Assessing parameter identifiability for multiple performance criteria to constrain model parameters

ABSTRACT

Reliable simulations of hydrological models require that model parameters are precisely identified. In constraining model parameters to small ranges, high parameter identifiability is achieved. In this study, it is investigated how precisely model parameters can be constrained in relation to a set of contrasting performance criteria. For this, model simulations with identical parameter samplings are carried out with a hydrological model (SWAT) applied to three contrasting catchments in Germany (lowland, mid-range mountains, alpine regions). Ten performance criteria including statistical metrics and signature measures are calculated for each model simulation. Based on the parameter identifiability that is computed separately for each performance criterion, model parameters are constrained to smaller ranges individually for each catchment. An iterative repetition of model simulations with successively constrained parameter ranges leads to more precise parameter identifiability and improves model performance. Based on these results, a more consistent handling of model parameters is achieved for model calibration.     

The development of stochastic space transformation and diagrammatic perturbation techniques in subsurface hydrology

This paper develops concepts and methods to study stochastic hydrologic models. Problems regarding the application of the existing stochastic approaches in the study of groundwater flow are acknowledged, and an attempt is made to develop efficient means for their solution. These problems include: the spatial multi-dimensionality of the differential equation models governing transport-type phenomena; physically unrealistic assumptions and approximations and the inadequacy of the ordinary perturbation techniques. Multi-dimensionality creates serious mathematical and technical difficulties in the stochastic analysis of groundwater flow, due to the need for large mesh sizes and the poorly conditioned matrices arising from numerical approximations. An alternative to the purely computational approach is to simplify the complex partial differential equations analytically. This can be achieved efficiently by means of a space transformation approach, which transforms the original multi-dimensional problem to a much simpler unidimensional space. The space transformation method is applied to stochastic partial differential equations whose coefficients are random functions of space and/or time. Such equations constitute an integral part of groundwater flow and solute transport. Ordinary perturbation methods for studying stochastic flow equations are in many cases physically inadequate and may lead to questionable approximations of the actual flow. To address these problems, a perturbation analysis based on Feynman-diagram expansions is proposed in this paper. This approach incorporates important information on spatial variability and fulfills essential physical requirements, both important advantages over ordinary hydrologic perturbation techniques. Moreover, the diagram-expansion approach reduces the original stochastic flow problem to a closed set of equations for the mean and the covariance function.     

Mental Maps and Fuzziness in Space Preferences*

Mental maps are widely used to represent aggregate residential preferences in a population. This study examines the contention by researchers that the dominant viewpoint in a group in terms of residential desirability is not affected by the fuzziness in individual space preferences. Results indicate that a significant misrepresentation of group preferences can result when fuzziness of individual preferences is overlooked. The use of ordinal scales to generate mental maps is likely to distort the actual pattern of residential preferences that dominates in the group because of the failure of the ranking approach to account for imprecision and ambiguity in individual preferences. Because interval scales used in rating or evaluating tasks do not force individuals to give a crisp judgement of places, they are more adequate than ordinal scales for mental mapping and for behavioral analysis.     

倾斜相机式投影的几何解法及其与外心投影的比较

本文根据透视投影的基本原理，给出了关于倾斜相机式投影的几何解法，在此基础上分析了倾斜相机式投影与外心投影的异同，提出了二者比较的一致性条件，并给出了实例验证。     

大气湍流的非线性动力学参量与其经典统计量之关系

本文利用大气边界层近地层中观测得的风和温度时间序列讨论计算了湍流的非线性动力学统计参量与其经典统计量的关系。初步结果表明:当层结稳定参数z/L处于-0.7相似文献   

应用“地磁观测数据处理和方法研究程序”初探四川省内震磁效应

本文应用“地磁观测数据处理和方法研究程序”，分析了１９８９年－１９９３年发生在四川省内Ｍｓ≥４．７地震的震磁效应，结果证明该程序包实用性强，可用于该地区的日常监视预报工作。     

Stochastic space transforms in subsurface hydrology — Part 2: Generalized spectral decompositions and plancherel representations

In earlier publications, certain applications of space transformation operators in subsurface hydrology were considered. These operators reduce the original multi-dimensional problem to the one-dimensional space, and can be used to study stochastic partial differential equations governing groundwater flow and solute transport processes. In the present work we discuss developments in the theoretical formulation of flow models with space-dependent coefficients in terms of space transformations. The formulation is based on stochastic Radon operator representations of generalized functions. A generalized spectral decomposition of the flow parameters is introduced, which leads to analytically tractable expressions of the space transformed flow equation. A Plancherel representation of the space transformation product of the head potential and the log-conductivity is also obtained. A test problem is first considered in detail and the solutions obtained by means of the proposed approach are compared with the exact solutions obtained by standard partial differential equation methods. Then, solutions of three-dimensional groundwater flow are derived starting from solutions of a one-dimensional model along various directions in space. A step-by-step numerical formulation of the approach to the flow problem is also discussed, which is useful for practical applications. Finally, the space transformation solutions are compared with local solutions obtained by means of series expansions of the log-conductivity gradient.     

松辽盆地北部源岩和盖层的时空匹配关系及其对天然气聚集与分布的控制

通过对松辽盆地北部5套泥岩盖层和3套气源岩空间分布面积的比较,以及对盖层封闭能力形成时期与气源岩大量排烃期的比较,研究了松辽盆地北部5套泥岩盖层与3套气源岩之间的时间和空间匹配关系及其对天然气聚集程度的控制作用,指出扶杨油层和萨、葡、高油层是松辽盆地北部天然气聚集与分布的有利层位。扶杨油层天然气富集程度在空间上存在差异,大庆长垣以东地区好于大庆长垣以西地区。萨、葡、高油层和黑帝庙油层的天然气富集程度在空间上存在差异,大庆长垣以西地区好于大庆长垣以东地区。     

基于地理空间概念的地理元数据组织管理研究

数据共享一直是大型GIS应用的瓶颈问题。为了能给用户提供一个统一的地理空间的概念和地理数据访问方式,该文从地理元数据在共享平台中的重要作用入手,分析了地理空间的时空特性、绝对空间和相对空间、多尺度特征,探讨了共享平台设计的关键技术：空间数学基础,多级格网的Morton编码,元数据的多维数据模型组织,地理数据评价模型。在技术实现上采和分布式数据库系统的模式结构,并分析了地理数据注册、更新和查询方式。