Coastal Terrain Research Articles

Propagation of Tidal Wave in Coastal Terrains with Complex Bed Geometry

Transient interaction of tides and groundwater has a direct impact on marine ecosystems and plays an important role in coastal aquifer management. The literature is replete with studies that analyze the influence of periodic tidal waves on the adjacent aquifers of various configurations underlain by horizontal or sloping bases. However, water table fluctuations in coastal aquifers whose base extends horizontally as well as sloping in a definite lateral domain cannot be addressed with existing studies. This paper presents a new model for tide induced groundwater flow in a coastal aquifer system whose base has mixed features of both horizontal and sloping terrains. Variations in water table are simulated by combining a linear diffusion equation with an advection-diffusion equation. Validity of spatial and temporal variables as well as performance of new analytical solution is assessed with numerical solution of nonlinear Boussinesq equations. Sensitivity of the solution is analyzed in both homogeneous and heterogeneous aquifer systems. Numerical experiments based on Tchebycheff and L2 norms indicate that the new analytical solution provides acceptable results in a large range of aquifer parameters.

Wind suitability in site analysis of coastal concave terrains using computational fluid dynamics simulation: a case study in East Asia

The effect of wind environment is becoming increasingly important in analyzing and selecting sites for better natural ventilation of residential buildings, external comfort, and pollution dispersion. The main purpose of this study was to develop a set of methods for wind environment assessment in coastal concave terrains. This set of methods can be used to provide quantifiable indicators of preferable wind conditions and help site analysis. Firstly, a total of 20 types of coastal bays with concave terrains in East Asia were characterized to find ideal locations. The selected areas were divided into five categories according to the main terrain features. Then a sample database for the concave terrains was compiled for modelling comparisons. Secondly, a number of key wind variables were identified. Computational fluid dynamics (CFD) models of the typical coastal concave terrains identified as a result of the study were created, and the local wind environments were simulated with input from geographic information system (GIS) and statistic package for social science (SPSS) analysis. A measure of wind suitability was proposed that takes wind velocity and wind direction into account using GIS. Finally, SPSS was used to find the relationship between wind suitability and key terrain factors. The results showed that wind suitability was significantly associated with terrain factors, especially altitude. The results suggest that residential building sites should be selected such that their bay openings face the direction of the prevailing wind and that the opposite direction should be avoided.

Terrain-Trapped Airflows and Orographic Rainfall along the Coast of Northern California. Part I: Kinematic Characterization Using a Wind Profiling Radar

AbstractThis study develops an objective method of identifying terrain-trapped airflows (TTAs) along the coast of Northern California and documenting their impact on orographic rainfall. TTAs are defined as relatively narrow air masses that consistently flow in close proximity and approximately parallel to an orographic barrier. A 13-winter-seasons dataset is employed, including observations from a 915-MHz wind profiling radar along the coast at Bodega Bay (BBY, 15 m MSL) and surface meteorology stations at BBY and in the coastal mountains at Cazadero (CZD, 478 m MSL). A subset of rainy hours exhibits a profile with enhanced vertical shear and an easterly wind maximum in the lowest 500 m MSL, roughly the same depth as the nearby coastal terrain. Both flow features have a connection to TTAs along the coast of Northern California. Based on the average orientation (320°–140°) and altitude of nearby topography, mean wind direction in the lowest 500 m MSL () between 0°–140° is used as the initial criterion to identify TTA conditions. Application of this threshold yields a CZD/BBY rainfall ratio of 1.4 (3.2) for TTA (NO TTA) conditions. More detailed analysis of the relationship between and orographic rainfall reveals that an upper threshold of 150° more precisely divides the TTA and NO-TTA regimes. A sensitivity analysis and comparison with a TTA documented in a previous case study show that the best TTA identification criteria correspond to with a duration of at least 2 h. This objective identification method is applied to seven case studies in Part II of the present study.

