Control of hydrologic systems for multiple uses in a closed-loop framework

The role of linear control theory as an aid to the integral control of hydrologic systems is investigated for the case of a combined lake and aquifer storage system that supplies either a deterministic or stochastic water demand. Only lumped time-invariant systems are considered but both deterministic and stochastic inflows to storage are allowed. The computational example allows for recharge of lake water into the aquifer as well as for the subsequent diversion of pumped groundwater back to the lake. Stability criteria are presented for the closed-loop features of the overall control system. Under a quadratic loss criterion, a calculus of variations problem, subject to constraints imposed by the system equations can be solved for the optimal release policy from the lake and aquifer and optimal feedback policy from aquifer to lake.     

Reviews of recent Australian publications

AUSTRALIA: A GEOGRAPHY. Volume 1: The Natural Environment edited by D. N. Jeans. 18 × 25 cm, viii and 347 pages. Sydney University Press: Sydney 1986 (ISBN 0 424 00114 4) $A55.00 (hard); (ISBN 0 424 00124 1) $A32.50 (soft).

Western Australia. Departments of Education and Lands and Survey (1979) Western Australia: an atlas of human endeavour, 1829–1979, Government Printer, Perth.

ATLAS OF SOUTH AUSTRALIA edited by T. Griffin and M. McCaskill. 28 × 40 cm, xiv and 134 pages. South Australian Government Printing Division and Wakefield Press on behalf of the South Australian Jubilee 150 Board: Adelaide 1986 (ISBN 0 7243 46880) $A55.00 (hard).

URBAN AUSTRALIA: Planning Issues and Policies edited by S. Hamnett and R. Bunker. 16 × 24 cm, 192 pages. Nelson Wadsworth: Melbourne 1987 (ISBN 0 17 007166 9) $A29.95 (hard).

AUSTRALIAN URBAN DEVELOPMENT AND INTERNATIONAL FINANCE CAPITAL (Working Paper No. 31) by M. T. Daly. 21 × 30 cm, viii and 39 pages. Transnational Corporations Research Project, University of Sydney 1985 (ISBN 0 908470 66 5) $A5.00 (soft).

TRANSNATIONAL CAPITAL AND URBANIZATION IN JAPAN (Research Monograph No. 25) by M. Douglass. 21 × 30 cm, viii and 42 pages. Transnational Corporations Research Project, University of Sydney 1987 (ISBN 0 908470 74 6) $A10.00 (soft).

MELBOURNE WESTERN REGION: Industrial Sites Atlas by Melbourne Western Region Joint Working Group. 45 × 32 cm, 40 pages. Melbourne Western Region Joint Working Group: Melbourne 1984 $A20.00 (soft).

MINE INFRASTRUCTURE AND ECONOMIC DEVELOPMENT IN NORTHERN AUSTRALIA by C. O'Faircheallaigh. 18 × 25 cm, vi and 87 pages. North Australia Research Unit, Australian National University: Darwin 1987 (ISBN 0 7315 0043 1) $A10.00 (soft).

AUSTRALIA'S CHANGING POPULATION: Trends and Implications by G. Hugo. 16 × 24 cm, x and 354 pages. Oxford University Press: Melbourne 1986 (ISBN 0 19 554680 6) $A40.00 (hard).

WOMEN OVER SIXTY: A Study of the Housing, Economic and Social Circumstances of Older Women (Publication No. 130) by L. Coleman and S. Watson. 17 × 24 cm, v and 89 pages. Australian Institute of Urban Studies: Canberra 1987 (ISBN 0 86419 112 X).

THE MANNING VALLEY: Landscape and Settlement 1824–1900 by W. K. Birrell. 21 × 29 cm, xvi and 280 pages. Jacaranda: Milton, Qld, 1987 (ISBN 0 7016 2170 2) $A29.95 (hard).

ISSUES IN THE MANAGEMENT OF AUSTRALIA'S WATER RESOURCES by J. J. Pigram. 15 × 23 cm, xvi and 331 pages. Longman Cheshire: Melbourne 1986 (ISBN 0 582 71139 8) $A24.95 (soft).

PROSPECTS FOR HARDWOOD FORESTS (Monograph No. 19) edited by J. Dargavel and G. Sheldon. 16 × 23 cm, xv and 334 pages. Centre for Resource and Environmental Studies, Australian National University, Canberra 1987 (ISBN 0 86740 226 1) $A19.95 plus $A5.00 post and packing (soft).

FOREST SOILS AND NUTRIENT CYCLES by P. M. Attiwill and G. W. Leeper. 15 × 22 cm, x and 202 pages. Melbourne University Press: Melbourne 1987 (ISBN 0 522 84315 8) $A29.90 (hard).

AUSTRALIAN SOILS: The Human Impact edited by J. S. Russell and R. F. Isbell. 26 × 18 cm, xi and 522 pages. University of Queensland Press: St Lucia 1986 (ISBN 0 7022 1968 1) $A50.00 (hard).

