Osman Abdalla

Hydrochemical characterization of the main aquifers in Khartoum, the capital city of Sudan

The present study assesses groundwater resources of the densely populated area of the Khartoum State, Sudan by integrating conventional hydrochemistry and statistical analysis. Groundwater is exploited from two aquifers: Gezira and Nubian. The Gezira aquifer, which occupies the upper part, is separated by impermeable unit from the lower Nubian aquifer. Both aquifers are part of thick sedimentary accumulations formed under fluviolacustrine environment during Tertiary and Cretaceous, respectively. The groundwater flows in the two aquifers from the White and Blue Niles (both rivers bound the area from west and east, respectively) into the center of the study area suggesting recharge from the rivers. This river-induced recharge is demonstrated by the hydrochemical evolution of the groundwater along the flow direction. Groundwater evolves in the Nubian aquifer from Ca2+–Mg2+–HCO3− type in the vicinity of the Niles to Na+–K+–Cl−–SO42− type in the central part of the area indicating precipitation of carbonates and dissolution of clay minerals and evaporites reported in the well logs. A third type of groundwater Na+–K+–HCO3− is formed in the mid zones between the Niles and the central part showing the ionic exchange and minerals dissolution/precipitation with the flow direction. In the Gezira aquifer, the water only changes from Ca2+–Mg2+–HCO3− type to Na+–K+–HCO3− type indicating a lesser degree of mineral dissolution. The factor analysis reveals three factors controlling the chemistry of groundwater in the study area: mineral dissolution and weathering, carbonate system, and anthropogenic effect. Factor 1 (mineral dissolution and weathering) includes high values of TDS, EC, Na+, K+, CI−, HCO3−, and SO42− in respective order; Factor 2 (carbonate system) includes Ca2+, Mg2+, CO32−, and pH; Factor 3 (anthropogenic effect) includes NO3− and F−. It has been demonstrated that the integration of conventional hydrochemical analysis with factor analysis represents a powerful mean to understand the factors controlling groundwater chemistry.

The application of air-sparging, soil vapor extraction and pump and treat for remediation of a diesel-contaminated fractured formation

Abstract The present study addresses the efficiency of an integrated air sparging, soil vapor extraction, and pump and treat system in the remediation of a diesel contaminated site in Oman. Cleanup efforts have targeted groundwater and soil in fractured formations. Site hydrogeological characterization was conducted including sampling and analysis of water and soil. Within seven months of the start of the treatment system, benzene gas in the unsaturated zone fell from an initial range of 15–60 ppm to below detection level, while total petroleum hydrocarbon in the groundwater dropped from 25–50 ppm to less than 0.5 ppm. Treatment processes have ceased while groundwater and soil are being monitored. Thus far, benzene gas has been undetected for the past 18 months, but total petroleum hydrocarbon in groundwater has rebounded to 1.2 ppm during the last four months.

Factors affecting groundwater chemistry in regional arid basins of variable lithology: example of Wadi Umairy, Oman

Understanding factors influencing groundwater chemistry in regional groundwater basins is important to prevent groundwater pollution especially in arid areas where rainfall is low and water resources are limited. The present study assesses such factors in the regional, geologically diverse, groundwater basin of Wadi Umairy in Oman. The basin is composed of five different lithostratigraphic units with different hydraulic properties. Water samples (41) have been collected from the different units and analyzed for the major ions. Factor analysis and conventional hydrochemical methods were used to define the factors that have significant impact on the aquifers hydrochemistry. It was found that evaporation and mineral weathering/dissolution are the main factors defining the groundwater chemistry along the flow path from recharge to discharge zones, whereas anthropogenic activities and alkalinity are found to be of lesser effect, and the latter prevails when the rocks are predominantly monomineralic. It was concluded that in regional groundwater basins, recharge/discharge relations together with the flow scale control the hydrochemistry irrespective of lithological variation in the basin.

Groundwater recharge to ophiolite aquifer in North Oman: constrained by stable isotopes and geochemistry

Abstract The current study employs geochemical and isotopic tools to understand hydrochemical and recharge processes characterizing ophiolite aquifer in North Oman in conjunction with the Hajar Super Group (HSG) aquifer. A total of 57 samples were analyzed for major ions and stable isotopes 2H and 18O. The geochemical composition of groundwater indicates that water–rock interaction and mixing are the main processes controlling groundwater chemistry. Groundwater in the HSG is characterized by carbonate minerals dissolution contrary to the groundwater in the ophiolites where silicates dissolution dominates. This results in differences in the groundwater chemical composition in the two systems. Isotopic characteristics of precipitation collected during the study period indicate two main moisture sources from the Indian Ocean and the Mediterranean Sea. Groundwater δ2H and δ18O values suggest two recharge sources to the ophiolite aquifer: lateral flow from the HSG and direct infiltration. Recharge from direct infiltration in the highlands, which is depleted in δ2H and δ18O, retains the same isotopic signature of precipitation, whereas that in the low land substantially reflects an evaporation effect.