Coastal Anthropology: A Future Dynamics in India

Indian coastline is a crucial natural resource and important economic asset which extends around 7500 km and nurtures vast human population. Indian coastline is primarily dichotomized into east and west coastline. India’s east coastline covers West Bengal, Orissa, Andhra Pradesh and Tamil Nadu and west coastline encompasses Gujarat, Maharashtra, Goa, Karnataka and Kerala. Owing to rich coastal biodiversity, people are involved in fishing, agriculture and other economic activities so as to fulfil their daily-life necessities. A strong and elaborate sexual division of labour prevails in most fishing communities in world. Human populations inhabit these diverse ecological zones and have adapted to the climatic conditions of these zones. This adaptation is manifested in health, physiological, cultural, cognitive and genetic aspects of coastal populations. A limited number of researches have been conducted to provide a narrow understanding of coastal populations. It has been observed that work has been done from zoological, marine and other medical science point of view on the coastal aspect. This paper attempts to propound the term ‘Coastal Anthropology’ which provides comprehensive understanding of human populations inhabiting various coastal terrains. It lays emphasis upon anthropological input to coastal research which provides scientific insight into human adaptation in the coastal regions. Few suggestions have also been given to highlight the relevance of coastal anthropology in the present scenario.

Importance of Intertidal Wetlands for the French Coastal Endemic Bluethroat Cyanecula svecica namnetum and Conservation Implications in the Context of Global Changes

Coastal specialised species have naturally restricted distribution areas and may be drastically affected by fragmentation or loss of their habitats due to ongoing changes, such as artificialisation, shoreline erosion, rising water levels or colonisation by invasive species. In this context we characterise the land occupation strategies of a Western Atlantic French coastal endemic bird: the Bluethroat Cyanecula svecica namnetum. Our study focuses on a key period of the life cycle of this species: the post-breeding moult. Capture and recapture sessions in intertidal habitats have allowed us to retrieve 26% of local breeders during their moulting period. The modeling of moult kinetics revealed that moult of flight feathers takes 37–50 days. A radio-tracking survey of moulting birds revealed exploitation by individuals of both the lowest and tallest vegetal formations of intertidal sites and exploitation of small home ranges (0.42–1.34 ha), typical of locations where trophic resources tend to be abundant and predictable. Analyses of droppings highlighted that Coleoptera, Aranea and marine crustaceans (Amphipoda) contributed most of the prey biomass consumed, amphipods being particularly selected by birds in active moult. Our results underline the importance of intertidal wetlands in terms of trophic opportunities to compensate for the energy costs of moult for the Bluethroat. Given the global changes already dramatically affecting coastal habitats, we emphasise that special attention should be given to the conservation of intertidal wetlands for marshland passerines of conservation concern such as the Bluethroat, and that restoration of adjacent coastal terrain is a promising development.

Extreme daily precipitation in coastal western Norway and the link to atmospheric rivers

AbstractThis work investigates the link between the most extreme daily precipitation (EDP) events observed since 1900 on the west coast of Norway and the large‐scale moisture fluxes over the North Atlantic Ocean. Using station precipitation data, vertically integrated water vapor (IWV) from Special Sensors Microwave Imager/Sounder (SSMIS) satellite observations and the state of the art NOAA‐twentieth Century (NOAA‐20C) reanalysis, it is shown that 55 out of 58 EDPs are associated with narrow plumes of intense low‐level moisture defined as atmospheric rivers. Despite the high spatial correlation between IWV fields in the SSMIS and NOAA‐20C data sets, the significant positive relationship between the maximum amount of observed precipitation at all stations and the IWV content hitting the coastal terrain is only observed in the SSMIS data set. Further, the composite analyses of synoptic conditions show that the preferred circulation type consists of a mean sea level pressure (MSLP) dipole pattern where a high‐pressure system over central Europe and a series of low‐pressure systems to the east of Iceland and over the Norwegian Sea are present. The west coast of Norway is located in the exit region of the anticyclonically curved upper tropospheric polar jet stream implying that the coupling of upper troposphere and surface dynamics begins to weaken at the time of EDPs. It is also found that the primary synoptic‐scale precursors are persistent positive 500 hPa height geopotential and MSLP anomalies over central Europe up to 10 days before the occurrence of EDP events.

