Flat Basin Research Articles

Differential Elite Learning Particle Swarm Optimization for Global Numerical Optimization

Although particle swarm optimization (PSO) has been successfully applied to solve optimization problems, its optimization performance still encounters challenges when dealing with complicated optimization problems, especially those with many interacting variables and many wide and flat local basins. To alleviate this issue, this paper proposes a differential elite learning particle swarm optimization (DELPSO) by differentiating the two guiding exemplars as much as possible to direct the update of each particle. Specifically, in this optimizer, particles in the current swarm are divided into two groups, namely the elite group and non-elite group, based on their fitness. Then, particles in the non-elite group are updated by learning from those in the elite group, while particles in the elite group are not updated and directly enter the next generation. To comprise fast convergence and high diversity at the particle level, we let each particle in the non-elite group learn from two differential elites in the elite group. In this way, the learning effectiveness and the learning diversity of particles is expectedly improved to a large extent. To alleviate the sensitivity of the proposed DELPSO to the newly introduced parameters, dynamic adjustment strategies for parameters were further designed. With the above two main components, the proposed DELPSO is expected to compromise the search intensification and diversification well to explore and exploit the solution space properly to obtain promising performance. Extensive experiments conducted on the widely used CEC 2017 benchmark set with three different dimension sizes demonstrated that the proposed DELPSO achieves highly competitive or even much better performance than state-of-the-art PSO variants.

Performance enhancement of a v-corrugated basin hemispherical solar distiller combined with reversed solar collector: An experimental approach

The low freshwater production of the solar distillers is one of the most crucial obstacles to their effective use in distillation applications. In this work, an attempt has been made to ameliorate the distilled yield of the hemispherical solar distiller. This was fulfilled by using a v-corrugated basin and reversed solar collector in order to augment the evaporation area and assist in reflecting more solar irradiance onto the outer surface of the v-corrugated basin. Two hemispherical solar distillers, namely; v-corrugated basin hemispherical distiller integrated with a reversed solar collector (VBHD-RSC) and traditional flat basin hemispherical distiller (TFBHD) were designed and examined at the same outdoors conditions of El-Oued (33°27′N, 7°11′E), Algeria. Moreover, a comparative energic-economic analysis of the two proposed hemispherical distillers has been conducted in terms of freshwater productivity, daily energy efficiency, and freshwater distillate cost. The results show that the daily accumulative yield of the VBHD-RSC was 7.85 kg/m2.day which was higher than that of TFBHD by 68.82%. Moreover, the daily energy efficiency was obtained to be 59.70% and 35.52% for VBHD-RSC and TFBHD, respectively. Furthermore, the economic assessment indicates that the usage of a v-corrugated basin embedded with a reversed solar collector was more cost-efficient as it reduces the cost of freshwater production by 27.12% compared to TFBHD.

Depositional history of Lake Chala (Mt. Kilimanjaro, equatorial East Africa) from high-resolution seismic stratigraphy

Sediments deposited in Lake Chala (Kenya/Tanzania) constitute a high-resolution archive of past climate and environmental change in equatorial East Africa spanning two glacial-interglacial cycles. To correctly interpret the proxy records it contains, it is crucial to understand the evolution of lacustrine sedimentation in this volcanic crater basin. Building on previous seismic stratigraphic analysis by Moernaut et al. (2010) of a dense grid of 37 km high-resolution seismic reflection profiles with up to 270 ms two-way travel time (ca. 210 m depth) of sub-bottom penetration, this study presents a seismic-based reconstruction of the complete depositional history of Lake Chala as well as a first-order age model for the major documented stages in lake evolution. The seismic stratigraphic sequence comprises 16 distinct and finely-stratified units (U1-U16, youngest to oldest), grouped into five major depositional stages. Stage I (U16, ca. 249-212 ka) marks the initiation of sedimentation in an originally ring-shaped depositional area surrounding two central tuff cones emerging from the basin floor. Stage II (U15-U12, ca. 212-114 ka) represents the onset of basinwide sedimentation above the tuff cones, implying a gradual rise in lake depth and shift to more strictly hemipelagic sedimentation. Stage III (U11-U8, ca. 114-97 ka) represents the development of a relatively flat lake floor during a period of significantly reduced lake depth. Stage IV (U7-U4, ca. 97–20.5 ka) is again characterized by largely undisturbed hemipelagic sedimentation under mostly high lake-depth conditions. Stage V (U3-U1, 20.5 ka BP to Present) represents the establishment of the present-day, very broad and flat basin floor under fluctuating lake level. Reassessing the Moernaut et al. (2010) suggestion of a minor disconformity at ca. 100 m sub-bottom depth, we here interpret this seismic feature as a thick turbidite related to a mass wasting event. Consequently we can affirm continuity of lacustrine sedimentation in the depocenter of Lake Chala throughout the past ca. 250,000 years.

