Linking landscape structure and rainfall runoff behaviour in a thermodynamic optimality context

在热力学最优性背景下将景观结构和降雨径流行为联系起来

• 批准号: 268244115
• 负责人: Professor Dr.-Ing. Erwin Zehe
• 金额: --
• 依托单位: Max-Planck-Institut für Biogeochemie (MPI-BGC)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/268244115?language=en
• 关键词: Linking; landscape; structure; rainfall; runoff

Our main objective is to explore an alternative thermodynamic perspective on rainfall runoff generation on the hillslope and headwater scale. From a thermodynamic perspective any water mass flux is equal to a ¿potential gradient¿ divided by a ¿resistance¿, and fluxes deplete due to the second law of thermodynamics their driving gradients. Relevant potentials controlling rainfall runoff are soil water potentials, piezometric heads and surface water levels and their gradients are associated with spatial differences in associated forms of free1 energy. Rainfall runoff processes thus are associated with conversions of capillary binding energy, potential energy and kinetic energy. These conversions reflect energy conservation and irreversibility as they imply small amounts of dissipation of free energy into heat and thus production of entropy. Energy conversions during rainfall runoff transformation are, though being small, nevertheless of key importance, because they are related to the partitioning of incoming rainfall mass into runoff components and storage dynamics. This splitting and the subsequent subsurface dynamics is strongly controlled by preferential flow paths as they reduce subsurface flow resistances along their main extent, resulting in accelerated fluxes against the driving gradient. This implies an enlarged power in the subsurface flux and with it either enlarged free energy export or increased depletion of internal driving gradients, and thus a faster relaxation back towards local thermodynamic equilibrium. Thermodynamic optimality principles allow for a priory optimization of the resistance field at a given gradient, not in the sense how they exactly look like but in the sense how they function with respect to export and dissipation of free energy. We will thus explore the possibility of independent predictions of rainfall runoff in this project, in the sense that the a-priory optimum model structures should match independent observations at the hillslope and headwater scale. We also explore whether an apparent disequilibrium in landscape structure (reflected in topography, vegetation pattern, soil catena and apparent preferential pathways) implies temporally persistent patterns of soil moisture states in the sense that they coincide with local thermodynamic equilibria. This might offer the opportunity for useful backward predictions of distributed state dynamics by using observed dynamics of stream and ground water levels as boundary conditions characterizing the levels of relevant minima in geo-potential and zero matric potential in the subsurface. Last not least we test the feasibility to define hydrological similarity with respect to free energy stocks and conversions related to rainfall runoff (instead of focusing directly on the mass balance) with respect to classify catchments and hillslopes with respect to similar behavior.

我们的主要目的是探索有关山坡和源头量表降雨径流的替代热力学观点。从热力学的角度来看，任何水质量通量都等于潜在的梯度。除了抗电阻，并且由于热力学的第二定律而定义了通量，其驱动梯度。控制降雨径流的相关电势是土壤水电势，压电头和地表水位，它们的梯度与相关形式的free1能量的空间差异有关。因此，降雨径流过程与毛细管结合能，势能和动能的转化有关。这些转化反映了能源守恒和不可逆性，因为它们暗示着少量的自由能耗散成热量，从而产生了熵。降雨径流转换期间的能量转换虽然很小，但关键的重要性仍然很重要，因为它们与将降雨量质量分配到径流组件和存储动力学中有关。这种分裂和随后的地下动力学受到首选流动路径的强烈控制，因为它们沿其主要范围降低了地下流动阻力，从而导致对驱动梯度的加速通量。这意味着在地下通量中增加了功率，并增加了自由能的出口或增加内部驾驶梯度的部署，从而更快地恢复了朝向局部热力学平衡的放松。热力学最优性原理允许在给定梯度处对阻力场进行事先优化，而不是从某种意义上说，而是从某种意义上说，它们如何相对于出口和自由能的耗散。因此，我们将探讨该项目中对降雨径流的独立预测的可能性，从某种意义上说，A-Priory最佳模型结构应与Hillslope和Headwater量表的独立观测值匹配。我们还探讨了景观结构中明显的拆卸（在地形，植被模式，土壤曲纳和明显的优先途径中反映）是否意味着土壤水分状态的暂时持续模式，因为它们与局部热力学平衡相吻合。这可能为分布式状态动力学的有用向后预测提供了机会，通过使用观察到的流和地下水位的动力学作为边界条件，表征了地下表面中地球电位和零矩阵潜力的相关最小值水平。最后，最后我们测试了针对自由能量库存定义水文相似性的可行性，以及与降雨径流有关的转换（而不是直接集中在质量平衡上），相对于类似行为，相对于分类流域和山坡。