Groundwater recharge estimation in arid hardrock-alluvium aquifers using combined water-table fluctuation and groundwater balance approaches

This paper proposes an approach to estimate groundwater recharge using an optimization-based water-table fluctuation method combined with a groundwater balance model in an arid hardrock-alluvium region, located at the Oman-United Arab Emirates (UAE) border. We introduce an “effective hardrock thickness” term to identify the percentage of the considered hardrock thickness in which effective groundwater flow takes place. The proposed method is based upon a Thiessen polygon zoning approach. The method includes sub-polygons to represent specific geologic units and to enhance the confidence of the estimated groundwater recharge. Two linear and one nonlinear sub-models were developed to evaluate the model components for the calibration (Oct. 1996 to Sep. 2008) and validation (Oct. 2008 to Sep. 2013) periods. Long-term annual groundwater recharge from rainfall and return flow over the model domain are estimated as 24.62 and 5.71 Mm3, respectively, while the effective groundwater flow circulation is found to occur in the upper 7% of the known hardrock thickness (42 m), confirming conclusions of previous field studies. Considering a total difference in groundwater levels between eastern and western points of the study area of the order of 220 m and a 12-year monthly calibration period, a weighted root mean squared error in predicted groundwater elevation of 2.75 m is considered quite reasonable for the study area characterized by remarkable geological and hydrogeological diversity. The proposed approach provides an efficient and robust method to estimate groundwater recharge in regions with a complex geological setting in which interaction between fractured and porous media cannot be easily assessed.

Impurity effect on clear water evaporation: toward modelling wastewater evaporation using ANN, ANFIS-SC and GEP techniques

ABSTRACT The growing shortage of freshwater resources and increasing environmental awareness give rise to the use of treated wastewater as an alternative resource for water supply. Accurate estimation of wastewater evaporation (WWE), as the main cause of water losses, is necessary for proper water resources management. Unfortunately, few studies have focused on modelling WWE despite its vital importance. This study investigates the ability of gene expression programming (GEP), adaptive neuro-fuzzy inference system (ANFIS) and artificial neural networks (ANN) techniques to estimate WWE as a function of variables including wastewater properties, clear water evaporation and climatic factors. The study uses measured data from an experiment conducted in Neishaboor municipal wastewater treatment plant, Iran. Results indicate that the ANN model is superior among the three methods, and also demonstrates higher accuracy when compared with those of a dimensional analysis model using the F-test statistic.

Interaction of surface water and groundwater in the Nile River basin: isotopic and piezometric evidence