基于地理探测器的喀斯特山区生态系统服务关系分异特征及驱动力解析——以贵州省为例

PDF HTML阅读 XML下载 导出引用 引用提醒 基于地理探测器的喀斯特山区生态系统服务关系分异特征及驱动力解析——以贵州省为例 DOI: 10.5846/stxb202109012470 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学青年基金项目（42001090）；重庆市教委科学技术研究项目（KJQN202000512） Differentiation characteristics and driving factors of ecosystem services relationships in karst mountainous area based on geographic detector modeling:A case study of Guizhou Province Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:生态系统服务关系的空间异质性及其驱动机制分析一直都是喀斯特生态系统服务研究的关键问题。以典型喀斯特山区--贵州省为例，选取植被净初级生产力(NPP)，土壤保持(SC)和产水(WY)3类生态系统服务，在对其进行准确估算的基础上，采用相关分析法、均方根误差法从多角度剖析生态系统服务关系变化及其空间分异规律，借助地理探测器对生态系统服务关系变化的驱动机理进行解析。结果表明：①2000-2015年贵州省NPP、土壤保持、产水服务均值均呈增长趋势，其中，NPP和土壤保持服务在研究区东北部及西北角增长最显著，产水服务在研究区东南部增加最明显。②研究时段内，区域生态系统服务关系以协同为主，只是协同关系在减弱并有向权衡发展的趋势。③不同背景条件下区域生态系统服务关系具有明显的分异特征。相较于白云岩，NPP与土壤保持的权衡度在石灰岩上更大；土壤保持与NPP的权衡度在地势平缓的岩溶盆地上较大，产水服务与NPP、土壤保持间的权衡度在陡峭的岩溶槽谷(峡谷)上更大；产水服务与土壤保持间的权衡度随着植被覆盖度的增加而逐渐增大。④地理探测器结果表明：造林总面积是影响NPP与土壤保持间权衡关系变化的主导因子，降水总量已成为制约NPP与产水服务间协同的最主要因子，高程和人均国内生产总值(GDP)是影响土壤保持与产水服务间关系的最主要因子；因子间的交互影响均高于单因子的影响。研究深化了喀斯特地区生态系统服务权衡/协同关系变化的机理解析研究，为喀斯特生态系统有效保护和管理提供了科学参考。 Abstract:The spatial heterogeneity of ecosystem services relationships and their driving mechanisms have always been the research focus regarding karst ecosystem services. Taking Guizhou Province, a typical karst mountainous area, as an example, this study selected three ecosystem services:net primary productivity (NPP), soil conservation (SC), and water yield (WY). Based on the accurate estimation of three ecosystem services through the Carnegie-Ames-Stanford approach (CASA) model, the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model and the water balance formula, the spatio-temporal change and differentiation characteristics of ecosystem services relationships were analyzed using correlation analysis and root mean square error (RMSE). The driving mechanisms of changes in ecosystem services relationships were then analyzed using a geographic detector modeling. The results showed that:① from 2000 to 2015, the average values of NPP, SC, and WY in Guizhou Province showed an increasing trend. In terms of spatial distribution, NPP and SC presented an increasing trend in the northeast and northwest corner of the study area. The WY increased in the southeastern study area. ② During the study period, the relationships of regional ecosystem services were mainly synergistic, but the synergistic relationship was weakening, accompanied by a trade-off trend. So, due attention should be given to the coordination of ecosystem services relationships. ③ The relationship of regional ecosystem services under different conditions had obvious differentiation characteristics. Compared with dolomite, the trade-off intensity between NPP and SC was greater on limestone; the trade-off intensity between SC and NPP was greater on flat karst basins, and the trade-off intensity between WY and NPP, WY and SC was greater on steep karst slot valley (canyons). The trade-off intensity between WY and SC gradually increased with the increase in vegetation coverage. ④ The results of the geographic detector modeling showed that the total afforestation area was the leading factor affecting the trade-off change between NPP and SC. The total precipitation was the main factor restricting the collaboration between NPP and WY. The elevation and per capita gross domestic product (GDP) were the main factors affecting the relationship between SC and WY. Meantime, the explanatory power of the interaction of any two factors was higher than that of the single factor, indicating the influence intensity of the factor was obviously increased after the interaction. In the future, attention should be paid to multi-factors and their interactions. This study provided deeper insights into the mechanisms of the trade-off/synergy changes among ecosystem services in the karst area, and a scientific reference for the effective protection and management of the karst ecosystem. 参考文献 相似文献 引证文献