THE AUSTRALIAN SUMMER MONSOON, TELECONNECTIONS, AND FLOODING IN THE LAKE EYRE BASIN (South Australian Geographical Papers No. 2) by R. J. Allen. 18 × 25 cm, 47 pages. Royal Geographical Society of Australasia (South Australian Branch): Adelaide 1985 (ISBN 0 909112 09 6).     

Diversity and distribution of gelatinous zooplankton in the Southwestern Mediterranean Sea

Gelatinous zooplankton species composition, distribution and abundance were investigated in the bay and the lagoon of Bizerte (North Tunisian coast) from January 2004 to December 2005. In total, 48 species were identified in the study area: 24 medusae, 11 siphonophores, four appendicularians, six chaetognaths, two pteropods and one doliolid. The hydromedusa Eutima mira was recorded for the first time in the Western Mediterranean Sea. The diversity in the Bay of Bizerte was greater than the diversity in the Bizerte lagoon. There was a loss of species diversity. Siphonophores were the most sensitive group to anthropogenic discharge. Only two species of siphonophores were recorded in the lagoon. Four species of gelatinous zooplankton, Muggiaea kochi, Lensia conoidea, Oikopleura longicauda and Podocorynoides minima were the most frequent species in the lagoon and may benefit from eutrophication. Appendicularians were numerically the most dominant group in the bay and the lagoon of Bizerte. Mesozooplankton density declined significantly in autumn and winter of 2004 and 2005 in relation to the dense aggregations of the scyphomedusae Pelagia noctiluca. Statistical analysis divided the study area into three zones: lagoon zone, bay zone and channel zone.     

Crustal tomographic imaging of a transitional continental rift: the Ethiopian rift

In this study we image crustal structure beneath a magmatic continental rift to understand the interplay between crustal stretching and magmatism during the late stages of continental rifting: the Main Ethiopian Rift (MER). The northern sector of this region marks the transition from continental rifting in the East African Rift to incipient seafloor spreading in the southern Red Sea and western Gulf of Aden. Our local tomographic inversion exploits 172 broad-band instruments covering an area of 250 × 350 km of the rift and adjacent plateaux. The instruments recorded a total of 2139 local earthquakes over a 16-month period. Several synthetic tests show that resolution is good between 12 and 25 km depth (below sea level), but some horizontal velocity smearing is evident along the axis of the Main Ethiopian Rift below 16 km. We present a 3-D P -wave velocity model of the mid-crust and present the first 3-D Vp / Vs model of the region. Our models show high P -wave velocities (6.5 km s⁻¹) beneath the axis of the rift at a depth of 12–25 km. The presence of high Vp / Vs ratios (1.81–1.84) at the same depth range suggest that they are cooled mafic intrusions. The high Vp / Vs values, along with other geophysical evidence, suggest that dyking is pervasive beneath the axis of the rift from the mid-crustal depths to the surface and that some portion of partial melt may exist at lower crustal depths. Although the crustal stretching factor across the Main Ethiopian Rift is ∼1.7, our results indicate that magma intrusion in narrow zones accommodates a large proportion of extensional strain, with similarities to slow-spreading mid-ocean ridge processes.     

Magnetic storm acceleration of radiation belt electrons observed by the Scintillating Fibre Detector (SFD) onboard EQUATOR-S

On the basis of the currents induced by electron fluxes in the Scintillating Fibre Detector (SFD) onboard the EQUATOR-S satellite launched on 2 December 1997, an in-situ acceleration of radiation belt electrons is found to possibly contribute to the increase of the flux of electrons with energies greater than 400 keV. The data acquired between 16 December 1997 and 30 April 1998 on the 500–67300 km, 4° inclination EQUATOR-S orbit show that the increase of the energetic electron flux corresponds to the enhanced geomagnetic activity measured through the Dst index.     

Introduction to the special issue of Meteoritics & Planetary Science on the Winchcombe meteorite

This issue of Meteoritics & Planetary Science celebrates the science of the Winchcombe meteorite, which fell to Earth on the 28th February 2021 close to the town of Winchcombe, Gloucestershire in the UK.     

The Winchcombe fireball—That lucky survivor

On February 28, 2021, a fireball dropped ∼0.6 kg of recovered CM2 carbonaceous chondrite meteorites in South-West England near the town of Winchcombe. We reconstruct the fireball's atmospheric trajectory, light curve, fragmentation behavior, and pre-atmospheric orbit from optical records contributed by five networks. The progenitor meteoroid was three orders of magnitude less massive (∼13 kg) than any previously observed carbonaceous fall. The Winchcombe meteorite survived entry because it was exposed to a very low peak atmospheric dynamic pressure (∼0.6 MPa) due to a fortuitous combination of entry parameters, notably low velocity (13.9 km s⁻¹). A near-catastrophic fragmentation at ∼0.07 MPa points to the body's fragility. Low entry speeds which cause low peak dynamic pressures are likely necessary conditions for a small carbonaceous meteoroid to survive atmospheric entry, strongly constraining the radiant direction to the general antapex direction. Orbital integrations show that the meteoroid was injected into the near-Earth region ∼0.08 Myr ago and it never had a perihelion distance smaller than ∼0.7 AU, while other CM2 meteorites with known orbits approached the Sun closer (∼0.5 AU) and were heated to at least 100 K higher temperatures.     