Past discussions around water-resources management and development in the River Nile basin disregard groundwater resources from the equation. There is an increasing interest around factoring the groundwater resources as an integral part of the Nile Basin water resources. This is hampered by knowledge gap regarding the groundwater resources dynamics (recharge, storage, flow, quality, surface-water/groundwater interaction) at basin scale. This report provides a comprehensive analysis of the state of surface-water/groundwater interaction from the headwater to the Nile Delta region. Piezometric and isotopic (δ18O, δ2H) evidence reveal that the Nile changes from a gaining stream in the headwater regions to mostly a loosing stream in the arid lowlands of Sudan and Egypt. Specific zones of Nile water leakage to the adjacent aquifers is mapped using the two sources of evidence. Up to 50% of the surface-water flow in the equatorial region of the Nile comes from groundwater as base flow. The evidence also shows that the natural direction and rate of surface-water/groundwater interaction is largely perturbed by human activities (diversion, dam construction) particularly downstream of the Aswan High Dam in Egypt. The decrease in discharge of the Nile River along its course is attributed to leakage to the aquifers as well as to evaporative water loss from the river channel. The surface-water/groundwater interaction occurring along the Nile River and its sensitivity to infrastructure development calls for management strategies that account groundwater as an integral part of the Nile Basin resources.RésuméLes discussions passées sur la gestion et le développement des ressources en eau dans le bassin du Nil n’introduisent pas dans l’équation les ressources en eau souterraine. Il y a un intérêt croissant pour intégrer les ressources en eau à part entière dans les ressources en eau du bassin du Nil. Le manque de connaissances concernant la dynamique des ressources en eau souterraine (recharge, stockage, écoulement, qualité, interaction entre les eaux de surface et les eaux souterraines) à l’échelle du bassin freine le développement. Cet article fournit une analyse complète de l’état de l’interaction entre les eaux de surface et les eaux souterraines de la tête de bassin à la région du delta du Nil. Les données piézométriques et isotopiques ((δ18O, δ2H) mettent en évidence que le Nil passe d’un état de cours d’eau drainant dans les régions de tête de bassin à un état de cours d’eau drainé principalement dans les zones basses arides du Soudan et de l’Egypte. Des zones spécifiques d’infiltration d’eau vers les aquifères adjacents sont cartographiées à l’aide de deux sources de données probantes. Jusqu’à 50% du débit d’eau de surface dans la région équatoriale du Nil provient des eaux souterraines, constituant le débit de base. Les données montrent également que la direction naturelle des écoulements et des taux d’échange dans les interactions entre les eaux de surface et les eaux souterraines sont en grande partie perturbées par les activités humaines (dérivation, construction de barrages) particulièrement en aval du Haut Barrage d’Assouan en Egypte. La diminution du débit du Nil le long de son cours est attribuée à des infiltrations vers les aquifères ainsi qu’à la perte d’eau par évaporation à partir du lit du fleuve. Les interactions entre les eaux de surface et les eaux souterraines qui se produisent le long du Nil et leur sensibilité au développement d’infrastructure nécessitent des stratégies de gestion qui prennent en considération les eaux souterraines en tant que partie intégrante des ressources en eau du bassin du Nil.ResumenLas discusiones pasadas sobre la gestión y el desarrollo de los recursos hídricos en la cuenca del río Nilo desprecian los recursos hídricos subterráneos de la ecuación. Existe un creciente interés por la influencia de los recursos hídricos subterráneos como parte integral de los recursos hídricos de la Cuenca del Nilo. Esto se ve obstaculizado por la falta de conocimientos sobre la dinámica de los recursos hídricos subterráneos (recarga, almacenamiento, flujo, calidad, interacción agua superficial / agua subterránea) a escala de cuenca. Este artículo ofrece un análisis exhaustivo del estado de la interacción agua de superficie / agua subterránea desde las cabeceras hasta la región del delta del Nilo. Las evidencias piezométricas e isotópicas (δ18O, δ2H) revelan que el Nilo cambia de una corriente ganadora en las regiones de cabeceras a perdedora en la mayor parte de las tierras bajas áridas de Sudán y Egipto. Las zonas específicas de la filtración del agua del Nilo hacia los acuíferos adyacentes se mapean utilizando dos fuentes de evidencia. Hasta el 50% del flujo superficial de agua en la región ecuatorial del Nilo proviene del agua subterránea como flujo base. La evidencia también muestra que la dirección natural y la tasa de interacción agua de superficie / agua subterránea está en gran medida perturbada por las actividades humanas (desvío, construcción de presas) particularmente aguas abajo de la presa de Aswan en Egipto. La disminución en la descarga del río Nilo a lo largo de su curso se atribuye a la filtración hacia los acuíferos, así como a la pérdida de agua por evaporación del canal del río. La interacción agua de superficie / agua subterránea que se produce a lo largo del río Nilo y su sensibilidad al desarrollo de infraestructuras requiere estrategias de manejo que consideren el agua subterránea como una parte integral de los recursos de la Cuenca del Nilo.摘要过去有关尼罗河流域的论述及水资源管理和开发忽视了地下水资源这一部分。把地下水资源作为尼罗河流域水资源不可分割的一部分越来越得到了人们的重视。但由于缺乏流域尺度上对地下水资源动力学(补给量、储存量、水流量、质量、地表水/地下水相互作用)方面的了解而受到阻碍。本文综合分析了河流源头到尼罗河三角洲地区地表水/地下水相互作用的状态。压力水面和同位素(δ18O和 δ2H)证据显示,尼罗河在河头地区为潜水补给河,而到苏丹和埃及的干旱低地通常变为渗失河。利用两个证据来源绘出了尼罗河河水渗流到毗邻含水层的特定区域图。在赤道地区,多达50%的尼罗河地表水流来自作为基流的地下水。证据还显示,地表水/地下水相互作用的自然方向和强度很大程度上受到人类活动的影响(引水及大坝建设),特别是受到下游阿斯旺水坝的影响。尼罗河沿河道的排泄量减少主要是因为渗漏至含水层以及河道的蒸发损失。沿尼罗河出现的地表水/地下水相互作用及其对基础设施建设的敏感性迫切需要采纳新的管理策略,即把地下水作为尼罗河水资源不可分割的一部分。ResumoDiscussões passadas sobre a gestão dos recursos hídricos e desenvolvimento na bacia do Rio Nilo desconsideraram os recursos hídricos subterrâneos da equação. Existe um interesse crescente sobre consignar os recursos hídricos subterrâneos como uma parte integrante dos recursos hídricos da Bacia do Nilo. Isso é dificultado pela falta de conhecimento sobre a dinâmica dos recursos hídricos subterrâneos (recarga, armazenamento, escoamento, qualidade, interação águas superficiais/subterrâneas) na escala da bacia. Esse artigo apresenta uma análise abrangente do estado da interação entre águas superficiais/subterrâneas da cabeceira a região do delta do Nilo. Evidencias piezométricas e isotópicas (δ18O, δ2H) revelaram que o Nilo muda de uma corrente de ganho em suas cabeceiras para praticamente correntes de perda nas planícies áridas do Sudão e do Egito. Zonas específicas de infiltração das águas do Nilo aos aquíferos adjacentes são mapeadas usando as duas fontes de evidencia. Mais de 50% do escoamento das águas superficiais da região equatorial do Nilo vem das águas subterrâneas como escoamento de base. A evidencia também mostra que a direção natural e taxa de interação entre as águas superficiais/subterrâneas é amplamente perturbada por atividades humanas (diversões, construções de barragens) particularmente a montante da barragem Aswan High no Egito. A diminuição da descarga do Rio Nilo ao longo do seu curso é atribuída à infiltração aos aquíferos como para perdas evaporativas pelo canal fluvial. A interação das águas superficiais/subterrâneas ocorrendo ao longo do Rio Nilo e sua sensitividade a desenvolvimentos de infraestrutura clamam por estratégias de gestão que considerem as águas subterrâneas como uma parte integrante dos recursos da Bacia do Nilo.

