Influence of pumped-storage power plant’s daily operation on the density of veligers of Limnoperna fortunei

Dandan Yu, Mengzhen Xu, Hongwu Tang, Zhao-Yin Wang

Friday 3 july 2015

9:00 - 9:15h at Europe 1 (level 0)

Themes: (T) Hydro-environment, (ST) Ecohydraulics and ecohydrology

Parallel session: 14G. Environment - Renewable

Invasion and biofouling of golden mussel (Limnoperna fortunei) in pumped-storage plants (PSPs) in China has caught wide attention. The specific operation way of PSPs is regarded as the main reason causing golden mussel biofouling in the water intakes and tunnels. PSPs generate electricity by releasing water stored in the upper reservoirs to the lower reservoirs during peak power-consuming hours, and pump water up to the upper reservoirs during low electrical demand hours. Except the operation hours, PSPs are usually stopped. The golden mussel veligers are stirred up from the reservoir beds and delivered into the intakes and tunnels during the processes of releasing and pumping water, and settled down on the tunnel walls and all structures they have touched under no operation, resulting in biofouling. In particularly, the cooling water systems of PSPs usually consist of small tubes that are under high risk of being clogged. This study is aimed to find the relationship between the daily operation of the LangyashanPSP, located in a tributary watershed of the Yangtze River in East China, and the variation of density of golden mussel veligers in the reservoir of the PSP. It will be helpful for making adjustment of daily operation to avoid golden mussel biofouling in tunnels and structures of the PSP. A series of continuous investigations was conducted by taking the water samples from the reservoir of the PSP during three months in 2014, which is among the peak reproducing season. The monitoring result shows that the density of veligers increased with the operation time of pumping water. In contrast, the density of veligers decreased significantly when the pumps stopped. Nevertheless, the mortality of veligers is also influenced by the operation. It was usually high mortality when there was no operation of pumping or releasing water. As the movement ability of the veligers is weak, we suppose the veligers were settled down to the reservoir bed and killed by sediment precipitation and lacking of oxygen under no operation. During the operation, the veligers were stirred up into the water by the turbulences.