The adoption of green roofs is an effective practice for mitigating environmental issues in urban areas caused by extreme weather conditions. However, certain design aspects of green roofs, such as the characterization of the physical properties of their substrates, need a better understanding. This study proposes a simple method for estimating two hydraulic properties of green roof substrates based on the evolution of moisture during drying periods, or drydowns, where evaporative processes dominate: the weighted-mean diffusivity and the saturated hydraulic conductivity. Soil moisture was monitored using 12 in situ sensors from 2015 to 2020 in a study involving six different green roof plots composed of various mixtures of demolition-recycled aggregates and organic substrates. A universal parameterization for determining water diffusivity in soils was applied to estimate the weighted-mean hydraulic diffusivity. As a by-product, the saturated hydraulic conductivity was estimated from the evaluated diffusivity and the measured water retention data. The median values obtained for $\overline{D}$ and $k_s$ range from 14.5 to 29.9 cm²d⁻¹ and from 22 to 361 cmd⁻¹, respectively. These values fall within the ranges reported by other research groups using direct measurement methods and supports the validity of Brutsaert’s model for green roof substrates. Furthermore, an increase in $\overline{D}$ and a decrease in $k_s$ were observed as the percentage of recycled aggregates in the substrates increased, which could be considered for design purposes.

Aim of study: To assess the economic viability of implementing carbon fertilisation (CF) on the Campo de Dalías greenhouse agricultural sector. Area of study: Agricultural area of Campo de Dalías (Southeast of Spain), the highest density of greenhouses for horticulture in Europe, with an area of 21,285 ha of greenhouses, spread over an entire area of 33,000 ha. Material and methods: Based on the technology currently used in the Campo de Dalías, we estimated the impact of introducing technology that could incorporate CF (multi-span greenhouses) and that of CF itself. The main indicators analysed were value added, employment, gross output, and input use, and especially water consumption. Main results: The results show an improvement in the most important indicators analysed, making CF an economically viable technique that will help the development process of the agricultural sector in Campo de Dalías. Research highlights: Campo de Dalias production competes in Central European markets with others coming from areas with lower costs (North Africa) or those with higher technical standards (mainly the Netherlands). Species traditionally grown in the Campo de Dalías greenhouses have disappeared due to their low profitability. Technological innovation is the only way out to prevent this important sector from continuing losing value.

Making effective decisions about scaling up on-farm irrigation practices to the district level requires a comprehensive assessment of irrigation management at the farm level. In this context, a bucket-type water mass balance model was developed, calibrated, and validated over five irrigation seasons on a 121-hectare rice farm located in the lower Ter River valley (north-east Spain), to assess the water use efficiency and the impact of different irrigation practices on water savings. The model was implemented considering the spatial variability of the soils within the farm. It showed a satisfactory performance in both the calibration (2020, 2021, 2022) and validation (2023, 2024) cropping seasons, with NSE values greater than 0.50, PBIAS lower than ±20%, and RSR lower than 0.70. After model validation, the simulation of alternative water management practices revealed that the 10-day fixed-turn irrigation reduced irrigation water use by 30% compared to the traditional water management, although it may negatively impact rice yield. Simulations of an early irrigation cut-off at the end of the season and dry seeding with delayed flooding accounted for 17% and 15% irrigation water savings, respectively. The implementation of the no-runoff practice only accounted for a 6% reduction in water use. The water-saving potential of the simulated strategies was mainly driven by shortening the flooded period of rice paddies, thus demonstrating that managing the ponding water level is critical to diminishing water use in rice irrigation.