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This work introduces diagnostic methods for land surface model (LSM) evaluation that enable developers to identify structural shortcomings in model parameterizations by evaluating model 'signatures' (characteristic temporal and spatial patterns of behavior) in feature, cost-function, and parameter spaces. The ensemble-based methods allow researchers to draw conclusions about hypotheses and model realism that are independent of parameter choice. I compare the performance and physical realism of three versions of Noah LSM (a benchmark standard version [STD], a dynamic-vegetation enhanced version [DV], and a groundwater-enabled one [GW]) in simulating high-frequency near-surface states and land-to-atmosphere fluxes in-situ and over a catchment at high-resolution in the U.S. Southern Great Plains, a transition zone between humid and arid climates. Only at more humid sites do the more conceptually realistic, hydrologically enhanced LSMs (DV and GW) ameliorate biases in the estimation of root-zone moisture change and evaporative fraction. Although the improved simulations support the hypothesis that groundwater and vegetation processes shape fluxes in transition zones, further assessment of the timing and partitioning of the energy and water cycles indicates improvements to the movement of water within the soil column are needed. Distributed STD and GW underestimate the contribution of baseflow and simulate too-flashy streamflow. This work challenges common practices and assumptions in LSM development and offers researchers more stringent model evaluation methods. I show that, because of equifinality, ad-hoc evaluation using single parameter sets provides insufficient information for choosing among competing parameterizations, for addressing hypotheses under uncertainty, or for guiding model development. Posterior distributions of physically meaningful parameters differ between models and sites, and relationships between parameters themselves change. 'Plug and play' of modules and partial calibration likely introduce error and should be re-examined. Even though LSMs are 'physically based,' model parameters are effective and scale-, site- and model-dependent. Parameters are not functions of soil or vegetation type alone: they likely depend in part on climate and cannot be assumed to be transferable between sites with similar physical characteristics. By helping bridge the gap between the model identification and model development, this research contributes to the continued improvement of our understanding and modeling of environmental processes. / text

When a train enters a bridge, passenger sitting inside will feel a sudden bump in the track, which not only affect the riding comfort of the passengers but also put a dynamic impact on the bridge structure. Due to this impact force, we have very serious maintenance problems in the track close to the bridge structure. This sudden bump is produced when train travelling on the track suddenly hit by a very stiff medium like bridge structure. In order to reduce this effect, transition zones are introduced before the bridge so that the change in stiffness will occur gradually without producing any bump.   This master thesis examine the effect of track stiffness on the bridge dynamic response under different train speeds from 150 to 350 km/h with interval 5 km/h and also estimate the minimum length of transition zones require to reduce the effect of change in stiffness on the bridge. Study also gives us some guidelines about the choice of loading model of the train, location of maximum vertical acceleration, effect of ballast model on the results and minimum length of transition zone needs to include in the bridge-track FE-model, for dynamic analysis of the concrete bridges. To carry out this research MATLAB is used to produce an input file for the ABAQUS FEM program. ABAQUS will first read this file, model the bridge and then analysis the bridge. MATLAB will again read the result file, process the result data and plot the necessary graphs.   The Swedish X2000 train is used for this study, which has been modeled with two different methods: moving load model and sprung mass model, in order to see the difference in results. For verification of the MATLAB-ABAQUS model, a 42m long bridge is analysed and results are compared with known results. In this study, concrete simply supported bridges with spans of 5, 10, 15, 20, 25 m have been analysed.