The available Bayesian European Palaeosecular Variation Curves (PSVC) based on archaeomagnetic data have been used to derive an initial regional model for the geomagnetic field in Europe for the last 2000 years by using the Spherical Cap Harmonic Analysis (SCHA) technique. The resulting SCHA.DI.00 model provides the directional behaviour of the Earth’s magnetic field, but no information about intensity is supplied because input data are only directional. The first spherical cap harmonic coefficient, , has been used to normalise the rest of the coefficients. The spherical expansion extends up to Kint = 2 which, given the size of the spherical cap used and the maximum data resolution, is equivalent, in terms of spatial wavelength, to a maximum degree of approximately 5 in the ordinary Spherical Harmonic Analysis (SHA). The SCHA.DI.00 model fits the present archaeomagnetic database for Europe more accurately than global models, although it is necessary to consider that regional SCHA model and global models did not use the same database. Palaeosecular variation curves given by SCHA.DI.00 are compared with available archaeomagnetic data from Bulgaria (Sofia), Italy (Etna) and Austria (Radstadt), not used in the development of the model. The SCHA.DI.00 model improves the fit to these palaeomagnetic data with respect to the CALS7K.2 [Korte, M., Constable, C.G., 2005. Continuous geomagnetic field models for the past 7 millennia: 2. CALS7K. Geochem. Geophys. Geosyst. 6, Q02H16. doi:10.1029/2004GC000801] global model, especially for Italy.
The behavior of electrotelluric time series associated to an Ms=7.4 earthquake occurred in September 14, 1995 in Mexico has been studied by means of several nonlinear tools [Seismo Electromagnetics: Lithosphere–Atmosphere–Ionosphere Coupling, 2002, p. 99; Seismo Electromagnetics: Lithosphere–Atmosphere–Ionosphere Coupling, 2002, p. 107]. In this work we present a statistical study of spectral exponent β and the correlation time τ of time series recorded during almost two years. Although our measuring procedure may introduce noise, the analysis shows interesting results which suggest that the preparation, occurrence and relaxation processes could be characterized by means of those parameters. Both β and τ, exhibit evident changes during the different phases of the seismic process suggesting a possible seismic precursor phenomenon.
A case study has been performed on the lower ionospheric perturbations as seen from the Japanese subionospheric VLF (very low frequency, 3–30 kHz) /LF (low frequency, 30–300 kHz) propagation network for a recent powerful earthquake, i.e., the Miyagi-oki earthquake on 16 August 2005 (magnitude 7.2, and depth 36 km). Different propagation paths were examined and the two paths from a transmitter with call sign of JJY (f = 40 kHz, in Fukushima prefecture) to both receiving stations of Kamachatka, Russia and Moshiri, Hokkaido, exhibit clear signatures of ionospheric perturbations a few days before and a few days after the earthquake. We have detected a clear nighttime amplitude decrease and an enhancement in nighttime fluctuation, both exceeding the corresponding three standard deviations from the mean. We discuss other seismogenic phenomena in order to study the lithosphere–ionosphere coupling.
Prior to the 17-1-1983 event, the seismicity of the broader area of the Ionian islands and western Greece exhibited several phenomena interpretable in the context of a self-organised critical system with long range interactions. The regional seismic energy release exhibited power law acceleration towards the time of rupture, the numerical modelling of which yields a time-to-failure of 1983.1 ± 0.2. Time dependent changes were also observed in the b-values, assuming the form of monotonic increase that promptly reversed after the earthquake. This indicates the induction of instability to the region due to the earthquake preparation process, which is consistent with the critical point earthquake model. The critical point model predicts that failure is a co-operative effect occurring at small scale, and cascading from the microscopic to the macroscopic scale. This involves a crack propagation avalanche at the terminal phase of the seismic cycle, the time function of which has been modelled with a limited class of characteristic transient bay-like shapes, featuring a corner frequency and inverse power energy distribution law. Electrification processes due to crack propagation may generate an electrical precursor with similar characteristics. Such a potential precursor has been observed independently on 15-1-1983, approx. 120km from the epicentre. In consequence of our observations, we discuss a model relating seismicity and electrical precursors.
Nothing indeed demonstrates more forcefully the extent to which Dutch water management corresponds to the nature and the needs of the Dutch people and their land, and how it has emerged there from in a natural fashion than the fact that the revolutionaries of 1795, despite being so intoxicated by their unexpected victory and sudden power that they overturned everything … nonetheless refrained from laying hands on institutions whose extreme antiquity would in those days have provided more of an excuse to abolish than to preserve them (J.W. Welcker, De Noorder-Lekdijk Bovendams en de doorsteking van den Zuider-Lekdijk bij Culemborg 1803–1813. Een bijdrage tot de geschiedenis van den Nederlandschen Waterstaat geschetst en met onuitgegeven stukken toegelicht (‘s-Gravenhage: 1880), p. 2).
In this paper, the author wants to explore the knowledge development in two crucial fields, river management and coast management in the 19th century and first decades of the 20th century. Were there similar characteristics in this development? Which types of knowledge can be distinguished? Who were the principal actors in these processes? Did the knowledge evolution have a Dutch stamp or a rather international flavour?To structure the analysis, the author uses the concept of technology regime, a set of technical rules which shapes the know-how of engineers, their design rules and research processes. The analysis shows that the knowledge development of river management and coastal management followed different evolution paths between 1800 and 1940. In the field of river management, a substantial amount of mathematical and physical theories had been gradually developed since the end of the 17th century. After 1850, the regularization approach met gradually a widespread support. Empirical data, design rules, theoretical knowledge and engineering pivoted around the regularization approach, and a technology regime around this approach emerged. The regularization regime further developed in the 20th century, and handbooks were increasingly shaped by mathematical and physical reasoning and formulas. On the other hand, coastal management was until the 1880s a rather marginal activity. Coastal engineering was an extremely complex and multidimensional field of knowledge which no engineer was able to grasp.The foundation of a Dutch weather institute was a first important step towards a more theoretical approach. The Zuiderzee works (starting in 1925) gave probably the most important stimuli to scientific coastal research. It was also a main factor in setting up scientific institutes by Rijkswaterstaat. So from the 1920s, Rijkswaterstaat became a major producer of scientific knowledge, not only in tidal modelling but also in coastal research. Due to a multidisciplinary knowledge network, coastal research transformed from a marginal to a first-rank scientific field, and this transformation enabled Rijkswaterstaat to set a much higher level of ambition in coastal management. The 1953 flood and the Deltaworks marked a new era. New design rules for sea dykes and river levees, based on a revolutionary statistical risk approach were determined, and design rules for the Deltaworks estuary closures were developed, being enabled by the development of hydraulic research.