Investigation of the characteristics and long-runout movement mechanisms of the Luanshibao landslide on the eastern margin of the Qinghai-Tibet Plateau

The Luanshibao (LSB) ancient landslide is a typical long-runout landslide that occurred on the eastern margin of the Qinghai-Tibet Plateau. To examine the long-runout mechanism of the LSB landslide, a detailed field investigation and a series of saturated soil triaxial and ring shear tests were carried out. The field investigation results revealed that the flat and broad Maoyaba (MYB) basin provides the required topographic conditions for the long-runout movement of the LSB landslide. The shallow deposit of the MYB basin is mainly composed of saturated weathered granite sand, which plays a key role in resulting in the high mobility of landslides. The results of the triaxial tests reveal that the soils show the characteristics of shear contraction first and then dilatation under static loading, and cyclic mobility occurs under cyclic loading. The results of the ring shear test reveal that the pore water pressure of the sample has undergone three stages of increase-decrease-increase. Finally, the pore-water pressure ratio increases to a constant of approximately 0.79, and the shear resistance decreases significantly. Grain crushing results in pore-water pressure generation and the liquefaction of saturated weathered granite sand for long shear displacement. It is proposed that sliding surface liquefaction is the main reason for the formation of complex surface landforms and the long-runout movement of LSB landslides.

The spatial and trophic ecology of culpeo foxes (Lycalopex culpaeus) in the high Andes of northern Chile

ABSTRACT The spatial and trophic ecology of the culpeo fox (Lycalopex culpaeus) was studied in the Salar de Punta Negra basin and the Llullaillaco National Park, in the high Andes of the Region of Antofagasta in northern Chile. The objectives of this study were to understand the feeding ecology, habitat use, and home range and activity pattern of culpeo fox. The study was conducted in an area of approximately 2800 km2 inside the Punta Negra salt flat basin, Llullaillaco NP, the surrounding mountains, and within areas of mining operations. We used methodologies including camera trapping, live trapping and satellite monitoring of L. culpaeus individuals, and diet analysis. Fifteen captures and five recaptures of culpeos were made, and three of them were equipped with satellite tracking collars. The home ranges estimated using the Minimum Convex Polygon (MPC 95%) were: 1029 km2 (female), 809 km2 (female) and 215 km2 (male). Culpeo foxes were nocturnal animals. A larger sample of 282 fecal scats was collected, with the main trophic prey in culpeo fox diet by frequency of occurrence being rodents (74.3%), arthropods (48%), camelids carrion (43.6%), birds (16.3%), vegetation (13.8%) and reptiles (2.5%). Niche breadth was low (0.367).

Subaqueous geomorphology and delta dynamics of Lake Brienz (Switzerland): implications for the sediment budget in the alpine realm

Non-invasive techniques such as seismic investigations and high-resolution multibeam sonars immensely improved our understanding of the geomorphology and sediment regimes in both the lacustrine and the marine domain. However, only few studies provide quantifications of basin wide-sediment budgets in lakes. Here, we use the combination of high-resolution bathymetric mapping and seismic reflection data to quantify the sediment budget in an alpine lake. The new bathymetric data of Lake Brienz reveal three distinct geomorphological areas: slopes with intercalated terraces, a flat basin plain, and delta areas with subaquatic channel systems. Quasi-4D seismic reflection data allow sediment budgeting of the lake with a total sediment input of 5.54 × 106 t sediment over 15 years of which three-quarter were deposited in the basin plain. Lake Brienz yields extraordinarily high sedimentation rates of 3.0 cm/yr in the basin plain, much more than in other Swiss lakes. This can be explained by (i) its role as first sedimentary sink in a high-alpine catchment, and by (ii) its morphology with subaquatic channel-complexes allowing an efficient sediment transfer from proximal to distal areas of the lake.

