A CTA GEO GRA PH ICA S IN ICA

55 5 2000 9 A CTA GEO GRA PH ICA S IN ICA V o l. 55, N o. 5 Sep., 2000 : 037525444 (2000) 0520627210 1, 2 (11, 100101; 21, ) :, 4,, : ; ; : X91515; P33215 : A 1, 40% [1 ], 206 1949 1 092, 5 0133 10 8 hm 2 100, 70% [2 ], 7318 km 2, 40% 35% 60% [3 ] (1950 1997 ), 91016 10 4 hm 2, 50415 10 4 hm 2,,,,,,,,, 2 [4 ], 60 ( 1), 1954 1964, : 2000202215; : 2000205212 : (59890200) [ Foundation Item: N ational N atural Science Foundation of China, N o. 59890200 ] : (19632 ),, E2m ail: chxsh i@hkusua1hku1hk

628 55,, 1 007 10 4 hm 2, 652 10 4 hm 2,, 1965 1978, 469 10 4 hm 2, 215 10 4 hm 2, 1979 1997 1954 1964, 1 263 hm 2 681 10 4 hm 2 1991 1997 1674 10 4 hm 2 936 10 4 hm 2 1 F ig11 Changes in areas covered and dam aged by floods and the estim ated increase in flooded area due to sedim ent accum ulation 60 2, 1954 1993, [6 ] 1950 1966 1978 1993 ( ) [7 ] 2 1951 1989 ( [5 ] ) F ig12 Changes in annual p recip itation during 1951 1989 in Ch ina (after Zhao, 1993),, 1949 1987, 206 10 7 hm 2 [8 ] 1950 1990, 627164, 553135 10 8 m 3, 22182 10 8 m 3,, ( 1) 60

5 : 629 1 Tab11 Changes in area of waterlogg ing prone farm land and fulf illmen t of managemen t 1950 1958 1965 1978 1990 g(10 16 m 3 ga) 61061 111577 191342 131859 g(10 8 m 3 ga) 01240 01276 01652 01855 g(10 4 hm 2 ) 1 813 1 944 2 032 2 237 2 371 Ξ 01507 01439 01374 01287 01264 g(10 4 hm 2 ga) Ξ 91912 85314 76010 64210 62519 Ξ, ; ( [ 8]),, 50 10 8 t, 35 10 8 t, 12 10 8 t [8 ], 12 10 8 t,,,, 8 10 8 m 3 ( 115 ggcm 3 ) 0125 m ( : 250 mm [9 ] ), 8 10 8 m 3 32 10 4 hm 2, 1, 1965, 30 960 10 4 hm 2,,,,,,,, [8 10 ],,, 1966 1990 16914 10 4 hm 2 [8 ], 3g4, 3,, 311 1993, 84 614, 4 71616 10 8 m 3, 2 936, 4 13316 10 8 m 3 [8 ] 80 231, 1413%, 213%, [11 ] 1989 0101 10 8 m 3 740, 543 10 8 m 3, 1990, 11515 10 8

630 55 m 3, 2113% 7 164119 10 8 m 3, 79162 10 8 m 3, 4815% [12 ] 31, (p ) (V gv s) [12 ] : p = 1184 (V gv s) - 01985 r 2 = 0193 (321),,, 83 400 km 2, 2715%, [13 ],,, (1825 ) 6 300 km 2,,, [8 ] 1951 1966, 11383 10 8 m 3, 01232 2 10 8 m 3, 01416 2 10 8 m 3, 11199 10 8 m 3 112 10 8 m 3,, 1967 1987 11067 10 8 m 3, 01277 2 10 8 m 3, 01789 8 10 8 m 3, 1949 4 350 km 2, 1977 2 740 km 2 [8 ] 1952 1988, ( 33 m ) 11318 10 8 m 3, 1952 4018% [14 ], 35123 10 8 m 3, 31% ( ), 50 3017%, 1973 1983 2515% [14 ] 312,,,,, 13, 8134 10 4 km 2, 60 70 1989, 13 311 10 8 m 3,, 10% 75%, 20% 80% [15 ],, 1950 1996 212 10 8 t, 318 cm,,,,

5 : 631 7, 1950 1996 3 000 m 3 gs 716 cm, 3 000 m 3 gs [16 ],,,,,,,, 7 500 3 000 a BP, 3 m [17 ], 1494 1855 ( ) 6 8 m, 915 m, 3 7 m, 10 m ( 345 a BP),,, 1949, 10 m, 14 m 5 000 12 m, 800 10 m,, [18 ], [19 ],,,,,,,,, 3512 10 4 hm 2,,,, [8 ],,,, 1990, 2312 10 4 hm 2,,,,, [8 ], 1963,, 20 18, 1958 1989 1 862 10 4 m 3, 5812 10 4 m 3, 711 m, [20 ] 313 1815 10 8 t,,, 9112 10 8 t (1950 1996 ),, 1855 26 km 2 ga 120 km 220 m ga 4183 10 8 t (1951 1979 ), 4136 10 8 t,, 9 km 2 2 000, 25 m ga [8 ] 8 336 10 4 t, 150 170 m ga, 100 120 m ga [21 ],, ;,

632 55,,,,,,,, [22, 23 ] 314, 265 kggm 3, 10%,,, [12 ], 4,,,,,,,,, 1g3 [24 ] [3, 25 ], 1950 1979 430 km 2,, 3418 10 8 t, [26 ], 1855,, 1 430 km 2 ( [ 25 ]),,, 50 15 70 cm, 65 70 cm [27 ],,,,,,,,,,,,,,,,, [15, 28 ],,

