Decline of Yangtze River water and sediment discharge: Impact from natural and anthropogenic changes

Transcription

1 Decline of Yangtze River water and sediment discharge: Impact from natural and anthropogenic S.L. Yang, K.H. Xu, J.D. Milliman, H. F. Yang, C.S. Wu Table S1 ost-tgd annual precipitation (), water discharge (), sediment flux ( S ), and their (%) relative to the averages of the pre-tgd periods Upstream basin at Yichang a ( km 2 ) S ( km 2 ) S Averages over pre-tgd periods ( km 2 ) S Lake oyang basin ( km 2 ) S Basin upper than Datong (tidal limit) ( km 2 ) b c d ( 1.2%) (+0.4%) (+0.2%) 903 (+4.0%) (+5.6%) (+5.4%) 852 ( 1.8%) ( 0.4%) ( 1.8%) ( 0.4%) 886 (+2.1%) (+3.6%) (+3.4%) 791 ( 7.6%) 865 ( 0.3%) (+1.2%) (+1.0%) (+3.1%) (+4.6%) 843 ( 2.9%) ( 1.4%) ( 1.5%) ost-tgd amount (between the brackets are in percent relative to the pre-tgd periods (first row), (second row), and (third row), respectively) 410 ( 6.8%) ( 4.7%) 414 ( 8.8%) ( 5.9%) (.7%) 459 (+4.3%) (+6.8%) 285 (7%) (5%) (4%) 400 ( 6.9%) 419 ( 7.7%) ( 4.8%) ( 8.0%) ( 5.9%) 9 ( 25%) ( 23%) 465 (+2.4%) (+8.1%) 398 ( 9.5%) ( 88%) ( 92%) ( 99%) ( 99%) 43 ( 92%) (+27%) (+38%) 876 ( 1.1%) (+0.1%) (+7.3) 1035 (+17 %) (+18%) (+27%) 762 (-6.7%) 917 (+3.5%) (+4.8%) 916 (+3.4%) 826 ( 6.8%) 923 (+4.2%) (+5.5%) (+13%) 901 (+1.7%) (+3.0%) 832 ( 6.1%) ( 4.9%) (+2.0%) 911 (+2.8%) (+4.1%) 55 (+3.8%) (+15%) (+57%) 39 (+11%) 68 (+28%) (+94%) (8%) 45 ( 6.3%) (8%) 45 ( 6.3%) 66 (+25%) (+38%) (+89%) 51 (.8%) (+6.3%) (+46%) 43 (+23%) 48 ( 9.4%) (0%) (+37%) 15 ( 72%) (+92%) 7.6 ( 2.6%) 17 (+119%) 2.8 ( 95%) ( 64%) 8.3 ( 85%) (+6.4%) 4.6 ( 96%) ( 41%) 4.9 ( 96%) (7%) 12 (+54%) 5.4 ( 95%) 3.7 ( 97%) ( 53%) 8.3 ( 85%) (+6.4%) (+2.2%) (+1.3%) 1303 ( 6.0%) ( 6.7%) (%) 1356 ( 2.1%) ( 2.9%) (+2.3%) (+1.4%) (+9.3%) (+1.7%) 954 (2%) (6%) 1513 (+9.2%) (+8.3%) (+0.8%) 1305 ( 5.8%) ( 6.6%) 176 (+5.4%) (+3.5%) ( 7.4%) ( 8.4%) 155 ( 7.2%) ( 8.8%) ( 9.6%) (+9.0%) (+7.1%) ( 4.3%) 103 (8%) (9%) ( 46%) 180 (+7.8%) (+5.9%) ( 5.3%) 152 ( 9.0%) 18 ( 49%) (%) ( 5%) 9.1 ( 70%) ( 58%) ( 88%) 12 (5%) ( 76%) ( 72%) ( 56%) 1300 (%) ( 25%) (+5.8%) ( 0.1%) ( 9.1%) 1630 (+9.8%) (+3.8%) ( 5.8%) 1270 (%) 1460 ( 1.6%) ( 7.1%) (+34%) (+22%) 1160 (3%) 2030 (+37%) (+17%) 1520 (+2.4%) (.2%) 90 (0%) 66 (7%) ( 41%) ( 49%) 109 (+4.8%) 119 (+14%) (+6.3%) 75 ( 28%) (3%) (6%) ( 44%) 159 (+53%) (+24%) 64 (9%) ( 43%) 158 (+52%) (+41%) (+22%) 100 (.8%) 5.3 ( 65%) ( 55%) (2%) 7.2 ( 58%) ( 28%) ( 61%) (+30%) (%) a Yichang is 40 km downstream from TGD. b eriod before decline in sediment flux at Datong due to construction of dams 35. c Long term period prior to construction of the TGD during which precipitation, water and sediment discharges have longest continueous data. d re-tgd decade which has the same time duration as the post-tgd decade ( 61%) 1016 (.3%) (.0%) ( 5.5%) 1046 ( 0.1%) 1016 (.3%) (.0%) ( 5.5%) 962 ( 8.5%) ( 8.1%) 978 ( 6.9%) ( 6.6%) ( 9.1%) 1058 (+0.7%) ( 1.6%) (+8.5%) (+8.9%) (+6.0%) 865 (%) 1130 (+7.5%) (+7.9%) (+5.1%) 1015 (.4%) (.1%) 925 (+1.4%) (+2.2%) ( 4.0%) ( 0.9%) ( 0.3%) ( 6.4%) ( 8.4%) (+13%) (+6.0%) 667 (%) 1002 (+3.9) 838 ( 7.9%) ( 7.4%) S 206 (6%) 147 ( 54%) ( 68%) 130 ( 70%) 111 ( 65%) 185 ( 64%) ( 68%) ( 63%) 145 ( 55%)

