Investigating potential future changes in surface water flooding hazard and impact     

Alison C. Rudd  Alison L. Kay  Steven C. Wells  Timothy Aldridge  Steven J. Cole  Elizabeth J. Kendon  Elizabeth J. Stewart 《水文研究》2020,34(1):139-149

Surface water flooding (SWF) is a recurrent hazard that affects lives and livelihoods. Climate change is projected to change the frequency of extreme rainfall events that can lead to SWF. Increasingly, data from Regional Climate Models (RCMs) are being used to investigate the potential water-related impacts of climate change; such assessments often focus on broad-scale fluvial flooding and the use of coarse resolution (>12 km) RCMs. However, high-resolution (<4 km) convection-permitting RCMs are now becoming available that allow impact assessments of more localised SWF to be made. At the same time, there has been an increasing demand for more robust and timely real-time forecast and alert information on SWF. In the UK, a real-time SWF Hazard Impact Model framework has been developed. The system uses 1-km gridded surface runoff estimates from a hydrological model to simulate the SWF hazard. These are linked to detailed inundation model outputs through an Impact Library to assess impacts on property, people, transport, and infrastructure for four severity levels. Here, a set of high-resolution (1.5 km and 12 km) RCM data has been used as input to a grid-based hydrological model over southern Britain to simulate Current (1996–2009) and Future (~2100s; RCP8.5) surface runoff. Counts of threshold-exceedance for surface runoff and precipitation (at 1-, 3- and 6-hr durations) are analysed. Results show that the percentage increases in surface runoff extremes, are less than those of precipitation extremes. The higher-resolution RCM simulates the largest percentage increases, which occur in winter, and the winter exceedance counts are greater than summer exceedance counts. For property impacts, the largest percentage increases are also in winter; however, it is the 12-km RCM output that leads to the largest percentage increase in impacts. The added-value of high-resolution climate model data for hydrological modelling is from capturing the more intense convective storms in surface runoff estimates.  相似文献   

Fault zone hydrogeology in arid environments: The origin of cold springs in the Wadi Araba Basin,Egypt     

Mahmoud M. Khalil  Kay Hamer  Thomas Pichler  Abotalib Z. Abotalib 《水文研究》2021,35(5):e14176

The role of faults in controlling groundwater flow in the Sahara and most of the hyper-arid deserts is poorly understood due to scarcity of hydrological data. The Wadi Araba Basin (WAB), in the Eastern Sahara, is highly affected by folds and faults associated with Senonian tectonics and Paleogene rifting. Using the WAB as a test site, satellite imagery, aeromagnetic maps, field observations, isotopic and geochemical data were examined to unravel the structural control on groundwater flow dynamics in the Sahara. Analysis of satellite imagery indicated that springs occur along structurally controlled scarps. Isotopic data suggested that cold springs in the WAB showed a striking similarity with the Sinai Nubian aquifer system (NAS) water and the thermal springs along the Gulf of Suez (e.g., δ¹⁸O = −8.01‰ to −5.24‰ and δD = −53.09‰ to −31.12‰) demonstrating similar recharge sources. The findings advocated that cold springs in the WAB represent a natural discharge from a previously undefined aquifer in the Eastern Desert of Egypt rather than infiltrated precipitation over the plateaus surrounding the WAB or through hydrologic windows from deep crystalline basement flow. A complex role of the geological structures was inferred including: (1) channelling of the groundwater flow along low-angle faults, (2) compartmentalization of the groundwater flow upslope from high-angle faults, and (3) reduction of the depth to the main aquifer in a breached anticline setting, which resulted in cold spring discharge temperatures (13–22°C). Our findings emphasize on the complex role of faults and folds in controlling groundwater flow, which should be taken into consideration in future examination of aquifer response to climate variability in the Sahara and similar deserts worldwide.  相似文献   

Using GIS-based distributed soil loss modeling and morphometric analysis to prioritize watershed for soil conservation in Bago river basin of Lower Myanmar   总被引：1，自引：0，他引：1  

Kay Thwe Hlaing  Shigeko Haruyama  Maung Maung Aye 《Frontiers of Earth Science》2008,2(4):465-478

