A Hydropedological Morphed Block-Crack Capillary Barrier: Human Influence and Lessons From Nature.

A smart capillary barrier (CB) was discovered during a hydropedological study of soil profiles of the reservoir bed of Al-Khoud dam, Oman. The CB showed fascinating sedimentation pattern which evolved into an intricate composition of silt blocks and cracks filled with a “proppant” sand. The genesis of the CB is attributed to the complex interactions of the geogenic, pedogenic, and anthropogenic factors. The soil morphology of the discovered CB demonstrates the complex topology of water motion (infiltration-seepage-evaporation) through the cracks and blocks both during rare flood events with ensuing periods of ponding, and long and common dry-dam periods. The hydrological optimality and “smartness” of these soils is attributed to the existence of a unique matrix-crack harmonious system which enable them to preserve a large quantity of water in the silty blocks at a depth from 0.5 to 1.5 m, despite the high temperature and long periods of dryness of the top soil. In situ plantation of an ivy (Convolvulaceae) in the vertical face of soil pedons having this type of CB showed an intensive growth without irrigation. An agricultural engineering pot experiment revealed the possibility of increasing irrigation efficiency by mimicking theses naturally discovered block-crack barriers. Soil moisture content data confirmed hydrological immobility of water in the silty blocks if not depleted by transpiration. The novel and smart phenomena reported in this study unveils the possible alteration of soil heterogeneity for optimization of the soil-water cosmos in soils of the arid zone.    

Key words: Hydropedology, Capillary Barrier, Block-Crack, Sedimentation pattern, Arid-zone, Evapotranspiration, Redistribution, Optimization.