Hydrogeology

Hydrological and Water Quality Characterisation of a Tropical Riverine Wetland: Nabajjuzi-Masaka, Uganda

by Najib Lukooya Bateganya

Abstract
In East Africa where wetlands are becoming essential systems for waste water treatment and potable... more Abstract
In East Africa where wetlands are becoming essential systems for waste water treatment and potable water supply, hydrological characterisation is crucial to understand the dynamics of their functioning on a spatial and temporal scale. Beside ecosystem services, basic ecological properties such as vegetation structure and nutrient cycling of wetland ecosystems depend on hydrology. Nabajjuzi wetland, in central Uganda, East Africa is internationally recognised as a Ramsar site and currently used for potable water supply in addition to other essential ecological and social economic services to the riparian communities. To contribute to the limited and scanty information of this ecosystem, the study focussed on hydrological and water quality characterisation using a water-nutrient mass balance as the major output. Also, the flow dynamics of Fe and allochthonous suspended solids loading into the wetland were investigated.

Results show that the water balance of Nabajjuzi wetland is dominated by surface flow, which is influenced by rainy and dry periods. During peak flow, the estimated hydraulic retention time was found to be 1 month compared to 1.5 months during the low flow period. Also, water loss flux due to evapotranspiration in this region is high and in Nabajjuzi wetland, it is twice the daily rate of abstraction. Analysis of long term flow data also revealed that the current water abstraction rate can potentially result in hydrological stress to the system during extremely low flow periods. However, the wetland N and P loading is very low compared to other urban disturbed wetlands. Consequently, high concentration of Fe and suspended solids loading are the major constraints to the surface water quality hence potable water supply. Generally, there is need for a more comprehensive hydrological-water quality study and careful planning of the future catchment land use strategies. This can enhance management and conservation of the wetland to guarantee the crucial ecosystem services it provides.

Keywords: Hydrology, Riverine wetland, Hydrological gradient, Surface-flow, Nutrients, Iron, Mass-balance, Lake Victoria basin.

Monitoraggio idrometrico del Lago di Tovel e del suo bacino

by Andrea Borsato

Studi Trent. Sc. Nat., Acta Biol., 2006 - 81, Suppl. 2: 205-223.

Studio idrogeologico della Valle e del Lago di Tovel

by Andrea Borsato

Studi Trent. Sci. Nat.,  Acta Biol., 2006 - 81, Suppl. 2: 189-203.

Present-day and Holocene groundwater fluctuations in Bus de la Spia – Acquasanta karst system and their impact on the formation of hypogean calcareous tufa.

by Andrea Borsato

Proceedings XXXV Congress International Association of Hydrogeologists – Groundwater and Ecosystem, Lisbon 2007: 7 pp.

Hydrogeological-Environmental investigation of groundwater horizons north-westerly of Argos

by Dimitrios Zouzias

Dimitrios Zouzias (2003) University of Patras, Department of Geology, Laboratory of Hydrogeology, Supervisor: N. Lambrakis [BSc thesis] 

Sustainable Development of Nisyros volcano and new volcanological characteristics of the adjacent area with the aid of Remote Sensing (511pp)

by Dimitrios Zouzias

Dimitrios Zouzias (2011) University of Patras, Department of Geology, Greece University of Patras, Faculty of Sciences, Department of Geology Laboratory of Ore Deposits and Volcanology, University campus Rio, Patras Achaia 26504 Greece