Bago River is an important river in Myanmar. Although shorter than other rivers, it has its own river system, and people along the river rely heavily on it for their daily lives. The upper part of the watershed has changed rapidly from closed forest to open forest land in the 1990s. Since the recent degradation of the forest environment, annual flooding has become worse during the rainy season in Bago City. This paper aims at determining soil conservation prioritization of watershed based on soil loss due to erosion and morphometric analysis in the Bago Watershed by integrating remote sensing and geographic information system (GIS) techniques. In this study, soil erosion of the Bago watershed was determined using the Universal Soil Loss Equation. Such factormaps as rainfall, soil erodibility, slope length gradient, and crop management were compiled as input parameters for the modeling; and the soil loss from 26 sub-watersheds were estimated. Then, the soil erosion maps of the Bago watershed for 2005 were developed. The resulting Soil Loss Tolerance Map could be utilized in developing watershed management planning, forestry management planning, etc.  相似文献   

Avalanche Climatology of the Western United States,with an Emphasis on Alta,Utah*   总被引：1，自引：0，他引：1  

Cary J. Mock  Paul A. Kay 《The Professional geographer》1992,44(3):307-318

Climate and snowpack characteristics of avalanches vary spatially across the western United States, distinguishing three regions. The coastal mountain renges have warmer, denser snow; interior (continental) ranges have colder, less-dense snow; and intermountain ranges have intermediate characteristics. Avalanche character of Alta, Utah, is related to eastern Pacific 700-mb height anomalies for December, January, and March, but not for February. Avalanche conditions around Alta do not always relate to localized pressure gradient winds for December and February.  相似文献   

Projected changes in area of the Sundarban mangrove forest in Bangladesh due to SLR by 2100     

Andres Payo  Anirban Mukhopadhyay  Sugata Hazra  Tuhin Ghosh  Subhajit Ghosh  Sally Brown  Robert J. Nicholls  Lucy Bricheno  Judith Wolf  Susan Kay  Attila N. Lázár  Anisul Haque 《Climatic change》2016,139(2):279-291

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Observation of the Soya Warm Current using HF ocean radar     

Naoto Ebuchi  Yasushi Fukamachi  Kay I. Ohshima  Kunio Shirasawa  Masao Ishikawa  Toru Takatsuka  Takaharu Daibo  Masaaki Wakatsuchi 《Journal of Oceanography》2006,62(1):47-61

Three High Frequency (HF) ocean radar stations were installed around the Soya/La Perouse Strait in the Sea of Okhotsk in order to monitor the Soya Warm Current (SWC). The frequency of the HF radar is 13.9 MHz, and the range and azimuth resolutions are 3 km and 5 deg., respectively. The radar covers a range of approximately 70 km from the coast. The surface current velocity observed by the HF radars was compared with data from drifting buoys and shipboard Acoustic Doppler Current Profilers (ADCPs). The current velocity derived from the HF radars shows good agreement with that observed using the drifting buoys. The root-mean-square (rms) differences were found to be less than 20 cm s⁻¹ for the zonal and meridional components in the buoy comparison. The observed current velocity was also found to exhibit reasonable agreement with the shipboard ADCP data. It was shown that the HF radars clearly capture seasonal and short-term variations of the SWC. The velocity of the Soya Warm Current reaches its maximum, approximately 1 m s⁻¹, in summer and weakens in winter. The velocity core is located 20 to 30 km from the coast, and its width is approximately 40 km. The surface transport by the SWC shows a significant correlation with the sea level difference along the strait, as derived from coastal tide gauge records at Wakkanai and Abashiri. Deceased.  相似文献   

Do Harpacticoids (Copepoda) Use Water‐Borne Cues to Aid in Locating Food Parcels?     

