Abstract:

With the intensification of human activities, massive amounts of pollutants have entered aquatic environments, posing a significant threat to ecosystems. To address the frequent sudden water pollution incidents in the Deting and Beigou River tributaries of the Yiluo River Basin, a one-dimensional hydrodynamic-water quality coupled model was constructed based on the Hydraulic Engineering Calculation and Analysis System (HEC-RAS). This model simulates the dispersion and migration patterns of characteristic pollutants and proposes emergency response strategies. River cross-sections were constructed using measured hydrological and topographic data, incorporating Manning’s roughness coefficient and contraction/expansion coefficients. The model validation was validated using tracer tests to calibrate the longitudinal dispersion coefficients. The results demonstrated average relative errors below 2.38% for the water level simulation and 8.29% for the flow velocity simulation, with water quality simulations showing a high correlation with measured values. Scenario simulations indicated that a 6×10³ m³ slurry leak of hexavalent chromium (Cr⁶⁺) in the Deting River during the flood season would form a 7.6 km pollution plume within five hours. After 670 min, pollutants entered the main stem of the Yi River, reaching a maximum mass concentration of 3.35 mg·L⁻¹ (exceeding the standards for 1380 min). Emergency measures, such as ecological flow regulation and precipitation agent addition, are recommended to address this issue. Following a 5-ton diesel spill in the Beigou River, a 3-km pollution zone formed and continued to spread, affecting the Yihe River mainstem after 950 min with a maximum mass concentration of 6.53 mg L⁻¹ (exceeding standards for 850 min). Containment, adsorption, and chemical degradation are thus recommended. This study demonstrated that the HEC-RAS model effectively predicted the spatiotemporal distribution characteristics of pollutants. A tiered emergency response strategy was proposed based on variations in topography, flow rate, and pollutant properties of the river. This study provides a scientific basis for rapid responses to sudden pollution incidents in small- and medium-sized rivers and for mitigating associated ecological and public safety risks.

Key words: tributaries of the Yiluo River, HEC-RAS, Pollutant migration, sudden water pollution accidents, emergency management

摘要：

伴随人类活动的加剧，大量污染物进入水环境，对生态环境造成了巨大的威胁。针对伊洛河流域支流德亭河与北沟河频发的突发性水污染问题，基于河道水力分析模型（HEC-RAS）构建一维水动力-水质耦合模型，模拟特征污染物的扩散迁移规律，并提出应急策略。通过实测水文数据与地形数据构建河道断面，设置曼宁糙率系数和收缩/扩张系数，并利用示踪试验率定纵向离散系数进行模型验证，结果显示水位和流速模拟平均相对误差分别低于2.38%和8.29%，水质模拟结果与实测值高度吻合。通过情景模拟分析可知德亭河六价铬（Cr⁶⁺）在丰水期泄漏6×10³ m³泥浆，5 h后形成7.6 km污染带，670 min后污染物汇入伊河干流，最大质量浓度达3.35 mg∙L⁻¹（超标1380 min），建议通过生态流量调控或投加沉淀剂应急；北沟河在5 t柴油泄漏后形成3 km污染带并持续扩散，950 min后影响伊河干流，最大质量浓度达6.53 mg∙L⁻¹（超标850 min），推荐采取围堵吸附和化学降解措施。研究表明HEC-RAS模型能有效预测污染物的时空分布特征，结合地形、流量与污染物特性的差异，提出了分级应急策略。该研究可为中小河流突发污染事故的快速响应以及降低其生态与公共安全风险提供科学依据。

关键词: 伊洛河支流, HEC-RAS, 污染物迁移, 突发水污染事故, 应急管理