Exploring the Impact of Landscape Ecological Risk on Water Quality in the Danjiangkou Reservoir, China

Abstract

Evaluating the spatial‐temporal dynamics in ecological risk and understanding its impact on water quality in reservoirs could optimize watershed land use and protect reservoir water quality. However, this impact remains elusive due to the lack of long‐term field data, the heterogeneity of land use, and scale effects. Therefore, Danjiangkou Reservoir area was selected as the study area, where rapid urban expansion and ecological conservation and restoration measures have significantly changed the ecological environment, altering the water quality. We investigated the spatial‐temporal changes of land use from 1990 to 2020 and evaluated how landscape ecological risk changed, as well as explored the impact of landscape ecological risk changes on water quality. The landscape ecological risk was calculated by landscape vulnerability and landscape disturbance (based on fragmentation, separation, and fractal dimension). The results indicated that the growth rate of water bodies surged (7.65 km2/a) and cropland experienced an apparent reduction (14.39%) over the past 30 years. These landscape changes decreased ecological risk, especially after the water transfer. The results revealed that the impacts of ecological risk on water quality were better explained at the riparian scale than at the reach and catchment scales. Specifically, the ecological risk was strongly relevant to dissolved oxygen, Turbidity, Cl− and NO3− ${{\text{NO}}_{3}}^{-}$, and moderately correlated to Ca2+ and pH. While it was not correlated with total nitrogen, total phosphorus, and F−, possibly due to the irregular reservoir operations, occasional excessive use of fertilizers, and rock weathering. This study preliminarily discloses the impact of landscape ecological risk on water quality in a basin reservoir and provides a theoretical basis to take measures in advance for the sustainable development of a reservoir basin.

Sustainability Assessment of Urban Waterscape Belt Ecological Reconstruction Based on LCA–Emergy–Carbon Emission Methodology

“…The similarity is that some scholars have studied the waterscape zone with a single method, rather than comprehensively. This is the limitation of current research and the direction that needs to be improved [48][49][50][51][52].…”

The Temporal Variation and Flood Determined the Characteristics of the Water Quality Pattern in Danjiangkou Reservoir, China

“…Phosphorus was found to be the limiting factor for phytoplankton growth (represented by Chl a) in all seasons. Cao et al [25] noticed a significant relation between water quality and parameters such as DO, Turb, Cland NO-3, but not with TN or TP. This finding indicates that the reservoir dispatching, fertilizer utilization, and rock weathering have an impact on the water quality.…”

“…Danjiangkou Reservoir is the important water source of the south-north water diversion in China, and its water quality and the factors that affect it have received widespread attention [25][26][27]. In many reservoirs across China, phosphorus is considered the primary determinant of water quality [12,[28][29][30].…”

Spatio-Temporal Assessment of Landscape Ecological Risk and Associated Drivers: A Case Study of the Yellow River Basin in Inner Mongolia

“…From 1990 to 2020, the overall area of low risk areas in the study area increased and the area of high risk areas decreased, mainly owing to the large shift from grassland and bare land to cropland, construction land, and forest during the study period, and the landscape dominance increased. Landscape fragmentation and separation decreased significantly [18], leading to a shift in risk levels to lower levels. The ecological risk-sensitive areas (hot spot areas) of the basin mainly contain land types such as cropland, bare land, and construction land, which have a high degree of landscape fragility and strong human interference.…”

“…A landscape ecological risk assessment model with a landscape ecology angle is more appropriate for assessing the environmental risks caused by human interventions than risk assessment models based on ecological risk sources [15]. Landscape heterogeneity, resilience, stability to disturbances, and ecosystem diversity are closely related [18], all of which emphasize the importance of landscape as an element of ecological risk assessment. Landscape ecological risk assessment focuses more on the spatial and temporal heterogeneity of ecological risks than traditional ecological risk assessment methods [19].…”