Cascade Dam-Induced Hydrological Disturbance and Environmental Impact in the Upper Stream of the Yellow River
The construction of a dam converts the natural streamflow to human control. It is necessary to learn the accumulated effect of cascade dams on hydrological characteristics, sediment and nutrient pollution discharge. The current research describes the analysis and simulation of streamflow, sand concentration and nutrient pollutant discharge alterations caused by the construction of a cascade of eight dams along the Longliu section of the upper stream of the Yellow River. The analysis shows that the maximum monthly streamflow difference between the inlet and outlet of the Longliu section decreased from 430 to 115 m<Superscript>3</Superscript>/s, after the appearance of the cascade dams between 1977 and 2006. In the same period, the correlation coefficient (R <Superscript>2</Superscript>) of monthly streamflow between the inlet and outlet of Longliu dropped from 0.959 to 0.375. The peak of streamflow shifted from June to May and October. The difference in sand concentration between two sections decreased from 0.52 to 0.39 kg/m<Superscript>3</Superscript>, which was the direct consequence of the operation of the reservoirs. The R <Superscript>2</Superscript> value of sand concentrations of the inlet and outlet were also reduced from 0.504 to 0.356. A t-test analysis indicates that the original hydrological nature was significantly disturbed by the cascade dams. The influence of the dams on nutrient pollutant transport was simulated by the SWAT model. This simulation suggests that the cascade dams decreased the discharge of total nitrogen and total phosphorus from 15.4 × 10<Superscript>3</Superscript> t and 1,996 t to 0.4 × 10<Superscript>3</Superscript> t and 328 t, respectively. In conclusion, the accumulated impact of cascade dams on streamflow, sand concentration and nutrient pollutant discharge were analyzed, which were helpful for understanding the environmental features of the entire watershed. Copyright Springer Science+Business Media B.V. 2011
