Analysis of Turbulence and Wind Shear Characteristics in the Hilly Terrain of the Geba Catchment Tigray, North Ethiopia

This paper investigates wind speed, wind shear (α), and turbulence intensity (TI) characteristics using measurements from meteorological mast data from three sites in the Geba Catchment, Tigray, Ethiopia: Dera, Hagere Selam, and Mayderhu. Wind speed analysis shows significant spatial and temporal variations, with Hagere Selam exhibiting the highest annual average wind speeds (8.0 m/s), while Dera showed the lowest (4.5 m/s). Diurnal and seasonal patterns indicated that wind speeds peak in the afternoon and vary with temperature, with Dera experiencing more pronounced vertical wind shear (α = 0.1–0.3) due to complex terrain interactions. In contrast, Hagere Selam and Mayderhu displayed lower shear (α = 0.0–0.1), suggesting smoother wind flow. Dera also showed pronounced diurnal α variations linked to nighttime cooling. TI was highest at Dera (TI ≈ 0.5), particularly at night, while Hagere Selam and Mayderhu maintained more stable conditions (TI < 0.25). Across all locations, analysis of wind speed variability revealed that Dera experiences greater turbulence compared to the International Electrotechnical Commission (IEC) standards but remains within acceptable limits for wind turbine operations. Wind direction analysis highlighted the prevailing winds at Dera, predominantly from the north, northeast, and southeast, which correspond to higher α and TI levels, emphasizing the role of local topography. Further, seasonal shifts were observed at Dera and Mayderhu, whereas Hagere Selam exhibited consistent northeasterly winds. The findings underscore the influence of topography and atmospheric stability on wind dynamics, providing critical insights for wind energy deployment in similar hilly terrains.