Diurnal Variations of the Land–Sea Breeze and Its Related Precipitation over South China

Abstract Convection-permitting numerical experiments using the Weather Research and Forecasting (WRF) Model are performed to examine the diurnal cycles of land and sea breeze and its related precipitation over the south China coastal region during the mei-yu season. The focus of the analyses is a 10-day simulation initialized with the average of the 0000 UTC gridded global analyses during the 2007–09 mei-yu seasons (11 May–24 June) with diurnally varying cyclic lateral boundary conditions. Despite differences in the rainfall intensity and locations, the simulation verified well against averages of 3-yr ground-based radar, surface, and CMORPH observations and successfully simulated the diurnal variation and propagation of rainfall associated with the land and sea breeze over the south China coastal region. The nocturnal offshore rainfall in this region is found to be induced by the convergence line between the prevailing low-level monsoonal wind and the land breeze. Inhomogeneity of rainfall intensity can be found along the coastline, with heavier rainfall occurring in the region with coastal orography. In the night, the mountain–plain solenoid produced by the coastal terrain can combine with the land breeze to enhance offshore convergence. In the daytime, rainfall propagates inland with the inland penetration of the sea breeze, which can be slowed by the coastal mountains. The cold pool dynamics also plays an essential role in the inland penetration of precipitation and the sea breeze. Dynamic lifting produced by the sea-breeze front is strong enough to produce precipitation, while the intensity of precipitation can be dramatically increased with the latent heating effect.

Accidental benzene release risk assessment in an urban area using an atmospheric dispersion model

This study applied the American Meteorological Society and Environmental Protection Agency Regulatory Model (AERMOD) to assess the risk caused by an accidental release and dispersion of the toxic chemical benzene in the vicinity of a highly populated urban area. The modeling domain encompasses the Korean megacity of Ulsan, which includes two national industrial complexes and is characterized by a complex coastal terrain. Multiple AERMOD simulations were conducted for an assumed emission scenario using background wind data from August between 2009 and 2013. The series of experiments produced the spatial accident probability patterns for different concentration levels during daytime and nighttime scenarios based on the corresponding dominant wind patterns. This study further quantifies the potential accident risk based on the number of affected individuals by combining the accident probability with the indoor and outdoor population estimates. The chemical gas dispersion characteristics depend on various local meteorological conditions, such as the land-sea breeze direction, which alternates between daytime and nighttime, and the atmospheric stability. The results reveal that benzene dispersion affects a much larger area during the nighttime owing to the presence of a nocturnal stable boundary layer with significant temperature stratification. The affected area is smaller during the daytime owing to decreased stability and enhanced vertical mixing in the boundary layer. The results include a high degree of uncertainty during the nighttime owing to weak wind speeds and the lack of a prevailing wind direction, which impact the vulnerable area. However, vulnerable areas are more effectively identified during the daytime, when more consistent meteorological conditions exist. However, the potential risk becomes much lower during the nighttime owing to a substantial reduction of the outdoor population.

Detection of thermal pollution from power plants on China’s eastern coast using remote sensing data

The acceleration of the industrialization process in China has increased the demand for electricity and triggered a power-plant building boom, especially along China’s eastern coast, where the economy gets off early and enjoys a fast development. The thermal plumes, residual chlorine, nuclides and other pollutions produced by the thermal and nuclear power plants have exerted an impact on the coastal eco-environment. To monitor the thermal pollution from the power plants at Yueqing Bay on the eastern coast, in this research, the distribution of sea surface temperature (SST) surrounding the power plants is obtained by using the SST retrieval methods developed for Landsat Enhanced Thematic Mapper Plus (ETM+), HJ-1B infrared sensor (IRS) and Terra moderate resolution imaging spectroradiometer (MODIS) data. The comparison of the SST retrieval results before and after the operation of power plants indicates that the total area of sea waters that is impacted by the thermal discharge from the two power plants at Yueqing Bay is approximately 17.95 km2, with the highest SST rise of 4.5 °C appearing over the waters around the outlet of the Huaneng Yuhuan power plant on the eastern shore, whereas the highest SST rise around the Zheneng Yueqing power plant on the western shore reaches 3.8 °C. The intensity and scope of influence of the thermal discharge mainly depend on the installed capacity of power plants, coastal terrain, and tide. Although the area where the SST rise is more than 3 °C is not large, thermal discharge still has an impact on bay ecosystems due to the relatively closed nature of the bay environment. Due to the influence of rising water temperatures on the reproduction and individual evolution of fish, shrimp, crabs, shellfish and other aquatic creatures, in the long term, the thermal pollution from coastal power plants will affect the volume of natural fishery and biological resources throughout the waters. The quantitative retrieval results also suggest that relative to MODIS data, Landsat ETM+ and HJ-1B IRS data with a high spatial resolution are more applicable to the estimation of small-scale SST, and IRS data with a high temporal resolution are more helpful in the study of spatio-temporal variability of thermal plumes from coastal power plants.

