Water take and energy
How do energy generation activities potentially influence water flows?
Taking of river water for energy generation impacts on water levels and natural fluctuations. Large quantities of water are needed by thermal power plants for cooling the steam turbines. Hydro-dams also impact on river water levels and modify the natural hydrology of a waterway by permanently altering water levels and flows. Both regulating and taking water from a river has the potential to reduce water quality and mahinga kai habitat.
Impacts of water take (abstraction) on water quality and mahinga kai
- Changes in flow - changes in water levels and flow variability alters available mahinga kai habitat and the invertebrates they feed on.
- Reduction of habitat - a decrease in water levels reduces habitat for fish and can impact feeding and spawning success.
- Reduction of specialist habitats - a decrease in water levels reduces flow to riparian wetlands, backwaters, and intermittent streams.
- Decreases in species abundance and diversity - aquatic species have developed life history strategies in direct response to natural flows; for example, diadromous fish species migrate up and down the river at various times of the year and rely on preferred velocities and depths.
- Changes in sediment accumulation - flow reduction affects movement and deposition of sediments in streams and rivers.
- Changes in water quality parameters - for example, turbidity and temperature levels can increase with reduced flows in rivers.
- Increases in algae accumulation - algae respond to changes in temperature and nutrients, which are likely to increase with reduction of flow, especially during summer months.