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.     

攀西特色水果产业发展面临的限制、问题与建议

以攀西特色水果产业发展动态为主,分析指出技术和市场是约束该产业进一步发展壮大的双因子。其形成因素多,包括劳动者素质低下和家庭经营规模小、生产与市场之间的联系渠道不畅和农村技术服务体系发育滞后等;并提出促进特色水果产业壮大的建议。     

A method for the interpolation of nonnegative functions with an application to contaminant load estimation

The objective of this work is to extend kriging, a geostatistical interpolation method, to honor parameter nonnegativity. The new method uses a prior probability distribution based on reflected Brownian motion that enforces this constraint. The work presented in this paper focuses on interpolation problems where the unknown is a function of a single variable (e.g. time), and is developed both for the case with and without measurement error in the available data. The algorithms presented for conditional simulations are computationally efficient, particularly in the case with no measurement error. We present an application to the interpolation of dissolved arsenic concentration data from the North Fork of the Humboldt River, Nevada.     

雪峰山陆内造山带的构造特征与演化

在对雪峰山的地质构造及其演化作了研究,并和阿尔卑斯式、阿巴拉契亚式的造山带和远程推覆体作了对比研究以后,作者认为：雪峰山地区的地质构造以具有多期,多层次的层滑构造为主要特色。其主要特征表现为在垂向剖面上有着多个区域性滑脱层,发育株罗山式褐挣矣逆冲叠瓦推覆构造,但它不是阿巴拉契式远程异地推覆体而是准原地型的。逆掩推覆虽然使原来沉积相带变窄,但并未破坏原来扬子地块东南边缘自北西向南东的由台地相－－斜坡相－－深水盆地相的沉积古地理格局,它是陆内造山带常见的构造样式,是在陆内裂陷的背景上由于裂谷关闭时陆块拼贴碰撞(即所谓软碰撞)和陆内俯冲产生的。雪峰山地区也发育伸展剥离和滑覆构造,伴随每一次挤压造山、地壳加厚的过程,在后造山期,也有地壳的隆升、地壳的拉伸和厚度减薄,它是深部岩石圈拆沉作用在地壳中的表现。     

主成分估计与附加条件的参数平差

证明了主成分估计实质上是附着条件的参数平差，并根据此性质结合算例分析了主成分估计的局限性，提出了改进方法。     

Stress constraints and hydrofracturing stress data for the continental crust

Faulting and seismicity in the upper continental crust require considerable differential stresses. Application of experimentally developed friction, fracture and flow laws shows that high differential stresses can only exist in the uppermost crust. Direct hydraulic fracturing measurements in deep boreholes seem to support this rock mechanics conclusion. The experimental data base presently consists of approximately 500 hydrofrac tests conducted in about 100 boreholes at about 30 different geographical locations. To illustrate the variation of measured stresses with depth, the data are expressed as dimensionless horizontal stresses in the formS _H,h/S_v=(/z)+, whereS _v=gz Extrapolation of the experimental data to greater depth shows that the minor horizontal stress approaches the valueS _h/S_v=0.5 which limits friction on wet faults, and that the major horizontal stress approaches a value close toS _H/S_v=1 at rather shallow depth (5 to 10 km.). This limits faulting and seismicity in most of the upper crust to either strike-slip or normal faults. The lower boundary for seismicity is mainly dependent on tectonic strain accumulation and rock creep at the environmental conditions at depth.     

A cross entropy method for flood frequency analysis

The cross-entropy method with fractile constraints has been developed to estimate a random variable when the data are a set of independent observations of the variable. The method can claim several advantages over existing methods. It uses a reference distribution like the prior distribution in Bayesian analysis and likewise generates a posterior distribution.The method is of interest, in particular, because it satisfies two fundamental requirements for selfconsistency in the analysis of a probabilistic system based on data: a principle of invariance and a principle of data monotonicity.The method is applied to flood analysis. Robustness of the minimum cross-entropy method is compared with other methods: the methods of moments and the maximum likehood.     