Causes and systematics of inundations of the Krasnodar territory on the Russian Black Sea coast

Abstract. The inundation situations on the Black Sea coast of the Krasnodar territory for the period from 1945 until 2013 were analysed and the main types of inundations at the coast are described. Synoptic factors of the formation of extreme precipitation and rainfall floods, features and regularities of the downstream flood wave transformation in the rivers are also studied. Therefore, assessments of seasonal and maximum flow of the Black Sea coast rivers for the period of hydrometric measurements were done. Regularities of change of the occurrence of inundations and their characteristics on the coastal terrain were analysed, for a year and on a perennial timescale. Most catastrophic and exceptional inundations arise in the summer and in early autumn. Small inundations during the remaining year reflect the seasonal distribution of river flow and floods in the Black Sea rivers. Extensive and sometimes extreme precipitation dominates the river flow regimes. The seasonal distribution of small and moderately dangerous inundations reflects, on average, a water regime of two groups of rivers of the coast – to the north and to the south of the Tuapse River. To the north of the Tuapse River, floods prevail from November until March (up to 70 % of observed floods took place in this period) as a result of precipitation and winter snowmelt during frequent thaw periods. In winter, high waters often overlap to form a multi-peak high water of 2–3 weeks' duration. In the summer and in early autumn we observe a steady low flow. The total amount of runoff increases both in a southeast direction, and with the altitude of the river basins. Interannual variability of mean annual runoff, as well as maximum runoff, on the contrary decreases in the southern direction and with an increasing area of the river basins. The coastal high waters of the rivers of the Sochi part of the coast are typical at any time of the year, but more often floods in the cold season result from incessant rain, and thawing snow. Annually up to 25 floods have been observed. The principal reason of such distribution is the increase of extreme rainfall in the warm season. Orographic features of the coast and detailed features of rainfall only cover a small number of local river basins and a limited area. The geographical correlation of individual rainfall and subsequent floods ceases to be statistically significant for distances over 40–60 km. The annual flow cycle is mainly determined by two seasons, winter/spring and summer, with strong and weak flows, respectively; almost 71 % of all catastrophic and exceptional inundations took place in July–August (71 %) and in October–November (29 %). The characteristic features of dangerous floods are their rapid formation and propagation, a significant increase of water level (up to 5–7 m and more) and the multiple increase of water discharges in comparison with low flow period. Analysis of the interannual changes of the number of inundations at the Black Sea coast of the Krasnodar territory has shown some increase of the number of inundations in the period from the early 1970s until the early years of the twenty-first century. Quantitative assessments of risk, hazard and damage for the population and economic activities from accidental inundations in the valleys of the Black Sea coast rivers show that economic and social losses from inundations at the Black Sea coast of the Krasnodar territory are some of the highest in the Russian Federation. The basic conclusion from recent inundations is the need to consider not only the lower reaches and mouths of the Black Sea coast rivers where the main part of the social and economic development of the coast is concentrated, but also whole river basins and catchments. Further, an analysis of the efficiency of the measures applied at the coast to mitigate inundations and their after-effects is provided.

Tsunami waves extensively resurfaced the shorelines of an early Martian ocean.