Hydro-chemical evolution of groundwater in a sequence of Tertiary Formations in Northwest Oman

Tertiary Formations, which are widely spread in the Arab Peninsula, are fundamental to the oil industry in the world’s largest oil producing area. These formations host major aquifers that satisfy water demands for oil production such as steam injection and reservoir pressure maintenance . The current study investigates the hydro-chemical evolution of groundwater in a sequence of Tertiary Formations in Northwest Oman in the Kingdom of Saudi Arabia and the United Arab Emirates borders. Stable isotopes (18O and 2H) show three different groundwater types: (1) groundwater formed from precipitation originating from the Mediterranean Sea, (2) groundwater formed from mixing of northern (Mediterranean) and southern (Indian Ocean) moisture sources, and (3) groundwater affected by evaporation. Radiogenic isotopes 14C and 3H indicate younger groundwater close to the recharge source in North Oman Mountains and older age in the plain desert area that constitutes the discharge zone. Groundwater chemistry notably evolves from Ca–Mg–HCO3 dominant in the recharge area to Na–Cl–SO4 dominant type in the discharge zone. Water–rock interaction is the main process controlling groundwater chemistry in the recharge zone while evaporation becomes progressively effective down the gradient. The geochemistry and stable and radiogenic isotopes of the Tertiary Formations indicate that the study area has witnessed wet periods during the Early Holocene with surface water bodies formed by groundwater discharge at distal parts. The sustainability of such old groundwater that is being exploited for oil production should be thoroughly investigated to secure future oil production.

Coupling isotopic and piezometric data to infer groundwater recharge mechanisms in arid areas: example of Samail Catchment, Oman