A New Method for Fault‐Scarp Detection Using Linear Discriminant Analysis in High‐Resolution Bathymetry Data From the Alarcón Rise and Pescadero Basin

AbstractThe linear discriminant analysis (LDA) is a common technique used in machine learning and pattern recognition for dimensionality reduction problems. Here, the LDA is applied to detect faults‐scarps in high‐resolution bathymetric profiles in the Southern Pescadero Basin (SPB) in the Gulf of California. The LDA uses fault scarps and cuestas (sloping topography) identified by a geomorphologist in the neighboring Alarcón Rise (AR). These geometric representations are transformed into a parametric space by an idealized fault‐scarp degradation model. Through inversion, we extracted the product of the mass diffusion coefficient with time (τ), scarp height (u0), and goodness of fit of the model on the scarp profiles and cuestas (ε). The LDA transforms the parametric space τ, u0, ε by the Fisher’s criterion into a 1D dimensional space that maximizes separability of classes. Then, the classification is performed by Bayes decision rule using the probability density functions (PDF) built from the 1D projected data for each class (fault‐scarps and cuestas). The implementation results in cross‐sectional profiles across the SPB show the ability to detect faults in the deepest part of the basin where the flat basin floor is interrupted by morphologically young fault‐scarp arrays. The LDA interpretation outperforms manual identification, particularly in faults scarps that are longer than ∼3 km, whereas shorter faults are challenging to discern from other linear features like channels. The model can extract information about the state of degradation of the scarps. This application allows the identification of fault generation episodes and resolves kinematic interactions between faults.

Modified Parker's Method for Gravitational Forward and Inverse Modeling Using General Polyhedral Models

AbstractWe propose a new modified Parker's method for efficient gravitational forward modeling and inversion using general polyhedral models. We have made several important modifications to the classical method, including: (a) The new method is now applicable to a general polyhedron represented by triangulated surface or tetrahedral mesh, and with arbitrarily variable 3D density distribution. (b) An optimal Fourier‐domain sampling strategy is used to improve the numerical accuracy of the new algorithm significantly. (c) A simple and effective automatic layering technique is introduced to accelerate the convergence rate of Parker's method. The method is demonstrated using both synthetic and real polyhedral models, including a sphere model approximated by a polyhedron, two asteroids, a digital elevation model in the Himalaya region, and the Yucca Flat basin model in Nevada. The numerical results show that, compared with analytical solutions of polyhedral models in the space domain, the modified Parker's method can improve the computational efficiency by several orders of magnitude while obtaining almost the same simulation results. The difference is well below existing instrumentation error level. By embedding the new forward algorithm into an iterative process, it can be used for fast inversion of density interfaces. Our new method is suitable for the efficient modeling and inversion of gravitational potential, gravitational vector, and gravitational gradient tensor caused by polyhedral models with a large number of faces, representing geological abnormal bodies, asteroids, and single or multilayer density interface models with triangulated surfaces.

Experimental investigation on single basin tilted wick solar still integrated with flat plate collector

In this study, an experimental work has been carried out on conventional solar still (CSS), horizontal wick solar still with flat plate collector (FPC) and basin tilted wick solar still at 30° integrated with flat plate collector. The performance of all these stills were compared with each other under similar atmospheric conditions. The experiment has been conducted for two cases i.e. horizontal wick solar still (HWSS) with FPC compared with CSS is referred as case-1, while the tilted wick solar still at 30° integrated with FPC compared with horizontal wick is referred as case 2. The total distillate production of HWSS and CSS was found to be 3.216 kg/m2-day and 2.894 kg/m2-day respectively. While, the overall cumulative and day efficiency of the horizontal wick solar still was higher as compared to CSS by 16.6% and 12.1% respectively. The temperature of various components was found to be more for solar still with tilted wick at 30° coupled with FPC as compared with normal horizontal wick solar still with FPC, when flow rate of the water from FPC was 0.041 kg/sec for both the cases. The total overall productivity of distillate for tilted wick solar still at 30° integrated with flat plate collector was found to be 3.99 kg/m2 -day for 3 cm water depth and 0.041 kg/s flow rate. The cumulative and day efficiency of solar still with tilted wick at 30° coupled with FPC was found to be 22.1% and 16.3% higher as compared to horizontal wick solar still with FPC.

