Vadose zone modeling to identify controls on groundwater recharge in an unconfined granular aquifer in a cold and humid environment with different meteorological data sources

Groundwater recharge (GR) is a complex process that is difficult to quantify. Increasing attention has been given to unsaturated zone modeling to estimate GR and better understand the processes controlling it. Continuous soil-moisture time series have been shown to provide valuable information in this regard. The objectives of this study were to (i) analyze the processes and factors controlling GR in an unconfined granular aquifer in a cold and humid environment and (ii) assess the uncertainties associated with the use of data from different sources. Soil moisture data monitored over three years at three experimental sites in southern Quebec (Canada) were used to calibrate the HYDRUS-1D model and to estimate ranges of possible GR in a region where groundwater is increasingly used as a source of fresh water. The simulations identified and quantified important factors responsible for the near-surface water balance that leads to GR. The resulting GR estimates from 2016 to 2018 showed marked differences between the three sites, with values ranging from 347 to 735 mm/y. Mean GR for the three sites was 517 mm/y for 2016–2018 and 455 mm/y for the previous 12-year period. GR was shown to depend on monthly variations in precipitation and on soil textural parameters in the root zone, both controlling soil-water retention and evapotranspiration. Monthly recharge patterns showed distinct preferential GR periods during the spring snowmelt (38–45% of precipitation) and in the fall (29% of precipitation). The use of different meteorological datasets was shown to influence the GR estimates.

GRANULAR AQUIFER SYSTEM OF WEST CHALKIDIKI AREA, REGION OF CENTRAL MACEDONIA, NORTHERN GREECE

The granular aquifer system of the western Chalkidiki peninsula covers an area of 667 Km2 occupying Neogene and Quaternary sediments. The present study deals with the hydrogeological and hydrogeochemical characterization of the granular aquifer system for the purposes of efficient utilization and management of groundwater resources. It is a multilayered formation, composed of unconsolidated to semi-consolidated sands, gravels, conglomerates, sandstones and marly limestones with intercalated impermeable to semi-permeable beds of clays, marls or mixed with pebbles and sands. The aquifer system is characterized by medium to moderate hydrocapacity and the pumped groundwater consumptions are 74*106 m3/yr. Piezometric studies carried out in the period of 2003-14, conclude that the piezometric surface decline is located in the S and SE parts of the aquifer system, while in the rest Central and NW parts there is a noticeable rising of the groundwater table. Groundwater is generally characterized by a good quality; however, groundwaters of the broader Triglia area, have excessively high contents of As (10 to 3400 μgr/l) and B (1.5 to 4.0 mg/l). Other natural pollutants are Fe and Mn. Salinization and high values of nitrate are mainly detected in water boreholes of Moudania-Portaria, Akrotiri-Epanomi and Agelochori areas.

GROUNDWATER RESOURCES ASSESSMENT OF GRANULAR AQUIFERS IN GREECE

Sound groundwater resources management is a matter of paramount importance in Circum-Mediterranean, for the ecologic status of the underlying aquifer systems. Freshwater resources in Greece are identified within all types of aquifer formations, however two distinct types are the ones that draw the attention of the scientific and the engineering community; the granular as well as the karst aquifers. This paper describes the groundwater resources potential that are found within granular aquifer formations, in combination with the major environmental threats associated with their exploitation and management.

OVEREXPLOITATION OF GROUNDWATER RESOURCES IN THE COASTAL AQUIFER SYSTEM OF ARGOLIS

Intense abstraction of groundwater resources in the coastal aquifer system of Argolis is investigated since the late 1950’s. The increasing water demands due to the agricultural development of the area (mainly citrus trees) during the last years, in combination with the touristic growth, has led to the overexploitation of groundwater resources of the coastal aquifer system of Argolis. This paper presents the piezometric conditions in the plain of Argos during the period between 1986 and 2014, analysing the fluctuations of groundwater levels and highlighting the problem of seawater intrusion in the study area. In October 2014, measurements were made in app. 160 wells and drills which are located within the boundaries of the granular aquifer of the study area. Selected piezometric maps are presented, which demonstrate the problem of overexploitation of groundwater in the plain of Argos.

ANÁLISE DA RECARGA NO SISTEMA AQUÍFERO GRANULAR E FISSURAL NA ÁREA DO CAMPUS PAMPULHA DA UNIVERSIDADE FEDERAL DE MINAS GERAIS

No presente estudo analisou-se a recarga no sistema aquífero existente na área do campus Pampulha da UFMG, em Belo Horizonte, Minas Gerais. Este Sistema Aquífero é composto por dois aquíferos em um ambiente geológico com duas identidades litoestratigráficas distintas. Sendo, um aquífero granular, sobrejacente, caracterizado pelo manto de intemperismo, e um aquifero fraturado, subjacente, caracterizado por rochas do Complexo Belo Horizonte, principalmente gnaisses e granitos. A área de estudo possui uma rede de poços tubulares profundos e poços de monitoramento, formada por doze poços tubulares profundos e sete poços de monitoramento. Neste estudo a recarga foi qualificada a partir de premissas das principais variáveis que a influenciam, entre elas a precipitação, a litologia, a profundidade do nível potenciométrico e o relevo. O trabalho se baseou em dados pré-existentes advindos do monitoramento do nível d’água, realizado entre 1997 e 2000, em poços e piezômetros existentes na área de estudo. A análise estatística apontou a precipitação e a textura dos solos como os fatores que mais influenciam na recarga local. Foi constatado que há uma conexão hidráulica entre os dois aquíferos e, por conseguinte uma recarga indireta do aquífero superior para o basal.Palavras-chave: Recarga direta; monitoramento de nível d’água; conexão hidráulica; aqüíferos poroso e fraturado. Abstract: ANALYSIS ON RECHARGE OF AQUIFER SYSTEM GRANULAR AND FISSURE ON UFMG CAMPUS AREA, BELO HORIZONTE, MG. In the present paper we analyzed the existing aquifer recharge system in the campus area UFMG, in Belo Horizonte, Minas Gerais. This aquifer system consists of two aquifers in a geological environment with two distinct lithostratigraphic identities. Being a granular aquifer, overlying, characterized by weathering mantle, and a fractured aquifer, underlying, characterized by rocks of the Complex Belo Horizonte, mainly gneisses and granites. The study area has a network of deep wells and monitoring wells, formed by twelve deep wells and seven monitoring wells. In this study the clearance was qualified from the premises of the main variables that influence it, including precipitation, lithology, depth of potentiometric level and relief. The work was based on pre-existing data obtained from the monitoring of the water level, conducted between 1997 and 2000 in existing wells and piezometers in the study area. The statistical analysis showed precipitation and soil texture as the factors that most influence in local recharge. It has been found that there is a hydraulic connection between the two aquifers and therefore an indirect upper aquifer recharge to baseline.Keywords: Recharge; water level monitoring; hydraulic connection; fractured and granular aquifer.