Abstract: The Kos - Nisyros study area is located at the easternmost edge of the active Quaternary volcanic arc of the... more Abstract: The Kos - Nisyros study area is located at the easternmost edge of the active Quaternary volcanic arc of the southern Aegean Sea and includes the islands of Kos and Nisyros and the islets of Gyali, Strongyli, Pachia and Pyrgoussa. The volcanic activity of Kos island is characterized by Upper – Miocene ignimbrite deposits and Pliocene - Pleistocene volcanic products such as volcanic domes, the Kefalos pyroclastic sequence of hydromagmatic tuffs and the large-scale pyroclastic formation Kos Plateau Tuff (KPT) deposits which is also found on the Kalymnos, Pserimos and Tilos islands. Nisyros is a calcalkaline stratovolcano which consists of Pliocene volcanic products such as andesite and basaltic andesite lavas that are overlain by pyroclastic deposits, lava flows and lava domes of dacitic – rhyodacitic composition. The islets of Gyali, Strongyli, Pachia and Pyrgoussa represent Pliocene lava domes of rhyolitic (Gyali), andesitic (Strogyli) and dacitic composition (Pachia and Pyrgoussa) On these domes, pyroclastic deposits of the Upper Pumice unit of Gyali (in Strogyli) and pyroclastic deposits of the Kos Plateau Tuff (KPT) and Panayia Kyra formation (in Pachia and Pyrgoussa) have been identified. In this thesis, the volcanic products of the Kos-Nisyros area are examined using mineral chemistry, geochemical and petrographical methods, while volcanic structures and morphological features are identified and mapped using remote sensing techniques. The aim of this thesis is to understand the volcanic evolution of the study area, by drawing conclusions regarding the consanguineous relationship of the magmatic products, magma mixing phenomena and the magma chamber system of the area, as well as, the surface expression of this magma chamber system in the form of caldera structures. For this purpose, in this thesis, it is investigated the consanguineous relationship of the Kos Tuff (Kos Plateau Tuff) found on Kos, Tilos and Kalymnos islands, as well as, the geochemical differentiation of the most violent and explosive ignimbrite units D and E of the Kos Tuff, confirming the stratigraphic correlation of these deposits as it was previously presented by physical volcanology data. The petrochemical study of the Kos - Nisyros area as a single "volcanic complex" reveals that the volcanism of the study area is divided into a Miocene and a Pliocene – Pleistocene activity. The Miocene activity is characterized by magmatic and volcanic products such as the monzonite of Kos and the Miocene ignimbrites of Kos and the Pliocene – Pleistocene volcanic activity consists of volcanic products such as lava domes and pyroclastic deposits from Kos, Gyali and Nisyros volcanoes where it is revealed the consanguineous magmatic relationship of these Pliocene – Pleistocene products. Using “Nomarski” interferometry method it is revealed that magma mixing/mingling phenomena are unquestionable for the magma chamber system of Nisyros and provide evidence that these phenomena were active throughout the volcanic evolution of Nisyros volcano. Field observations and remote sensing methods revealed caldera structures in the Kos - Nisyros area which are identified and classified according to new perceptions regarding the volcanic evolution. The volcanic structures of Nisyros volcano are examined using remote sensing methods such as satellite image and digital elevation models interpretation, as well as, the geomorphometric analysis of the Nisyros terrain in combination with geomorphotectonic features of the volcano as presented by other researchers and new perceptions on the volcanic evolution. It is also presented a model of proto-caldera, caldera and post-caldera evolution of Nisyros volcano based on new perceptions on the volcanic evolution in relation to the stratigraphic evolution. Finally, it is studied the subvolcanic magma chamber system of the Kos - Nisyros area, as well as, mixing phenomena in the volcano of Nisyros using the “Nomarski” interferometry method and the distribution of major, trace and rare earth elements revealing the consanguineous nature of these volcanic centers by providing the widest volcanic area of Kos - Nisyros as a major volcanic center characterized by a complex caldera system. Sustainable development of Nisyros volcano represents a management tool which combines the volcanic evolution with the environmental preservation and can promote volcanic regions as geotopes. The investigation of the present conditions of the island reveals, despite the fact that Nisyros is characterized by a strong environmental, energy, social, cultural and economic potential, it remains undeveloped and unexploited due to lack of an integrated sustainable development management plan, based on which, decisions should be equal, equivalent simultaneously and in harmony. Based on the study of the Nisyros water resources, the energy potential from renewable energy sources, the management of natural and urban environment of the volcano of Nisyros and the study of the positive and/or negative effects of the mining industry in Gyali volcanic islet it is proposed an integrated sustainable development according to the views and the perspectives of the local community. From this intergraded plan are generated recommendations for an integrated management of the volcano of Nisyros which satisfy equal, equivalent, simultaneously and in harmony the principles of sustainable development aiming to refocus the local economy, the management of natural and urban environment and the social development.

