DIC - Artículos

Spatial assessment of groundwater variability and drought impacts on ATES system suitability in Spain

Spatial assessment of groundwater variability and drought impacts on ATES system suitability in Spain Ramos Escudero, Adela; Toledo, Carlos; Gómez-Gómez, Juan-de-Dios; Bloemendal, Martin; Collados Lara, Antonio J.; Pulido Velázquez, David Study region This study is conducted across groundwater bodies within mainland Spain, as defined under the European Water Framework Directive. Study focus We conduct a preliminary, national-scale assessment of groundwater-body suitability for Aquifer Thermal Energy Storage (ATES) in Spain from a water-energy nexus perspective. The methodology is based on two complementary indicators derived from long-term piezometric records: (i) a Drought Stress Response Index (DSRI), reflecting aquifer reliability, resilience, and vulnerability over decadal time scales, and (ii) groundwater-level variability and long-term trends as proxies for hydraulic stability. Together, these indicators support a first-order screening of groundwater bodies from less suitable to more suitable conditions for ATES operation. New hydrological insight of the region The analysis of drought-response indicators reveals clear spatial patterns in aquifer vulnerability, resilience, and reliability across Spain, with only weak correlations with mean groundwater levels. Groundwater-level amplitude and trend analyses indicate that unstable conditions are concentrated in southern and eastern Spain, whereas northern regions generally exhibit more stable regimes. Building on these indicators, the results reveal pronounced spatial contrasts in ATES suitability, with generally more favorable conditions in northern regions and lower suitability in large parts of southeastern Spain, while extensive areas with intermediate suitability are also identified. Based on this national-scale screening, the study provides a preliminary assessment of ATES suitability for the main Spanish urban areas, offering an initial indication of where groundwater conditions are more or less favorable for ATES deployment.

Turbulence in a small arctic pond

Turbulence in a small arctic pond MacIntyre, Sally; Crowe, Adam T.; Cortés Cortés, Alicia; Arneborg, Lars Small ponds, numerous throughout the Arctic, are often supersaturated with climate-forcing trace gases. Improving estimates of emissions requires quantifying (1) their mixing dynamics and (2) near-surface turbulence which would enable emissions. To this end, we instrumented an arctic pond (510 m2, 1 m deep) with a meteorological station, a thermistor array, and a vertically oriented acoustic Doppler velocimeter. We contrasted measured turbulence, as the rate of dissipation of turbulent kinetic energy, ε, with values predicted from Monin–Obukhov similarity theory (MOST) based on wind shear as u*w, the water friction velocity, and buoyancy flux, β, under cooling. Stratification varied over diel cycles; the thermocline upwelled as winds changed allowing ventilation of near-bottom water. Near-surface temperature stratification was up to 7°C per meter. With respect to predictions from MOST: (1) With positive β under heating and strong near-surface stratification, turbulence was suppressed; (2) under heating with moderate stratification and under cooling with light to moderate winds, measured ε was in agreement with MOST; (3) under cooling with no wind and when surface currents had ceased, as occurred 20% of the time, turbulence was measurable and predicted from β. Near-surface turbulence was enhanced under cooling and light winds relative to that under a neutral atmosphere due to higher values of drag coefficients under unstable atmospheres. Small ponds are dynamic systems with wind-induced thermocline tilting enabling vertical exchanges. Near-surface turbulence, similar to that in larger systems, can be computed from surface meteorology enabling accurate estimates of gas transfer coefficients and emissions.

Sediment respiration drives circulation and production of CO2 in ice-covered Alaskan arctic lakes

Sediment respiration drives circulation and production of CO2 in ice-covered Alaskan arctic lakes MacIntyre, Sally; Cortés Cortés, Alicia; Sadro, Steven The goals of our study were to (1) quantify production of CO2 during winter ice-cover in arctic lakes, (2) develop methodologies which would enable prediction of CO2 production from readily measured variables, and (3) improve understanding of under-ice circulation as it influences the distribution of dissolved gases under the ice. To that end, we combined in situ measurements with profile data. CO2 production averaged 20 mg C m−2 d−1 in a 3 m deep lake and ∼ 45 mg C m−2 d−1 in four larger lakes, similar to experimental observations at temperatures below 4°C. CO2 production was predicted by the initial rate of loss of oxygen near the sediments at ice-on and by the full water column loss of oxygen throughout the winter. The time series data also showed the lake-size and time dependent contribution of sediment respiration to under-ice circulation and the decreased near-bottom flows enabling anoxia and CH4 accumulation.

A multi-lake comparative analysis of the General Lake Model (GLM): Stress-testing across a global observatory network

A multi-lake comparative analysis of the General Lake Model (GLM): Stress-testing across a global observatory network Bruce, Louise C.; Frassl, Marieke A.; Arhonditsis, George B.; Gal, Gideon; Hamilton, David P.; Hanson, Paul C.; Hetherington, Amy L.; Melack, John M.; Read, Jordan S.; Cortés Cortés, Alicia; Rueda Valdivia, Francisco José; Hipsey, Matthew R. The modelling community has identified challenges for the integration and assessment of lake models due to the diversity of modelling approaches and lakes. In this study, we develop and assess a one-dimensional lake model and apply it to 32 lakes from a global observatory network. The data set included lakes over broad ranges in latitude, climatic zones, size, residence time, mixing regime and trophic level. Model performance was evaluated using several error assessment metrics, and a sensitivity analysis was conducted for nine parameters that governed the surface heat exchange and mixing efficiency. There was low correlation between input data uncertainty and model performance and predictions of temperature were less sensitive to model parameters than prediction of thermocline depth and Schmidt stability. The study provides guidance to where the general model approach and associated assumptions work, and cases where adjustments to model parameterisations and/or structure are required. GLM development and funding support for LCB, BDB, CB and MRH was provided by the Australian Research Council (ARC) (grants DP130104078 & LP130100756).

Flowpath and retention of snowmelt in an ice-covered arctic lake

Flowpath and retention of snowmelt in an ice-covered arctic lake Cortés Cortés, Alicia; MacIntyre, Sally; Sadro, Steven The extent to which snowmelt flowing into ice-covered lakes spreads horizontally and mixes vertically influences retention of solutes derived from the landscape. To quantify these transport processes and retention, we combine time series temperature and specific conductance measurements in Toolik Lake (Alaska) and its major inflow, with measurements of discharge and meteorology, and profiles of specific conductance, temperature, fluorescence, chlorophyll a, and dissolved organic carbon (DOC) in spring of 3 yr. During early snowmelt, the concentration of DOC in the stream was 750 μM, twice that in the lake. During slow melt (discharge (Q) < 4 m3 s−1), the incoming solute-rich intrusion spread lakewide below the ice. During melt with Q > 6 m3 s−1, the incoming water partially flushed the inlet basin and the more dilute water flowed over the original intrusion with a preferential flowpath to the outlet. Penetrative convection was restricted by the increased density gradients from the incoming plume and initially constrained to shallow mixing zones associated with the step changes in density. As ice thickness decreased to less than 1 m, heating caused density instabilities at the base of the intrusions that mixed solutes ∼ 10 m vertically, contributing to retention. Near-surface layers enriched with DOC persisted for ∼ 10 d during a rapid melt and for over 3 weeks when the melt was slow. Retention, of order 10–20%, also depended on the rapidity of melt and magnitude of discharge.