The impacts of five factors (wind speed, crack width, crack distance, crack depth and crack orientation (compared to wind direction)), on evaporation from cracked soil under moist soil conditions were investigated experimentally. Experiments were carried out under laboratory conditions in a wind tunnel with a 1 m × 1 m × 2.5 m test section using large‐scale (50 cm diameter, 25 cm depth) samples of natural soils wetted to a soil water content of 0.2 g g−1. To reduce the number of necessary experiments, a 2k factorial experimental design was used. Crack widths, crack distances, crack depths and crack orientations of 5–20 mm, 40–100 mm, 50–200 mm and 0–90°, respectively, were used. Effects of each factor on evaporation rate, individually and by interaction between multiple factors, were subsequently calculated. Results showed that individual effects of all five factors on evaporation rate were significant at the 95% level. Wind speed had the largest impact on evaporation rate, followed by crack width, crack distance, crack depth and crack orientation in that order. Overall, the four crack properties together explained 47% of the variations in evaporation rate.Highlights Evaporation from cracked, moist soil under windy conditions was investigated. Crack orientation significantly affects wind conditions close to the surface. Both wind speed and crack properties significantly affected evaporation rate. Crack properties together explained 47% of variations in evaporation rate.

Biochar (BC) has been proposed as an alternative soil amendment in landfill cover. Its effects on soil hydraulic properties (e.g. soil water retention) have been explored to some extent, while its influence on landfill gas flow characteristics is not clear yet. The objective of this study is to investigate the water retention and gas permeability (kg) of BC-amended soil and its relationship with soil water content in unsaturated state. In total, three BC contents (0, 5 and 10%) were considered in clay–sand mixtures. Soil suction, water content and gas pressure were measured continuously using a new in-house developed apparatus. Test results show that the presence of BC increased soil water content and the increased amount was almost the same over a wide range of suction values (up to 3 MPa). kg increased linearly with soil suction in semi-log scale, regardless of the BC content. The addition of 5 and 10% of BC could decrease kg by up to 50 and 65%, respectively, compared with that of the bare soil. kg decreased with water content for both soil and BC -amended soils. Moreover, the decrease rate of kg with water content became smaller when the BC percentage was higher.

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