COMPARATIVE EFFECTS OF RAISED BED AND TRADITIONAL FLAT BASIN ON WHEAT YIELD AND WATER PRODUCTIVITY UNDER EGYPTIAN CONDITIONS

Field experiments were carried out at Sakha Agricultural Research Station in Egypt to compare the effect of the newly developed raised bed technique with different bed widths (RB130, RB100, RB80 cm) on wheat productivity to the conventional flat basin (FB) method during 2019/2020. The statistical analyses were carried out using a randomized complete block design. According to the results of statistical analysis, using RB130 cultivation gave the highest significant averages of water-saving (21.81%) and the highest averages of wheat 1000 kernels weight (50.05 g) over the FB method. However, no significant differences were found between RB130 and FB method, which produced the highest averages of grain yield, straw yield, and biological yield. Wheat sowing on FB gave the highest significant average of grain yield, straw yield, and biological yield than RB100, RB80 at 5% level of significance, but there were no significant differences in the number of kernels per spike, kernel weight spike, and harvest index ratio between wheat sowing on FB and RB130, RB100 or RB80. There were no significant differences in the number of kernels per spike, kernel weight spike, number of spikes per m2, straw yield, biological yield, and harvest index ratio at 5% level of significance between wheat sowing on RB130, RB100, RB80. But wheat sowing on RB130 produced the highest significant average of crop water productivity and grain yield than RB80 at 5%. Finally, according to the study findings, using raised beds cultivation resulted in saving irrigation water by 15~21% compared to a flat basin.

IMPROVING IRRIGATION PERFORMANCE OF RAISED BED WHEAT USING THE WinSRFR MODEL UNDER EGYPTIAN CONDITIONS

Abstract: Field experiments were carried out at the Sakha Agricultural Research Station in the governorate of Kafr el Sheikh, Egypt to evaluate and optimize the irrigation performance of raised beds wheat using the WinSRFR model during 2019/2020. Raised beds (RB130 cm, and RB100 cm) were prepared using Raised bed planter. The model calibration was based on a close match between the observed and simulated curves of advance and recession time. Simulation Analysis World was used to evaluate the current irrigation performance of the raised bed furrows (RB) and the flat basin (FB) methods. The simulation analysis shows that for RB130 cm, RB100 cm, and FB irrigation systems, the application efficiencies were 80, 64, 43%, and distribution uniformities were 86, 88, 90%, and deep percolation losses were 20, 36, 56%, and adequacy were 1.07, 1.37, 2.08%, respectively. Physical Design World was used to optimize and develop different design strategies. The results showed that irrigation performance decreased with the increasing length of furrow and basin, so extremely long lengths should be avoided because they result in decreased efficiency and uniformity, as well as big deep percolation loss. Managing the inflow rate and irrigation cut-off through Operation Analysis World can increase application efficiency and reduce deep percolation losses by more than 15%, 60%, and 17%, 33%, and 23%, 17.5% respectively, for RB130 cm, RB100 cm, and FB.

An Overview of the Geomorphological Characteristics of the Pergamon Micro-Region (Bakırçay and Madra River Catchments, Aegean Region, West Turkey)

Current landforms are the basis for understanding past geomorphodynamics and human activities. Based on multiple materials and methods, including geomorphometric analyses of a digital elevation model and visual interpretations of satellite images, different landscape units of the Bakırçay and Madra River catchments in the environs of ancient Pergamon are described. The area was mainly shaped by tectonics that formed a horst-and-graben structure; small Miocene horsts and NE-trending subgrabens in the Kozak and Yunt Dağı Mountains were separated by the NEE-trending Plio-Pleistocene Bergama Graben. The asymmetry in relief, drainage network, and sediment accumulation between the Kozak Mountains to the north and the Yunt Dağı Mountains to the south of the lower Bakırçay plain characterize the Pergamon Micro-Region. The regional relief characteristics, with wide flat basin and plateau areas, are suitable for agriculture. Complemented by its richness in natural resources, the Pergamon Micro-Region became a preferred settlement area, with evidence of human impact since the Hellenistic–Roman period at the latest. As a consequence of settlement activities, several landscape engineering measures were implemented simultaneously with a parallel change in morphodynamics.

