The exploratory dataset of isotopic composition of different water sources across Kazakhstan

This work presents the dataset of stable water isotopes of oxygen and hydrogen measured in water samples from different sources (precipitation, surface water, groundwater, tap water) across Kazakhstan from 2017 to 2018 and from 2020 to 2023. The dataset includes results on isotopic composition of 399 water samples, namely precipitation: event-based (n = 108), cumulative monthly (n = 22); surface water: lakes, reservoirs, brooks, rivers, channels (n = 175), groundwater: shallow and artesian groundwater, spring (n = 85), tapwater (n = 9). For each sample name of the source, location, latitude, longitude and date of sampling, measurement uncertainty (one standard deviation) are available. The samples were assessed by plotting the data in dual δ18O vs. δ2H isotope space with reference to values found in the published literature and fitting a linear regression equation for Astana (event) precipitation. Overall, this is the first dataset covering wide range of sources across Kazakhstan, which could be used by global and regional water resource assessments and studies such as tracing water sources, hydrograph separation and end-member analyses, isotope mass balance, evapotranspiration partitioning, residence time analysis and groundwater recharge.

Data on stable isotopic composition of δ18O and δ2H in precipitation in the Varaždin area, NW Croatia

The dataset in this article consists of one year of monthly observations of water stable isotopes in precipitation (July 2019 - May 2020). The samples were collected by rain gauge installed in the Hrašćica village in the Varaždin area, NW Croatia. The data presented in the article are raw isotope data of precipitation supplemented by calculated d-excess values, and local meteoric water lines (LMWL). The measured data is an extension to previous two year investigations (June 2017 – June 2019), which was published in the research article “Application of Stable Water Isotopes to Improve Conceptual Model of Alluvial Aquifer in the Varaždin Area” [1]. Local meteoric water lines (LMWL) are calculated for the entire period for which isotope analyses exist (June 2017 - May 2020). Presented data can be used as a background for investigation of precipitation, groundwater and surface water origin and their interrelationships.

Rainfall isotope variations over the Australian continent - Implications for hydrology and isoscape applications

This paper presents a continental scale interpretation of δ²H and δ¹⁸O in Australian precipitation, incorporating historical GNIP data at seven sites (1962-2002) and 8-12 years of new monthly data from 15 sites from 2003 to 2014. The more than doubling of stations and the significant time series duration allow for an improved analysis of Australian precipitation isotopes. Local meteoric water lines were developed for each site, and for the Australian continent. When the annual precipitation weighted values were used, the Australian meteoric water line was δ²H = 8.3 δ¹⁸O + 14.1‰. Precipitation amount was found to be a stronger driver of precipitation isotopes than temperature at most sites, particularly those affected by tropical cyclones and the monsoon. Latitude, elevation and distance from the coast were found to be stronger drivers of spatial variability than temperature or rainfall amount. Annual isoscapes of δ²H, δ¹⁸O and deuterium excess were developed, providing an improved tool to estimate precipitation isotope inputs to hydrological systems. Because of the complex climate, weather and oceanic moisture sources affecting Australia, regional groupings were used instead of the climate zone approach and additional data was included to improve the coverage in data poor regions. Regression equations for the isoscape were derived using latitude, altitude and distance from the coast as predictor variables. We demonstrate how this isoscape can be used as a tool for interpreting groundwater recharge processes using examples from across Queensland and New South Wales, including the Murray Darling Basin. Groundwater isotopes at sites where direct local recharge occurs are similar to rainfall, but for inland sites, which are often arid or semi-arid, a disconnect between shallow groundwater and local rainfall is observed; the departure in deuterium excess for these sites increases with aridity and distance from the headwaters where flooding originates.