Evaluation of windproof and sand fixation effect of protective system in the Desert oasis ecotone of Mingsha Mountain Dunhuang.

The Desert oasis ecotone (DOE) protects the oasis from wind and sand intrusion, thereby playing a crucial role in controlling desertification. However, there is limited knowledge about how DOE functions in windproof and sand-fixation. Therefore this study employs a three-dimensional (3D) laser scanner to monitor surface accumulation and erosion, and through field observations, collects data on wind profiles, grain size, and sand transport rates to uncover the role of DOE in aeolian sand protection. The results indicate that, compared to the desert area, the wind speed and sand transport rate decreased by 39.8% and 44.64% respectively in the DOE, while the friction velocity u* increased by 18. 51% and roughness Z increased by 8 times. The average grain size gradually diminished from desert area to DOE, and the sorting worsened. Observations show that in both desert area and DOE, wind erosion pits form on the windward side and dunes on the leeward side. The volume of sand accumulation shows an exponential increase with wind speed, while the erosion volume decreases linearly in the desert and sand barrier fence zones. The DOE effectively mitigated wind speed and the sand flow entering the oasis, demonstrating a remarkable windproof and sand-fixation effect. This study can provide important references for the establishment and optimization of protective systems in DOE.