Hydrochemistry and well hydrographs are coupled to assess groundwater recharge in the regional catchment of Samail, Oman. The complex geology comprises three aquifers: limestones of the Hajar Supergroup (HSG) at the highlands of North Oman Mountains (NOM); fractured/weathered ophiolites; and Quaternary alluvium. Groundwater flows south–north from the NOM to the coast. Samples from groundwater wells and springs (38) were analyzed for isotopes and major ions. Corrected 14C dating reveals modern groundwater across the entire catchment, while 87Sr/86Sr (0.70810–0.70895) shows greater homogeneity. Groundwater in the upper catchment is depleted in 2H and 18O, indicating a high-altitude recharge source (NOM), and becomes enriched downstream, with a slope indicating an evaporation effect. The hydrographs of nested piezometers located in the upper, middle and lower catchment show different recharge responses between deep and shallower depths. Head difference in response to recharge is observed upstream, suggesting a lateral recharge mechanism, contrary to vertical recharge downstream reflected in identical recharge responses. The homogeneous 87Sr/86Sr ratio, head changes, downstream enrichment of 2H and 18O, and the presence of modern groundwater throughout the catchment suggest that groundwater recharge takes place across the entire catchment and that the three aquifers are hydraulically connected. The recharge estimated using the chloride mass balance method is in the range of 0–43% of the mean annual rainfall.RésuméL’hydrochimie et les chroniques piézométriques sont utilisées conjointement pour évaluer la recharge des eaux souterraines dans le bassin hydrologique de Samail, Oman. La géologie complexe du bassin implique l’existence de trois aquifères: les calcaires du « Hajar Supergroup » (HSG) dans les parties hautes des montagnes nord-omanaises (NOM), les ophiolites fracturées/altérées et les alluvions du Quaternaire. Les directions d’écoulement des eaux souterraines sont Sud–Nord depuis les NOM jusqu’au littoral. La signature isotopique et les concentrations en ions majeurs des échantillons d’eau souterraine issus de forages et de sources (38) ont été déterminées. La datation au 14C corrigée indique des eaux souterraines récentes dans l’intégralité du bassin et le 87Sr/86Sr (0.70810–0.70895) montre une grande homogénéité. Les eaux souterraines dans la partie haute du bassin sont appauvries en 2H et 18O, indiquant une recharge en haute altitude (NOM), alors qu’à l’aval celles-ci deviennent enrichies et suivent une pente indiquant un effet d’évaporation. Les chroniques piézométriques mesurées sur une batterie de piézomètres (en « flûte de pan ») situés dans la partie haute, intermédiaire et basse du bassin présentent des réponses à la recharge, contrastées entre mesures profondes et plus superficielles. Dans la partie haute, les différences de charge observées en réponse à la recharge suggèrent un mécanisme de transfert latéral de la recharge alors que dans la partie basse, la réponse des piézomètres pour une recharge identique indique un transfert vertical. L’homogénéité du rapport 87Sr/86Sr, les variations de charges hydrauliques, l’enrichissement en 2H et 18O vers l’aval, et la présence d’eau souterraine récente dans tout le bassin suggèrent que la recharge des eaux souterraines opère dans l’intégralité du bassin et que les trois aquifères sont hydrauliquement connectés. La recharge, estimée par la méthode du bilan de masse en chlorures, est comprise entre 0 et 43% de la pluviométrie annuelle moyenne.ResumenSe acoplaron la hidroquímica y los hidrogramas de pozos para evaluar la recarga del agua subterránea en la cuenca regional de Samail, Omán. La compleja geología comprende tres acuíferos: calizas del Supergrupo Hajar (HSG) en las tierras altas de las montañas del norte de Omán (NOM); ofiolitas fracturadas/erosionadas; y aluvión cuaternario. El agua subterránea fluye al sur–norte desde la NOM a la costa. Las muestras de los pozos y manantiales del agua subterránea (38) se analizaron para detectar isótopos e iones mayoritarios. La datación corregida de 14C revela la presencia de agua subterránea moderna en toda la cuenca, mientras que 87Sr/86Sr (0.70810–0.70895) muestra una mayor homogeneidad. El agua subterránea en la cuenca superior se empobrece en 2H and 18O, lo que indica una fuente de recarga a gran altitud (NOM), y se enriquece aguas abajo con una pendiente que indica el efecto de la evaporación. Los hidrogramas de piezómetros anidados ubicados en la cuenca superior, media e inferior muestran diferentes respuestas de la recarga entre las mayores y menores profundidades. La diferencia de la carga hidráulica en respuesta a la recarga se observa aguas arriba, lo que sugiere un mecanismo de recarga lateral, contrariamente a la recarga vertical aguas abajo reflejada en idénticas respuestas de recarga. La relación homogénea 87Sr/86Sr, los cambios de carga hidráulica, el enriquecimiento aguas abajo de 2H y 18O, y la presencia de agua subterránea moderna sugieren que la recarga de agua subterránea se realiza en toda la cuenca y que los tres acuíferos están conectados hidráulicamente. La recarga estimada utilizando el método de balance de masa de cloruro está en el rango de 0-43% de la precipitación media anual.摘要结合水化学和井水位图评价了阿曼Samail区域汇水区地下水补给量。复杂的地质条件包括三个含水层:阿曼山脉北部高原Hajar超级组石灰岩层;断裂/风化蛇绿岩层;第四纪冲积层。地下水从阿曼山脉北部自南向北流向沿海。对地下水井和泉的水样进行了同位素和主要离子分析。校正的14C测年结果揭示整个汇水区为现代地下水,而87Sr/86Sr (0.70810–0.70895)显示出更高的均质性。在汇水区上游地下水中的2H 和 18O所剩无几,表明存在着高海拔补给源(阿曼山脉北部),在下游呈坡度富集,表明有蒸发效应。位于汇水区上游、中游和下游的测压计水位图显示,在深的和较浅的深度,补给响应不同。在上游观测到对补给响应的水头差,表明有侧向补给机理,与相同补给响应中反映出的下游垂直补给形成对比。均质的87Sr/86Sr比值、水头变化、2H 和 18O在下游的富集以及整个汇水区为现代水表明,整个汇水区都有地下水补给,三个含水层水力上有联系。采用氯化物质量平衡法估算的补给量为平均每年降水量的0-43%。ResumoHidrogeoquímica e hidrografas de poços são acopladas para avaliar a recarga das águas subterrâneas na bacia regional de Samail, Omã. A geologia complexa compreende três aquíferos: calcários do Supergrupo Hajar (SGH) nos planaltos das Montanhas do Norte de Omã (MNO); ofiolitos fraturados/intemperizados; e aluviões Quaternários. A água subterrânea flui do norte para o norte do MNO até a costa. Amostras de poços e nascentes de água subterrânea (38) foram analisadas para isótopos e íons principais. A datação 14C corrigida revela águas subterrâneas modernas em toda a bacia, enquanto 87Sr/86Sr (0.70810-0.70895) mostra maior homogeneidade. A água subterrânea na bacia superior está esgotada em 2H e 18O, indicando uma fonte de recarga de alta altitude (MNO), e torna-se enriquecida a jusante com um declive indicando o efeito da evaporação. Os hidrogramas de piezômetros aninhados localizados na bacia superior, média e inferior mostram diferentes respostas de recarga entre profundidades profundas e rasas. A diferença de carga em resposta à recarga é observada a montante sugerindo um mecanismo de recarga lateral, ao contrário da recarga vertical a jusante refletida em respostas de recarga idênticas. A relação homogênea 87Sr/86Sr, mudanças de carga, enriquecimento a jusante de 2H e 18O e a presença de águas subterrâneas modernas em toda a bacia sugerem que a recarga de água subterrânea ocorre em toda a bacia hidrográfica e que os três aquíferos estão conectados hidraulicamente. A recarga estimada usando o método de balanço de massa de cloreto está na faixa de 0-43% da precipitação média anual.