This paper demonstrates that the historical dynamism of the Dutch river Meuse in the period 1839–1925 cannot possibly be understood exclusively from a political, economical or hydraulic angle. Although all these categories are essential in the analysis, the fact that the large-scale improvement of this river was accompanied by such emotions, incomprehension and mistrust about the way in which the Dutch government handled this hydraulic problem in a peripheral province – that nationally and culturally differed very considerably from the centre of the nation state in the Northern Netherlands – calls for a broader-based approach. The first indictor for this explanation can be sought in theoretical understanding of nationalism and its historiography in general, and the course of Dutch state and nation forming and the construction of national and regional identities in particular. Taking this as the analysis framework, we have demonstrated that the struggle to improve the Meuse in Limburg not only involved the political, hydraulical and economic dimensions already referred to, but also encompassed a cultural dimension. A dimension that can best be described as an integration problem in the framework of state and nation forming and as part of a more extensive field of tension between the provincial stakeholders and the government, which contributed to the forming a of a regional Limburg identity.
Many moderate events reported by Italian earthquake catalogues (either historical or recent) are listed with an epicentral intensity derived from intensitymagnitude relationships or evaluated based on preliminary sources. Contradictions may arise among different catalogues when the effects of a given earthquake are not assessed through a specific macroseismic study as each catalogue generally uses its own criteria for evaluating the intensity. In this paper we present the case of the June 19 1975 earthquake, a ML = 5.1 (ING seismological bulletin) event that occurred in the Gargano area (southern Italy). The intensity reported by the ING catalogue is VIII MCS (estimated from magnitude), that reported by the NT4.1 catalogue is VI MCS, while the PFG catalogue does not report an intensity. The case of this event is well representative of a period during which macroseismic studies were not undertaken systematically in Italy. In this paper we reassess the macroseismic intensity of this event using procedures implemented and routinely used at ING.
Twenty Largemouth yellowfish Labeobarbus kimberleyensis (Gilchrist and Thompson, 1913) were collected in the Vaal Dam in the vicinity of RAU Island (Groot Eiland). Muscle-, spinal cord- and liver tissue were removed from each fish and the intestine opened to obtain Bothriocephalus acheilognathi. The tissues were then digested in a microwave digester and the metal concentrations were determined in each tissue with an ICP-MS. The results indicate that the worms have potential use as bioindicators, because in 8 elements (lithium, beryllium, manganese, selenium, mercury, thallium, lead and uranium) out of the 23 elements measured the cestodes have accumulated the highest metal concentrations, and in 7 elements (chromium, iron, zinc, molybdenum, cadmium, tin and barium) out of 23 elements the cestodes had the second highest metal accumulation recorded.
The management of the Rhine is often seen as an exemplary case of international river basin management. In the Rhine basin, countries that went to war with each other twice in the last century have managed to reach agreements on many issues and water quality has improved considerably. The improvement in water quality is often attributed to the activities of the International Commission for the Protection of the Rhine and in particular to its Rhine Action Plan. In order to test this assertion, this paper describes and analyzes the development of international co-operation on the water quality of the Rhine since 1945. It concludes that water quality improvement cannot be attributed to any single factor. Instead, a whole array of interrelated factors are at play, including the European Union, other international fora such as the North Sea Ministerial Conferences, domestic legislation, the activities of environmental NGOs and waterworks, growing environmental awareness, and the changing structure of the industry in the basin. Because of the importance of contextual factors, the Rhine experiences cannot simply be applied to basins with a different context. In many cases, international river basin management may be promoted most effectively by promoting co-operation at the river basin level. In many other cases, however, it may be more effective to identify and then work on the contextual factors that (1) have the biggest leverage effect in the specific case and (2) can be influenced most effectively.
The present work describes a 44-year integration of a two dimensional sea level model forced by atmospheric pressure and wind over the Mediterranean Sea. As an output of such long-term hindcast a sea surface residual database containing storm surge events was created. Storm surge is a critical parameter in different kinds of studies, from harbor design to coastal dynamics. This work focuses on studying the regional evolution of the atmospheric forcing contribution to the residual sea surface variation. Modeling sea level residual in the Mediterranean Sea is of particular interest because the response of the sea to the atmospheric forcing may be important in comparison to the tidal amplitudes. The integration was performed by means of the HAMSOM numerical model in a barotropic mode. Hourly HIPOCAS hindcast wind and atmospheric sea level pressure fields were used to force the sea level model. These forcing fields were generated by dynamical downscaling from the NCEP/NCAR global reanalysis through the atmospheric REMO model. Measured residual sea surface is well reproduced by the model with a coefficient of correlation of the order of 0.82 at various Spanish harbor locations. On the other side, the study of the climatological sea surface elevation shows that the Mediterranean Basin has undergone negative trends over the past 44 years: a mean negative rate of −0.8 mm/yr is found in the central basin and extreme values as large as −2.0 mm/year in the Adriatic Basin.
The paper proposes a classification of deep cyclones determining the weather in Poland grouped according to their track. The study used data from NCEP/NCAR reanalysis spanning the period 1971–2000. The analysis considered: values of 1000 hPa geopotential height at 12 UTC recorded at selected grid points, maps of 1000 and 500 hPa geopotential height and maps of sea-level air-pressure field at 12 UTC.Seven groups of deep cyclones were identified. The dominant groups involved cyclones originating over the North Atlantic and crossing over Iceland (T2 = 29.3%), and those moving from west to east, typically over the British Isles (T3 = 26.8%). Other large groups of cyclones involved systems travelling from the Mediterranean towards north-eastern Europe (T7 = 10.5%), and those moving from the Norwegian Sea though the Baltic Sea into northern and north-eastern Europe (T1 = 8.4%).Cyclones, with air pressure ranging from 940 to 1000 hPa, were found to have different levels of influence depending on the region. Most of the systems were recorded between October and March (86.4%), but isolated cases were also observed in summer. No statistically significant long-term trends in their occurrence were identified.
This paper describes an extraordinary tsunami-like event that occurred on 21 June 1978 that encompassed the middle and south Adriatic Sea. The flood had its culmination in Vela Luka, where a maximum wave height of 6 m was reported. This paper contains a detailed description of the event as seen by eyewitnesses, its outreach along both the eastern and western coasts, and the aftermath and recovery activities in Vela Luka. All available records have been collected and analysed to detect the source and the generating mechanism of the long ocean waves. Seismic generation is fully excluded from the consideration, while a submarine landslide seems rather unrealistic as it does not explain the characteristics of the measured ocean waves. Therefore, the source of the event was presumably in the atmosphere, where a travelling disturbance was detected that had the capability to resonantly transfer energy to the ocean via the Proudman resonance mechanism. Although these data prove the proposed mechanism, the final confirmation for such a scenario should come from a process-oriented numerical modelling study.