CALANDO I VECCHI MONTI, E ALZANDOSENE DE'NUOVI LE SCIENZE DELLA TERRA NEL PENSIERO DI ANTONIO VALLISNERI

by Francesco Luzzini

Oceanic molybdenum isotope fractionation: Diagenesis and hydrothermal ridge-flank alteration

by Chris Siebert

Geochemical modeling of iron, sulfur, oxygen and carbon in a coastal plain aquifer. Journal of Hydrology, 237: 147-168.

by Martin Schoonen

Brown, C.J., Schoonen, M.A.A., Candela, J.L., 2000. Geochemical modeling of iron, sulfur, oxygen and carbon in a coastal plain aquifer. Journal of Hydrology, 237: 147-168.

Fe(III) reduction in the Magothy aquifer of Long Island, NY, results in high dissolved-iron concentrations that... more Fe(III) reduction in the Magothy aquifer of Long Island, NY, results in high dissolved-iron concentrations that degrade water quality. Geochemical modeling was used to constrain iron-related geochemical processes and redox zonation along a  ̄ow path. The observed increase in dissolved inorganic carbon is consistent with the oxidation of sedimentary organic matter coupled to the reduction of O2 and SO42P in the aerobic zone, and to the reduction of SO42P in the anaerobic zone; estimated rates of CO2 production through reduction of Fe(III) were relatively minor by comparison. The rates of CO2 production calculated from dissolved inorganic carbon mass transfer 􏰄2X55 £ 10P4 to 48X6 £ 10P4 mmol lP1 yrP1􏰅 generally were comparable to the calculated rates of CO2 production by the combined reduction of O2, Fe(III) and SO42P 􏰄1X31£10P4 to 15£ 10P4 mmol lP1 yrP1􏰅X The overall increase in SO42P concentrations along the  ̄ow path, together with the results of mass- balance calculations, and variations in d 34S values along the  ̄ow path indicate that SO42P loss through microbial reduction is exceeded by SO42P gain through diffusion from sediments and through the oxidation of FeS2. Geochemical and microbial data on cores indicate that Fe(III) oxyhydroxide coatings on sediment grains in local, organic carbon- and SO42P-rich zones have been depleted by microbial reduction and resulted in localized SO42P-reducing zones in which the formation of iron disul®des decreases dissolved iron concentrations. These localized zones of SO42P reduction, which are important for assessing zones of low dissolved iron for water-supply development, could be overlooked by aquifer studies that rely only on groundwater data from well-water samples for geochemical modeling.

GEOLOGICAL AND GEOELECTRICAL SURVEY OF GROUNDWATER POTENTIAL IN THE ASTANEH-KOUCHESFAHAN PLAIN, IRAN

by Masoud Saatsaz

Journal of Environmental Hydrology, Paper 23, Volume 19, 2011

The Astaneh-Kouchesfahan Plain, an extensive and productive aquifer system in Iran, is located in the south Caspian... more The Astaneh-Kouchesfahan Plain, an extensive and productive aquifer system in Iran, is located in the south Caspian Sea basin which is part of the Alborz tectonic range in the Alpine fold belt. A permeable aquifer system provides water for industrial, agricultural and domestic uses. Geological and geophysical studies indicate a number of important facts about the groundwater system. For this reason, detailed regional geological, tectonic and geophysical data were gathered to better understand the behavior of hydrogeological zones in the system. Geological studies show that the area is predominantly covered by recent alluvium, which consists of Pleistocene and Holocene stream deposits, coastal deposits, beach deposits and alluvial fan deposits. The bedrock mainly consists of impermeable clay of the Mesozoic era. Also, based on available geological cross sections, geophysical surveys, and well logs, it is shown that the system contains an unconfined, shallow Quaternary alluvial aquifer which is composed of heterogeneous sequences of relatively coarse grained gravel and sand interconnected with different thicknesses of silt and clay. The final results of this study are extremely useful for geotechnical activities, environmental strategies, and water resource management.

Spatial and temporal variation of uranium in a shallow weathered rock aquifer in southern India

by Elango L

K Brindha, L Elango, and R N Nair
J. Earth Syst. Sci. 120, No. 5, October 2011, pp. 911–920

Coupling mineral analysis with conceptual groundwater flow modelling: The source and fate of iron, aluminium and manganese in a back-barrier island

by Stephen McLoughlin

Reference:
Hodgkinson, J., Cox, M.E. & McLoughlin, S., 2008. Coupling mineral analysis with conceptual groundwater flow modelling: The source and fate of iron, aluminium and manganese in a back-barrier island. Chemical Geology 251: 77-98.

