The Analysis of Short-Term Dataset of Water Stable Isotopes Provides Information on Hydrological Processes Occurring in Large Catchments from the Northern Italian Apennines

Abstract

This study discusses a dataset of water stable isotopes from precipitation (4 rain gauges) and surficial water (9 rivers) from the northern Italian Apennines, an area in which clay-rich bedrocks widely outcrop and the runoff response to precipitation events is very rapid. The dataset has been compiled starting from existing data that had previously been published in the literature and consists of monthly values of stable isotopes oxygen-18 (18O) and deuterium (2H) lasting over the period from January 2003 to December 2006 (precipitation) and from January 2006 to December 2007 (surficial water). For this period, mean residence times estimated by means of a sine-wave fitting technique make evident the significant differences over time spent by water molecules within the 9 catchments. Moreover, isotopic compositions of rivers deviated from those of precipitations revealing the influence of some catchment characteristics in differentiating the isotopic composition in rivers. Further correlations between mean residence times of river water and selected catchment characteristics reveal the role of orography and bedrocks in delaying the water molecules during their flow-paths. In addition, time series and cross–correlation analyses indicate a certain control by the main watershed divide on the isotopic composition of river waters, which is reflected in a progressive isotopic variation with longitude. The study shows that, despite using a short-time dataset (2-years for surficial water) of sparse stable isotopes can provide remarkable indications for depicting hydrological processes in large catchments made up of clay-rich bedrocks.

Inferring Hydrological Information at the Regional Scale by Means of δ18O–δ2H Relationships: Insights from the Northern Italian Apennines

“…This study aims to verify whether such discrepancies in slopes and intercepts from different regression methods are present (thus significant) or not in four water types (precipitation, surface water, groundwater collected in wells from the lowlands, groundwater from low-yield springs) from the northern Italian Apennines. For this reason, we exploited datasets already published in the literature, e.g., [7,11,[16][17][18], and we carried out visual inspection (heat maps) and statistical comparison of results from the three aforementioned approaches (OLS, RMA, MA) already tested in [15]. With reference to OLS approach, we further verified whether preliminary weighting of the isotopic data to the corresponding values of discharge or precipitation may have induced changes to our results or not.…”

“…Rivers originating from the most elevated parts of the main watershed divide (Secchia, Panaro) are characterised by a nival-pluvial discharge regime as they are influenced by the melting of snow cover accumulated during the winter months in the upper parts of their catchments [21]. [7]) with locations where sampling has been carried out by previous studies for precipitation (rain gauges with letters a to d), surficial water (rivers numbered 1 to 9), groundwater from springs (Greek letters α and β), and groundwater from wells (located in the alluvial fans with capital letters A to D). Hydrogeological complexes are reported following [20]; GC: clay; GM: marl; GF: flysch; GFF: foreland flysch; GL: limestone; GO: ophiolite.…”

“…Highlight pre-infiltrative evaporation/evapotranspiration that acted by modifying the waters before their infiltration towards the aquifer and, subsequently, to the base flow of rivers [7];…”

Variation Characteristics of Stable Isotopes in Precipitation and Response to Regional Climate Conditions during Pre-monsoon, Monsoon and Post-monsoon Periods in the Tianshui Area

“…Affected by ground weather conditions, different regions have local meteoric water lines (LMWL) that reflect their precipitation patterns. Analyzing the local meteoric water line can provide a reference for the study of the local water cycle process [33][34][35].…”

Application of Stable Water Isotopes to Improve Conceptual Model of Alluvial Aquifer in the Varaždin Area

“…Different methods are used, and one of them is an isotopic technique, which is often used successfully to help elucidate hydrological studies [1]. Knowledge about the isotopic ratios of oxygen (δ 18 O) and hydrogen (δ 2 H) in atmospheric precipitation and groundwater is important for hydrological, hydrogeological, climatological, and meteorological applications [1][2][3][4][5][6][7][8] because it can provide information on the mean recharge elevation of the aquifer, the mean residence time, water-rock interactions, etc.…”