5 : 633,,, 10 m, [29 ],, 3317% 2 m, 4136 10 8 t, 7215 10 4 tga,, [30 ] [12 ] [31, 32 ] [33, 34 ] [35 ],,,,,, 1949 1987 3 236, 1 717 [8 ],,,,,,,,, (References) : [1 ] Zhang J iacheng. P relim inary A nalysis on N atural D isasters[a ]. In: L iaison Group of Comp rehensive Study of Co smo s, Earth, and L ife, Society of Ch inese Science and T echno logy ed. P rogresses in Comp rehensive Study of the M utual R elations Among Co smo s, Earth, and L ife[c ]. Beijing: Ch inese Science and T echno logy P ress, 1989. 1852188. ( In Ch inese) [. [A ]. : [C ]. :, 1989. 1852188. ] [ 2 ] Ch inese Society of D isaster P revention, D epartm ent of Seism ic D isaster M itigation of N ational Bureau of Seism. Key P roblem s of D isaster A lleviation in Ch ina[m ]. Beijing: Seismo logy P ress, 1992. 15217. ( In Ch inese) [,. [M ]. :, 1992. 15217. ] [3 ] N ational Statistics Bureau of P. R. Ch ina, C ivil A dm inistration of P. R. Ch ina ed. R epo rt of the dam age caused by disaster in Ch ina, 1949 1995[R ]. Beijing: Ch ina Statistics P ress, 1995. 20222. ( In Ch inese) [,. 1949 1995[R ]. :, 1995. 20222. ] [ 4 ] Edito rial Comm ission of W ater Conservation A nnalṡ A nnals of W ater Conservancy in Ch ina [Z ]. Beijing: W ater Conservancy and E lectric Pow er P ress, 1990 1998. ( In Ch inese) [. [Z ]. :, 1990 1998. ] [5 ] Zhao Zongci. Impacts of H um an A ctivities and Increase of Greenhouse Gases on Global and Ch inese C lim ate [A ]. In: D eng Genyun ed. Impacts of Clim atic Changes on A griculture in China [C ]. Beijing: China Science and Techno logy P ress, 1993. 19235. ( In Ch inese) [. [A ]. :. [C ]. :, 1993. 19235. ] [ 6 ] Ye D uzheng, H uang Ronghui ed. R egularities and Causation of D rough t and W aterlogging in the Yangtze and Yellow R iver Basins [M ]. J inan: Shandong Science and T echno logy P ress, 1996. 15216. ( In Ch inese) [,. [M ]. :, 1996. 15216. ] [ 7 ] Zheng Shuangzh i. Changes in distribution of flooding disasters in Ch ina [J ]. D isaster R ed uction in Ch ina, 1995, 5 (3): 32235. ( In Ch inese) [. [J ]., 1995, 5 (3): 32235. ] [ 8 ] O ffice of N ational General H eadquarter of F lood and D rough t P revention, N anjing Institute of H ydro logy and W ater R esources of

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636 55 channels and lakes in the p lain s, reservo irs, irrigation areas, and flood deten tion areas in Ch ina. Suppo sing the annual increase in the vo lum e of w ater flooding the farm land is equal to the annual vo lum e of the 112 b illion ton s of depo sits, there w ou ld be a good agreem en t betw een the calcu lated changes in flooded area and the actual increase in the flooded o r dam aged a rea after the yea r 1965. It suggest s tha t the sed im en t accum u la t ion in the rivers, lakes, reservo irs, etc. in Ch ina m ay be con sidered as one of the m ain cau ses fo r aggravating flooding disasterṡ T he pattern s of impacts of sedim en tation on flooding disaster are generalized as depo sition in lakes and reservo irs, depo sition in river channels, depo sition in river mou th, and h igh sedim en t concen tration in flow ṡ Sedim en t accum u lation resu lts in the decrease in the flood2regu lating capacity of the lakes and reservo irṡ It low ers the drainage capacity of the channels and canals and also raises the riverbed to fo rm a perch ing river channel. T he ex ten sion of river mou th due to sedim en t accum u lation w ill low er the slope of channel, enhancing sedim en t depo sition up stream s and deterio rating the flood p rone situation of delta areas. T he large amoun t of sedim en t carried by w ater flow s can obviou sly en large the d ischa rge of p eak flood, and the hyp er2concen t ra ted flow s show an un stab le behavio r, leading to ab rup t rise and fall of peak flood, an unfavo rab le situation to flood con tro l. To alleviate the impacts of sedim en tation on flooding disasters, so il ero sion con tro l, en largem en t of sedim en t tran spo rt capacity of the river channels, decrease of the heigh t d ifference betw een the river channels and su rround ing p la in s, and reduce of depo sit ion2 induced ex ten sion of river mou th shou ld be the m easu res. How ever, the feasib ility of these m easu res in the sen ses of econom y and techno logy is no t so clear now and they m ay have nega t ive effect s on econom ic developm en t, environm en t and society. T hu s, the feasib ility as w ell as the po sitive and negative effects of these m easu res shou ld be studied and compared comp rehen sively in o rder to ach ieve the best resu lts in reducing the impacts of sedim en tation on flooding disasters in the fu tu re. Key words: flooding disaster; sedim en tation; disaster p reven tion