Mineral and aqueous geochemical data are combined with a conceptual groundwater flow model, to establish the origin... more Mineral and aqueous geochemical data are combined with a conceptual groundwater flow model, to establish the origin and fate of iron, aluminium and manganese in the groundwater system of a small backbarrier island. The flow model domain consists of an unconfined island fresh groundwater lens overlying a semi-confined hypersaline aquifer. The two aquifers are separated by a discontinuous, clay-rich aquitard and both contain diffusion governed variable density flow fields. High concentrations of dissolved iron and manganese are associated with brackish to hypersaline groundwater, although there is no systematic relationship with salinity. Calculation of S2_/SO4 2_ and Fe2+/Fe3+ redox couples and the results of thermodynamic modelling show that redox disequilibrium in the groundwater is widespread. Groundwater samples containing aqueous sulphide and ferric iron complexes are supersaturated with respect to pyrite, goethite and haematite but the prevailing state of redox disequilibrium controls mineral dissolution and precipitation. Aqueous iron in the deeper regions of both aquifers is derived from the dissolution of iron oxide–hydroxides in lateritic palaeosols controlled by seasonal fluctuations in groundwater redox state. Aqueous manganese is potentially derived from the dissolution of ilmenite and amorphous oxide– hydroxides. The oxidation of iron sulphides contributes to the aqueous iron concentration and sulphuric acid production in the shallow groundwater. The solubility of aluminium is also limited by this process, governed by acidity regulation. A significant proportion of aqueous iron is transmitted from the semi-confined to the overlying unconfined aquifer through discontinuities in the aquitard layer. Movement of metals in solution outside the island groundwater system is restricted by the presence of diffusion boundaries within variable density transition zones.

Lithological heterogeneity in a back-barrier sand island: Implications for modelling hydrogeological frameworks

by Stephen McLoughlin

Reference:
Hodgkinson, J., Cox, M.E. & McLoughlin, S., 2008. Lithological heterogeneity in a back-barrier sand island: Implications for modelling hydrogeological frameworks. Sedimentary Geology 203: 64-86.

Sediment mineralogy, quartz-grain surface-textures, grain-size analysis, bore-hole logging and ground penetrating... more Sediment mineralogy, quartz-grain surface-textures, grain-size analysis, bore-hole logging and ground penetrating radar are combined to develop a three dimensional stratigraphic model of a back-barrier sand island in southeast Queensland, Australia. The island consists of an unconsolidated sedimentary pile above an erosional bounding surface at the top of the underlying bedrock. The stratigraphy is complex, recording the shift in depositional environments from fluvio-deltaic to strandplain, via estuarine stages of evolution. The back-barrier island deposits are correlated with the stratigraphy of the adjacent coastal plain to the west and the barrier island to the east. Extrapolation of optically stimulated luminescence dates obtained from the barrier island combined with direct dating of the back-barrier island sediments is used to constrain the depositional age and chronology of the back-barrier island stratigraphy. The modern depositional environment evolved from a chenier plain into a barrier island system by the flooding of an interdune swale and development of a shore-parallel back-barrier tidal lagoon. The lithological heterogeneity of the back-barrier island succession was controlled by the presence of a bedrock incised palaeovalley and changes in relative sealevel.
Sedimentary facies associations constrain the spatial distribution of hydraulic properties controlled by lithological heterogeneity. Postdepositional alteration horizons are integrated with the facies model to account for the effects of weathering and diagenesis on hydraulic behaviour. The derived hydrostratigraphy describes a vertically stacked, dual aquifer, island groundwater system consisting of a semi-confined palaeovalley aquifer overlain by an unconfined strand-plain aquifer.
Hydrostratigraphic analysis based on sedimentary facies associations, integrated with post-depositional alteration characteristics reveals great complexity of groundwater systems within small island settings. The facies modelling approach employed in this study more accurately estimates the distribution of lithological heterogeneity and the associated variations in hydraulic properties in the sedimentary pile.

