Fish Injury and Mortality During Passage Through Pumping Stations

Abstract

An unwanted side effect of pumping stations is that fish suffer from injury and mortality when passing through the pumps and that fish migration is hampered. In recent years, the development of so-called fish-friendly pumping stations has received increasing attention from European governmental institutions and pump manufacturers. In the Netherlands, many field studies have been conducted over the last decade to assess the chances of survival for fish passing through pumps. A clear correlation between observed injury or mortality and, for example, flow rate, shaft speed, or pump type could not be established. This paper presents a new analysis of these field studies. It uses American studies on the biological criteria for fish injury, the most important of which are pressure changes, shear forces, and mechanical injury. A blade strike model is adapted to fish passing through centrifugal pumps of radial, mixed-flow, and axial type. It reveals the relation between fish injury and the type of pump, its size, shaft speed, and pressure head. The results correlate fairly well with experiments. The flow through a typical mixed-flow pump is calculated using computational fluid dynamics (CFD). The results show that pressure fluctuations and shear forces are not likely to add much to fish mortality. Guidelines for the design and selection of fish-friendly pumps are given with the introduction of two new dimensionless numbers: the blade strike probability factor and the blade strike velocity factor. It shows that fish-friendliness of pumps decreases with increasing specific speed value.

Direct and indirect impacts of pumping station operation on downstream migration of critically endangered European eel

“…The majority of injuries were likely caused by blade strike, evident from the high levels of severance and degloving (Buysse et al., ), and mechanical processes such as collision and grinding, evident from abrasion and internal haemorrhage. The amount and/or severity of entrainment impact differs with turbine or pump diameter (Van Esch, ), operating speed (Grizzle & Lovshin, ; Rodgers & Patrick, ) and number of blades (Pracheil et al., ), which is consistent with other investigations. However, care must be taken when interpreting the results of this study because the impact of passing through the entire pumping station was assessed, i.e., not just the pump, so the impact of other features inside the pumping station cannot be ruled out, including flow guide veins, the angle of pipe bends and pump chamber walls.…”

Validation of a model to predict fish passage mortality in pumping stations

“…Based on several investigations, Cada et al (1997) suggested a minimum of 30% for physostomes and 60% for physoclists for the allowed pressure ratio p/p a during turbine passage. van Esch (2012) showed that mechanical injury by blade strike is the primary cause of damage to fish passing through pumping stations operating at pressure heads up to about 8 m. Similar conclusions were drawn in relation to damage rates of fish passing through turbine systems with heads up to 30 m (Turnpenny et al 2000;Cook et al 2003;Amaral et al 2011).…”

“…Several investigations have shown that of all possible mechanisms for damage to fish in both turbines and centrifugal pumps, mechanical damage by a blade strike is the most important (Turnpenny et al 2000;Cook et al 2003;van Esch 2012). Many models to predict fish survival in pump or turbine systems exist, but they are not often used owing to a lack of proper validation (Ferguson et al 2008).…”

“…The survival rate of fish passing through the pumps at Grand Coulee Dam was predicted using a blade strike model, but no test results were available to validate their method. Another more recent study by van Esch (2012) showed that mechanical injury by blade strike should be considered the primary injury mechanism in pumping stations. Predictions of fish damage using a blade strike model were shown to correlate fairly well with the injury and mortality rates reported in several monitoring studies that were conducted in the Netherlands over the past 10 years ( Van der Wal et al 2012).…”

A review of potential factors promoting fish movement in inter‐basin water transfers, with emergent patterns from a trait‐based risk analysis for a large‐scale project in china

“…Three major injury types that occur during passage include blade strikes, barotrauma (expanding gas in rapid pressure changes) and shear forces (adjacent hydrological locations with vastly different velocities) (van Esch, 2012;van Esch & Spierts, 2014). Among juvenile and adult fish, blade strikes likely have the highest mortality rate, while barotrauma and shear injuries may have higher mortality rates in eggs and/or larval fish (Boys et al, 2016;Navarro et al, 2019;van Esch, 2012).…”