White Rann of Kachchh harbours distinct microbial diversity reflecting its unique biogeography

The understanding of sub-surface soil microbial diversity is limited at both saline and hypersaline ecosystems, even though salinity is found to affect the microbial community in aqueous and terrestrial environment. In this study, a phylo-taxonomy analysis as well as the functional characteristics of microbial community of flat salt basin of White Rann of Kachchh (WR), Gujarat, India was performed along the natural salinity gradient. The high throughput sequencing approach has revealed the numerical abundance of bacteria relative to the archaea. Salinity, TOC, EC and sulphate concentration might be the primary driver of the community distribution along the transect at WR. The much anticipated effect of salinity gradient on the microbial composition surprisingly turned out to be more speculative, with little variance in the community composition along the spatial distance of WR. The metabolic pathways involved in energy metabolism (like carbon, nitrogen, sulphur) along with environmental adaptive genes (like osmotic and oxidative stress response, heat and cold shock genes clusters) were abundantly annotated from shot-gun metagenomic study. The carbonic anhydrase harbouring bacteria Bacillus sp. DM4CA1 was isolated from WR, having a catalytic ability for converting the gaseous carbon dioxide in presence of calcium carbonate into calcite at 25 % higher rate as compared to non-harbouring strains. The enzyme has a role in multiple alternative pathways in microbial metabolism. With the array of results obtained, the study could become the new reference for understanding the diversity structure and functional characteristics of the microbial community of terrestrial saline environment.

Exergy and thermo-economic analyses of various tubular solar still configurations for improved performance

ABSTRACT Solar energy is being used for the purpose of water distillation since long. The present work demonstrates the comprehensive experimental investigation of various heat transfer enhancement arrangements on tubular solar still for its performance improvement. These arrangements include; case-1: Tubular solar still (TSS) with flat plate basin (TSS-FP), case-2: TSS with U-corrugated basin (TSS-UA), case-3: TSS with the coupled cylindrical parabolic collector (TSS-CPC). According to the available literature, the exergy and economical analysis of tubular solar stills are not explored much in the previous studies. Thus, a comparative thermo-economic analysis, exergy analysis and system productivity analysis have been carried out. In addition to this, the study investigates the effects of different basin water depths on system productivity. It has been found that the case-3: TSS-CPC gives the highest productivity; it was 37.75% and 80.63% higher as compared to the case-2 and case-1 respectively. Also, in the same arrangement, the enhancement in the exergy efficiency was around 48.6% and 85.2% as compared to case-2 and case-1 respectively. The per liter cost of water obtained by TSS-FP, TSS-UA, and TSS-CPC were about 0.00592, 0.00511, and 0.00567 US $/m2 respectively. The study concludes that the U-Corrugated basin surface, less basin water depth, and the secondary heating arrangement improve the productivity of the tubular still significantly.

A generalized second-order 3D theory for coupling multidirectional wave propagation from a numerical model to a physical model. Part II: Experimental validation using an I-shaped segmented wavemaker