In this paper, a relationship between M ⩾ 5.0 earthquakes and diurnal variations of the total geomagnetic field recorded at eight magnetometers in Taiwan during 1988–2001 are examined. One magnetometer station was setup in a seismic quiet area as a reference, while the others were located in areas of high seismicity or crustal activity observing earthquake effects. We compute the distribution of diurnal range ratios between the reference and each observation station for the entire thirteen years as a background and compare it with the monitored distributions during five different time periods before and after an M ⩾ 5.0 earthquake occurring within a distance of 50 km from the observation station. Three specific earthquakes with different magnitudes, including the M = 7.3 Chi–Chi earthquake show that the monitored distributions one month before and during the month of the earthquakes significantly depart from the associated background. It is found that changes of underground conductivities and currents around the forthcoming epicenter significantly affect the near-by geomagnetic field on the ground during the earthquake preparation period. The statistical results demonstrate that the monitored distributions of geomagnetic anomalies are highly related to the focal mechanism.
The Avene flood, with a peak discharge between 600 and 900 m3/s for a drainage area of 57 km2, appears as one of the most important flash floods reported in the French Mediterranean area during the last decades for similar catchment areas. The watershed is ungauged and interviews were conducted to gather valuable information about the flood sequence. Most of the collected data seems reliable. These data indicate that the swelling of the Avene river was sudden and late compared to the measured rainfall sequence. The flood appears to have been mainly produced by surface runoff. Moreover, the late response of the watershed shows that its thin soils, dried out during the preceding summer period, had surprisingly high infiltration rate and capacity: estimated about 100 mm/h and 200 mm respectively.
The scanning low frequency microwave radiometer (SLFMR) was used to map surface soil moisture (0–5 cm depth) during the Southern Great Plains 1997 (SGP97) hydrology experiment. On June 29, July 2, and July 3, surface soil moisture maps with a pixel resolution of 200 m were obtained using a soil moisture retrieval algorithm, developed for L-band (1.4 GHz frequency, 21 cm wavelength) passive microwave data. In comparison with the 800 m resolution data from the electronically scanned thinned array radiometer (ESTAR), the higher resolution SLFMR data required a more site specific calibration. After calibration root mean square difference (RMSD) between model and observed surface soil moisture observations were on the order of 5%. Although the higher pixel resolution generally provided brightness temperatures of individual fields, it is also meant the greater spatial variability in land cover properties (primarily vegetation cover) were affecting the microwave observations and had to be accounted for in the soil moisture algorithm. Parameters in the soil moisture algorithm required local recalibration, particularly for the heavily vegetated fields, in order to account for vegetation effects on the microwave brightness temperatures. Thus having microwave data at resolutions that differentiate field boundaries with sharp contrasts in vegetation cover amounts will likely require greater variation in parameter values (and more uncertainty) be assigned to the soil moisture algorithm than at coarser resolutions. This result indicates that parameter values in the soil moisture algorithm may be resolution dependent under certain land cover conditions, particularly at resolutions that discriminate field boundaries.
Previous studies on Spitak, Loma Prieta, and Guam earthquakes indicate that large earthquakes were accompanied by preceding magnetic anomalies. In order to confirm these facts and to investigate ULF phenomena in details, a network of ULF magnetometers has been installed in Japan. Network observations including small arrays have been carried out. Also, the geomagnetic data observed at Matsukawa station associated with Iwateken Nairiku Hokubu earthquake (M6.1, September 3, 1998, depth 10 km) are presented. 4.5 years data have been analyzed and the obtained result is discussed. The variation of spectral density ratio between the horizontal and vertical components (polarization) exhibits an anomalous behavior two weeks before the earthquake. This is a unique change discovered from the rather long-term analysis, which suggests that this anomalous change might be a possible signal associated with the earthquake preparation phase.
Satellite thermal infrared (TIR) imaging data have recorded short-lived anomalies prior to major earthquakes and associations with fault systems. Others have proposed that these signals originate from electromagnetic phenomena associated with pre-seismic processes, causing enhanced IR emissions, that we are calling TIR anomalies. The purpose of this exploratory study is to verify if TIR anomalies can be found in association with known earthquakes by systematically applying satellite data analysis techniques to imagery recorded prior-to and immediately after large earthquakes. Our approach utilizes both a mapping of surface TIR transient fields from polar orbiting satellites and co-registering geosynchronous weather satellites images. The significance of these observations was explored using data sets of recent worldwide strong earthquakes (1999–2003) and the techniques used to capture the trace of TIR anomalies.
This paper presents a brief summary of several types of precursors in the lithosphere, atmosphere and ionosphere that have been positively identified in relation to the 20 September 1999 Mw 7.6 Chi-Chi earthquake and its aftershocks under the iSTEP Program.
One year of aerosol size distribution and chemical composition measurements conducted at the Zeppelin station on Svalbard (78° 58′ N and 11° 53′E) is presented. The data, which cover the period March 2000–April 2001, show a very strong seasonal dependence of the number mode particle size. The transition from one seasonal characteristic regime to the other occurs rapidly and takes place over only a few days. As expected, the largest integrated aerosol surface and particle volumes are observed during the Arctic haze period in spring. On a seasonal scale the total number density covariate with the incoming solar radiation, which points to photochemistry as an important component during new particle formation in the Arctic summer. However, maximum number densities are observed during the second part of the summer concurrent with a relative reduction in the incoming radiation. The onset of this period of enhanced particle number densities coincides in time with the surface temperature remaining steadily above the freezing point and the melting of the snow cover. A similar transition occurring over the Siberian tundra is proposed as a potential source of aerosol precursor gases, which could explain the enhanced particle number densities during the second half of the summer. A second maximum of ammonium in particles during late summer and fall, concurrent with a reduction in sea salt and nss-sulfate present in particles would be consistent with continental source without a significant anthropogenic component. The data presented in the study also illustrate the usefulness of measurements that extend over several seasons where phenomenon that occur with in one season, the summer in this case, can be put into context.
In order to extract any ULF signature associated with earthquakes, the singular spectral analysis (SSA) and the principal component analysis (PCA) have been performed to investigate a possibility of discrimination of signals from different sources (geomagnetic variation, artificial noise, and the other sources (earthquake-related ULF emissions)). We apply SSA to the time series data observed at closely spaced stations; Seikoshi (SKS), Mochikoshi (MCK), and Kamo (KAM) stations. Then, PCA is applied to the time series data sets filtered at 0.01 Hz of NS component at three stations. In order to remove the most intense signal like the first principal component, we make the differential data sets of SKS–MCK and MCK–KAM for the above data. The major findings are summarized as follows. (1) It is important to apply simultaneously SSA and PCA, because SSA gives the structure of signals and the number of sensors for PCA is estimated. This makes the results more convincing. (2) There is a significant advantage using PCA with differential data sets of filtered (0.01 Hz band) signal between SKS–KAM and MCK–KAM in NS component for removing the most intense signal like global variation (solar–terrestrial interaction). This yields that the anomalous changes in the second principal component were detected more clearly, and the contribution of the second principal component is found to be 20–40%. It is enough to prove mathematical accuracy of the signal. Further application is required to accumulate events. These facts demonstrate a possibility of monitoring the crustal activity with using the SSA and PCA.
