闸控河段水质多相转化机理研究

Reaches controlled by sluice (RCS) is the river segment where hydraulic engineering (sluice or dam) is built, and hydrological circumstances and water quality transform process are influenced remarkably by sluice operation. Due to having a strong disturbance action to environmental factors (such as water flow, suspended substance and sediment) caused by sluice operation, the transform process of water quality in RCS shows the characteristics of multi-media, multi-phase and multi-form. Taking Huaidian Sluice in Shaying River as research object, a new research idea on multi-phase transform driving mode of water quality in the water- algae-suspension-sediment interface is developed innovatively, based on recognizing sufficiently occurrence forms of water quality and its main influencing factors. Utilizing synthetically simultaneous monitoring experiment with sluice operation, parameter identification technique, multi-model integrated technology and scenario analysis method, an original multi-phase transform model of water quality in RCS is established. Some scenarios of sluice operation and pollution load are designed from different aspects, and temporal and spatial change processes of water quality concentration under each scenario are simulated. In the end, the driving action of sluice operation on multi-phase transform of water quality and the water environment evolution law of RCS are revealed. The research achievements can provide scientific base for recognizing the value of sluice operation in water environment protection, and have a practical guiding significance to rivers’ water resources sustainable utilization and pollution prevention with the cooperation of upper and lower reaches.

闸控河段是指在河道上建有闸坝等水利工程，且其水文情势和水质迁移转化过程受闸坝调控作用影响显著的河段。由于闸门调度对河道内水流、悬浮物、底泥等环境要素具有强烈的扰动作用，故闸控河段水质转化过程呈现出多介质、多相态、多形式的特点。本次研究以沙颍河干流槐店闸为研究对象，在充分认识水质在不同介质中的赋存形态以及影响水质相态转化的主要环境因子基础上，创新地提出闸控河段水体—藻类—悬浮物—底泥界面水质多相转化驱动模式研究思路；综合采用水闸调度同步监测实验、参数识别技术、多模型集成技术等技术方法，研制新颖的闸控河段水质多相转化数学模型；从不同角度设计闸门调度和来水负荷情景，模拟各相水质的浓度时空变化过程，进而揭示水闸调度对水质多相转化的驱动作用和闸控河段水环境演化规律。该研究可为客观认识水闸调度在水资源保护中所起的作用提供科学依据，并对河流水资源可持续开发利用和水污染联防调度有一定的现实指导意义。

闸坝是辅助人类开发管理水资源的重要工具，它在防洪排涝、拒咸蓄淡、灌溉供水、通航养殖、景观娱乐、生态保护等方面起着积极作用。但近年来，闸坝建设的负面效应逐渐凸显出来，造成水污染事故频繁发生、生态与环境持续恶化、生物多样性减少等一系列问题。在此背景下开展闸控河段水质多相转化过程及机理研究，加强闸控河段水环境系统演化机理研究和水闸调度在水质改善方面的功效评估，对客观认识闸坝在水资源开发和保护中所起的作用，减少水利工程建设所带来的生态与环境风险，具有重要的实际应用价值。项目主要从以下几个方面对闸控河段水质多相转化过程及机理开展研究：.（1）对闸控河段内水质多相转化的机理进行归纳总结，提出闸控河段水体—悬浮物—底泥—藻类界面水质多相（溶解相、悬浮相、底泥相、生物相）转化驱动模式的整体架构；分析水闸调度对水质多相转化的驱动作用。.（2）研制考虑水闸调度作用的水质多相转化数学模型。.（3）对研制的数学模型进行参数率定和验证，并对闸控河段的水动力过程以及不同相态水质之间的物理、化学、生物等反应过程进行模拟，揭示受水闸调控作用后水质在水体—悬浮物—底泥—藻类界面内的重新分配关系及其对水闸调度的响应程度。.（4）通过情景分析和数值模拟，识别不同调度方式下水质多相转化的主导反应机制，计算水闸调度对水质多相转化的贡献率大小，构建不同物质浓度变化率与主要影响因子之间的量化关系。.通过研究，分析了闸控河段水质多相转化过程中起主导作用的物理、化学、生物反应过程，构建了考虑水闸调度驱动作用的水质多相转化数学模型，分析了物质在水闸调控作用下在水体—悬浮物—底泥—藻类界面内的重新分配关系及其对水闸调度的响应程度，识别了水质在不同调度方式下迁移转化过程的时空差异，评估了不同调度方式对水质多相转化的驱动作用大小，计算了水闸调度在水质多相转化过程中的贡献率大小，建立了水质浓度变化率与闸门开度、闸门开启个数等因素之间的量化关系。

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