GEO GRA P HICAL RESEA RCH

Transcription

1 GEO GRA P HICAL RESEA RCH Vol125, No12 Mar1, 2006 (, ) :,, 50,,, ,,,,,, 0162,,,,, : ; ; ; ; : (2006) , 20 80, [ 1 3 ] 20 70,,,,,,,,, [4 8 ] [9,10 ] [11 ] [ 12, 13 ], 2, 3 : ; : : ( ) ; ( G ) : (19482),,, 180 E2mail

2 2 : 277 [4 ],,,, [ 14 ],, ;,, ( ),,,,, (Sediment budget) [6 ],,, Qs, i, Qs, o, Qs, t1, Qs, t2,, Qs, t, : Qs, i + Qs, t = Qs, o + Qd, s (1) Qd, s ( ) ( ) : Qs, o Qd, s = 1 - Q s, i + Qs, t Q s, i + Qs, t,, Fs,, Fs,,, (Sink),, Fs, 3, ( ),,, : Fs = Qs, l Q s, s + Qs, h + Qs, x - Qs, div, Qs, s, Qs, l, Qs, h, Qs, x, Qs, div, : Fs, h2g = Qs, gao/ ( Qs, hua - Qs, div, h2g ) (4) Qs, hua Q s, gao, Qs, div, h2g, (2) (3)

3 a,,,,, (a) (b) Fig11 Temporal variation in sediment transferring function index of the lower Yellow River (a) and the different stages ( b) ( 1b), 6, : (1) ,,, ; (2) ,,,,,, 1158 ; (3), ,, ;,,,,, 0173, ; (4) 1973,,,,,,,, ,

4 2 : , 01781,,, ; (5) ,,,, 11049, 1 ; (6) ,,,,,,, 01612, 5, ( 2),,, 2 Fig12 Temporal variations in sediment transferring function index of the lower Yellow River and the area2averaged annual precipitation in the drainage basin 6,, 611,,,,,,, ( 3),, [15 ],,,,,,,, ( 3) [14 ],,

5 280 25,, 3 Fig1 3 Temporal variations in sediment transferring function index of the lower Yellow River and in the percentages of high2flow season runoff of annual runoff at Lanzhou and Sanmenxia stations 612,,,,,,, 4, ( 4a), ,, 4b,,, ( 4b), 0154, 0101,, 750 hm 2,, 613, 1800 hm 2, 580 m 3, 2 %, 15 % 12 % [16 ], 20 80,,, %,,,, 90,,,,,,

6 2 : (a) (b) Fig14 Temporal variations in sediment transferring function index of the lower Yellow River and in the area of soil2water conservation measures (a) and the relationship between them ( b), 5, 5 Fig15 Temporal variations in sediment transferring function index of the lower Yellow River and in the quantity of water diversion by man and its proportion of the annual natural runoff

7 ,, ( ) ( ),,,,,,, 6a, (a) ; (b) ; (c) ; (d) 3000m 3 / s - 6 Fig16 Variation in channel geometry and its influence on sediment transferring f unction of the lower Yellow River 20 70,,, ( 6b),,,,,,,, 6c,, 0147, 0101,,

8 2 : 283,,,, 3000m 3 / s, 3000m 3 / s, d,, 8 50, 6, : (1) ,, ; (2) ,,, 1158 ; (3) ,,, 0173, ; (4) ,, 01792, 0173, 0178,,, ; (5) ,,, ; (6) ,,,,,, 01612,,, : [ 1 ] 1 1,1997,19 (10) : 1 91 [ 2 ],,, 1 1,1997,19 (10) : [ 3 ] 1 1,2001, (7) : 1 71 [ 4 ] Schumm S A1 The Fluvial System1 New York : John Wiley & Sons, [ 5 ] Goudie A1 The Human Impact on t he Natural Environment1 Oxford, U K: Blackwell, [ 6 ] Knighton D1 Fluvial Forms and Processes : A new Perspective1 London, U K: Arnold, [ 7 ] Maheshwari B L, Walker K F, McMahon T A1 Effect s of regulation on t he flow regime of t he River Murray, Aus2 tralia1 Regulated River, 1995,10 : [ 8 ] Graf W L1 Dam nation : a geographic census of American dams and t heir large2scale hydrologic impact s1 Water Re2 sources Research,1999, 35 (4) : [ 9 ], :,20031 [ 10 ], :,20031 [ 11 ] 1 1,2004, (5) :8 141 [ 12 ] 1 1,2002, 21 (2), [ 13 ], 1 1,2003, 22 (1) : [ 14 ], 1 1 :,19831

9 [ 15 ] 1 1 :, [ 16 ], 1 1 :, Temporal variation in sediment transferring f unction of the Lower Yellow River and the formative causes XU Jiong2xin ( Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing ,China) Abstract : The decline in sediment t ransferring f unctio n of t he lower Yellow River has drawn attention f rom t he scientific community, the government and t he p ublic1 Hence, finding out the cause for it is an important and urgent issue in harnessing t he Yellow Riv2 er, bot h in theory and in engineering p ractice1 An index of sediment transferring f unction ( Fs), which is defined as the ratio of sediment outp ut f rom a given river reach to t he sedi2 ment inp ut to t his river reach, is applied in t his st udy to reveal the temporal variation in sediment transferring f unction of t he lower Yellow River1 It is found t hat in the past 50 years, sediment transferring f unction index ( Fs) of t he lower Yellow River showed a de2 creasing t rend1 Due to t he changing operatio n mode of t he Sanmenxia Reservoir and t he varying combinations of runoff and sediment load, the temporal variation of Fs can be di2 vided into 6 stages1 During t he period f rom 1986 to 1997, due to t he decrease in annual precipitation and increase in water diversion, the incoming flow of t he lower Yellow River was significantly less t han t he average1 As a result, channel shrinking occurred, and t he index of sediment transferring f unction decreased to 0162, t he minimum in the hydro2met2 rical history1 To elucidate t he fo rmative cause for t he decrease in sediment for t he sedi2 ment transferring f unction, the temporal variation in Fs has been compared wit h the tem2 poral variations in a number of drainage basin factors, including drainage basin factors and river channel characteristics1 The result s show t hat t he decreasing t rend of Fs is basically synchronic wit h t he decreasing trends in the area2averaged annual precipitation in t he up2 per and middle drainage basin, t he index of reservoir regulation (defined as t he percentage of high2water seaso n flow of t he annual total) at Lanzho u and Sanmenxia statio ns, t he bankf ull cross sectional area of t he typical braided reach and t he water surface gradient of t he Huanyuanko u2gaocun reach at a given discharge1 The Fs index increased wit h t he total area of all soil2water conservation measures, t he quantity of water diversion and it s pro2 portion of t he annual flow1 Thus, it is demonstrated t hat t he changing drainage basin fac2 tors and channel characteristics resulted in t he decrease in t he sediment transferring f unc2 tion of the lower Yellow River1 Key words :sediment transferring f unction ; drainage basin factors ; human activities ; tem2 poral variatio n ; Yellow River