Lake Balaton has the largest freshwater surface in Central Europe. The water budget of this shallow water body is characterised in most of the years with significant water excess, expressed in regular releases from the Lake through a partly artificial stream, Sio. Unexpectedly, negative annual values of natural water budget occurred in the period 2000–2003, virtually without any release from the lake following May 2000. This happened first time since 1921, i.e. the start of instrumentally measured water budget elements. The extreme situation has been manifested by quick drop of water levels. Water levels recovered during 2004, but the first release through control gates could be started only in September 2005. Components of the water budget are compared with the normal situation, and different exceedance probabilities, based on the previous 80 years. Besides the given analysis, an attempt is made to answer the question in the title by presenting a quantitative methodology and three parallel macro-circulation classifications. The lack of precipitation during the 4-year period could not be sufficiently explained by shifted frequency of the circulation types combined by conditional average precipitation. However anomalous behaviour of meso-scale processes strongly contributed to the given extreme situation, endangering not only tourism of the lake, but its flora and fauna.
Electromagnetic phenomena associated with large earthquakes have been investigated to establish any method to monitor the crustal activity such as earthquakes and volcanic eruptions. The ULF geomagnetic approach is considered to be one of the most promising methods for the imminent prediction. In this paper, a new method of principal component analysis (PCA) has been applied to the ULF geomagnetic data associated with 2000 Izu Islands earthquake swarm. This swarm activity started on June 26, 2000 and terminated in September, 2000, and during this activity there were observed 5 large earthquakes whose magnitude was grater than 6 (July 1, 8, 15, 30, and August 18). During this period our ULF stations were fortunately in operation, and there are three stations closely distributed (about 5 km distances). The epicentral distances are about 80–100 km. The PCA has been applied to the ULF horizontal NS component, because we can distinguish a few noises sources based on the orthogonal decomposition in the PCA. We investigate the temporary variations of eigenvalues and eigenvectors of PCA results, and the results are summarized as follows. The first principal component is found to be the signal originated in the solar–terrestrial effects such as geomagnetic pulsation. The variation of eigenvector for the first principal component suggests that this signal is very stable over the whole analyzed period. As for the second principal component, the local artificial noise is included. As for the smallest third component in the local midnight at the Izu Peninsula, it indicated an apparent increase in the third eigenvalue a few days before the large earthquakes. Also about three months before the beginning of swarm activity, the level of the third eigenvalue was slightly enhanced. Correspondingly, the pattern of eigenvector direction in the signal subspace is changed simultaneously and it recovered to the original position after the swarm activity. These features are likely to be correlated with large earthquakes. Finally we want to emphasize that PCA approach is promising for monitoring the crustal activity.
Telemetric observations of pulse-like geoelectric signals induced in a vertical buried dipole at Erimo in Hokkaido, Japan reveal the occurrence of anomalous signals associated with precursor activity to the 2000 Mt. Usu eruption and 2003 Tokachi-Oki earthquakes. The anomalous signals, at least 10 times stronger than the usual background level, are free of contamination due to meteorological or anthropological noise. These geoelectric signals are hypothesized to occur due to electrostatic coupling as a synergetic effect of thermal stimulated exoelectron emission and the release of gas trapped in rock at depth in the precursor stage of major activity.
This paper measures the scientific impact of two regional water resources capacity building programmes in Southern Africa: WaterNet and WARFSA. The articles emanating from the annual symposia organised jointly by both programmes during the period 2001–2005 and published in special issues of Physics and Chemistry of the Earth were analysed in terms of numbers and citations. The paper concludes that these articles represent a significant portion of all published articles covering similar topics. Moreover, these articles were also frequently cited, on average, approximately 0.8 times during the two year period after their publication. This is positive evidence of the scientific impact that the capacity building programmes are having. The data presented in this paper provide a useful baseline for measuring success in the coming years.
The extraordinary meteorological conditions of summer 2003 provide a singular case of study of the response of vegetation to drought under conditions that are similar to what is expected by some scenarios to be a normal summer by the latter decades of the 21st century. After collecting climatic and meteorological information to produce monthly fields of mean temperature, precipitation and precipitation deficit (as the difference between precipitation and potential evapo-transpiration), we have analyzed a monthly series of fields of normalized difference vegetation index (NDVI). Our results indicate strongly negative anomalies of satellite NDVI: a 25% of the area covered by herbaceous vegetation had a relative anomaly of NDVI in August lower than −17%, while the equivalent value for deciduous forests was −11%. Geographically, the most affected area was located to the SE of a diagonal line crossing France from SW to NE. As low values of NDVI in August indicate early leaf withering, some deciduous forests experienced a serious reduction of the number of valid days for photosynthesis.
Anomalous ULF geomagnetic field change is considered to be one of the most convincing and promising phenomena among earthquake-related electromagnetic effects, because we expect emissions from the crust of the source region. There has been a great deal of accumulated and convincing evidence of ULF magnetic signatures before large earthquakes as reported in the previous studies. In order to verify these phenomena preceding large earthquakes and to clarify the relationship between electromagnetic phenomena and possible physical mechanism, we have investigated the data of ULF geomagnetic observations at Kototabang and Biak stations associated with the 2004/2005 Sumatra earthquakes. A case study is carried out in this work to investigate the pre-earthquake ULF geomagnetic anomalies during the Sumatra–Andaman earthquake on December 26, 2004 (magnitude Mw = 9.0 and depth = 30 km from USGS catalog), and Sumatra–Nias earthquake on March 28, 2005 (Mw = 8.7 and depth = 30 km). For the aim of finding any precursors, we have adopted the spectral density ratio analysis and transfer functions analysis based on wavelet transform method. Results of the spectral density analysis indicate similar variations to those of amplitude for the induction arrow in transfer function analysis. Both of these variations at Kototabang exhibit strange or anomalous changes from a few weeks before the Sumatra–Andaman earthquake to July 2005, while there are no apparent changes at remote station of Biak. To make these results more convincing, the fractal analysis based on a Higuchi method has been applied to the same observed data, which also show a significant change (or decrease) in mono-fractal dimension a few weeks before the earthquakes. This result would lend a further support to those by the spectral density ratio and transfer function analyses. So, we can conclude that the anomalous change as observed simultaneously by the three methods, might be a possible signature related with the earthquake preparation phase of Sumatra earthquakes.