Recent Trends in Rainfall-Runoff Characteristics in the Alzette River Basin, Luxembourg

The effects of rainfall structure and atmosphericcirculation variability on streamflow in the AlzetteRiver basin (Grand Duchy of Luxembourg, Europe) wereinvestigated. Evidence is presented regarding the local-scalesensitivity of the Alzette River basin to large-scalechanges in atmospheric circulation. Since the1950s, there has been a marked increase in thecontribution of the westerly component of atmosphericcirculation to rainfall. These changes in atmosphericcirculation are on a par with an increase in rainfallintensity and duration, which has induced a significantincrease in the winter maximum daily storm flow in theAlzette River basin since the 1970s.     

Shock metamorphism in plagioclase and selective amorphization

Plagioclase feldspar is one of the most common rock‐forming minerals on the surfaces of the Earth and other terrestrial planetary bodies, where it has been exposed to the ubiquitous process of hypervelocity impact. However, the response of plagioclase to shock metamorphism remains poorly understood. In particular, constraining the initiation and progression of shock‐induced amorphization in plagioclase (i.e., conversion to diaplectic glass) would improve our knowledge of how shock progressively deforms plagioclase. In turn, this information would enable plagioclase to be used to evaluate the shock stage of meteorites and terrestrial impactites, whenever they lack traditionally used shock indicator minerals, such as olivine and quartz. Here, we report on an electron backscatter diffraction (EBSD) study of shocked plagioclase grains in a metagranite shatter cone from the central uplift of the Manicouagan impact structure, Canada. Our study suggests that, in plagioclase, shock amorphization is initially localized either within pre‐existing twins or along lamellae, with similar characteristics to planar deformation features (PDFs) but that resemble twins in their periodicity. These lamellae likely represent specific crystallographic planes that undergo preferential structural failure under shock conditions. The orientation of preexisting twin sets that are preferentially amorphized and that of amorphous lamellae is likely favorable with respect to scattering of the local shock wave and corresponds to the “weakest” orientation for a specific shock pressure value. This observation supports a universal formation mechanism for PDFs in silicate minerals.     

Constraining the links between the Himalayan belt and the Central Myanmar Basins during the Cenozoic:An integrated multi-proxy detrital geochronology and trace-element geochemistry study

Geological and tectonic analysis of the Eastern Himalayan basins has given rise to a decade-long debate on the geodynamic evolution of the Burmese terrane and on the extent of reorganization of the main SE Asia drainage systems.However,the influence of the Himalayan belt on the Central Myanmar Basin(CMB)system remains poorly documented,although it is key to providing more accurate models for the evolution of the Himalayan-Burmese orogen.In this contribution,we present geochronological,isotopic and geochemical analysis from 2500 zircon,1700 titanite,700 rutile and 850 apatite detrital grains from fifteen Cenozoic siliciclastic samples and one Cretaceous igneous rock.The samples were collected within the fore-and back-arc basins of the Central Myanmar Basin domain(CMB)to constrain the provenance,maximum depositional ages,and depositional environments of the west Burma terrane.Nine key lithological units,the Sadwingyi,Ketpanda,Wabo Chaung,Gwegon,Minwun,Padaung,Okmintaung and Irrawaddy formations have detrital age spectra spanning from the Miocene to Paleoarchean.The entire data set has common age peaks at ca.20,40,60,90,100 Ma,with about 80%of the U–Pb ages younger than ca.140 Ma and only ca.1%of the grains predating ca.3.0 Ga.Our results shed light on the current ambiguities on the transport pathways of Himalayan detritus in the CMB.They show that the fore-arc basin was open to the trench and fed by the unroofing of both the Wuntho Popa volcanic arc to the east and possibly from the Burmese basement and/or from Himalayan-derived Bengal Fan detritus to the west during the Eocene,from at least ca.44 Ma to before ca.39 Ma.We show that the west Burma Terrane was partitioned into pull-apart basins such as the Minwun Basin,which during the Oligocene recorded the first evidence of a new source contribution into the CMB at ca.27 Ma.This new source is characterized by detritus highly compatible with the SE Asia basement rocks,which we suggest corresponds to the initiation of the palaeo–Irrawaddy River.This geodynamic evolution does not require any Yarlung Tsangpo-Irrawaddy-Brahmaputra paleodrainage reorganization,since from the Oligocene to the Early Miocene,the Irrawaddy River fed an internally drained basin,and from the Late Miocene onwards,the Yarlung drained into the Brahmaputra in the Bengal Basin.