An energy-based liquefaction potential evaluation method (EBM) previously developed was applied to a uniform sand model shaken by seismic motions recorded at different sites during different magnitude earthquakes. It was also applied to actual liquefaction case histories in Urayasu city during the 2011 M9.0 Tohoku earthquake and in Tanno-cho during the 2003 M8.0 Tokachi-oki earthquake. In all these evaluations, the results were compared with those by the currently used stress-based method (SBM) under exactly the same seismic and geotechnical conditions. It was found that EBM yields similar results with SBM for several ground motions of recent earthquakes but has easier applicability without considering associated parameters. In Urayasu city, the two methods yielded nearly consistent results by using an appropriate coefficient in SBM for the M9.0 earthquake, though both overestimated the actual liquefaction performance, probably because effects of plasticity and aging on in situ liquefaction strength were not taken into account. In Tanno-cho, EBM could evaluate actual liquefaction performance due to a small-acceleration motion during a far-field large magnitude earthquake while SBM could not. 相似文献
Agricultural sediment and pesticide runoff is a widespread ecological and human health concern. Numerical simulation models, such as Root Zone Water Quality Model (RZWQM) and Pesticide Root Zone Model (PRZM), have been increasingly used to quantify off‐site agricultural pollutant movement. However, RZWQM has been criticized for its inability to simulate sedimentation processes. The recent incorporation of the sedimentation module of Groundwater Loading Effects of Agricultural Management Systems has enabled RZWQM to simulate sediment and sediment‐associated pesticides. This study compares the sediment and pesticide transport simulation performance of the newly released RZWQM and PRZM using runoff data from 2 alfalfa fields in Davis, California. A composite metric (based on coefficient of determination, Nash–Sutcliffe efficiency, index of agreement, and percent bias) was developed and employed to ensure robust, comprehensive assessment of model performance. Results showed that surface water runoff was predicted reasonably well (absolute percent bias <31%) by RZWQM and PRZM after adjusting important hydrologic parameters. Even after calibration, underestimation bias (?89% ≤ PBIAS ≤ ?36%) for sediment yield was observed in both models. This might be attributed to PRZM's incorrect distribution of input water and uncertainty in RZWQM's runoff erosivity coefficient. Moreover, the underestimation of sediment might be less if the origin of measured sediment was considered. Chlorpyrifos losses were simulated with reasonable accuracy especially for Field A (absolute PBIAS ≤ 22%), whereas diuron losses were underestimated to a great extent (?98% ≤ PBIAS ≤ ?65%) in both models. This could be attributed to the underprediction of herbicide concentration in the top soil due to the limitations of the instantaneous equilibrium sorption model as well as the high runoff potential of herbicide formulated as water‐dispersible granules. RZWQM and PRZM partitioned pesticides into the water and sediment phases similarly. According to model predictions, the majority of pesticide loads were carried via the water phase. On the basis of this study, both RZWQM and PRZM performed well in predicting runoff that carried highly adsorptive pesticides on an event basis, although the more physically based RZWQM is recommended when field‐measured soil hydraulic properties are available. 相似文献
Two primary concerns in performing watershed overland flow routing are the numerical instability and computational efficiency. The stability of executing an explicit scheme has to be maintained by observing the Courant–Friedrich–Lewy criterion, which is adopted to confirm that the numerical marching speed is larger than the wave celerity. Moreover, there is another criterion of time step devised in previous studies to avoid back‐and‐forth refluxing between adjacent grids. The situation of refluxing usually occurs on flat regions. In light of this, the selection of a small time increment to honor both restrictions simultaneously is believed to decrease the computational efficiency in performing overland flow routing. This study aims at creating a robust algorithm to relax both restrictions. The proposed algorithm was first implemented on a one‐dimensional overland plane to evaluate the accuracy of the numerical result by comparing it with an analytical solution. Then, the algorithm was further applied to a watershed for 2D runoff simulations. The results show that the proposed integrated algorithm can provide an accurate runoff simulation and achieve satisfactory performance in terms of computational speed. 相似文献
India's growing role in the global climate debate makes it imperative to analyse emission reduction policies and strategies across a range of GHGs, especially for under-researched non-CO2 gases. Hydrofluorocarbons' (HFCs) usage in cooling equipment and subsequent emissions are expected to increase dramatically in India with the phase-out of hydrochlorofluorocarbons (HCFCs) as coolants in air-conditioning equipment. We focus on the residential air-conditioning sector in India and analyse a suite of HFC and alternative coolant gas scenarios for understanding the implications for GHG emissions from this sector within an integrated assessment modelling framework. We find that, if unabated, HFC410A emissions will contribute to 36% of the total global warming impact from the residential air-conditioner sector in India in 2050, irrespective of the future economic growth trajectory, and the remaining 64% is from energy to power residential air-conditioners. A move towards more efficient, low global warming potential (GWP) alternative refrigerants will significantly reduce the cumulative global warming footprint of this sector by 37% during the period 2010–2050, due to gains both from energy efficiency as well as low GWP alternatives. Best practices for reducing direct emissions are important, but only of limited utility, and if a sustainable lifestyle is adopted by consumers with lower floorspace, low GWP refrigerants, and higher building envelope efficiencies, cumulative emissions during 2010–2050 can be reduced by 46% compared to the Reference scenario.
Policy relevance
Our analysis has important implications for Indian climate policy. We highlight that the Indian government's amendment proposal to the Montreal Protocol is a strong signal to the Indian market that the transition away from high GWP refrigerants towards low/zero GWP alternatives will happen sooner or later. The Bureau of Energy Efficiency should extend building energy conservation code policy to residential buildings immediately, and the government should mandate it. Government authorities should set guidelines and mandate reporting of data related to air-conditioner coolant recharge frequency and recovery of scrapped air-conditioner units. For contentious issues like flammability where there is no consensus within the industry, the government needs to undertake an independent technical assessment that can provide unbiased and reliable information to the market. 相似文献