Numerical modelling for ecologically successful spawning-site restoration in Chin-sha River, China

Abstract

Context The construction of dams on the Chin-sha River will affect fish spawning sites, leading to a decline in fish species. Aims This paper presents a model to evaluate the ecological status of restoration strategies aimed at fish species living at a spawning site. Methods The model comprises hydro-morphodynamic and habitat modules. The modelling approach was applied with two restoration strategies (side-channel addition and riverbank reconstruction) and their corresponding post-restoration effects. Key results Three indicators were utilised to assess the ecological status of the spawning site. Modelling results showed poor ecological status under current hydrological conditions, with weighted usable area and overall suitability index values of 1.07 × 106 m2 and 0.41. Without implementing a restoration strategy, the ecological status would continue to fragment and deteriorate. Conclusions The weighted usable area can be recovered to 2.86 × 106 and 1.67 × 106 m2 in scenarios of side-channel and bank construction respectively. The overall suitability index values increase to 0.67 and 0.63 respectively. Implications It is also noted that the ecological restoration strategy (side-channel addition) can considerably enhance the freshwater Reeves shad’s habitat status. Additionally, the restoration strategy illustrated the feasibility of the side-channel addition restoration strategy.