Hydrogeological framework and water balance studies in Astaneh-Kouchesfahan Plain, Iran

by Masoud Saatsaz

Published in International Conference on Water Resources: Emphasis on Regional Development. Shahroud. Iran

Role of geomechanically grown fractures on dispersive transport in heterogeneous geological formations

by Hamid Nick

Influence of hydrogeochemical processes on temporal changes in groundwater quality in a part of Nalgonda district, Andhra Pradesh, India

by Elango L

R. Rajesh • K. Brindha • R. Murugan • L. Elango
Environ Earth Sci (2012)
DOI 10.1007/s12665-011-1368-2

Quality and pollution of surface and groundwaters in the Chalkidiki district, Macedonia, N. Greece

by Miltiadis Nimfopoulos

Authors: M.K. Nimfopoulos, C. Katirtzoglou, D.A. Polya, N. Veranis, I. Anagnostaras
Proceedings 6th Hydrogeological Congress of the Geological Society of Greece, 353-364, November 8, 2002

The Chalkidiki peninsula, Macedonia, N. Greece, is predominated to the E by metamorphic rocks of the Serbomacedonian... more The Chalkidiki peninsula, Macedonia, N. Greece, is predominated to the E by metamorphic rocks of the Serbomacedonian massif, in the middle by rocks of the Circum Rhodope belt and to the W by the Peonia zone of the Stip Axios belt. The W part is rather a plain crossed by shallow water streams, whereas, the middle and the E part is mountainous with a sharp relief and a dense network of deep valleys and shears. The W part was filled with, up to 3.5 km thick, loose sediments of the Neogene-Quaternary period consisting of marly limestone, marls, sands, red clays, conglomerates, scree deposits and beach sands. Comparative chemical analyses of groundwater from different aquifer and host rock associations and in relation to hydrothermal activity, intrusion of seawater, anthropogenic influence, and the chemistry of polluted surface water from different influence and the formation of brackish surface water by natural processes are given and explained based on the geological, hydrogeological and hydrological associations.

Study of Influence of Terrain and Climatic Factors on Groundwater-Level Fluctuation in a Minor River Basin Using GIS

by Elango L

N. Radhakrishnan, L. Elango
Geo-spatial Information Science 14(3):190-197

Intrinsic vulnerability assessment using a modified PI method: A case study from central Greece

by Evangelos Tziritis

Co-authored with N. Evelpidou. Published In: Advances in the Research of Aquatic Environment. Environmental Earth Sciences, Springer, v.2, p.343-350

The assessment of an aquifers’ vulnerability to pollution is of great importance, and can be used as a tool to augment... more The assessment of an aquifers’ vulnerability to pollution is of great importance, and can be used as a tool to augment planning, effective protection and management of groundwater resources’ quality, especially in the case of karstic aquifers. The present study aims to assess the intrinsic vulnerability of a karstic groundwater system, with the use of a modified version of the PI method. The assessments are functional to the effectiveness of the protective cover, as well as to the degree to which the protective cover is bypassed due to flow conditions. The used data was obtained by field work, empirical and semi-quantitative approaches regarding lithology, fissuring and karstification of bedrock, soil characteristics, hydrology, hydrogeology, topography and vegetation. The combinational effect of the above parameters, as processed with the aid of a GIS system, yielded the final calculation of the protection factor (π) and subsequently the vulnerability of the aquifer to pollution.

A qualitative-quantitative study of water and environmental pollution at the broader area of the Mygdonia basin, Thessaloniki, N. Greece

by Miltiadis Nimfopoulos

Authors: M.K. Nimfopoulos, N. Milopoulos, C. Katirtzoglou
Proceedings 6th Congress of the Geographical Society of Greece, Volume II, 436-444, 2002

The Migdonia drainage basin, located some 10 km NE of the Thessaloniki town, encloses the lakes Koronia, Volvi,... more The Migdonia drainage basin, located some 10 km NE of the Thessaloniki town, encloses the lakes Koronia, Volvi, Mavrouda and Lantza, and contains Pleistocene and Holocene loose sediments formed on an active tectonic depression. A shallow phreatic aquifer (d<50 m) and a deep one (d=80-500 m) are recognized in the basin, while in the depth of 50-80 m impermeable clayey layers of unilateral to lensoid formation predominate. In the period 1996-2000 the drop in the water table of the phreatic aquifer in the area of lake Volvi was constant (0 to 1.2 m). The same period, the water table drop in the lake Koronia was 0.11 to 7.59 m. The dropping Migdonian annual natural water flows, combined with the urban and industrial impact, lead to water quality degradation and ecological death.