2 Table S2 contributions from various driving factors to post-tgd water-discharge (relative to pre-tgd averages in (first row) and (second row)) Upstream basin at Yichang (430 km 3 /yr in ; 440 km 3 /yr in ) (Method 1) a (35 km 3 /yr in ; 48 km 3 /yr in ) (Method 1) a (190 km 3 /yr in ; 170 km 3 /yr in ) (Method 1) a Lake oyang basin (129 km 3 /yr in ; 110 km 3 /yr in ) (Method 1) a Basin upstream from Datong (tidal limit) (964 km 3 /yr in ; 905 km 3 /yr in ) (Method 1; Method 2) a b c d e b c e b c e b c e b c d e 0 +1±0 2±0.1.3±1 7.0±1 ± ±2 +25±5 +6±2 18±5 +5 1±2 0±2 +16±2 +35± ±5-32± ±5 +10± ±5; 1±7 44±2.3±1 +46; +76±8 +78± ±1 +30±1 51±1 56± ±0.2 +1±0.6 8±0.2 9±0.7 +2±0.2 1±0.7 22± ±5 ±0.5 22±5 19± ±2; 12±1 1±0.1; 1±2; 164±1 6± ±0.1 6± ± ± ± ±3 +23±0.2 +4±3 7 ±1 16±2 2±1 16±2 0 4±2 1± ±5; 56±4 44±2 +9±5 ; 6±4 +41±2; ±3 70±3 9.5±1 62±4 75±4 2 2±0.4 ±3 0±0.4 2±3 5 ±1 7±0.6 ±1 12± ±1 +6±0.1 +1±1 +1± ±10; 166±12 122±6 9.5±1 129±11;9±13 84±7 0 4±0.1 6±0.2 26±0.2 4± ±0.8 7± ±2 1±2 18±2 +1± ±6 6±0.7 5±6 1± ±8; 128±9 0±5 76±8 ; 65±9 4± ±1 +18±1.1±1 19±2 25±2 2 7±1 18± ±0.7 +3±0.2 0±0.7 22±0.2 7 ±3 ±0.3 8±3 7± ±1;±1 +16±0.8.1±1 0±2;6±2 78± ±2 49±2 9±2 +1± ±0.2 6±1 +10±0.2 +3± ±3 5±3 ±3 0± ±5 0±0.6 ±5 ± ±12; 5±14 160±8 ±12; +23±14 +37± ±0.3 +3± ±0.3 28±1 5± ± ±1 +14± ± ±2 ±0.2 7± ±5 +64±1 ±5 ± ±5; +71±5 +130±6 2.5±0.3 16±5 ; ±5 ± ±3 64±3 7± ±0.2 +2± ±0.2 +1± ±4 68±5 ±4 +1± ±7 50±1 4±7 +2± ±18;3±21 260±13 46±18; 2±21 +22± ±1 +24±1 +6±1 +1± ±0.2 5±1 +7±0.2 0± ± ±1 ±0.1 7± ±4 +55±1 4±4 9± ±5; +89±6 +119±5 ±5; 51±6 22± ±0.4 8±0 4.2±0.4 18±0.9 0± ±1 ± ±1 ±2 4± ±3 6±0.1 7±3 6± ±5; 81±6 46±3 4.2±0.4 49±5 ; 41±6 ±3 a In Method 1, precipitation-based water discharge was predicted directly using post-tgd basin-wide precipitation data and the pre-tgd correlation between water discharge and precipitation in In Method 2, the precipitation-based water discharge at Datong was predicted first using post-tgd sub-basin precipitation data and the pre-tgd correlations between water discharge and precipitation of the sub-basins, and then using water delivery models for the middle and lower reaches of the main river. Method S 2, was omitted for the prediction of precipitation-based change in water discharge from to 12, considering that the result of this method is comparable to the result of Method S 1 as suggest by the predicted from to 12. b Change measured over the post-tgd period relative to the pre-tgd averages in (first row) and t (second row). c recipitation-based change. The error of this change is determined by Equations 22 and 23. d Change due to TGD