Author(s): Afrah Al-Shukaili; Hilal Al-Mamari; Hamed Al-Busaidi; Anvar Kacimov

Linked Author(s): Afrah Al-Shukaili

Keywords: Sustainable Irrigation Units; Capillary barrier; Dunes eco-hydrology; Structured porous medi

Abstract: Understanding the eco-hydrology of natural dunes helped us to design mini-dunes (≤ 1 m) which we tested as sustainable irrigation units. They can intercept moisture from humid air or even from shallow water tables (e.g. in sabkha landforms). Thus, ornamental plants or crops can be cultivated at the crest of the minidune with minimum irrigation frequencies. Two SMDs of a conical shape (150 cm in diameter and 45 cm high) were constructed in the field under a controlled water table. SMDs are similar to natural mini-dunes “Nabkhas”. SMDs’ core soil was medium sand (d50= 0.25 mm) for SMD-1. In SMD-2 the core soil was shielded by 5 cm thick coarser sand (d50= 0.7 mm). Decagon 5TE sensors were placed at the depths of 25 and 75 cm to monitor the volumetric moisture content (VMC). After two months, the VMW in the lower sensors in both designs was almost the same at 0.186 m3/m3. However, in the upper sensors, SMD-2 had a VMC about two times higher than SMD-1. The average VMC in SMD-1 and SMD-2 is about 0.074 m3/m3 and 0.1 m3/m3, respectively. Then, the evaporation through the SMD-2 soil profile was simulated by HYDRUS2D for 15 days. HYDRUS2D findings appear to be well substantiated by the experimental results. This qualitatively agrees with our hypothesis that the course sand-gravel sheath (tilted and horizontal) acts as a capillary barrier similarly to ones found in large dunes (Al-Shukaili et al., 2019). The SMDs are advocated as a cutting-edge solution for cultivating plants in arid regions especially in areas affected by the water table rise. The novelty of these structured dunes is that the plants can be cultivated with minimum irrigation and capital cost. The design can be a backbone encouragement for a new way to revegetate the deserts and sabkhas landforms.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221722

Year: 2022