Marine 3D seismic volumes from 2D seismic survey with large streamer feathering

Marine Geophysical Research - Strong ocean current influences a marine seismic survey and forces the streamer off-course from the survey line. The sideway drift of the streamer results in that the...     

The Driving Effect of Spatial Differences of Water Intensity in China

This paper adopts the logarithmic mean Divisia index in the family of spatial index decomposition analysis to decompose the driving effect of spatial differences of water intensity in China into intensity effect and structure effect employing data spanning 2000–2017. The results show that water use efficiency of the eastern provinces was always higher than that of the central provinces and western provinces except for Jiangsu and Hainan, and in the central and western regions, only Shanxi, Henan, Chongqing, and Shaanxi had higher efficiency levels than the national average level. Over that 17-year time period, the gap in water intensity exhibits a decreasing trend between the provincial level and average level (except for Heilongjiang and Chongqing). For industry water intensity, those provinces with a lower than average level were mainly in the eastern region. Except for Shanghai, Jiangsu, and Guangdong, the primary industry water intensity of the eastern provinces was always lower than the average level. Except for Fujian, Shanghai, Jiangsu, and Hainan, the secondary industry water intensity of the eastern provinces was always lower than the average level. Except for Guangdong, Fujian, and Hainan, the tertiary industry water intensity of the eastern provinces was always lower than average level. The water intensity of the secondary and tertiary industries in Shanxi and Inner Mongolia in the central and western regions was always lower than the average level. Lastly, the provinces in which the provincial proportion of the primary industry was lower than the average level were mainly in the eastern region, while conversely the same proportion of the primary industry among central and western provinces was generally high. Therefore, provinces should formulate and implement water resource policies that are different and pertinent to their own actual conditions.

     

Annual and sub-annual effects of EUV heating—II. Comparison with density variations

By a detailed comparison of annual and sub-annual components of EUV absorption heat input with those of the Jacchia density models, we consider the importance of EUV heating in the annual and sub-annual variations of the upper atmosphere. When all the geometrical effects of EUV heat input have been taken into account, it is found that a remarkable correspondence exists between properties of each harmonic component of EUV heat input and Jacchia model temperature and densities. Equinoctial latitude independence of diurnal averaged annual and sub-annual components of heat input and density is proposed as a test of the significance of the EUV heat input. The Jacchia model is found to satisfy this test rigourously.     

Potential benefits of increased application of water to paddy fields in Taiwan

The potential benefits of increased application of water to paddy fields in Taiwan are investigated in this paper. A conceptual model is used to represent the hydrological system of the paddy field. A technique is presented to estimate the parameters of the model. Field experiments also are performed for parameter estimation and model verification. The simulated results are in good agreement with the observed during model verification. With parameters estimated from the field data, the model is used to simulate the effects of applying water beyond current practice. The simulation results show that the downward percolation increases when the irrigation water increases. However, the percolation reaches a capacity rate no matter how large the amount of water applied. This phenomenon results from the existence of a hard layer below the paddy field. The effects of raising the height of levees around paddy fields are also studied. Copyright © 2001 John Wiley & Sons, Ltd.     

Upstream morphological effects of a sequential check dam adjustment process

Sediment flushing and the morphological responses to the procedure of check dam removal are still unclear. Following laboratory experiments that revealed three stages (deepening, widening, and volume release) of check dam adjustment, a check dam built in 2007 at Landao Creek in central Taiwan was adjusted in 2015 by removing central bars and cutting 2.5 m from the middle two piers (stage 1 + 2), with the purpose of regulating sediment transfer and keeping the thalweg at the center of the channel, while also preventing hill slope toe erosion. In 2019, four central piers were removed (stage 3) to increase the volume of sediment released. Annual surveys were conducted after the initial adjustment in 2015 through to 2020 using unmanned aerial vehicles (UAVs). The check dam adjustments revealed that the channel had narrowed and stabilized as indicated by regenerating riparian vegetation. Additionally, distinct terraces had formed on the hill slope toes of the creek channel in proximity to the check dam. The meander upstream weakened following the dam adjustments. This study combining laboratory experiments with actual field observation contributed immensely to check dam decommissioning. Additionally, this study illustrated how an adjustable check dam may aid regulation of sediment transport and thereby sediment balance. It can be adjusted accordingly based on the prevailing channel condition.