We have carried out the observation of ULF/ELF electromagnetic waves below 50 Hz at Nakatsugawa (in Gifu Prefecture in Japan) with three component induction coil antennas (the permalloy of 1.2 m length with 1,00,000 turns of the copper wire) since 1998. We have observed the excitation of anomalous resonances possibly associated with earthquakes at Nakatasugawa station. In this paper, we analyzed the anomalous strong Schumann resonance and an additional anomalous resonance observed before the 2004 Mid-Niigata Prefecture earthquake and the 2007 Noto Hantou earthquake. The intensity of a particular mode of the Schumann resonance increased before the large earthquake near the observation station, and decreased after the occurrence of earthquake. An excitation of another anomalous resonance was also observed at the frequency shifted by about 2 Hz from the typical frequency of the Schumann resonance. Since the temporal changes of the intensity of the anomalous Schumann resonance and another excited anomalous resonance were almost the same, there is a possibility that another anomalous resonance was related with the Schumann resonance. However, we need to consider a more convincible generation mechanism of anomalous resonances.
Employing a GPS receiver we have monitored ionospheric total electron content (TEC) at Agra (Geographic Lat. 27.2°N, Long. 78°E), India since 24 June, 2006. In this paper we have analysed 15 months of data for the period between 01 September, 2006 and 30 November, 2007 statistically. The results show anomalous depletions and enhancements which are examined in the light of magnetic storms and earthquakes. As magnetic conditions have remained quiet throughout the period of data except some sporadic cases, majority of the TEC anomalies are interpreted as due to earthquakes. We find that out of 43 cases of moderate and high magnitude earthquakes (M ⩾ 5.0) there are 23 cases in which both depletions and enhancements occurred and in the remaining 17 cases (no data available in three cases) either of enhancement or depletion occurred. In general the anomalies occurred 0–9 days before the earthquakes as precursors. The correlation coefficient of 0.8 is found between the two sets of data which satisfy null hypothesis. A mechanism responsible for TEC anomalies under the influence of earthquakes is discussed also.
Six microsatellites termed Formosa Satellite 3 and Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC or F3/C in short) are employed to study the 3-D structure of the ionospheric electron density during two M7.0 offshore earthquakes occurred near Pingtung, the most south county of Taiwan, on December 26, 2006. Results show that around the epicenters the F2-peak height descends and the ionospheric electron density between 300 and 350 km altitude significantly decreases within 5 days prior to the earthquakes.
The Solomon Islands earthquake with magnitude Mw = 8.1 occurred on 2 April 2007 at 7:39 local time. We used six L-band Synthetic Aperture Radar (SAR) images acquired by the Advanced Land Observing Satellite (ALOS) Array L-band Synthetic Aperture Radar (PALSAR) data to roughly estimate the shoreline and vertical displacements associated with this earthquake. We processed the raw SAR data with the SIGMA-SAR software package, produced by Japan Aerospace Exploration Agency (JAXA). Our measurements showed good agreement with field observations performed by Japanese scientists just a few weeks after the earthquake. We estimated the dislocation related to this earthquake between Ranongga Island and Simbo Island. Moreover, we compared the radar imagery analysis data with Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and found that the SAR images were more efficient for investigating vertical displacements than similar techniques based on data from optical sensors. Measurements of offset cross-correlation intensities in SAR images indicated about 1.4 m of uplift on southwestern New Georgia Island.
High-volume aerosol particle samples have been collected onto glass fibre filters at Ny-Ålesund, Svalbard. The filters have been assayed for 210Pb by measuring the alpha particles of its in-grown daughter nuclide 210Po. The observed 210Pb activity concentrations at Mt. Zeppelin, Ny-Ålesund, Svalbard vary between 11 and 620 μBq/m3 in 2001. The 25%, 50%, and 75% percentiles of the 210Pb activity concentrations at Mt. Zeppelin are 42, 83, and 220 μBq/m3. The values are clearly lower than at Sodankylä, northern Finland with corresponding values of 100, 170, and 270 μBq/m3. The arithmetic mean concentrations in 2001 were 144 and 245 μBq/m3 at Ny-Ålesund and Sodankylä, respectively.The lowest 210Pb activity concentrations are found during summer both at Svalbard and in Finland. The highest concentrations occur in March–April at Svalbard. This differs from the seasonal behaviour of 210Pb in Finland, where the highest concentrations are usually observed in February–March. This 1-month difference between Svalbard and Finland may be related to the strength of solar radiation and its capability to cause vertical mixing of the air. Air mass back trajectory analysis shows that the lowest concentrations found at Svalbard are associated with air masses coming from the North Atlantic Ocean, Greenland and the Canadian Arctic. The highest concentrations are associated with air masses originating from northern Europe and Siberia, and during winter also in air masses coming from the central Arctic Ocean.
Two key questions concerning geological disposal of high-level radioactive waste are (i) how robust is the barrier system during long term disturbances and (ii) do we know the possible disturbances well enough? One step towards answers is to study how groundwater flow systems have behaved in the past. Studying naturally occurring radioactive tracers in groundwater offers useful information. Uranium isotopes 234U and 238U are oft-used tracers. A characteristic of the 234U/238U activity ratio (AR) is its considerable variation in groundwater. It is known that the reason for variation is isotopic fractionation at the rock–water interface. However, the reason why AR varies in groundwater is not clear. We tried to answer this question by carefully examining the geochemical and nuclear chemical origins of U isotopic fractionation and by studying a large body of U data from Finnish and Swedish investigation sites. We found that despite large variations in AR and U concentrations, the respective 234U and 238U activities show a correlation which contains useful information of the flow system behaviour which is in line with other hydrochemical data.
This paper presents a mathematical model, an asymptotic theory and an appropriate numerical algorithm to study, in the scalar approximation, VLF point source field propagation problem within the non-uniform Earth-ionosphere waveguide. We have taken into account a 3D local ionospheric inhomogeneity over the ground of the solar terminator transition. The local ionospheric perturbation whose centre is situated above the model earthquake, is simulated by a bell-shaped impedance inhomogeneity of the ionospheric waveguide wall. The ionosphere model parameters are computed with allowing for the geomagnetic field. Our numerical results show that the inclusion of the local ionospheric inhomogeneity in the radio wave propagation across the solar terminator path deforms the diurnal variations of field amplitude and phase in accordance with the observational data.
