Chiara et al. (2026) Assessing the effects of climate trends and drought periods on the undeterred aquifer of Castelporziano Nature Reserve (Rome, Italy)

Identification

Journal: RENDICONTI LINCEI
Year: 2026
Date: 2026-02-20
Authors: Sbarbati Chiara, Lacchini Alessandro, Petitta Marco
DOI: 10.1007/s12210-025-01384-8

Research Groups

Department of Ecological and Biological Sciences, Tuscia University, Viterbo, Italy
Department of Earth Sciences, Sapienza University of Rome, Rome, Italy

Short Summary

This study analyzed 30 years of groundwater level trends in the Castelporziano Presidential Estate, revealing a significant decline in the Coastal and Central sectors driven by increased evapotranspiration due to rising temperatures, despite stable rainfall, leading to a critical aquifer crisis since 2016.

Objective

To understand the significant decline in the water table within the Castelporziano Presidential Estate by conducting a 30-year analysis of groundwater level trends and correlating them with climate indices (SPEI-12, SPEI-3, SGI) and soil water content.
To provide a comprehensive insight into the effects of drought periods on groundwater resources, focusing on water table levels and soil water content variations, and to offer a realistic, 30-year depiction of aquifer conditions, nearly net of anthropogenic pressure, using the Standardized Groundwater Index (SGI).

Study Configuration

Spatial Scale: Castelporziano Presidential Estate, a State Natural Reserve located along the Tyrrhenian Sea coast, south of Rome city centre, Italy. The study area is divided into four homogeneous hydrogeological sectors: Coastal, Central, Northern, and Eastern.
Temporal Scale: 30-year analysis, primarily covering the period from 1995 to 2024 for groundwater levels, and 1995–2023 (Castello station) and 1999–2023 (Tor Paterno station) for meteorological data.

Methodology and Data

Models used:
- Mann-Kendall trend test (α = 0.05) for groundwater level trends.
- Kriging-based geostatistical interpolation (ANUDEM) for spatial distribution maps.
- Thornthwaite and Mather method (with 100 mm available water capacity) for calculating monthly and annual evapotranspiration.
- Standardized Precipitation and Evapotranspiration Index (SPEI) at 12-month and 3-month temporal scales.
- Standardized Groundwater Index (SGI) at a 12-month scale, following Guo et al. (2021) procedure.
Data sources:
- Groundwater levels: 37 monitoring wells (13 equipped with automated probes) distributed across the CPE, providing monthly water table time series (1995–2024).
- Meteorological data: Castello and Tor Paterno weather stations (monthly rainfall and mean monthly temperature data for 1995–2023 and 1999–2023, respectively). Missing data imputed using FCS multiple imputation.
- Soil moisture data: Campo di Rota weather station (soil water content at 100 cm depth).

Main Results

Groundwater levels in the Coastal and Central sectors of the Castelporziano Presidential Estate show a significant negative trend over the 30-year period (1995–2024).
The Coastal sector (represented by F7 well) experienced a negative trend since 2016, with mean annual levels consistently below the 30-year average (2.46 m above sea level) and a record low of 2.0 m above sea level in 2024.
The Central sector (represented by E11 well) shows an even more pronounced and continuous decline, reaching its lowest value of 2.91 m above sea level in 2024, with a total depletion of up to 2 m.
The Eastern sector shows a distinct positive trend, while the Northern sector exhibits substantial stability in groundwater levels, largely buffered by external regional aquifer inputs.
No clear temporal trends were observed in rainfall or net infiltration, but mean annual temperature increased by more than 1 °C over the last 28 years, driving higher evapotranspiration.
SPEI-12 analysis revealed prolonged dry periods: Castello station showed a critical drought from 1999 to 2008 and another from 2020 to 2023. Tor Paterno station indicated a continuous critical period from 2016 to 2023.
Groundwater levels in the Coastal and Central sectors strongly correlate with SPEI-12 trends, confirming that water table declines are linked to prolonged dry periods and increased evapotranspiration.
Soil water content at 100 cm depth, correlated with SPEI-3, shows a general decline since 2016–2017, with the duration of periods exceeding 30% moisture decreasing by half (from 1.9 months/year to 1 month/year).
The Standardized Groundwater Index (SGI) confirms consistently negative conditions in the Coastal sector since 2016, with absolute minimum values (<−1) recorded in 2024. In the Central area, SGI became negative around 2006–2007 and has worsened, reaching lowest values (<−1) by the end of 2024.
The aquifer's resilience allowed it to withstand the 1999–2008 drought, but a new prolonged drought period starting in 2016, coupled with rising temperatures and increased evapotranspiration, has led to an irreversible crisis in the locally recharged areas.

Contributions

Provides a comprehensive 30-year analysis of groundwater level trends in a protected Mediterranean coastal ecosystem (Castelporziano Presidential Estate) under climate change.
Demonstrates the crucial role of evapotranspiration, driven by rising temperatures, in aquifer depletion, even in the absence of significant rainfall trends.
Utilizes the Standardized Groundwater Index (SGI) to assess aquifer drought conditions, offering a realistic depiction of aquifer status largely independent of anthropogenic pressure, which is a less explored application of SGI in existing literature.
Highlights significant spatial variability in aquifer response to drought within a relatively small area, attributing it to differing hydrogeological characteristics and external inputs.
Establishes a strong link between declining groundwater and soil moisture levels and the observed forest decline in the Castelporziano forest since 2016, providing valuable insights for managing groundwater-dependent ecosystems.

Funding

Accademia Nazionale delle Scienze
Servizio Tenuta Presidenziale di Castelporziano
Project: “Studio della falda e della zona non satura della Tenuta di Castelporziano”

Citation

@article{Chiara2026Assessing,
  author = {Chiara, Sbarbati and Alessandro, Lacchini and Marco, Petitta},
  title = {Assessing the effects of climate trends and drought periods on the undeterred aquifer of Castelporziano Nature Reserve (Rome, Italy)},
  journal = {RENDICONTI LINCEI},
  year = {2026},
  doi = {10.1007/s12210-025-01384-8},
  url = {https://doi.org/10.1007/s12210-025-01384-8}
}

Original Source: https://doi.org/10.1007/s12210-025-01384-8