Study On The Wind Erosion In Southeast Inshore Of Fujian Province

We choose the five typical land use types in the wind erosion area in Dongshan County, Fujian Province, including Forest area(casuarina equisetifolia shelter forest), orchard(planted with Chinese Lichi), arable land ( planted with asparagus) , standard naked land CK and the beach. On the basis of field investigation and sample analysis, statistically, we analyze and appraise the intensity of the wind erosion against the soil, as well as different wind erosion affect caused by factors of soil water capacity, the climate and the vegetation covering level etc.And we find that:The vegetation covering level is the most sensitive factor that causes the wind erosion against the soil. It is proved that there are negative correlation between the vegetation covering level and wind erosion effect under certain space time conditions. As the soil tends to be at the weakest against the wind erosion effect right when the lowest vegetation covering level is at the lowest. Normally, the higher the vegetation covering level is ,the more resistance the soil has against the wind erosion. From the aspect of the vegetation covering level of the five different land types above, the standard naked land CK as the comparable is the most vulnerable against the wind erosion, less the arable land planting with asparagus, and we find that increasing the vegetation covering level of lands, especially the farming lands, could be one major solution against the season of which the wind erosion occurs mostly. The land vegetation covering could reduce the wind speed effectively, sorted by the levels of which by five different land types above is, the maximum the casuarina equisetifolia shelter forest, then the orchard with Chinese Lichi, and then arable land with asparagus, then wasteland and the last the comparable standard naked land CK. We also find that the casuarina equisetifolia shelter forest can reduce the wind speed very effectively. The tested speed is 60% to 70% less when the sea wind comes through the casuarina equisetifolia shelter forest than it comes above the standard naked land CK as the comparable standard land.The sand-blown wind speed is directly relative to the underlying surface. The tested sand-blown wind speed data of the same soil sample is different under the condition of different kinds of underlying surface. Most of the underlying surface are sea sands in areas that suffered from wind erosion in Dongshan county. Considering about this, we do the wind speed test by simulating the comparable naked standard land by selecting a naked land without vegetation covering, which has the similar condition with the comparable naked standard land in the vegetation covering level, soil water capacity and the natural condition of the soil. There is no obstacle between the sea and the selected testing land to avoid the kinetic energy loss of the wind. The tested samples are all from the comparable naked standard land CK, with a sample depth of 0 to 5 cm. Under all those conditions, the tested sand-blown wind speed ( 2m above the ground) is 6.2m/s.According to the comparison of the wind speed, the precipitation and evaporation data, the wind erosion effect tends to occur mostly in January, February, March, October,November and December. The level of the Roughness plays an important role in wind erosion effects, hence we can hold back the occurrence of the wind erosion by increasing the surface Roughness of the land, which also increases the Friction Wind Velocity. We can increase the vegetation covering level and Ridge Culture of Crop to increase the Roughness of the soil. This study sorted the sample land types by descending as: the maximum the casuarina equisetifolia shelter forest, then arable land with asparagus, and then the orchard with Chinese Lichi, then the comparable naked standard land (CK) and finally the wasteland.Finally we introduce the GM(1,1) model to forecast the average wind speed at multiple altitudes by integrating the data from the local weather station and try to understand how the factor of the weather-wind erosion affects hence provide a solution against that.