A Multiscale Assessment of Shallow Groundwater Salinization in Michigan     

Zachary K. Curtis  Hua-sheng Liao  Shu-Guang Li  Prasanna Venkatesh Sampath  David P. Lusch 《Ground water》2019,57(5):784-806

Managing nonpoint-source (NPS) pollution of groundwater systems is a significant challenge because of the heterogeneous nature of the subsurface, high costs of data collection, and the multitude of scales involved. In this study, we assessed a particularly complex NPS groundwater pollution problem in Michigan, namely, the salinization of shallow aquifer systems due to natural upwelling of deep brines. We applied a system-based approach to characterize, across multiple scales, the integrated groundwater quantity–quality dynamics associated with the brine upwelling process, assimilating a variety of modeling tools and data—including statewide water well datasets scarcely used for larger scientific analysis. Specifically, we combined (1) data-driven modeling of massive amounts of groundwater/geologic information across multiple spatial scales with (2) detailed analysis of groundwater salinity dynamics and process-based flow modeling at local scales. Statewide “hotspots” were delineated and county-level severity rankings were developed based on dissolved chloride (Cl⁻) concentration percentiles. Within local hotspots, the relative impact of upwelling was determined to be controlled by: (1) streams—which act as “natural pumps” that bring deeper (more mineralized) groundwater to the surface; (2) the occurrence of nearly impervious geologic material at the surface—which restricts fresh water dilution of deeper, saline groundwater; and (3) the space–time evolution of water well withdrawals—which induces slow migration of saline groundwater from its natural course. This multiscale, data-intensive approach significantly improved our understanding of the brine upwelling processes in Michigan, and has applicability elsewhere given the growing availability of statewide water well databases.  相似文献   

Formation Mechanism of Mud Bank Along the Southwest Coast of India     

K. R. Muraleedharan  P. K. Dinesh Kumar  S. Prasanna Kumar  Sebin John  B. Srijith  K. Anil Kumar  K. Naveen Kumar  S. Gautham  V. Samiksha 《Estuaries and Coasts》2018,41(4):1021-1035

Mud bank formation during the southwest monsoon along the southwest coast of India remains an enigma to the researchers and coastal community in spite of several earlier studies. The present study attempts to unravel the mystery through a high-frequency, season-long time-series observation at Alappuzha, located at the southern part of the west coast of India, a region of frequent occurrence of mud bank. Using 7-month-long weekly time-series observation, we identified strong winds and high waves associated with onset of the southwest monsoon and subsequent three episodic atmospheric low-pressure events (LPEs).With the help of in situ time-series data, we show that the strong winds and high waves associated with southwest monsoon pre-conditions the near shore bottom sediment to bring it into suspension. The high amplitude waves associated with the southwest monsoon, while propagating from the deep water to shallow water region, interact with the bottom initiating bottom-sediment movement and its suspension due to wave refraction and shoaling. The sporadic occurrence of the atmospheric LPEs enhances the process of suspension of bottom sediment in the near shore region leading to the formation of fluid mud. Simulations with a cohesive sediment transport model yielded realistic estimates of sediment transport, in the presence of an onshore current, a pre-requisite for transporting the fluid mud toward the coast. The prevailing onshore upwelling current during the southwest monsoon provides the favorable pre-requisite conditions for transporting the fluid mud through depression channel network towards the coast. Once sufficient quantity and thickness of fluid mud is accumulated in the near shore region, it acts as a wave damper for subsequent high monsoon waves, as indicated by the time-series wave data, leading to the formation of tranquil mud bank region. Depression channel networks extending from the shelf to the coast off Alappuzha, Kochi, Ponnani, Beypore, and Ullal were found in the bathymetric charts, thus explaining why mud banks occur only at few locations in spite of the prevalence of similar monsoon conditions.  相似文献   

Debris flow susceptibility zonation using statistical models in parts of Northwest Indian Himalayas—implementation,validation, and comparative evaluation     

Dash  Rajesh Kumar  Falae  Philips Omowumi  Kanungo  Debi Prasanna 《Natural Hazards》2022,111(2):2011-2058

Natural Hazards - Debris flows are natural disasters with devastating consequences and frequent recurrence in changing climatic regime of the Indian Himalayas. Therefore, it is necessary to...  相似文献   

Differentiating Between Pollutants Build‐Up on Roads and Roofs: Significance of Roofs as a Stormwater Pollutant Source          下载免费PDF全文

An Liu  Nadeeka S. Miguntanna  Nandika P. Miguntanna  Prasanna Egodawatta  Ashantha Goonetilleke 《洁净——土壤、空气、水》2016,44(5):538-543

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Interacting CMEs and their associated flare and SEP activities     

