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Quality aspects of the surface water used for irrigation in the Neretva Delta ( Croatia )

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Romic D. , Zovko M. , Romic M. , Ondrasek G. , Salopek Z.

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tom no. 12

59-70

EN

The research was set up in the Neretva River valley in the Southern part of Croatian Karst area, where implementation of modern hydrotechnical practices within the river catchment's area led to intrusion of seawater to groundwater resulting in soil salinization in the delta. The region has great agro-ecological potential for intensive production of vegetables and Mediterranean fruits. Since the combination of the effects of saline groundwater and the use of this water for irrigation may have disastrous effects on the productivity of agricultural soils water, a project was started in order to set up a permanent monitoring network. The aim of this study was to determine the salt dynamics in the surface water on five locations which are considered as potential sources of the irrigation water (Modric canal, Neretva River near Opuzen, Crepina, Jasenska and Vidrice pumping station) during a 4-year period (1999-2002). The surface water samples had been collected on monthly basis and analyzed for all parameters required in the irrigation water quality classification. The results show considerable spatial and temporal variability of determined parameters. Thus, in the Neretva River near Opuzen, total salt concentrations in water ranged from 0.4 to 7.7 dS·m-¹, and in Modric from 1.65 up to17.2 dS·m-¹. Dominant cations and anions on all observed locations were Na+ and Cl-. Constantly high concentration of Na+ in sampled surface waters is of a special concern. Utilization of the water of such quality may cause problems related to the use of alkaline waters for irrigation, which can further cause permanent loss of fertile soil.

PL

Badania prowadzono w dolinie Neretwy, w południowej części chorwackiego obszaru krasowego, na którym działania hydrotechniczne w zlewni doprowadziły do napływu wody morskiej do warstw wodonośnych i w konsekwencji spowodowały zasolenie gleb w delcie rzeki. Region charakteryzuje się dużym potencjałem agroekologicznym i możliwością produkcji warzyw i owoców śródziemnomorskich. Ponieważ nałożenie się efektów zasolenia wód gruntowych i użycia tych wód do nawodnień może mieć fatalne skutki dla produktywności gleb, zainicjowano założenie sieci stałego monitoringu jakości wód. Celem tych badań było określenie dynamiki zasolenia wód powierzchniowych w czteroletnim okresie (1999-2002) na podstawie pomiarów w pięciu stanowiskach uznanych za potencjalne źródła wody do nawodnień (Kanał Modric, Neretwa koło Opuzen oraz stacje pomp Crepina, Jasenka i Vidrice). Próbki wód powierzchniowych pobierano co miesiąc i analizowano w nich wszystkie parametry niezbędne do oceny jakości wód do nawodnień. Stwierdzono znaczną zmienność mierzonych parametrów w czasie i w przestrzeni. Całkowita mineralizacja wód Neretwy koło Opuzen wynosiła od 0,4 do 7,7 dS·m-¹ a w Kanale Modric od 1,65 do 17,2 dS·m-¹. Na+ i Cl- były dominującymi jonami we wszystkich badanych stanowiskach. Stale duże stężenie Na+ w próbkach wód powierzchniowych wymaga szczególnej troski. Stosowanie wody takiej jakości może powodować problemy związane z użyciem do nawodnień wód alkalicznych, co w przyszłości może prowadzić do całkowitej utraty żyznej gleby.

2

Geophysical approach for assessment of seawater intrusion in the coastal aquifer of Wadi Nador (Tipaza, Algeria)

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Bouderbala A. , Remini B.

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tom Vol. 62, no. 6

1352--1372

EN

The aquifer of Nador has suffered significant salinization due to seawater intrusion. It was strongly exploited during the 1980s and 1990s. A piezometric analysis in April 2012 showed the piezometric level to lie at 0 m a.s.l. over the plain; as a result, this aquifer is highly sensitive to the marine intrusion with an electrical conductivity of the groundwater in of exceeds 2500 μS/cm and so there are no abstractions for irrigation or drinking purpose from these sectors. The geoelectric study also showed the lateral variation in the electrical resistivity for two moments separated in time by more than 45 years. The fall in resistivity may be due to the encroachment of seawater into previously freshwater zones and/or infiltration during the era of pumped abstractions downstream. The resistivity surveys reveal two distinct sectors: the saturated aquifer in brackish and saltwater having resistivity values to 36-10 Ωm, which extends nearly 1600 m inland.

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Application of Multivariate Statistical Techniques for Characterization of Groundwater Quality in the Coastal Aquifer of Nador, Tipaza (Algeria)

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Bouderbala A. , Remini B. , Saaed Hamoudi A. , Pulido-Bosch A.

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tom Vol. 64, no. 3

670--693

EN

The study focuses on the characterization of the groundwater salinity on the Nador coastal aquifer (Algeria). The groundwater quality has undergone serious deterioration due to overexploitation. Groundwater samplings were carried out in high and low waters in 2013, in order to study the evolution of groundwater hydrochemistry from the recharge to the coastal area. Different kinds of statistical analysis were made in order to identify the main hydrogeochemical processes occurring in the aquifer and to discriminate between different groups of groundwater. These statistical methods provide a better understanding of the aquifer hydrochemistry, and put in evidence a hydrochemical classification of wells, showing that the area with higher salinity is located close to the coast, in the first two kilometers, where the salinity gradually increases as one approaches the seaside and suggests the groundwater salinization by seawater intrusion.