 countermeasure and step of bend transformation5.1 make project inflow under dam 1The main problem of Tie xie project was inflow could not reach Lu cun project effectively, analyzing the reasons of river regimes changes, Tie xie project inflowed ascended continually was the one of mai

58、n reasons. In the current water and sediment condition, to solve the inflow ascend was to eliminate the Tie xie channel bars influence to inflow. Channel bar was mainly influenced by small river regime, digging north branch river of Tie xie channel bar and made small went north branch river into blo

59、cked project. A submerge dam was built before revetment 4 of main river channel to make main stream above medium water across revetment 4, inflow under dam 1, small water stream went Tie xie north branch of channel bar and the blocked bay was smooth.5.2 transformed the project to basic smooth bendTie xie project was incomplete and the upper bend was not a smooth bend, from the 70s,80s on, the blocked project was built, this did not reach the ide