Skip to Main Content

The TGD began impounding water in June 2003. Similar to other dams on this large alluvial river, the management of flood control, electric power generation, and navigation by the TGD caused a change in the hydrological regime of the river. Figure 2 and Table 1 show that dam regulation has little impact on the annual runoff. For example, compared with the average annual runoff during the pre-TGD period, the change in the post-TGD average annual runoff is no larger than 7%, except for the runoff during 2006 (an exceptionally dry year); however, the flow process is significantly altered. The main characteristics of the change in flow consist of a decrease in the flood peaks and an increase in the magnitude and duration of low-flow periods (Figure 2). As shown in Figure 3, the flow amplitude (ratio of maximum discharge to minimum discharge) changes from 10.9 to 7.3 between the pre-TGD and post-TGD periods. In comparison with the pre-TGD period, the frequency of the discharges of 6,000–19,000 m3·s−1 increased by 7.1% in the post-TGD period. In the same period, the frequency of observed river flows >19,000 m3·s−1 decreased significantly, especially for flood discharges, while the relative frequency of discharges >35,000 m3·s−1 was only 2.2%.

Table 1

Comparison of pre- and post-TGD annual runoff and sediment load at the Shashi gauging station

Pre-TGD average (1956–2002)20032004200520062007200820092010201120122013Post-TGD average (2003–2013)
Annual runoff (×108 m33,943 3,920 3,901 4,210 2,795 3,770 3,902 3,686 3,819 3,345 4,224 3,538 3,737 
Annual sediment load (×108 t) 4.34 1.38 0.956 1.32 0.245 0.751 0.492 0.506 0.48 0.181 0.617 0.402 0.666 
Pre-TGD average (1956–2002)20032004200520062007200820092010201120122013Post-TGD average (2003–2013)
Annual runoff (×108 m33,943 3,920 3,901 4,210 2,795 3,770 3,902 3,686 3,819 3,345 4,224 3,538 3,737 
Annual sediment load (×108 t) 4.34 1.38 0.956 1.32 0.245 0.751 0.492 0.506 0.48 0.181 0.617 0.402 0.666 

Close Modal

or Create an Account

Close Modal
Close Modal