Water Resources in Arid Areas: The Way Forward

The red sand dunes appear along the south east, -west coast of Tamil Nadu, India between the latitudes and longitudes of 8°07′56′′N to 8°22′11′′N; 77° 19′84′′E to 77°53′40′′E. The dune sands from this region were studied through magnetic methods such as magnetic susceptibility measurements and acquisition of isothermal remanent magnetization, geochemistry and X-ray diffraction methods. Optically stimulated luminescence (OSL) dating method was used to constrain the chronology of deposits. Three sections were excavated up to 5–9.5 m with one inland deposit (TPV) and two near coastal sections (THOP and MUT). Celeste Gomes—deceased A. Vidyasakar (&) S. Srinivasalu Department of Geology, Faculty of Science and Humanities, Anna University, Chennai, India e-mail: a.vidyasakar@gmail.com A. Vidyasakar H. Sant’Ovaia Pole of the Faculty of Sciences, Earth Sciences Institute, Rua do Campo Alegre, Porto 4169-007, Portugal L. Alappat Department of Geology and Environmental Science, Christ College, Irinjalakuda 680125, Kerala, India P. Morthekai Luminescence Dating Laboratory, Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow 226007, India A.K. Singhvi Planetary and Geoscience Division, Physical Research Laboratory, Ahmedabad 380009, India F. Jorge LaboratórioNacional de Energia e Geologia, I.P/Rua da Amieira, Apartado 1089, S. Mamede de Infesta, Porto 4466-901, Portugal C. Gomes CGUC, Department of Earth Sciences, Faculty of Sciences and Technology, University of Coimbra, Largo Marquês de Pombal, Coimbra 3000-272, Portugal