Andrea Fechter  David Thistle  Günter Arlt  Keith Suderman  & Kay Vopel 《Marine Ecology》2004,25(3):217-223

Abstract.  Harpacticoid copepod food is patchily distributed and individuals must episodically move to new food patches. Key questions in harpacticoid feeding ecology include how individuals detect food patches and how rapidly they move toward patches. Based on literature reports, we hypothesized that harpacticoids locate food parcels by sensing a water-borne cue. We tested this idea using individuals of Leptastacus coulli Huys, 1992 and Praeleptomesochra similis Lang, 1965 from a sandy beach in north Florida (29.948° N, 84.341° W). Individuals from both species selected seawater that had been exposed to food significantly more frequently than they selected control seawater. The rate of movement of these species was millimeters per second, which agreed with previous reports.  相似文献   

Properties of sea ice and overlying snow in the Southern Sea of Okhotsk     

Takenobu Toyota  Shinya Takatsuji  Kazutaka Tateyama  Kazuhiro Naoki  Kay I. Ohshima 《Journal of Oceanography》2007,63(3):393-411

The general properties of sea ice and overlying snow in the southern Sea of Okhotsk were examined during early February of 2003 to 2005 with the P/V “Soya”. Thin section analysis of crystal structure revealed that frazil ice (48% of total core length) was more prevalent than columnar ice (39%) and that stratigraphic layering was prominent with a mean layer thickness of 12 cm, indicating that dynamic processes are essential to ice growth. The mean thickness of ice blocks and visual observations suggest that ridging dominates the deformation process above thicknesses of 30 to 40 cm. As for snow, it was found that faceted crystals and depth hoar are dominant (78%), as which is also common in the Antarctic sea ice, and is indicative of the strong vertical temperature gradients within the snow. Stable isotope measurements (δ¹⁸O) indicate that snow ice occupies 9% of total core length and that the mass fraction of meteoric ice accounts for 1 to 2% of total ice volume, which is lower than the Antarctic sea ice. Associated with this, the effective fractionation coefficient during the freezing of seawater was also derived. Snow ice was characterized by lower density, higher salinity, and nearly twice the gas content of ice of seawater origin. In addition, it is shown that the surface brine volume fraction and freeboard are well correlated with ice thickness, indicating some promise for remote sensing approaches to the estimation of ice thickness.  相似文献   

Creation and destruction of lower continental crust   总被引：31，自引：0，他引：31  

R. W. Kay  S. Mahlburg-Kay 《International Journal of Earth Sciences》1991,80(2):259-278

Bulk continental crustal composition results from the net mass exchange between crust and mantle. Crustal addition is mainly by the rise of mantle-derived melts into and through the crust at convergent plate margins and (at a lower rate) within plate interiors. Crustal subtraction occurs by subduction of uppermost crust (sediment, continent-derived elements in hydrothermally altered oceanic crust), by subcrustal erosion at convergent margins and by delamination of lowermost crust following densifying gabbro-eclogite phase transformations that result in a crust-mantle density inversion. As the phase transformations only occur at high pressure, tectonic overthickening of the crust (to > 50 km) is required. The lowermost crust at continent-ocean and continent-continent convergent plate margins is more likely to experience these transient overthickening events (compressional orogenies) than is intraplate crust. Correspondingly, the preservation probability of mafic lower crust is greater for intraplate than for plate margin localities. Delamination of mafic lower crust is the main process for removing basic composition rocks from the crust, thereby creating »andesitic« crustal composition. Evidence for lower crustal delamination comes from »geochemically balanced« cross section of compressional belts, and from the high La/Yb ratios, lack of Eu anomalies, and high Sr contents in deep crustallyderived magmas from the base of tectonically over-thickened crust. These crustal magmas are often accompanied by mantle-derived basalts associated with crustal uplift and extension, both related to the coincident delamination of underlying mantle lithosphere.