The spatial distribution and properties of parent material components form the starting point for any soil and ecosystem. Initial phases of ecosystem development are predominantly characterized by the redistribution of sediment components. To improve the understanding of soil-landscape development, the initial sediments need to be quantified in space and time. This study aims at developing and testing methods for the quantification of initial sediment mass balances in the three dimensions of space and in time. The initial mass balance and composition of parent material in an artificially-created hydrological catchment were quantified from a 3D-model of the catchment’s water storage layer. Multi-date digital elevation models (DEMs) were constructed from photogrammetrically derived elevation data after the assessment and improvement of elevation data quality. Three-dimensional models of volume change were constructed from the digital elevation models. Regions of significant volume change were identified. Mass changes were calculated from the volume changes in combination with bulk density information. Based on information about the catchment’s construction, mass changes were separately analyzed in subregions of the models. Terrain attributes were computed to characterize surface structure and to examine correlations with mass change. From the 3D-model, an initial sediment volume of 122,608 m3 was quantified. A variation of about ±12,300 m3, due to uncertainty in DEMs from aerial photographs, was calculated. The 3D-model indicates differences in sediment properties between the western and eastern part of the catchment, which are most probably resulting from the dumping of two separate material deliveries during the construction. Models of volume and mass change are constructed for three time periods of catchment evolution. Spatial variations in volume and mass change are observed. The total mass balance reveals a considerable mismatch between the detected amounts of erosion and sedimentation, which gives reason to closely examine the quality of the DEMs. Terrain attributes of four elevation models reflect the diversification of surface structures. Correlations between volume change and surface structures show that erosion processes are dependent on initial surface structures and that these structures, in turn, are enhanced by the processes of sediment redistribution. Although there is a considerable uncertainty in the observed mass changes, the 3D-modelling approach allows a first approximation of the initial, mostly erosion-affected, surface structural dynamics of the artificial catchment. The comparison of multi-date elevation data allows a critical evaluation of the quality of models of change obtained from repeated topographical surveys.
This paper presents a further development of mathematical model, an asymptotic theory and an appropriate numerical algorithm to study the vector VLF point source field propagation problem within the non-uniform Earth–ionosphere waveguide. It is the sequential development of our previous article [Soloviev, O.V., Hayakawa, M., Ivanov, V.I., Molchanov, O.A., 2004. Seismo-electromagnetic phenomenon in the atmosphere in terms of 3D subionospheric radio wave propagation problem. Phys. Chem. Earth 29, 639–647. doi:10.1016/j.pce.2003.10.002]. We have taken into account 3D local anisotropic ionosphere inhomogeneity over the ground of the solar terminator transition. The local ionosphere inhomogeneity, whose centre is situated above the model earthquake, is simulated by a bell-shaped tensor impedance perturbation of the ionospheric waveguide wall. The various propagation paths, which cut across the terminator line at different angles, have been investigated. Numerical results show that the emergence of the local ionosphere inhomogeneity on the radio wave propagation across the solar terminator path deforms the curves of field amplitude and phase diurnal variations in accord with the experimental observational data.
SKB is currently preparing license applications related to the deep repository for spent nuclear fuel and an encapsulation plant. Recommended values for the diffusion-available porosity (ε), effective diffusivity (De) and distribution coefficient (Kd), as well as the associated uncertainties are derived and documented in a SKB technical report (Ochs, M., Talerico, C., 2004. SR-CAN: Data and uncertainty assessment. Migration parameters for the bentonite buffer in the KBS-3 concept. SKB Technical Report TR-04-18, SKB, Stockholm) for a total of 38 elements and oxidation states. Based on these results, this contribution focuses on issues of consistency and on quantification of the uncertainties associated with each parameter. The importance of consistency is twofold. First, the above parameters are conditional in nature. To assure consistency of the conditions assumed for parameter derivation versus those considered in the safety analysis, all parameters have to be derived explicitly for the expected in situ conditions, which especially in case of Kd include the specific bentonite porewater composition. Extrapolation of sorption data from experimental to the PA-relevant conditions was done with the help of thermodynamic sorption models or through semi-quantitative scaling factors. De for all radionuclides and ε were evaluated as a function of density for positively, negatively and uncharged species. Second, any set of parameters (ε, De, Kd) selected for a given element needs to be internally consistent. To this end, each selected parameter set was used to calculate apparent diffusivities (Da). These were then compared to independent, experimental Da values. Uncertainties in input parameters can be related to two fundamentally different sources: (i) the uncertainties of the underlying experimental data and models, including uncertainties introduced by scaling to reference PA conditions; (ii) parameter uncertainties caused by uncertainties in the conditions expected for PA. The impact of such variability was evaluated by specifically deriving input parameters for the reference PA conditions as well as for several alternative sets of PA conditions.
Bentonites are part of the engineered barrier system (EBS) of repositories for radioactive wastes. High salinity and high pH of the pore space solutions may cause changes in the mineralogical composition and of the swelling capacity of the bentonites, possibly affecting the long term performance of the EBS. Results of a 3 years study on the changes of MX-80 bentonite properties after reaction with solutions of different ionic strength and pH are presented. The effects of seven characteristic saline solutions potentially occurring in repositories in granite, clay and salt formations were investigated, with comparison with one “pure water” experiment. Each solution reacted differently with the bentonite, resulting in different mineralogy and swelling pressure (SWP). SWP were highest in contact with water (>4 MPa), significantly lower in contact with low ionic strength solutions (∼2 MPa) and lowest in contact with high saline brines (mostly under 1 MPa). An alteration and partial dissolution of montmorillonite was observed. Mg, Al and Si contents in the solutions increased with reaction time. Concomitantly in the octahedral layers of montmorillonite, Mg was substituted by Al and the interlayer charge decreased. Later, a loss of some octahedral layers led to an excess of Si in the montmorillonite particles. The correlation between the alteration process, the charge reduction and SWP is presented. Tentative explanations are given for the activation of bentonites with acids. Key factor for the observed mineralogical alteration may be the acidity of water in the interlayer space. This also may explain that the alteration in compacted experiments with a high solid–liquid ratio (less water, higher acidity) is faster than in batch experiments with a lower solid–liquid ratio.
The present study included analysis of the natural remanent magnetization (NRM) and magnetic characteristics of samples from the mars meteorite Allan Hills 84001. The NRM study revealed a soft moment demagnetized between 0 and 20 mT, which appeared in different sub-samples in varying amounts and directions. We found a magnetization of intermediate hardness from about 20 to 40 mT which had a consistent direction in mutually oriented sub-samples, and a harder component above 40 mT that could not be characterized. We conducted rock magnetic studies including IRM acquisition, backfield measurements, IRM and ARM demagnetization, hysteresis and thermomagnetic measurements. These studies on the carriers of magnetization show evidence for magnetite and a phase with a Curie point close to 100 °C. The ARM is used as an example of weak field magnetization analogous to thermal remanent magnetization. The ratio of NRM to IRM is between 1×10−3 and 2×10−3 in the intermediate demagnetization field range between about 20 and 40 mT. In this range of demagnetization fields the NRM behaves similarly to an ARM. This contrasts with ratios of 3×10−2 reported for single crystals of pyroxene [Science 275 (1997) 1629]. Our results suggest that the NRM is not grossly inhomogeneous on the scale of the sub-samples unless the Martian field was much stronger than 1 μT.
