水库径流输移物复合沉积过程及环境效应研究

It is the transport substances with run-off into reservoir that basically result in water pollution in it. When floods come into reservoir with sands, straws, etc., the water quality will become worse than before in whole or in part. Furthermore, water treatment measurements have to be taken to reply the sensitive situation such as strengthening water purifying processes or completely stopping water supply. On the other hand, after the transport substances with floods have sunk to the bottom of reservoir by composite sedimentation where the water is lack of oxygen and undisturbed, a soft and smelly sediment layer will come into being and then threatens the safety of water supply system. In order to explore the problems of the transportation modeling, discomposing processes and environment effects of transport substances, the research content of the project have been set. 1) monitor the runoff processes and entrained mass fluxes;2) reveal constitutions of the entrained mass and mechanisms when they are degraded and transformed; 3) uncover the sedimentation of the constitutions and model the responding water quality ;4) for sediment formed in recently past time, establish the responding relationship between flow processes and sedimentation layers by columnar sampling and slice analyzing; 5) give suggestions for the pollution treatment of reservoir based on the short and long environmental effect analysis. The total goal of the project is to systematically analyze the decomposed transformation process and the environmental effects of transport substances, and establish a technique system for analyzing the environmental effects of transport substances with flow.

进入水库的径流输移物是导致水体污染的根源。径流量越大携带的输移物就越多，几乎囊括了流域内相应径流可以冲走的所有东西。输移物进入水库之后首先会造成短期水质恶化，威胁供水安全；之后，径流输移物经过流动输移、对流扩散、复合沉积等过程，在水库底部低氧静水区逐年累积，形成稀软黑臭的淤积层，成为不断聚集增长的水环境隐患。为了深入剖析径流输移物在水库中迁移分布、分解转化及其环境效应的问题，本项目计划进行以下5方面的研究：1)入库径流过程及输移物通量监测；2)径流输移物组分解析及分解转化机理；3)多组分复合沉积过程及水质响应模拟；4)入库径流过程与层理性沉积间的响应关系；5)径流输移物的环境效应及治理对策。通过以上工作，深入分析研究径流输移物在水库中的迁移转化过程及环境效应，形成一套解析径流输移物对水库水质短期和长期影响的技术体系，为保障水库供水安全提供技术支撑。

水库输移物在径流驱动下进入库区，再经过一系列复杂的迁移转化过程，会对水库水质造成重大影响。特别是大洪水期间，流域内大量输移物被洪水径流冲刷携带入库，有时还会扰动原有沉积层，造成水质突变。.本基金通过现场调查、室内模拟实验以及多源地形数据融合等方法，开展水库径流输移物沉积过程及环境效应研究。为模拟入库径流过程，本研究提出了一种多源数据融合方法，更新碧流河库区地形图。并基于现场调查分析了夏季碧流河水库在暴雨径流输入前后的水体基本指标以及磷营养盐的通量及总量的变化特征，解析径流入库前后水库水体磷的主要转化机制。通过资料收集和现场调查，推算水库的沉积物总量及淤积形态，根据沉积物分布调查结果，分析碧流河水库的沉积特征，判断可能的影响因素，最终掌握水库库区沉积规律，以及库内沉积物二次迁移过程。调查了径流入库过程新淤颗粒质分布规律，通过分析新淤、历史淤积颗粒质携带磷规律，揭示了碧流河水库多年淤积规律及剖面沉积物的层理结构，明确了入库径流过程与层理性沉积间的响应关系。最后，综合分析径流输入给水库带来的环境效应，制定了汛期水库磷污染控制策略。.结果表明：入库颗粒物的沉降过程是流域流失的颗粒态磷重新分配的过程，同时决定了沉积物中营养盐的蓄积。水库高水位时沉淀的沉积物在较低起调水位时被冲到下游库区并重新沉淀分布，造成滚动输移的效果，这也是水库内形成冲刷-淤积分区的根本原因。水位变化导致的水力侵蚀与淤积交替可以促进营养盐向下游方向迁移，但是水位消落引起的植物生长可以阻止营养盐向下游方向迁移。.此外，构建了一套水库径流输移物的治理对策，包括利用输移中颗粒物的吸附释放特征降低水体磷、利用消落区特征控制外源磷入库对策和水库沉积物异位资源化利用，以及适合推广的水库滨库带水质保障技术，研究已取得了项目预期的理论成果，以期为水源水库水质治理提供参考依据。