Quantifying suitable dynamic water levels in marsh wetlands based on hydrodynamic modelling

Abstract

The water level of marsh wetlands is a dominant force controlling the wetland ecosystem function, especially for aquatic habitat. For different species, water level requirements vary in time and space, and therefore ensuring suitable water levels in different periods is crucial for the maintenance of biodiversity in marsh wetlands. Based on hydrodynamic modelling and habitat suitability assessment, we determined suitable dynamic water levels considering aquatic habitat service at different periods in marsh wetlands. The two-dimensional hydrodynamic model was used to simulate the temporal and spatial variation of water level. The habitat suitability for target species at various water levels was evaluated to obtain the fitting curves between Weighted Usable Area (WUA) and water levels. And then suitable water levels throughout the year were proposed according to the fitting curves. Using the Zhalong Wetland (located in northeastern China) as a case study, we confirmed that the proposed MIKE 21 model can successfully be used to simulate the water level process in the wetland. Suitable water levels were identified as being from 143.9-144.2 m for April to May, 144.1-144.3 m for June to September, and 144.3-144.4 m for October to November (before the freezing season). Furthermore, proposed water diversion schemes have been identified which can effectively sustain the proposed dynamic water levels. This study is expected to provide appropriate guidance for the determination of environmental flows and water management strategies in marsh wetlands.

Environmental flow mechanism and management for river–lake‐marsh systems

“…For aquatic organism protection in river–lake‐marsh systems, three papers are selected. Hu et al (2021) built a two‐dimensional model to obtain the fitting curves between fish's Weighted Usable Area (WUA) and water levels, and then identified suitable water levels in different periods. To control algal bloom in the middle and lower reaches of Han River, Li, Yin, et al (2021) established a hydrological management framework and determined the threshold flow velocities.…”