CFD Prediction of the Airflow at a Large-Scale Wind Farm above a Steep, Three-Dimensional Escarpment

The Duogu Wind Farm, China Huadian Group Corporation’s first wind project in Yunnan, China, has been approved by the Provincial Development and Reform Commission. The acquired site is in Mengzi, in the south-east of Yunnan Province. The developer has deployed thirty-three 1.5 MW turbines in this wind farm (49.5 MW), and the total cost of construction has been estimated to be CNY449.7 million ($69.61 million). The present study compared the prediction accuracy of two CFD software packages for simulating flow over an escarpment with a steep slope. The two software packages were: 1) Open FOAM (Turbulence model: SST k-ω RANS), which is a free, open source CFD software package developed by Open CFD Ltd at the ESI Group and distributed by the Open FOAM Foundation and 2) RIAM-COMPACT (Turbulence model: Standard Smagorinsky LES), which has been developed by the lead author of the present paper. Generally good agreement was obtained between the results from the simulations with Open FOAM and RIAM-COMPACT.

Effect of elevation on floristic diversity,life forms and chorotypes in the AlHada mountain escarpment,Saudi Arabia

Mountains are biodiversity hotspots,and due to their unique microclimatic circumstances,they host a vast range of endemic species.There are two main hypotheses,the Rapoport and the mid-domain effect hypotheses,which explain how elevation and species richness are linked.The current study was conducted in the Al-Hada escarpment,which is a unique area in the world.It is located on the border of Eurasia and Africa,where there are a lot of plant species from both places.The study aimed to detect the effect of elevation on the floristic composition of the study area.The obtained results showed that the Al-Hada escarpment flora consists of 297 species belonging to 194 genera and fifty-seven distinct families.Only two families,Poaceae and Asteracae,had 22%of the whole recorded species.The obtained results showed that with increasing elevation,the numbers of species,genera,and families increased,in accordance with the Rapoport hypothesis.The numbers of families increased by 62%from the lowest elevation to the highest one,while the numbers of both species and genera increased by more than twofolds.Therophytes exhibited the maximum number,which was 44%,and Chamaephytes came in second with 25%.Phanerophytes and hemicryptophytes made up 13%and 11%of all life forms,respectively,while geophytes made up just 7%.Monoregional elements represented 33.2%of the total recorded species,where Saharo-Sindian species had the most monoregional species,accounting for around 13%of the total species.At the highest elevation,succulents accounted for 7.6%of the research area,whereas Nfixing plants accounted for 6.2%.At the highest elevation,they had the lowest value,and at the middle elevation,they had the highest value.With the rise in elevation,the neotropical,endemic,and Mediterranean elements rose.Succulents and Nfixing species did not show a clear relationship with the elevation but exhibited the lowest value at the highest elevation,and vice versa.Therophytes and geophytes increased while the number of hemicryptophytes decreased with elevation.Surprisingly,phanerophytes did not show any relationship with elevation,while,with the rise in elevation,the pan-tropical,endemic,and Mediterranean elements rose.Neotropical and Saharo-Sindian elements decreased with the rise in elevation.Considering our results,we can conclude that the relationship of taxa diversity with the different altitude of the arid subtropical regions’mountains,whose elevation does not exceed 2000 m(without human disturbance),confirms the Rapoport hypothesis.

Hauterivian-Barremian Bivalves from the Boulouha Formation of the Dahar Escarpment, Southern Tunisia: Stratigraphy and Regional Correlation

The Lower Cretaceous mixed siliciclastic-carbonate successions of the Boulouha Formation at the type locality in the Dahar escarpment of southern Tunisia have yielded a new discovered assemblage of bivalves which contains Anomia laevigata (Sowerby);Modiolus sp. cf. M. dahuashuensis (Yu et Li);Astarte sp.;and ?Mytilus sp.. The temporal distribution of the Anomia laevigata (Sowerby) and Modiolus sp. cf. M. dahuashuensis (Yu et Li) is limited to the Aptian formations of northeastern China, Japan and Korea, thus we suggest a Hauterivian-Barremian age for the Boulouha Formation. Henceforth, the new biostratigraphic data are used to improve a regional chronostratigraphic correlation between the lower Cretaceous strata of the Saharan Platform domain and those coeval from the Chotts domain.

Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and power cone programming

In the present study,the stability of a vertical rock escarpment is determined by considering the influence of undercut.Lower bound finite element limit analysis in association with Power Cone Programming(PCP)is applied to incorporate the failure of rock mass with the help of the Generalized Hoek-Brown yield criterion.The change in stability due to the presence of undercut is expressed in terms of a non-dimensional stability number(σci/γH).The variations of the magnitude ofσci/γH are presented as design charts by considering the different magnitudes of undercut offset(H/vu and wu/vu)from the vertical edge and different magnitudes of Hoek-Brown rock mass strength parameters(Geological Strength Index(GSI),rock parameter(mi),Disturbance factor(D)).The obtained results indicate that undercut can cause a severe stability problem in rock mass having poor strength.With the help of regression analysis of the computed results,a simplified design equation is proposed for obtainingσci/γH.By performing sensitivity analysis for an undisturbed vertical rock escarpment,we have found that the undercut height ratio(H/vu)is the most sensitive parameter followed by GSI,undercut shape ratio(wu/vu),and mi.The developed design equation as well as design charts can be useful for practicing engineers to determine the stability of the vertical rock escarpment in the presence of undercut.Failure patterns are also presented to understand type of failure and extent of plastic state during collapse.

桂西土湖锰矿区泥盆系中的陡崖式假不整合构造

桂西下雷、土湖锰矿区于上泥盆统榴江组—五指山组—融县组—下石炭统巴平组与中泥盆统北流组之间,发育了一种特殊的、呈陡崖状的高角度"上超"状的地层接触关系——陡崖式假不整合。通过对下雷、土湖锰矿区该类型不整合的发育位置、产状、界面及图面效应等特征,尤其是横向沉积接触典型特征的研究,得出了其是在海底陡坡、悬崖等特定古地形条件下,形成的一种新老地层间的横向沉积接触关系,而非存在间断的上下地层关系的认识。土湖锰矿区的这种高角度上超接触关系,其形成始于中泥盆世吉维特期晚期至晚泥盆世之初,是中泥盆世晚期广西海域大裂解事件的产物,是造盆运动形成的一种横向沉积构造,与同生断裂有着密切的关系。这一发现对认识地层接触关系、不整合的多样性,对右江盆地的古地理格局、盆地发展演化史及赋存锰矿的深入研究具有重要意义。

Use of Topographic Map Evidence to Test a Recently Proposed Regional Geomorphology Paradigm: Wind River-Sweetwater River Drainage Divide Area, Central Wyoming, USA

Topographic map evidence from the Wyoming Wind River-Sweetwater River drainage divide area is used to test a recently proposed regional geomorphology paradigm defined by massive south- and southeast-oriented continental ice sheet melt water floods that flowed across the entire Missouri River drainage basin. The new paradigm forces recognition of an ice sheet created and occupied deep “hole” and is fundamentally different from the commonly accepted paradigm in which a pre-glacial north- and northeast-oriented slope would have prevented continental ice sheet melt water from reaching or crossing the Wind River-Sweetwater River drainage divide. Divide crossings (or low points) are identified as places where water once flowed across the drainage divide. Map evidence is interpreted first from the accepted paradigm perspective and second from the new paradigm perspective to determine the simplest explanation. Both paradigm perspectives suggest south-oriented water crossed the drainage divide, although accepted paradigm interpretations do not satisfactorily explain the large number of observed divide crossings and are complicated by the need to bury the Owl Creek and Bridger Mountains to explain why the Wind River now flows in a north direction through Wind River Canyon. New paradigm interpretations explain the large number of divide crossings as diverging and converging channel evidence (as in flood-formed anastomosing channel complexes), Owl Creek and Bridger Mountain uplift to have occurred as south-oriented floodwaters carved Wind River Canyon, and a major flood flow reversal (caused by ice sheet related crustal warping and the opening up of deep “hole” space by ice sheet melting) as being responsible for the Wind River abrupt turn to the north. While this test only addresses topographic map evidence, Occam’s Razor suggests the new paradigm offers what in science should be the preferred Wind River-Sweetwater River drainage divide origin interpretations.

St Lawrence Seaway: Eastern Great Lakes, the Niagara River and Welland Canal Replacement, Maintenance and Protection

