长周期动力形态模型中地形演变方法探讨
Approaches to morphological evolution in long-term morphodynamic model
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摘要: PRD-LTMM是一个模拟和描述三角洲地形中、长期演变过程的动力形态模型.在长时间尺度的模拟过程中,必须从模型输入、模型物理系统本身到模型输出等各个角度考虑模拟约减处理.代表性输入条件是实现模型约减的基础,而地形时间的步长延长是提高长周期模型模拟效率的关键.延长技术通常有直接推延、时间中心推延、潮汐延展及泥沙输运率公式线性化等四种方法.通过系列敏感性试验,对PRD-LTMM模型选择潮汐延展技术来进行地形时间步长的延长处理,推延的时间长度为10 a,基于此条件下的PRD-LTMM在长周期模拟中不仅稳定性较好,而且结果也较精确.Abstract: PRD LTMM (long term morpho dynamic model on the Zhujiang River Delta) is a morphodynamic model representing medium-long term evolution processes of delta.Reduction approaches should be considered in a modelinput, a modeling physical system and a model out put.Representative input conditions are the base of modeling reduction, and the increase of the morphological time step is a key point of improving modeling efficiency, the most common approaches are a straight forw ard extrapo lation, a time centered extrapolation, a lengthening tide and a linearity of sediment transport.The sensitive experimentindi-cates that the PRD LTMM should adopt the lengt hening tide method to increase morphological time step, and increasing time scale is 10 a.On the basis of the approaches, the stability of PRD LTMM is very good, and its modeling precision is very high also.
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Key words:
- long term morpho dynamic modeling /
- delta evolution /
- reduction approaches
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