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Zusammenfassung Die Gesamtzusammenfassung der Kontinentalen Kruste resultiert aus dem Massenaustausch zwischen Kruste und Mantel. Krustenzuwachs erfolgt hauptsächlich beim Aufstieg in und durch die Kruste von aus dem Mantel abstammenden Basalt an konvergierenden Plattengrenzen und zum geringeren Teil Plattenintern. Der Krustenabbau wird erreicht per Subduktion der obersten Kruste, durch subkrustale Erosion an konvergierenden Plattengrenzen (Sedimente, Elemente kontinentaler Herkunft von hydrothermal veränderter ozeanischer Kruste). Dies wird hervorgerufen von der Schichtspaltung der untersten Kruste nach der Verdichtung durch die Gabbro-Eklogit-Phasentransformation, welche in der Krusten-Mantel-Dichte-Inversion resultiert. Da die Phasentransformation nur unter hohen Drücken stattfindet, werden tektonische Mächtigkeitszunahmen der Kruste (> 50 km) benötigt. Die unterste Kruste in Bereichen von konvergierenden Kontinent-Ozean und Kontinent-Kontinent Plattengrenzen unterliegt einer größeren Wahrscheinlichkeit vorübergehende Mächtigkeitszunahmen zu erfahren als platteninterne Kruste. Dementsprechend ist die Erhaltungswahrscheinlichkeit von mafischer unterer Kruste für platteninterne Bereiche größer als für Plattengrenzen. Schichtspaltung von mafischer unterer Kruste ist der Hauptprozeß basisch zusammengesetzte Gesteine aus der Kruste zu entfernen, hierbei wird die Kruste in Richtung »andesitische« Zusammensetzung verändert. Hinweise für Schichtspaltung der unteren Kruste stammen von »geochemisch bilanzierten« Profilen aus druckhaft deformierten Zonen. Weiterhin sprechen dafür hohe La/Yb-Werte, das Fehlen von Eu-Anomalien und hohe Sr-Gehalte, wie sie an der Basis tektonisch verdickter Kruste in Magmen, die aus der tiefen Kruste stammen, gefunden werden. Diese krustalen Magmen werden häufig von Mantelbasalten begleitet, die zu Krustenhebung und Dehnung in Verbindung stehen; beides im Zusammenhang stehend zu der gleichzeitig stattfindenden Schichtspaltung der unterlagernden Mantellithosphäre.

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Résumé La composition d'ensemble de la croûte continentale résulte des échanges entre la croûte et le manteau. L'apport dans la croûte provient en ordre principal de la montée de basalte d'origine mantélique qui s'opère aux bordures des plaques convergentes et, dans une moindre mesure, à l'intérieur des plaques. Le départ hors de la croûte se produit par la subduction de la croûte supérieure (sédiments, éléments dérivés des continents dans la croûte océanique affectée d'altération hydrothermale), par érosion subcrustale le long des marges convergentes et par délamination à la base de la croûte, les transformations de phase gabbro-éclogitiques entraînant une augmentation de densité et une inversion de densité entre croûte et manteau. Comme ces transformations de phases ne se produisent qu'à haute pression, elles impliquent un épaississement tectonique de la croûte (jusqu'à plus de 50 Km). Le domaine probable de tels épaississement est la partie inférieure de la croûte en bordure des plaques convergentes continentocéan ou continent-continent (orogènes de compression), plutôt que la croûte intra-plaque. Inversement, la probabilité de conversion d'une croûte inférieure mafique est plus élevée au milieu des plaques que sur leurs bordures. La délamination de la croûte inférieure est le processus courant d'appauvrissement de la croûte en roches mafiques, avec création d'une composition crustale »andésitique«. Les arguments en faveur de cette delamination sub-crustale sont tirés de profils »géochimiquement équilibrés« dans les ceintures en compression, ainsi que des rapports La/Yb élevés, de l'absence d'anomalie de l'Eu et des hautes teneurs en Sr dans les magmas dérivés de la partie profonde des croûtes tectoniquement épaissies. Ces magmas crustaux sont souvent accompagnés de basaltes d'origine mantélique associés à un soulèvement et à une extension crustale, ces deux processus étant liés à la délamination concommittante de la lithosphère mantélique sousjacente.

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Conjoint analysis of small‐boat recreational fishers in New Zealand          下载免费PDF全文

Carla F. Muller  John D. Holland  Thomas J. Kay  Karen F. Hytten 《New Zealand geographer》2018,74(1):27-35

Conjoint analysis is a useful technique to assist recreational managers formulate policy, and develop strategies to efficiently and effectively distribute resources. Accurate estimates of the value of natural resources remain challenging, despite the development of a number of decision analysis techniques. This recreation geography study uses conjoint analysis to examine the relative importance of attributes associated with small‐boat recreational fishing experiences and demonstrates the value of conjoint analysis as a non‐market valuation tool. We found that the choices associated with companionship are the most important factors of recreational fishing and more tangible attributes such as the quality of launch facilities and catch probability are the least important factors.  相似文献