This paper provides the experimental validation of the generalized second-order three-dimensional (3D) coupling theory outlined by Yang et al. [Z. Yang, S. Liu, X. Ji, and H.B. Bingham, 2020. A generalized second-order 3D theory for coupling multidirectional nonlinear wave propagation from a numerical model to a physical model. Part I: Derivation, implementation and model verification, submitted for publication] using multidirectional nonlinear 3D irregular waves. Based on the second-order theory for two-dimensional (2D) irregular waves described by Yang et al. (2014a), this work provides a second-order dispersive correction for the physical wavemaker signal which improves the nonlinear 3D wave information transfer between the numerical and physical models compared to the first-order method of Zhang et al. (2007). The important coupling equation and its discretization schemes were presented in detail in Part I. For further validating the performance of the second-order 3D coupling model under complex waves and bathymetry conditions, in this Part II, a careful experimental validation has been carried out by establishing a flat coupling basin and a concave-convex coupling basin. In addition, a sequence of progressively more complex numerical target waves has been used and an I-shaped segmented piston-type wavemaker system has been considered for verification of the theory. The effectiveness, adaptability, and precision of the second-order 3D coupling model have been discussed in detail. The effects of the wave parameters and its nonlinearity on the coupling simulation have also been evaluated from the discrepancy error and a wave harmonic analysis. By defining a space synchronization error, the overall error of the spatial wave field has been analyzed. Coupling simulation experiments using oblique regular and irregular waves, unidirectional irregular waves, and multidirectional irregular waves show that the traditional first-order coupling model has limitations when coupling complex waves with strong nonlinearity. When controlling the waves using the second-order 3D coupling signal, the higher harmonics underlying the numerical waves are accurately captured and transferred into the physical model, and the unwanted second-order spurious free waves are substantially reduced. Results obtained from the experimental verification described in this paper demonstrate the strengths of the second-order 3D coupling theory, which are more evident with increased wave nonlinearity.

Using Dense Array Waveform Correlations to Build a Velocity Model with Stochastic Variability

ABSTRACTIn an ongoing effort to improve 3D seismic-wave propagation modeling for frequencies up to 10 Hz, we used cross correlations between vertical-component waveforms from an underground chemical explosion to estimate the statistical properties of small-scale velocity heterogeneities. The waveforms were recorded by a dense 2D seismic array deployed during the Source Physics Experiments for event number 5 (SPE-5) in a series of six underground chemical explosions, conducted at the Nevada National Security Site. The array consisted of 996 geophones with a 50–100 m grid spacing, deployed at the SPE site at the north end of the Yucca Flat basin. The SPE were conducted to investigate the generation and propagation of seismic and acoustic waves from underground explosions.Comparisons of decay rates of waveform cross correlations as function of interstation distance, computed for observed and synthetic seismograms from the SPE-5 chemical explosion, were used to constrain statistical properties of correlated stochastic velocity perturbations representing small-scale heterogeneities added to a geology-based velocity model of the Yucca Flat basin. Using comparisons between recorded and simulated waveform cross correlations, we were able to recover sets of statistical properties of small-scale velocity perturbations in the velocity model that produce the best-fit between the recorded and simulated ground motion. The stochastic velocity fluctuations in the velocity model that produced the smallest misfits have a horizontal correlation distance of between 400 and 800 m, a vertical correlation distance between 100 and 200 m, and a standard deviation of 10% from the nominal model velocity in the alluvium basin layers. They also have a horizontal correlation distance of 1000 m, a vertical correlation distance of 250 m, and a standard deviation of 6% in the underlying and consolidated sedimentary layers, up to a depth of 4 km.Comparisons between observed and simulated wavefields were used to assess the proposed small-scale heterogeneity enhancements to the Yucca Flat basin model. We found that adding a depth-resolved stochastic variability to the geology-based velocity model improves the overall performance of ground-motion simulations of an SPE-5 explosion in the modeled frequency range up to 10 Hz. The results may be applicable to other similar basins.

Improved 3D Cauchy-type Integral for Faster and More Accurate Forward Modeling of Gravity Data Caused by Basement Relief

In this study, a new approach to improve the 3D Cauchy-type integral is presented for faster and more accurate forward modeling of gravity data produced by a sediment-basement interface. The conventional method for calculating the gravity effect of a sedimentary basin is to discretize that into right-rectangular prisms. Its associated volumetric integral over the prisms has computational complexity which makes volumetric integral time-demanding for 3D modeling. A 3D Cauchy-type integral only discretizes the density contrast surface. In fact, it is a surface integral without transcendental functions, which enables fast computation of potential fields. The purpose of the technique is to increase the accuracy of the customary Cauchy-type integral in order to calculate the gravity field over a sedimentary structure which is more likely in real geological structures. To achieve this, the vertical planes located between basement edges and the horizontal reference plane are considered. The accuracy and computational cost is assessed by synthetic gravity data modeling. Three forward functions, namely improved Cauchy-type integral, customary Cauchy-type integral, and volumetric integral, are applied to calculate the gravity field over synthetic sedimentary basins with different geometries. The volumetric integral is set as a benchmark to validate the efficiency of the presented method. Results are analyzed by comparing the dissimilarities of gravity anomalies calculated using the volumetric integral and each of the customary and improved Cauchy-type integrals. The resulting anomaly differences indicate that, compared with the customary Cauchy-type integral, the improved Cauchy-type integral increases the accuracy in calculated gravity anomalies considerably. Furthermore, forward calculations using the improved Cauchy-type integral require approximately the same time as the customary Cauchy-type integral, and are about 50 times faster than the volumetric integral. In addition, the improved Cauchy-type integral gives better results if the edges of the basement are not at an equal level, which is very likely in real geological structures. The new approach is tested on the basement of the Yucca Flat basin to assess the viability of the proposed model in real cases.

