中文摘要：

水温和溶解氧是描述水生态系统最重要的两个参数，对于全面把握水质情况具有重要意义。利用实测数据进行水质分析会受到观测条件与成本的限制，因而模型与实测数据相结合的方法逐渐得到广泛应用。本研究对湖泊水质模型MINLAKE进行改进，考虑出入流使之适用于水库，并利用密云水库2005年实测水质数据对模型参数进行率定。随后利用改进的模型对密云水库1998—2011年热氧分布进行模拟。结果显示，密云水库水体的热氧分布存在规律性的年内波动，随着水位的变化，表层水温年平均值变化不明显，深层水温波动幅度加剧，年均水温显著上升；表层年均溶解氧含量没有明显变化，深层溶解氧浓度波动减弱，年均溶解氧浓度上升。改进后的MINLAKE模型能弥补现场监测频率和测点布置密度等方面的限制，给出密云水库较为合理的垂向热氧分布，基本反映出实际的热氧分布情况。

英文摘要：

Landslide dams, which often formed by quick deposits of landslide materials, are lack of suffi- cient consolidation, and loose in dam structure and material composition. Especially, the soil and rock ma- terials are highly heterogeneous, comprising high permeable regions with large particles. The presence of high permeable regions may lead to internal erosion or even piping failure under high water pressure. Tak- ing the Hongshihe landslide dam triggered by the Wenehuan earthquake as an example, the paper provides a method to analyze the stability of landslide dams under seepage by considering the influence of high per- meable regions. The instability of a landslide dam under seepage is defined as a circulatory process of inter- nal erosion and slope failure. The critical conditions of internal erosion and slope failure are identified with- in this method. From the seepage stability analysis of the Hongshiyan landslide dam with the present meth- od, it is found that the presence of highly permeable region does harm to seepage stability of landslide dams. The seepage stability becomes worse with longer high permeability region, higher permeability, and smaller distance to the dam downstream toe. The Hongshiyan landslide dam with high permeable regions is likely to occur internal erosion, but piping failure is not likely due to large dam width and gentle down- stream slope. Piping failure occur when the dana crest width is shorter and downstream slope gradient is larger.