operation; i.e., the loss of water discharge because of water impoundment and evaporation in the TGR. e Balance between the observed change and the predicted due to precipitation and TGD operation, presumably caused by drivers such as water consumption, other reservoirs, water-soil conservation and temperature change. The error of this predicted change for the Yichang and Datong gauging stations is determined by the errors of the predicted due to precipitation and TGD, i.e., being lower than the sum the errors of the predicted due to precipitation and TGD and larger than both of them..

3 Table S3 contributions from various driving factors to post-tgd sediment-load (relative to pre-tgd averages in (first row) and (second row)) Upstream basin at Yichang (378 Mt/y in ; 541 Mt/yr in ) (Method S 1) a (7.8 Mt/yr in ; 119Mt/yr in ) (Method S 1) a (19.3 Mt/yr in ; 35 Mt/yr in ) (Method S 1) a Lake oyang basin (10 Mt/yr in ; 17 Mt/yr in ) (Method S 1) a Basin upstream from Datong (tidal limit) (320 Mt/yr in ; 507 Mt/yr in (Method S 1; Method S 2) a d Changes d Changes ±2 ±3 166±6 43±7 257± ±3 +106±41 0.4±3 210± ±3 5.9±2 +6.7±3 ± ±2 6.2±1 +0.4±2 5.5± ±4; ±5 ±2 3±7 +23±9; +26±9 3± ±15 +24±3 9±4 230±17 52± ±0.5 ±8 +1.1±0.5 94±8 26.9±1-0.4± ±1 26± ±1 5.2±1 2.3±1 8.8± ±2; +6±1 +12±2 87±5 73±6; 92±6 285± ±4 195±5 55±8 211± ±2 +58± ±2 160±22 6.5±2.3±1 6.5±2 26± ± ± ±0.6 ± ±4; 18±3 ±2 0±6 +30±8; +24±8 166± ±32 6±15 6±2 7±31 00± ±1 4.3±2 1.2±1 2± ±2 2±0.8.7±2 23± ± ± ±0.4 12± ±7; 69±10 64±9 77±3 4±9; 89±12 181± ±4 26±3 2±5 4±8 260± ± ±0.1 2± ±3 6.1±2 2.2± ±±2 6.9±1 1.7±2 7.1± ±6; 7±6 50±8 5±6 7±9;±9 214± ±8 +7± ±6 8±12 280± ± ±0.3.1±0.1 5±0.3.8±1-0.4± ±1 ± ±1 2.7± ±1 ± ±1; +1± ±3 6±7 46±8; 55±7 263± ±23 85±11 5±4 62± ± ±1 1.9±2 0.4±1 2± ±3 6.9±3 6.6± ±2 5.1±1 2.1±2 8.9± ±8; 71±10 87±13 8±5 47±11; 0±13 1± ±0.4 ±2 224±4 9±4 1± ±0 +4.2± ±0 1± ± ±1 5.9±0.3 26± ±2 +17±4 1.8±2 21± ±3; +16±2 +95±14 1±7 6±7; 0±3 266± ±29 6±14 4±4 125±31 15± ± ±2 1.8±0.2 99±2 3 ±5 12±4 4±3 22± ±2 9.5±2 +0.4±2.5± ±12; 98±15 0±23 78±5 90±15; 72±18 257± ±12 +16±2 217±6 1±15 7± ±1 1.7± ±1 3± ± ±1 12±0.5 1± ±1 +15±4 4.5±1 23± ±3; +28±4 +87±13 7±7 ±9; 0±9 6± ±6 5±4 9±5 4±9 9± ±0 +1.6± ±0 3± ±2.3±1 4.9±2 24± ± ±0 1.7±0.7 ± ±4; ±5 ±3 3±6 9±8; 6±9 2±8 a In Method S 1, the precipitation-based sediment discharge was predicted directly using post-tgd basin-wide precipitation data and the pre-tgd correlations between precipitation and water and sediment discharge. In Method S 2, the precipitation-based sediment discharge at Datong was predicted firstly using the post-tgd sub-basin precipitation data and the pre-tgd correlations between precipitation and water and discharge of the sub-basins, and then using sediment delivery models for the middle and lower reaches of the main river. Method S 2, was omitted for the prediction of precipitation-based change in sediment flux from to 12, considering that