Variations in Stable Carbon Isotopic Composition of n-Alkanes from Ordovician and Triassic-Derived Oils in Lunnan Oilfield, Tarim Basin, NW China： Global Paleoenvironmental Constraints

Molecular stable carbon isotope technique was employed to study well-sourced crude oils collected from a single drilling well and from the entire Lunnan oilfield, Tarim Basin, NW China. The stable carbon isotopic composition of n-alkanes from crude oils showed that Ordovi-clan-derived oils are enriched in ^13C and Triassic-derived oils are depleted in ^13C. This is consistent with the distribution and evolution trend of stable carbon isotope ratios in crude oils/organic matter from all over the world in geological history (Stahl, 1977; Andrusevich et al. ,1998). An extensive survey of literature indicates that, except for thermal maturity, organic matter input and depositional environment, paleoenvironmental background is another key factor that affects the stable carbon isotopic composition of Ordovician- and Triassic-derived crude oils. The results showed that gas chromatographic-isotope ratio mass spectrometry ( GC-C-IRMS), combining with biogeoehemical evolution of organic matter in geological history, may be a powerful tool in refining oil/oil, oil/source correlations in multi-age, multi-source petroliferous basins like Tarim.     

湖南地热资源的构造制约与勘查标志

针对湖南省境内地热资源的区带分布特征，分析了NE向或NNE向花垣－永顺－桑植断裂、靖县－溆浦断裂、新宁－娄底－宁乡断裂、连云山－双牌断裂、临武－郴州断裂、汝城－桂东断裂对区域地热资源分布的控制作用。地热资源的分布主要受区域主干断裂控制，局限于主干断裂上盘的一定范围内，其赋水岩层主要为古生界灰石和花岗岩破碎带，单个热泉的产出距主干断裂20－40km，热泉温度分布不仅与赋水围岩有关，而且与热泉产出部位的构造强度关系密切，其中构造强度较大的湘西北及湘东南地区以中温热泉为特征，而在构造强度较小的湘东及湘西南地 区则以低温热泉为主。在 综合地热分布相关的构造控制因素前提下，提出了省内寻找地热资源的构造标志。     

Geodynamic significance of the Raspas Metamorphic Complex (SW Ecuador): geochemical and isotopic constraints

The Raspas Metamorphic Complex of southwestern Ecuador is regarded as the southernmost remnant of oceanic and continental terranes accreted in the latest Jurassic–Early Cretaceous. It consists of variably metamorphosed rock types. (1) Mafic and ultramafic rocks metamorphosed under high-pressure (HP) conditions (eclogite facies) show oceanic plateau affinities with flat REE chondrite-normalized patterns, Nd_{150 Ma} ranging from +4.6 to 9.8 and initial Pb isotopic ratios intermediate between MORB and OIB. (2) Sedimentary rocks metamorphosed under eclogitic conditions exhibit LREE enriched patterns, strong negative Eu anomalies, Rb, Nb, U, Th, Pb enrichments, low Nd_{150 Ma} values (from −6.4 to −9.5), and high initial ⁸⁷Sr/⁸⁶Sr and ^206,207,208Pb/²⁰⁴Pb isotopic ratios suggesting they were originally sediments derived from the erosion of an old continental crust. (3) Epidote-bearing amphibolites show N-MORB affinities with LREE depleted patterns, LILE, Zr, Hf and Th depletion, high Nd_{150 Ma} (>+10) and low initial Pb isotopic ratios.The present-day well defined internal structure of the Raspas Metamorphic Complex seems to be inconsistent with the formerly proposed interpretation of a “tectonic mélange”. The association of oceanic plateau rocks and continent-derived sediments both metamorphosed in HP conditions suggests that the thin edge of the oceanic plateau first entered the subduction zone and dragged sediments downward of the accretionary wedge along the Wadatti–Benioff zone. Subsequently, when its thickest part arrived into the subduction zone, the oceanic plateau jammed the subduction processes, due to its high buoyancy.In Ecuador and Colombia, the latest Jurassic–Early Cretaceous suture involves HP oceanic plateau rocks and N-MORB rocks metamorphosed under lower grades, suggesting a composite or polyphase nature for the latest Jurassic–Early Cretaceous accretionary event.