A. Shanmugaraju  S. Prasanna Subramanian 《Astrophysics and Space Science》2014,352(2):385-393

We have analyzed a set of 25 interacting events which are associated with the DH type II bursts. These events are selected from the Coronal Mass Ejections (CMEs) observed during the period 1997–2010 in SOHO/LASCO and DH type IIs observed in Wind/WAVES. Their pre and primary CMEs from nearby active regions are identified using SOHO/LASCO and EIT images and their height–time diagrams. Their interacting time and height are obtained, and their associated activities, such as, flares and Solar Energetic Particles (>10 pfu) are also investigated. Results from the analysis are: primary CMEs are much faster than the pre-CMEs, their X-ray flares are also stronger (X- and M-class) compared to the flares (C- and M-class) of pre-CMEs. Most of the events (22/25) occurred during the period 2000–2006. From the observed width and speed of pre and primary CMEs, it is found that the pre-CMEs are found to be less energetic than the primary CMEs. While the primary CMEs are tracked up to the end of LASCO field of view (30 R_s), most of the pre-CMEs can be tracked up to <26 R_s. The SEP intensity is found to be related with the integrated flux of X-ray flares associated with the primary CMEs for nine events originating from the western region.  相似文献   

Enrichment pattern of leachable trace metals in roadside soils of Miri City,Eastern Malaysia     

R. Nagarajan  M. P. Jonathan  Priyadarsi D. Roy  M. V. Prasanna  A. Elayaraja 《Environmental Earth Sciences》2014,72(6):1765-1773

This article presents the results on distribution and enrichment pattern of acid-leachable trace metals (ALTMs) from roadside soil of Miri city, Sarawak, East Malaysia. The city is one of the fastest developing in the Malaysian region with huge petroleum resources. ALTMs Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn and Cd along with organic carbon and carbonates (CaCO₃) were analyzed in 37 soil sediments collected from roadside. The enrichment of ALTMs [especially Cu (0.4–13.1 μg g^?1), Zn (9.3–70.7 μg g^?1), Pb (13.8–99.1 μg g^?1)] in the roadside soils indicate that these metals are mainly derived from sources related to traffic exhausts, forest fires and oil refineries. The comparative study and enrichment pattern of elements indicates that Mn, Cu, Zn and Pb are enriched multi-fold than the unpolluted soil and Ni, Pb, Cd in some samples compared to Sediment Quality Guidelines like Lowest Effect Level (LEL) and Effects Range Low (ERL) in the region which is mainly due to the recent industrial developments in the region.  相似文献   

A study on the interpretation of spontaneous potential and resistivity logs in layered aquifer sequence of Pondicherry Region,South India     

R. Thilagavathi  S. Chidambaram  M. V. Prasanna  S. Pethaperumal 《Arabian Journal of Geosciences》2014,7(9):3715-3729

Geophysical logs provide a strong mechanism for interpretation and determination of the depositional environments, facies and also help in interpretations of hydrogeologic units. Spontaneous potential (SP) and resistivity logs can be used as an indicator of textural parameters. Pondicherry region has a complicated geology and with formation of different ages. The boreholes (BH) of this region are examined for litholog, SP and resistivity from four different BH locations, viz, Ariyankuppam, Chinnaverampattinam, Thavalakuppam and Nallavadu. These locations were studied and interpreted by using the shapes of the curves to identify the depositional environments, and this was later compared with the vertical litholog profile. Comparing the variation of these logs, the lateral variation of sedimentary facies was also attempted. The average resistivity values of Ariyankuppam, Chinnaverampattinam, Thavalakuppam and Nallavadu are 42.4, 30.4, 50.4 and 28.3?Ωm, respectively. Majority of the resistivity values corresponds from fine- to medium-grained sand, clayey pebbles, fine to very coarse sand and clayey sand with lignite. Frequency of resistivity values in each BH were identified for determining the dominant representative grain size. The study has pointed out the lithological variation of the system laterally and vertically using geophysical well logs.  相似文献   

Plasma instability at the inner edge of the accretion disk— II     

S. C. Tripathy  C. B. Dwivedi  A. C. Das  A. R. Prasanna 《Journal of Astrophysics and Astronomy》1993,14(3-4):167-179

A two-dimensional instability analysis for a magneto-keplerian disk flow around a compact object is presented here. Using the eigenvalue technique, linearly coupled perturbed equations have been numerically solved within the local approximation. It is concluded that Kelvin-Helmholtz, magnetosonic (fast and slow) and resistive electromagnetic modes exist. However, only the magnetosonic mode can destabilise the disk structure. Further, we discuss the properties of different modes as a function of disk parameters and plot the eigenmode structures for different physical quantities.  相似文献   

Kinematics of Achankovil Shear Zone, South India     

V. Prasanna Kumar 《Gondwana Research》1998,1(3-4):407

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Physical and biological response of the Arabian Sea to tropical cyclone Phyan and its implications     

Byju P  Prasanna Kumar S 《Marine environmental research》2011,71(5):325-330

The response to the tropical cyclone Phyan, which developed in the eastern Arabian Sea during 9-11 November 2009, was rapid cooling of sea surface temperature (SST), enhancement of chlorophyll a and two-fold increase in net primary productivity (NPP). Cooling of SST was immediate in response to the strong wind-mixing, and the subsequent upward Ekman pumping sustained the cooling even after the dissipation of Phyan. The biological response mediated by the upward Ekman pumping driven vertical transport of subsurface nutrient showed a time lag of 3-4 days. The CO? flux to the atmosphere associated with Phyan was 0.123 Tg C, which accounted for ~85% of the total out-gassing from the eastern Arabian Sea during November. Thus, an increased occurrence of cyclones in a warming environment will lead to an enhanced biomass production and also increase in CO? out-gassing.  相似文献