Normalized pressure: a key variable to assess zebra mussel infestation in pressurized irrigation networks

Abstract

The impact of zebra mussel (Dreissena polymorpha) colonization on pressurized irrigation systems is becoming important in many areas of the world. If the infestation is not controlled, the conveyance capacity of the network reduces and mussels can completely block the system, preventing irrigation. A methodology to assess zebra mussel infestation in collective pressurized networks based on monitorization and hydraulic simulation is developed in this research. Normalized pressure, defined as the difference between simulated and measured pressure, is an indicator of the presence of zebra mussels (Morales-Hernández et al., 2018). When this variable is combined with the distributed discharge of the irrigation network, it is possible to use an optimization procedure to produce a roughness map of network pipelines. Roughness in excess of that characteristic of the pipeline material can be directly associated zebra mussel infestation. Different objective functions, optimization algorithms and strategies are proposed in this work, with the aim of attaining constant discharge-independent normalized pressure at each observation point in the network. Roughness values under different pipe conditions, reproducing levels of zebra mussel infestation, were experimentally obtained at a reference laboratory. The limitations and uncertainties of the proposed methodology are discussed. Normalized pressure was validated in an irrigation network belonging to a water users association, using continuous data recorded at different observation points during a complete irrigation campaign. The non-invasive hydraulic method has been designed to identify infested areas in real time and to optimize the chemical treatments controlling mussel development