Runoff characteristics of the Changjiang River during 2006: Effect of extreme drought and the impounding of the Three Gorges Dam (original) (raw)
Related papers
Hydrogeology Journal, 2010
Groundwater can play an important role in the compensation of runoff reduction due to extreme climate events such as droughts, as well as in response to anthropogenic actions such as the construction of a dam. The increase in 226 Ra specific activity and the runoff from September to December in 2006 is used to estimate the total discharge of groundwater along the mid-lower reaches of the Changjiang River. The total groundwater discharge was found to account for 31% of the increased discharge between Yichang and Datong. The groundwater discharge to lakes (i.e. Dongting Lake) constituted the major contribution of groundwater discharge to the mid-lower reaches of the Changjiang River. More importantly, the second impounding operation of the Three Gorges Dam from 20 September to 27 October 2006 induced a water level decrease in surrounding lakes and rivers, which led to an additional groundwater discharge of 63.3×10 8 m 3 , accounting for 85% of the total groundwater discharge in the same period. Taken together, these observations indicate that groundwater discharge along the mid-lower reaches plays an important role in maintaining stream flow in the drought season, especially in extreme drought years or in response to human activities.
Climate Change Impacts on Yangtze River Discharge at the Three Gorges Dam
Hydrology and Earth System Sciences Discussions, 2016
The Yangtze River Basin is home to more than 400 million people, contributes to nearly half of China's food production, and is susceptible to major floods. Therefore planning for climate change impacts on river discharges is essential. We used a physically-based distributed hydrological model, Shetran, to simulate discharge in the Yangtze River just below the Three Gorges Dam at Yichang (1,007,200 km 2), obtaining an excellent match between simulated and measured daily discharge, with Nash-Sutcliffe efficiencies of 0.95 for the calibration period (1996-2000) and 0.92 for the validation period (2001-2005). We then used a simple monthly delta change approach for 78 climate model projections (35 different GCMs) from the Coupled Model Intercomparison Project-5 (CMIP5) to examine the effect of climate change on river discharge for 2041-2070 for Representative Concentration Pathway 8.5. Projected changes to the basin's annual precipitation varied between-3.6% and +14.8% but increases in temperature and consequently evapotranspiration (calculated using the Thornthwaite equation) were projected by all CMIP5 models, resulting in projected changes in the basin's annual discharge from-29.8% to +16.0%. These large differences were mainly due to the predicted expansion of the summer monsoon north and west into the Yangtze basin in some CMIP5 models, e.g. CanESM2, but not in others, e.g. CSIRO-Mk3-6-0. This was despite both models being able to simulate current climate well. Until projections of the strength and location of the monsoon under a future climate improve there will remain large uncertainties in the direction and magnitude of future change in discharge for the Yangtze 1 Introduction The Yangtze (or Chang Jiang) River (Fig. 1) is the third longest river in the world (6418 km) and the longest river in Eurasia. Its source is located on the Qinghai-Tibet Plateau, at 5100m elevation, and extends to the East China Sea through the city of Shanghai. The River basin covers an area of 1,808,500 km 2 , and is home to a population greater than 400 million (Dai et al.,
Impacts of River Engineering on Multi-Decadal Water Discharge of the Mega-Changjiang River
Sustainability
Knowledge of river engineering impacts on water discharge is significant to flow guidelines and sustainable water resource managements for balancing human consumption and the natural environment. In this study, based on the collected multi-decadal discharge data at Yichang, Hankou, and Datong stations, we determined that in October, Three Gorges Dam contributed 34.4%, 24.5%, and 18.7% to the discharge decrease in the upper, middle, and lower reach, respectively, while Gezhouba Dam contributed 14.5%, 10.7%, and 10%. Danjiangkou Reservoir caused the discharge ratio of Hanjiang to Changjiang to decline from 7.2% during 1954–1973 to 6.3% during 1973–2014. Owing to growing water withdrawal and consumption, we suggest that the distribution of water diversion and consumption should be regulated to prevent the probable occurrence of the severe issue of salt water intrusion in the Changjiang Estuary in 2028.
The human influence on the river ecosystem has increased in recent years to feed the growing demand for water to communities by constructing different water structures. It is essential to understand the potential impacts of water structures on river hydrologic regimes. Thus, this study investigates the influence of the cascade dams located upstream of the Three Gorges Dam on the Yangtze River on the river ecosystem. The study was carried out for the period 2003-2015 for both Cuntan and Miaohe stations. The analysis was conducted considering two periods, pre-impact; before the dam construction and post-impact; after the dam construction. The assessment was carried out using "Indicators of Hydrologic Alteration." The results of this study revealed that the cascade dams built upstream of Three Gorges Dam has both positive and negative impacts at both stations. Flows were found to have positive impacts in July while low in October for both stations. The 1-day minimum flows were found to decrease by 7% over Miaohe Station while the 1-day maximum was decreased up to 2% in Cuntan. Overall, the results of the study indicate that there are undesirable impacts which should be adjusted to maintain the river ecosystem at an acceptable level compared to its natural state. It is expected that the findings of the study can guide water managers to adjust the hydropower operation sustainably.
Ambio, 2011
During the extreme dry year of 2006, abnormal salinity conditions in the Changjiang Estuary of the Yangtze River occurred in partial coincidence with the second impoundment phase of the TGD (Three Gorges Dam). Analysis of discharge observations in the upper reaches of the estuary and of salinity observations in the estuary as a whole reveals that in 2006 salinity was over 100 mg/l during 275 days, over 250 mg/l during 75 days and over 400 mg/l during 48 days. It is well known that this is due to extreme low discharges from the upper catchment area into the estuary. Moreover, large amounts of water consumed along the lower reaches of the Yangtze River can also aggravate the low discharges that lead to stronger saltwater intrusion in the estuary. Of the 75 days that salinity was over 250 mg/l, the low discharge was decreased further by 10 to 20% due to water consumption. The additional impact of the impoundment phase of the TGD (lasting 37 days in autumn) was noticeable only during 7 days in 2006. During that period, the relative contributions of the TGD and the water consumption in the lower reaches of the Yangtze River amounted to 70 and 30%, respectively. It may be concluded that the impact of the second impoundment phase of the TGD on salinity intrusion in the estuary was modest, while the extreme drought of 2006 was the dominant cause.
Assessment of extreme drought and human interference on baseflow of the Yangtze River
Hydrological Processes, 2010
Attention has been given to baseflow in large rivers, but up to now, no study on baseflow for the Yangtze River in combination with extreme drought and extensive human activities has been carried out. Discharge data in 2000-2005 and in the extreme drought years, 1978 and 2006, at stations along the main stream, lakes and distributaries of the Yangtze River were collected to analyse the features of baseflow in 2006 by using baseflow separation technique, HYSEP. It can be seen that the baseflow relative to the streamflow in 2006 was greater than those in other years. The variation of baseflow discharge in the Upper Yangtze River Stream (UYRS) was larger than that in the Mid-Lower Yangtze River Stream (MLYRS). Human activities in MLYRS are more intensive than that in the UYRS and the baseflow discharge was greater. The baseflow is influenced by the extreme climate and human activities along the Yangtze River with the former being the dominant factor in 2006. The contribution of human interference to baseflow discharge was about 10% in 2006.