It has been proposed that ~3.4 billion years ago an ocean fed by enormous catastrophic floods covered most of the Martian northern lowlands. However, a persistent problem with this hypothesis is the lack of definitive paleoshoreline features. Here, based on geomorphic and thermal image mapping in the circum-Chryse and northwestern Arabia Terra regions of the northern plains, in combination with numerical analyses, we show evidence for two enormous tsunami events possibly triggered by bolide impacts, resulting in craters ~30 km in diameter and occurring perhaps a few million years apart. The tsunamis produced widespread littoral landforms, including run-up water-ice-rich and bouldery lobes, which extended tens to hundreds of kilometers over gently sloping plains and boundary cratered highlands, as well as backwash channels where wave retreat occurred on highland-boundary surfaces. The ice-rich lobes formed in association with the younger tsunami, showing that their emplacement took place following a transition into a colder global climatic regime that occurred after the older tsunami event. We conclude that, on early Mars, tsunamis played a major role in generating and resurfacing coastal terrains.

Automatic Optimization for Large-Scale Real-Time Coastal Water Simulation

We introduce an automatic optimization approach for the simulation of large-scale coastal water. To solve the singular problem of water waves obtained with the traditional model, a hybrid deep-shallow-water model is estimated by using an automatic coupling algorithm. It can handle arbitrary water depth and different underwater terrain. As a certain feature of coastal terrain, coastline is detected with the collision detection technology. Then, unnecessary water grid cells are simplified by the automatic simplification algorithm according to the depth. Finally, the model is calculated on Central Processing Unit (CPU) and the simulation is implemented on Graphics Processing Unit (GPU). We show the effectiveness of our method with various results which achieve real-time rendering on consumer-level computer.

Soil carbon storage, respiration potential, and organic matter quality across an age and climate gradient in southwestern Greenland

Geological factors influence biological cycling of organic carbon in soils but are not well represented in our understanding of Arctic carbon dynamics. Landscape age, for instance, directly affects quantity and quality of soil carbon, which are two strong controls of the temperature sensitivity of soil organic matter. We investigated soil carbon storage, respiration potential, and organic matter quality for microbial decomposition across a climate and landscape age gradient in southwest Greenland that deglaciated during the Holocene. We measured soil respiration during a 370-day laboratory incubations of active layer soils collected from four study areas across this gradient (ages 1.8 × 102, 6.8 × 103, and 1.0 × 104, coinciding with a climate gradient from drier inland to wetter coastal terrain) and used a soil respiration model comparison approach to assess the substrate quality of stored organic matter for microbial decomposers. Soils store more than three times greater organic carbon at the 10,000-year-old, maritime climate study areas than the 180-year-old, continental climate study areas. Respiration rates were highest in the surface soils of the coastal areas. Model comparisons reveal important heterogeneity in the quality of organic matter for microbial decomposition between areas: coastal soils were best modeled by both one- and two-pooled models, and inland soils were best represented by one-pooled respiration models. Together, the measures of carbon quality (C:N, CO2 production, and model parameters estimating initial CO2 production rates from different organic matter pools) show that shallow soils at the southern coastal area, Kobbefjord, had the highest respiration rates from the recalcitrant carbon pool. This study reveals differences in carbon storage and turnover associated with landscape age and climate factors in western Greenland. When applied to thermodynamic theory, which predicts that temperature sensitivity increases with carbon recalcitrance, our findings suggest that carbon stored in coastal soils may be more sensitive to climate warming than inland soils.

InSAR Assessment of Surface Deformations in Urban Coastal Terrains Associated With Groundwater Dynamics

Monitoring ground deformations arising from groundwater dynamics in dense urban coastal terrains is crucial for the sustainable development of infrastructures in these highly populated areas. The city of Montreal, which is located in the Saint-Laurent plain in eastern Canada, with its fast-growing populations, is a unique case study for other similar cities in coastal terrains. The city undergoes high-level house foundation damages with densities reaching up to 89 repairs/km2 resulting from time-dependent ground deformations that are correlated to groundwater dynamics and evapotranspiration. Using Radarsat-2 C-Band synthetic aperture radar interferometry, we observe 3- to 5-mm ground line-of-sight displacement variations temporally outphased by few months relative to the 2-m subartesian aquifer hydraulic head variations. The deformations are observed over a 60-km2 area located in the central part of the Montreal Island in Canada, from 2008 to 2010. We observe displacements of ∼1 mm/year uplift in the areas covered by 15-m-thick clay layer. These displacements are well correlated to the number of house repairs. We also observe ∼2 mm/year subsidence on elevated terrains, associated with evapotranspiration. The amplitudes of the displacements observed during this two-year study are significant when integrated over the average lifetime of urban structures. We conclude that the observed ground deformations are related to the seasonal variation of hydraulic head in most of the areas of Montreal. Moreover, wetter climate forecasts over upcoming decades for this area, will accentuate groundwater level fluctuations; thus, more ground deformations are foreseen, and have to be considered in future infrastructure design standards.

