The Ecological Water Demand of Schizothorax in Tibet Based on Habitat Area and Connectivity

Abstract

Water resource regulation is convenient for humans, but also changes river hydrology and affects aquatic ecosystems. This study combined a field investigation and two-dimensional hydrodynamic model (MIKE21) to simulate the hydrodynamic distribution from 1 March to 30 April of 2008–2013 and establish the HDI (habitat depth suitability index) and HVI (habitat velocity suitability index) based on static hydraulic conditions at typical points. Additionally, by using MIKE21 to simulate the hydraulic state in the study area under 20 flow conditions from 530–1060 m3/s, and combining these states with the HCI (habitat cover type suitability index), HDI, and HVI, we simulated the WUA (weighted usable area) and habitat connectivity under different runoff regulation scenarios to study the water requirements of Schizothorax during the spawning period in the Yanni wetland. The results showed the following: (1) the suitable cover type was cobble and rock substrate, with nearby sandy land; furthermore, the suitable water depth was 0.5–1.5 m, and the suitable velocity was 0.1–0.9 m/s. (2) Using the proximity index to analyse the connectivity of suitable habitats, the range of ecological discharge determined by the WUA and connectivity was 424–1060 m/s. (3) Habitat quality was divided into three levels to detail the flow demand further. When the flow was 424–530 m3/s or 848–1060 m3/s, the WUA and connectivity generally met the requirements under natural conditions. When the flow was 530–636 m3/s or 742–848 m3/s, the WUA and connectivity were in a good state. When the flow was 636–742 m3/s, the WUA and connectivity were in the best state. This study complements existing research on the suitability of Schizothorax habitat in Tibet, and introduces the connectivity index to enrich the method for calculating ecological water demand, providing a reference for resource regulation and the protection of aquatic organisms.

Application of edge computing and GIS in ecological water requirement prediction and optimal allocation of water resources in irrigation area

“…Regarding model performance, the proposed ecological water demand prediction model based on mobile edge computing and GIS performs better than the prediction model. In the literature [31], due to the CNN utilized, the processing time of the model is better; however, for agricultural production, the issue of cost needs to be considered. Therefore, the proposed model is relatively more suitable for practical analysis.…”

The impact of floods triggered by natural dam breakage on the adaptability of downstream river fish—the 2018 baige outburst flood in the upper reaches of the Yangtze river in China

“…Schizothorax, a common fish that lives near the Baige landslide dam, was selected as the research object. In previous studies, several scholars determined the hydraulic suitability curve (HSC) of Schizothorax through field surveys, as shown in Figure 3 (Hung, H. et al, 2022;Zhou et al, 2019).…”

Spatial suitability evaluation of spawning reach revealing the location preference for fish producing drifting eggs

“…We used a 95% confidence interval for each hydrologic and hydrodynamic factor range of each cluster to calculate the suitability value of each hydrologic and hydrodynamic factor (see Figure 10). To more easily interpret the evaluation results of fish spawning ground suitability, we refer to previous studies (Gillenwater et al, 2006;Yi et al, 2016;Zhou et al, 2019) to divide suitability values into two classes, representing areas of high (a suitability value greater than 0.4) and low (a suitability value less than 0.4) suitability. Cluster 2, cluster 3, cluster 5, cluster 8, and cluster 10 indicated high suitability, with suitability values of 0.485, 0.410, 0.466, 0.467, and 0.510, respectively.…”