Effect of Mulching and/or Watering on Soil Moisture for Growth and Survival of the Transplanted Tree Seedlings in Dry Period

Dry mulch, as soil moisture conservation techniques, is seldom practiced for growth and survival of transplanted tree seedlings in dry period in Eritrea. Field experiment was conducted at Halhale, Eritrea with Dry Hyparrhenia rufa, as a mulch, on a flat basin for growth and survival of seedlings of Grevillea robusta and Acacia polyacantha subspecies Campylacantha by involving four management practices: 1) mulching and watering basins (MW); 2) no-mulching but watering basins (NMW); 3) mulching but no-watering basins (MNW); 4) no-mulching and no-watering basins (NMNW). The experimental design was CRD with three replications. MW and NMW were watered 180 litters (20 litters/month) but MNW and NMNW were not watered at all. Parameters such as soil moisture content of the basin, early growth performance of seedling and survival rate of the seedlings were studied. The result indicated that there were statistically significant differences (p 0.05) among the treatment for soil moisture content and early growth performance of the seedlings. The average volumetric water content (VWC%) on 0 - 20 cm soil depth at the end of dry period of MW, NMW, MNW, and NMNW were 10.08%, 7.7%, 6.3% and 3.9% respectively. Mean height increment of seedlings of G. robusta of MW (100 cm), NMW (83.3 cm), MNW (31.5 cm) and NMNW (9 cm) were recorded, while the mean height increments of seedlings of A. polyacantha subsp. Campylacantha of MW (48 cm), NMW (25 cm), MNW (4.5 cm) and NMNW (3 cm) were recorded. The mean survival rate of G. robusta was 91.8% of which the highest (100%) survival rate was recorded under MW, NMW and MNW, but the lowest (66.7%) was recorded by NMNW. All seedlings of A. polyacanth subsp. Campylacantha were survived, irrespective of the treatments. The study concluded that soil moisture content, early growth performance of seedlings, and survival rate of transplanted tree seedling was improved by application of mulch.

Water conservancy projects enhanced local resilience to floods and droughts over the past 300 years at the Erhai Lake basin, Southwest China

As a typical mountain area at the Yunnan-Guizhou Plateau in Southwest China, the Erhai Lake Basin has uneven precipitation (frequent droughts and floods), affected by the Southwest Monsoon in Asia and significant vertical zonal differences determined by local topography. Though with such harsh physical environment, this area sustained development in ancient times and has been considered a typical resilience case in many studies. With extensive investigation of various historical archives, this paper explores the situation and changes of water management in the Erhai Basin during the past 300 years, and aims to identify local factors in maintaining resilience to water stresses. Findings indicate that various strong and smart social regulations (governance, institutions, plans, management, motivations, orders, donations, dedication, etc.) enabled a wise development of many water conservancy projects that set up an effective irrigation system at the flat basin center. Lots of stream dams, sluice gates and terraced croplands jointly further enabled water storage, drainage and irrigation at the surrounding hillside areas. Additionally, by adopting drought-resistant and cold-resistant crops, agriculture production kept increasing and successfully fed the growing population. The complex but systematically developed river canal system, with its dams, reservoirs, and sluice gates, as well as adaptive cropping strategies, together maintained and enhanced the resilience of local communities to hydrological hazards. Over the 300 years of the study period, the changing water environment and the developing water conservancy projects showed a resilience loop, which offers a simple but valuable perspective on building human-water resilience in face of current and future water crises in this region and beyond.