Highly Potent Saccharification of Arthrospira maxima Glycogen by Fungal Amylolytic Enzyme from Trichoderma Species J113

Hydrolytic enzymes from fungi have been widely used to convert complex plant-based substrates into more suitable fermentation substrates. Recently, photosynthetic microorganisms, particularly cyanobacteria, are garnering interest as an alternative to plant-based biomass for renewable energy production. Our goal was to identify a new source of enzymes with improved amylolytic efficiency in cyanobacterial glycogen hydrolysis. We isolated a new Trichoderma species J113 strain from the coastal terrains of Korea and determined that the fungus has a high amylolytic enzyme activity. We cultured the fungus on wheat bran to stimulate enzyme production, and the crude extract was subsequently purified through filtrations, precipitation, and chromatography. We observed that J113 enzyme consists of two putative major amylases: Ayt40 and Ayt70, that were determined as an α-amylase and a gluco-amylase, respectively. While these two amylases exhibited different pH and temperature requirements for optimum performance, collectively J113 enzyme showed the highest activity at pH 4 and 60 °C. In addition, we were able to drastically enhance the amylolytic capacity of Ayt70 gluco-amylase by 291 % with 5 mM Mn2+ amendment. Significantly, J113 enzyme converted 20 g/L (10 g total carbohydrate) of Arthrospira maxima to 8.3 g/L of reducing sugar with Mn2+ compared to only 5.1 g/L without Mn2+ in 240 min of reaction. Our study demonstrated that the newly isolated amylase extract from Trichoderma species J113 has the potential to be further optimized for efficient large-scale saccharification of algal glycogen for bioethanol production.

The Impacts of California’s San Francisco Bay Area Gap on Precipitation Observed in the Sierra Nevada during HMT and CalWater

Abstract Atmospheric rivers (ARs) are narrow regions of enhanced water vapor transport, usually found on the warm-sector side of the polar cold front in many midlatitude storms formed primarily over the oceans. Nonbrightband (NBB) rain is a shallow orographic rainfall process driven by collision and coalescence that has been observed in some of these storms. NBB rain accounts for about one-third, on average, of the total winter season rainfall occurring at a coastal mountain site in Northern California. During the California Energy Commission’s CalWater project, nearly the same fraction of NBB rain was observed at a northern Sierra Nevada foothills site as compared to the coastal mountains, whereas less than half of the fractional amount of NBB rain was observed at a southern Sierra Nevada foothills site. Both Sierra Nevada sites often experience terrain-induced blocked flow, that is, Sierra barrier jet (SBJ) during landfalling winter storms. However, the northern Sierra Nevada site often is oriented geographically downwind of a gap in the coastal terrain near San Francisco during AR landfall. This gap allows maritime air in the AR to arrive at the northern site and enhance the collision–coalescence process in orographic feeder clouds as compared with the southern site. As a result, a greater amount and intensity of NBB rain and overall precipitation was produced at the northern site. This study uses a variety of observations collected in the coastal and Sierra Nevada ranges from the Hydrometeorology Testbed and CalWater field campaigns to document this behavior. A detailed case study provides additional context on the interaction between AR flow, the SBJ, and precipitation processes.

Integrated Geophysical and Hydrochemical Approach for Locating Fresh Water Locations in a Coastal Terrain