the result of this method is comparable to the result of Method S 1 as suggest by the predicted from to 12. b Change measured over the post-tgd period relative to the pre-tgd averages in (first row) and (second row). c Change generated by precipitation; i.e., the difference between the post-tgd precipitation-based sediment discharge and the average pre-tgd sediment discharge. The error of this change is determined by Equations 22 and 23. d Change in sediment discharge due to the TGD operation; i.e., the impact of sedimentation in the TGR and downstream deposition/erosion in response to TGD operation. For the Yichang station, the error of predicted change in sediment load is basically the error in estimating the sediment flux from the ungauged areas around the TGR, assuming that the error of sediment discharge at the gauging stations is negligible. The annual sediment fluxes from the ungauged areas in 12 were predicted by Yang et al. (2014) (see their Table). In this study, we estimated the relative errors of their predictions using Equation 22 and 23. e Balance between observed and predicted change due to precipitation and TGD operation, presumably caused by drivers such as other dams, water-soil conservation, sand mining, water consumption, and temperature change. The error of this predicted change is determined by the errors of the predicted due to precipitation and TGD.

4 Table S4 An example of error estimation for predicted water discharges at Datong using the regression relationship between annual precipitation and water discharge Measured values values ( Errors of predicted values Relative errors of predicted values (%) Regression of 1 Regression of 2 1 = , r = 0.91, p < = , r = 0.89, p < Error of predicted : The difference between predicted and measured water discharge. Relative error of predicted (%): ( -Measured ) *100/ Measured. A: average; S: Standard deviation A±S ±57 0±43 0±57 10±43 1±6 0±5 0±6 1±5

5 Table S5 Errors of predicted water and sediment discharges at Yichang and Datong stations for the pre-tgd decade (199302), using the regression relationships between annual precipitation and water discharge (Equation 2 and 6) and between water discharge and sediment flux (Equations 11 and 15) over the pre-tgd decade For the gauging station at Yichang For the gauging station at Datong (Tidal limit) : recipitation; : Water discharge; S : Sediment flux; S: rediction error estimated by Equations 22 and 23.. Relative error: ( v -M V )*100/M V, where v and M V represent predicted and measured values, respectively. Measured values values±s Relative errors Measured values values±s Relative errors S S (%) S (%) S S (%) S (%) ±20 471± ±74 344± ±15 269± ±63 308± ±17 365± ±64 302± ±16 302± ±63 296± ±14 225± ±59 282± ±21 570± ±79 368± ±19 469± ±71 3± ±19 451± ±69 322± ±16 301± ±58 271± ±17 326± ±74 348± ±18 375±84 0±5 3± ±68 317±42 0 ±7 1 ±15