Heat flow data from the Polish basin show a sharp change in the transition from the East European Craton (EEC) and Teisseyre–Tornquist Zone (TTZ) in the north-east to the accreted terranes in the south west (Paleozoic Platform). The analysis of this data and numerical modelling of the crustal temperatures show evidence of extensive crustal–mantle warming in the area between the Sudetes to the south and the Trans-European Suture Zone to the north. The change in heat flow is 100% when compared with values for the EEC. Heat flow in the anomalous zone is also higher than in the Sudetes. The axis of the anomaly is aligned with the Dolsk Fault and Variscan deformation front. Low crustal/mantle temperatures derived from the relationship between temperature and Pn velocities (more than 8.2 and as high as 8.4 km/s) are at odds with high crustal temperatures calculated from surface heat flow, seismic velocity based heat generation models and thermal conductivity. High heat flow (Variscan platform) and related high temperatures of the crust coincide with small crustal thickness (30–35 km). The opposite is the case for the low heat flow EEC (45–50 km). High heat flow above thin crust and low heat flow above thick crust with no major variation in elevation is supported by a simple isostatic balance model. Crustal heat generation explains part of the high heat flow within the zone with thick meta-sediments reaching down to 20 km depth, however, it is far from explaining high heat flow in Variscan crust and in the transition zone into a cold EEC. 2D numerical models of heat flow based on new seismic data require a contrast of 15 mW/m2 in mantle heat flow. High mantle heat flow (35–40 mW/m2) is likely to occur in the high heat flow zone while cold crust and cold and high-density mantle (mantle heat flow of 20–30 mW/m2) is typical of the EEC. Thermal lithosphere thickness for the craton is 200 km while it is only 100 km in the accreted terranes to the southwest of the TTZ. The TTZ in Poland appears as a relatively cold area.
Plan and policy development usually define the course, goal, execution, success or failure of any public utilities initiative. Urban water supply is not an exception. Planning and management in public water supply systems often determine the quality of service the water supply authorities can render. This paper, therefore, addresses the issue of effective planning and management as critical determinants of urban water supply and management with respect to two Nigerian cities Umuahia and Aba both in Abia State. Appropriate sampling methods systematic sampling and cluster techniques were employed in order to collect data for the study. The collected data were analyzed using multiple linear regression. The findings of the study indicate that planning and management indices such as funding, manpower, water storage tank capacity greatly influence the volume of water supplied in the study areas. Funding was identified as a major determinant of the efficiency of the water supply system. Therefore, the study advocates the need for sector reforms that would usher in private participants in the water sector both for improved funding and enhanced productivity.
The Beatrice Gold Belt, located 65 km south of Harare, lies astride the Mupfure River, a tributary of the Sanyati River, Zambezi Basin. The belt has been mined for gold since 1900, but was abandoned towards the year 2000. The Mupfure River provides water for commercial agriculture in the local farming areas and smallholder farming in Mhondoro Communal Lands, as well as other users downstream in Chegutu and Kadoma Districts.There were four mines in the belt: Beatrice, Joyce, Argyle and Roma. They are all closed, and rehabilitation has only taken place at Beatrice mine. Each mine is located under 5 km from the Mupfure River, and so run-off from the mines and their dumps can easily reach the main river system. The dominant sulphides are arsenopyrite (FeAsS), pyrite (FeS2), galena (PbS) and stibnite (Sb2S3). Gold is generally locked up in sulphides or occurs in close contact to the sulphides, so processing is associated with release of acid, arsenic and metals into streams that flow into the Mupfure River.This study was thus carried out to assess the potential impact of these abandoned mines on the water quality of the Mupfure river and its tributaries. Water samples were collected along the tributaries that drain the mining area, as well as from the mine-shafts. Parameters tested include pH, iron, copper, nickel, lead, zinc, antimony, and arsenic.Chemical results obtained show that the surface water is slightly contaminated with respect to Pb, Zn and Ni. Such contamination is attributed to the mine dumps. However, the near-neutral pH and only slight contamination show that the impact on water quality of the Beatrice mines is largely localised probably due to likely low run-off volumes from the mining sites compared to the rest of the catchment. The slight contamination could also indicate that acid mine drainage is proceeding at a slow rate or the fact that it is in its initial stages. Long term environmental management should therefore focus on controlling the localised impact of the old mines as well as controlling the acid drainage.
Colloid-assisted contaminant transport in soils depends on the concentration, the chemical composition and the charge of the carrier. These characteristics are altered when organic colloids derived from the forest canopy and the forest floor enters the mineral soil. Field studies and laboratory sorption experiments combined with destructive and non-destructive analytical methods were used to identify the controls on the colloidal organic matter immobilization during the passage of the mineral soil. The results indicated that the immobilization is mainly due to sorption on Fe and Al hydrous oxides. The degree of binding depends on the amount of sorbents, their initial loadings with organic matter, and the chemical features of the organic colloids. The lignin-derived moieties seem to be preferentially removed from the soil solution whereas the saccharides accumulate in the soil solution. Thus, the passage of organic solutes through the mineral soil is a chromatographic process which controls the amount and the chemical characteristics of organic colloids reaching the hydrosphere.
Atmospheric fluxes of CO2 and H2O above a mature spruce stand (Picea abies (L.) Karst.) have been investigated using the eddy- correlation technique. A closed path sensor adapted to the special requirements of long-term studies has been developed and tested. Field measurements have been performed since April 1995. Estimates of fetch showed a very narrow source area dimension under instable stratification (≤ 200 m). Fetch requirements at night are not met in some directions. Energy balance closure was influenced systematically by the wind direction indicating a substantial attenuation of the vertical wind motion by the tower (up to 40 %). Even for optimal flow directions, energy balance closure was about 88%. Intercomparison of the used ultra sonic anemometer (USAT-3) with a GILL - anemometer showed systematically lower values of vertical wind speed fluctuations (13 %). Average CO2-fluxes ranged between -13 at noon to 3 μmol m−2, s−1 at night in summer. In November and December the stand released CO2 on a daily basis. A preliminary estimate of the cumulative net carbon balance over the observed period of 9 months is 4–5 t, Cha−1.
One of the major challenges in contemporary climate research is to detect seasonal and inter-annual variabilities of water vapor for determining both the sign and the magnitude of its feedback to the Earth’s system on a global and regional scale. Here one important task is to understand and quantify the mechanisms that control moistening and dehydration of the upper troposphere / lower stratosphere from polar regions to the tropics. A key sub-task here is the investigation of the tropopause dynamics and the stratosphere-troposphere exchange processes. Further is necessary to improve our knowledge on the separation of water into gaseous and ice phases in cirrus clouds. On a more technical level it will be inevitable to provide a new, bias free reference for calibrating other remote sensing techniques, thereby unifying the global observational network for humidity in order to permit accurate regional trend analyses.
