Differences of Regulative Flexibility between Hydrological Isolated and Connected Lakes in a Large Floodplain: Insight from Inundation Dynamics and Landscape Heterogeneity

Abstract

The inundation areas of floodplains are crucial to wetland ecosystems, especially in supporting biodiversity. Accurately identifying the spatial and temporal patterns of inundation areas is important for understanding floodplain ecosystem processes. Here, lakes in the Yangtze River Floodplain were divided into two types according to hydrological conditions: the natural connected lakes (Dongting Lake and Poyang Lake) with natural water level fluctuations and the isolated lakes (lakes in Jianghan Plain) with stable water levels. We established a method to identify inundation areas using multi-sources remote sensing data based on the Google Earth Engine. The dynamics of inundation areas were determined, and the relative indices were calculated in common year (2017) and a drought year (2018). The differences between the connected lakes and the isolated lakes were analyzed, and impacts of hydrological fluctuations on inundation area and habitat quality were evaluated. The results show that lakes with natural hydrological fluctuations have a greater regulative flexibility, with both patch density (PD) and submerged elasticity index (SEI) values higher than that of isolated lakes. The trend of the vegetation index in the connected lakes and in the isolated lakes is also different. The mean EVI in Dongting Lake and Poyang Lake showed a U-shaped trend which is similar to the shape of the trend of PD. The trend of mean enhanced vegetation index (EVI) in the isolated lakes is the opposite and has a lower range of variation over a year. This study provides new indicators and rapid methods for habitat quality assessment in floodplains, as well as presenting scientific information useful for improving wetland management in the middle and lower Yangtze River.

Development of a Linear Regression Model Based on Vegetation Indices of Agricultural Crops

“…According to the results of this study, WBI and NDWI indices helped to recognise saturated soil and also NDII and LSWI indices showed better dynamic range of recognition due to stronger absorption of infrared rays to display different degrees of soil moisture. Other studies by these authors have shown that hydrological regimes such as flood frequency and inundation area determine habitat quality affect vegetation cover and biomass [8].…”

Temporal and Spatial Evolution of Herbivorous Waterbird Habitat in Floodplain Wetland Driven by Hydrology

“…Based on the filtered Landsat data (Table S2 in Supporting Information ), the water extraction method in J. K. Teng et al. (2020) was used to obtain the water surface distribution and area (X. Wang et al., 2018). The formula is in Supporting Information (Text S1 in Supporting Information ). Water body patch density (PD).…”

“…The formula is in Supporting Information (Text S1 in Supporting Information ). Water body patch density (PD). Patch density is used to measure the degree of landscape fragmentation (J. K. Teng et al., 2020) which reflects the spatial configuration and structural composition at the landscape scale (Hein et al., 2004). We calculate the water body patch density to analyze the change characteristics of Poyang Lake hydrology in distribution and structure.…”

Dynamic Monitoring and Ecological Risk Analysis of Lake Inundation Areas in Tibetan Plateau

“…The lake-inundated area refers to the area that was judged to have appeared as water during the study period, except for the area of the perennial stable lakes [45]. The inundation frequency refers to the proportion of the inundated time of a certain area to the total inundated time during the study period.…”