The Eastern Great Lakes region covers 51,000 square km of land, and is home to 15 million people. This region is rich in natural resources, industry and agriculture, and forms the heartland of both Canada and the United States. The development of this region has a history that is closely tied to waterways, and the development of canals that promoted growth and prosperity. The St. Lawrence Seaway connects Western and Eastern Great Lakes to the St Lawrence River and the Gulf of Saint Lawrence. The New York State Canal and the St. Lawrence Seaway were linked by the Oswego canal and provided a shorter route for cargo via barges to New York City. The New York State (NYS) Barge Canal and the St. Lawrence Seaway provided pathways for the settlement of the Eastern Great Lakes. Lake Erie drains into Lake Ontario via the Niagara River but the river was not navigable due to the obstacles of Niagara Falls and the Niagara Escarpment. Until the 1820s ships could not travel into Lake Erie. It was not possible to engineer a bypass of Niagara Falls with a series of locks due to the 100 m high Niagara escarpment. This escarpment obstacle to Niagara River navigation was overcome in 1829 with the completion of the first of four Welland Canals with locks 40 kilometers west of the Niagara River through the glacial till and alluvium that overlays the Niagara Escarpment. This permitted ocean going ships to enter Lake Erie and to continue on to Lake Michigan, Lake Huron and Lake Superior. The Eastern Great Lake shorelines, river banks and canals are actively eroding as a consequence of high surface water levels and flooding. The settlement of millions of people into the Eastern Great Lakes via the NYS Barge Canal and St. Lawrence Seaway migration pathways have created environmental and natural resource risks and challenges. These challenges and risks include deterioration of the Fourth Welland Canal and the need to replace it with the Fifth Welland Canal, industrial and urban wastewater disposal, shoreline, river bank and canal erosion as results of high water levels, the building of structures on the shoreline banks, invasive species and flooding.

Morphometric Analysis and Flash Floods Assessment for Drainage Basins of the Ras En Naqb Area, South Jordan Using GIS

Morphometric analysis and flash floods assessment were conducted for the watersheds of Ras En Naqb escarpment, south Jordan. The study area comprises of twelve small watersheds occupying the faulted-erosional slopes, and the dip slopes. The drainage network shows that dendritic and sub-dendritic patterns dominated the dip slopes, whereas trellis pattern characterized the faulted-erosional slopes. Stream orders range from fourth to sixth order. The mean bifurcation ratios vary between 4.2 and 5.38 for the dip slope basins, and between 3.5 and 5.0 for the faulted-erosional slope watersheds, indicating a noticeable influence of structural disturbances (i.e., faulting and uplifting), and rejuvenation of drainage networks. All watersheds have short basin lengths, ranging from 23.8 km to 42.2 km for the dip slope basins, and between 15.3 km and 45.4 km for the faulted-erosional slope catchments. This is indicative of high flooding susceptibility associated with heavy rainstorms of short duration. The circularity ratios range from 0.177 to 0.704 which denote that the catchments are moderately circular on the faulted-erosional slopes, and to some extent elongated on the dip slopes. The length of overland flow values ranges from 0.854 to 0.924 for the dip slope catchments, whereas LO values for the faulted-erosional slopes vary from 0.793 to 0.945 denoting steep slopes and shorter paths on both dip slope and faulted-erosional slope watersheds. Values of stream frequency range from 1.509 to 1.692 for the dip slope, and from 1.688 to 2.0 for the faulted-erosional slope catchments. FS values are also indicative of slope steepness, low infiltration rate, and high flooding potential. The watersheds of the dip slopes show lower values of form factor varying from 0.079 to 0.364, indicating elongated shape and suggesting a relatively flat hydrograph peak for longer duration. Similarly, values of Dd are high for catchments on the dip slope basins (1.709 - 1.85) and the faulted-erosional slope watersheds (1.587 - 2.0) indicating highly dissected topography, high surface runoff, low infiltration rate, and consequently high flooding potential. Furthermore, high relief values exist, ranging from 388 m to 714 m for the dip slope basins, and from 421 m to 846 m for the faulted-erosional slope catchments indicting high relief and steep slopes. Morphometric analysis, and flash flood assessment suggest that ten watersheds (83.3%) are categorized under high and intermediate flooding susceptibility, and the faulted-erosional slope catchments are more hazardous in terms of flooding. Thus the protection of Ma’an, El Jafr rural Bedouin settlements, and Amman-Aqaba highway from recurrent flooding is essential to ensure sustainable future development in Ras En Naqb-Ma’an area.

The Research of the Activity of the Piedmont Fault on the Tangshankou Segment of the Yuguang Basin Southern Marginal Fault

The Yuguang basin is a half-graben basin in the basin-range tectonic zone in northwest Beijing,located at the northern end of the Shanxi graben system,and the Yuguang basin southern marginal fault( YBSMF) controls the formation of this basin. A linear fault escarpment has formed in the proluvial fan on the piedmont fault zone of the Tangshankou segment of YBSMF. A trench across this escarpment reveals three paleo-earthquake events on two active faults. One fault ruptured at about 9 ka for the first time,and then faulted again at about 7. 3 ka,causing the formation and synchronous activity of another fault.Finally,they faulted for the third time,but we cannot determine the faulting time due to the lack of relevant surface deposition. The accumulative vertical displacement of these three events is about 8. 1 m. We estimate that the average recurrence period of the piedmont fault is about 1. 7 ka,and the average slip rate of the piedmont fault is about1. 6 mm/a. We also estimate the reference magnitude of each event according to the empirical formula.