All these tasks require globally available, essentially bias-free, vertically highly resolved and uncorrelated measurements of the water vapor profile. Current and possible near future space-borne passive observing systems fail to meet these requirements. The active differential absorption LIDAR (DIAL) method on the other hand has the potential to fulfill all these needs.
A mission employing such an active system was proposed to ESAs Earth Explorer Program under the name WALES. As a contribution to this effort the German Aerospace Center (DLR) developed an airborne demonstrator which implements all essential features of a possible space-borne instrument, for example a multi-wavelength approach in the 935 nm absorption band of H2O and the usage of state-of-the art solid state laser technology. With this instrument a large data set has been gathered in various airborne campaigns devoted to different topics concerning the atmospheric part of the global water vapor cycle over the past years. We will present a selection of results from these campaigns and comparisons to other measurement techniques, both in-situ and remote which cover the whole troposphere up to the UTLS.
The semi-arid areas of Zimbabwe receive low and erratic rainfall such that communities living and farming in these areas do not obtain adequate yields in most years forcing them to rely on surface and ground water resources during the dry season and dry years. Such water, which is a buffer during dry seasons and dry years should be managed appropriately. However, appropriate management of the limited water resources in such areas is hindered by inadequate knowledge of the changes in water resources due to rainfall, runin, evaporation, seepage and productive water use. Mutangi (5.7 km(2)) and Romwe (4.7 km(2)) micro-catchments that are in semi-arid Southern Zimbabwe were instrumented to enable measurements of all components of hydrology including rainfall, streamflow, dam water level, soil moisture and groundwater levels in the 1999/00 and 2000/01 season. Validation of the Agricultural Research Unit (ACRU) simulation model against field data revealed that ACRU adequately simulated measured streamflow, soil moisture and dam water storage changes. The model showed that removing all the remnant woodland and leaving all the cropped land fallow did not have a significant (P < 0.01) effect on both catchment streamflow and dam water level over the 27 year simulation period. However, planting trees over the whole catchment resulted in a significant decrease in streamflow by 51%. Construction of tied ridges significantly (P < 0.05) decreased streamflow from the catchment by 19%. Water abstraction from the dam could be increased 2, 4, 6, 8 and 10-fold without the dam drying to unacceptable levels (10% of dam capacity) except for 7%, 7%, 11%, 22% and 30% of the 27 simulation years (1972-1999) respectively. This demonstrates that currently small dams are not adequately utilized and vegetable yields and income could be increased by increased surface water abstraction.
US-based models for recreational water quality were applied to characterize the potential health risk (PHR) of infection with gastroenteritis (GI) and highly credible gastroenteritis (HCGI) illnesses from single exposure at several water abstraction points (WAPs) along the Njoro River in rural Kenya. Ambient geometric mean densities of Escherichia coli (EC) and intestinal enterococci (IE) were generally high (2–4 log units of cfu/100 ml) and risk levels were grossly in excess of acceptable health risk (AHR) levels for bathing and drinking. PHR was 2–3 times higher with the Cabelli (IE) model (Equation (2)) compared to the US EPA (EC) model (Equation (1)). Risk levels varied among WAPs in concomitance to the spatial and seasonal variability of ambient EC and IE densities. With the Cabelli IE model, PHR of HCGI illness on single exposure to the dry weather 95th percentile IE density for bathing was 2.5% of the exposed population at Logoman compared to 5.2% at Turkana Flats, 4.9% at Kenyatta or Nessuit and 4.6%, 4.5% and 4.2% at Treetop, Segotik and Njoro Bridge, respectively. PHR was ⩾5% on exposure to the wet weather 95th percentile IE density at all WAPs, excepting Treetop with 4.3%. Relative risk levels increased by at least 30 and 70 times for GI and HCGI illnesses, respectively, from drinking (250 ml) raw stream water, rising erratically in wet weather by >80% of the dry weather risk at Logoman, >30% at Njoro Bridge and Kenyatta and 10–15% at Segotik, Nessuit and Turkana Flats. By stipulating freshwater bathing water quality guidelines of 126 and 33 cfu/100 ml for EC and IE, respectively, US, EPA upholds maximum AHR levels at 0.7% and 1.9% for EC and IE, respectively. Hence, reducing current PHR levels at the WAPs to the US, EPA bathing AHR levels would require at least 2–4 log reductions of IE and EC densities with even further log reductions to achieve the WHO recommended drinking water AHR level of 0.1%. This would necessitate specialized treatment, in particular point-of-use treatment at the household level, as well as the implementation of comprehensive catchment management measures to protect the stream and the WAPs.
Using indices and indicators in assessment of progress of a developing country has two sides. Such indicators offer an easy-to-understand shorthand/synopsis of issues vital for a country’s development. The other side of the coin, however, is that this synopsis may be distorted due to incorrect data or inapplicability of an index or an indicator to a specific case. This paper assesses the applicability of Water Poverty Index for the countries riparian to the Sava sub-basin, a tributary to the Danube river basin and presents the results of its application. At the same time, the paper discusses the concept of water poverty and the appropriateness of its use in the case of Sava River Basin countries by differentiating the economic poverty in some of those countries from sufficient access to and use of water resources in all of them.
Governance structures in Botswana are highly centralized and top-down in orientation. For water and related resources management in rural areas, this creates particular difficulties – from lack of decision-making capacity to limited human and financial capital at the level of the resource base. In Ngamiland, government is currently undertaking the Okavango Delta Management Plan project as part of its commitment to the Ramsar Convention on Wetlands. The project purports to develop an integrated management plan based on an ecosystems approach. Meaningful participation by local people is a requirement of the process. Data from 43 village meetings undertaken under the auspices of the ODMP process reveal that local people’s access to their resource base is diminishing. Information from key informant interviews and a variety of government documents, however, suggests that policy makers are either unaware of or uninterested in this growing problem. Although citizens and government are engaged in an on-going dialogue, there is little evidence to suggest that policy and practice are moving toward sustainable solutions for all. This article highlights these issues in the hope that a more meaningful dialogue among all stakeholders may be undertaken.
This case study investigates access to potable water in HIV/AIDS related home-based care households in five rural communities in Ngamiland, Botswana. Primary data collected from five villages consisted of two parts. The first survey collected household data on demographic and rural livelihood features and impacts of HIV/AIDS. A total of 129 households were selected using a two-stage stratified random sampling method. In the second survey, a total of 39 family primary and community care givers of continuously ill, bed-ridden or non-bed-ridden HIV/AIDS patients were interviewed. A detailed questionnaire, with closed and open-ended questions, was used to collect household data. In addition to using the questionnaire, data were also collected through participant observation, informal interviews and secondary sources.