Integrated framework for assessing the impact of inland oil spills on a river basin: Model and case study in China

The rapid spread of oil pollution owing to river flow has vast consequences for human activities and ecosystems within the affected river basin. In the context of the profound impact of oil spills on river basins, an integrated riverine oil spill impact assessment framework is proposed. The framework combines a risk-matrix approach with an oil trajectory model and the environmental sensitivity index (ESI) methodology to estimate the impact level of the affected river basin. The framework was applied in simulation to the middle reaches of the Nenjiang River, China, to evaluate the impact of a hypothetical oil spill accident during different seasons. Our findings revealed similar propagation trends of the oil and impact level maps during normal water and flood seasons, largely owing to the regulating function of a downstream dam. Specifically, the oil front edge spread over 2 km/h along the initial 30-km downstream segment in normal water and flood seasons, and the speed slowed to 1.2 km/h in the dry season. The length of the polluted river during normal water and flood seasons was approximately 1.4 times that in the dry season, with contaminated zone lengths averaging 0.45, 0.61, and 0.82 km in the dry, normal water, and flood seasons, respectively. The output impact-level maps, which highlight the severely affected areas over time after the spill, are especially useful for decision makers. This framework is shown to be a valuable tool for quantitatively evaluating the dynamic impacts that a river basin may face following an oil spill, and is particularly useful for facilitating the initial emergency response.