Spatial wind speed and surface wind erosion characteristics of farm-shelter forest network in arid sandy area

Abstract: To accurately understand and evaluate the spatial distribution of wind speed and the erosion characteristics of farm-shelter forest network in a typical strong wind environment, the research on space wind speed and surface wind erosion characteristics of farmland shelterbelts in Yanchi County, Ningxia Hui Autonomous Region in arid sandy area is carried out. The spatial distribution of wind speed within 50 and 200 cm vertical space above the ground and the erosion characteristics have been studied at the different distances from the farm-shelter forest network with portable anemometer and trapping method respectively. The result shows that: With the increase of monitoring distance, the amount of wind erosion increased first and then decreased, while the wind speed changed in the opposite direction. The wind speed changes at 50 and 200 cm height are the same, which show a very regular inverted parabolic linear change of first gradually decreasing and then gradually rising. The effect of wind reduction at 12H height (12 times shelter forest height, the same below) is the most obvious. Wind speeds decreased by 51% and 46% at 50 and 200 cm height respectively. With the increase of the distance, the wind-break potency presented the tendency of increasing at first and then decreasing. The wind-break potency was the best at the 200 cm height from 12H, and the value was 53.65%. The amount of wind erosion was positively correlated with the distance from the farm-shelter forest network. The erosion modulus in the farm-shelter forest network was the least, and the order was 1H < 12H < 3H and 7H. The value at 3H height was the biggest, 21944.62 t/km2. The sand diameters were about 73.99, 87.99 and 104.6 μm, 82.53%-99.93% was under 248.9 μm, and the sand was the fine sand. However, the sand diameters of the bare land were about 104.6-148 μm. These reflected that the sandy irrigated farmland was the main dust source. So configurating the farm-shelter forest network scientifically and reducing the bare soil could prevent sand disaster effectively in the arid sandy area. Thus, even in the early growth of tree leaves, farmland shelterbelts in arid and sandstorm areas are also very effective in slowing wind speed during typical windy days. However, due to the rich source of sand in the forest network, the wind erosion is still serious and has a great impact on the local sandstorms. The farmland shelterbelt network is set scientifically to minimize the occurrence of wind erosion and sand damage as much as possible during the wind-affected season for farmland. This study can have certain technical reference to accurately grasp the wind erosion of the local forest network, and scientifically evaluate the forest network protection function.