Using soil water isotopes to infer the influence of contrasting urban green space on ecohydrological partitioning

Abstract

Abstract. Many urban areas are facing challenges in balancing domestic and industrial water demands while simultaneously maintaining the water supply for green infrastructure. Consequently, quantitative knowledge about ecohydrological partitioning in different types of urban green space is crucial for balancing sustainable water needs in cities during future challenges of increasing urbanization and climate warming. Using isotopic tracers in precipitation and soil water, along with conventional hydrometric measurements in a plot-scale study in Berlin, Germany, we investigated water partitioning under different generic types of urban vegetation (grassland, shrub and trees). This allowed assessment of effects on subsequent evapotranspiration, subsurface flow paths and storage during a prolonged drought period with episodic rainfall. Water losses under forest were slightly higher than grassland over the monitoring in the growing season of 2019. Despite higher soil evaporation losses under urban grassland, higher interception and transpiration likely contributed to slower turnover of soil water and older groundwater recharge under urban trees. Shrub vegetation seemed to be most resilient to prolonged drought periods, with lower evapotranspiration losses. Our results contribute to a better understanding of ecohydrological partitioning under mixed urban vegetation communities and an evidence base for better adaptive management of urban water and irrigation strategies to sustainably meet the water demands of urban green spaces.

Technical note: A fast and objective autosampler for direct vapor equilibration isotope measurements

“…Analyzing the distribution of stable water isotopes in groundwater has revealed hydrogeological differences and solute transport mechanisms (Hendry and Wassenaar, 2009;Hendry et al, 2011a;Hendry and Wassenaar, 2011;Stumpp and Hendry, 2012). Moreover, the use of stable water isotopes in plants has shed light on plant water uptake, water transit times, and partitioning effects, providing valuable insights into which sources of water plants utilize for various purposes (Bertrand et al, 2014;Smith et al, 2020;Kuhlemann et al, 2020).…”

Lawn Irrigation Contributions to Semi‐Arid Urban Baseflow Based on Water‐Stable Isotopes

“…Stable isotopes in water have been used extensively in understanding hydrological and ecological processes (e.g., de Wet et al, 2020). In urban settings, they have been used to study public water supply systems and effects of urbanization and climate on stream water-groundwater connectivity (Ehleringer et al, 2016;Gabor et al, 2017;Hibbs et al, 2012;Jameel et al, 2018;Jefferson et al, 2015;Kuhlemann et al, 2020Kuhlemann et al, , 2021Shah et al, 2019). Stable isotopes have been used to quantify the portion of urban streamflow from tap water, yielding low values in exurban Southern California and in San Diego streams during stormflow (Hibbs et al, 2012;Wallace et al, 2021) to 95% in Austin, Texas (Beal et al, 2020;Christian et al, 2011).…”

Modelling hourly evapotranspiration in urban environments with SCOPE using open remote sensing and meteorological data

“…Being measured by installation under the ground, the measured area is very limited in extent and difficult to compare to the surrounding areas in urban environments (Nouri et al, 2013). Furthermore, instruments such as gas exchange chambers for leaves or sap flow for individual trees only measure transpiration in plants rather than total ET (Kuhlemann et al, 2020; Maltese et al, 2018). None of these techniques are well-suited for the urban environment, whereas eddy covariance (EC) is the most adequate system to directly measure ET in cities (Liang and Wang, 2020;Nouri et al, 2013).…”