An integrated geophysical investigation viz., Vertical Electrical Sounding (VES), Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) were carried out in a coastal terrain at Vizag Steel Plant (VSP), Visakhapatnam, Andhra Pradesh., India for locating fresh water locations. The entire area was underlain by recent alluvial of varying thickness consists of sand, clay and silt with basement as Kondalite rock formation consisting of saline water in some parts of the area. Locating favorable groundwater locations in such a terrain is a difficult task. The area consists of saturated clay, saturated silt and saline water has the same resistivity signature and misleads resistivity data interpretation for identifying and recommending the suitable groundwater locations in a coastal terrain. To overcome these uncertainties, a second geophysical approach or combinations of geophysical methods become necessary to resolve these resistivity ranges in a more reliable and better fruitful interpretation of sub-surface layers. In order to pin-point the groundwater locations at VSP; VES, ERT and GPR investigations were carried out. Interpreted results of VES, ERT pseudo-section and GPR images (radargram) were correlated with each other to ascertain confidently the geophysical signature of the sub-surface. Combination of geophysical methods gives better resolution or interpretation of sub-surface information before made any recommendations for drilling of borewell. Based on integrated geophysical investigation few borewell sites were recommended and drilled. The observed drilled lithologs was well correlated with the VES, ERT and GPR data. Besides, this hydrochemical analysis of water samples was carried out from the existing borewells and dugwells. Total Dissolved Solids (TDS) and chloride concentration were ranges from 189 to 3398 mg/l and 5 to 1610 mg/l. The eastern and north-eastern part of the area has elevated concentration of TDS and chloride indicating intrusion of saline water. TDS concen- tration of drilled borewell was found to range from 400 to 500 mg/l. The observed yield of drilled borewells ranges from 104 to 3623 gal/hr.

Numerical Simulations of the Boundary Layer Jet off the Southeastern Coast of China

Abstract A strong coastal boundary layer jet (CBLJ) (~8 m s−1) off the southeastern coast of China (around 28°N, 122°E) is found from the July 2006–11 hourly model data simulated by the Advanced Research Weather Research and Forecasting Model (WRF-ARW) with a 9-km horizontal grid. The southerly CBLJ has a jet core at the 925-hPa level, located along the western periphery of the west Pacific subtropical high (WPSH). The CBLJ is mainly contributed by large-scale enhancement by diurnal forcing and orographic effects by the coastal terrain along the southeastern China coast and the terrain of Taiwan. Although the geostrophic winds offshore are faster in the afternoon due to the larger east–west pressure gradient caused by land surface heating over the China plain, the CBLJ has a nocturnal (~0200 LST) maximum. In the afternoon hours, easterly ageostrophic winds driven by differential land–sea thermal heating develop at low levels. After sunset, with the disappearance of land surface heating, the ageostrophic winds offshore veer southward by the Coriolis force and combine with the southerly geostrophic flow resulting in a nocturnal maximum in the CBLJ. Furthermore, from two model sensitivity experiments (NoTW and LowFJ), it is apparent that the terrain of Taiwan and Fujian exerts a secondary influence (1–2 m s−1) on the strength of the CBLJ. The orographic blocking by the terrain of Taiwan and Fujian is more significant with a larger (~1 m s−1) southerly wind component north of the Taiwan Strait at night than in the afternoon hours.

Ground Features of Sea Land Breezes in Hainan Island

In this study, based on the observed surface wind in 8 meteorological stations at coastal locations of Hainan Island, the frequency of sea-land breeze (SLB) is studied to depict the characteristics and spatial-temporal variation of the SLB. The statistics indicate that, because of the large variation in coastal terrain and orientation of the island, the number of SLB days and the duration of the SLB at different stations has significant regional difference and seasonal variations.

Synoptic and sub-synoptic circulation effects on wind resource variability – A case study from a coastal terrain setting in New Zealand

This paper investigates linkages between synoptic and sub-synoptic scale atmospheric circulation and temporal wind resource variability, adopting a synoptic weather typing approach. These linkages were examined in a complex terrain, coastal setting in southern New Zealand. Over a 28 month period, approximately 71% of the intermonthly variability in power density was explained by the monthly frequency of a subset of weather types. Within this subset, weather types associated with strong south-west or west orientated pressure gradients were related to enhanced power density, whereas weather types associated with stagnant pressure gradients were related to reduced power density. At the sub-synoptic scale, the effect of the sea breeze on the wind resource was found to be of importance but dependent on both the season and the ambient larger scale atmospheric circulation. Aspects of the sea breeze circulation also appear to be complicated by additional thermal and dynamical influences associated with the larger scale terrain complexity. Similar wind regimes likely occur elsewhere and should be examined specifically in the context of the wind resource.