Estimation of the quantity of aeolian saltation sediments blown into the Yellow River from the Ulanbuh Desert,China

The Ulanbuh Desert borders the upper reach of the Yellow River. Every year, a mass of aeolian sand is blown into the Yellow River by the prevailing wind and the coarse aeolian sand results in serious silting in the Yellow River. To estimate the quantity of aeolian sediments from the Ulanbuh Desert blown into the Yellow River, we simulated the saltation processes of aeolian sediments in the Ulanbuh Desert. Then we used a saltation submodel of the IWEMS （integrated Wind-Erosion Modeling System） and its accompanying RS （Remote Sensing） and GIS （Geographic Information System） modules to estimate the quantity of saltation sediments blown into the Yellow River from the Ulanbuh Desert. We calibrated the saltation submodel by the synchronous observation to wind ve- locity and saltation sediments on several points with different vegetation cover. The vegetation cover, frontal area of vegetation, roughness length, and threshold friction velocity in various regions of the Ulanbuh Desert were obtained using NDVI （Normalized Difference Vegetation Index） data, measured sand-particle sizes, and empirical relation- ships among vegetation cover, sand-particle diameters, and wind velocity. Using these variables along with the observed wind velocities and saltation sediments for the observed points, the saltation model was validated. The model results were shown to be satisfactory （RMSE less than 0.05 and IRel less than 17%）. In this study, a subdaily wind-velocity program, WlNDGEN, was developed using this model to simulate hourly wind velocities around the Ulanbuh Desert. By incorporating simulated hourly wind-velocity and wind-direction data, the quantity of saltation sediments blown into the Yellow River was calculated with the saltation submodel. The annual quantity of aeolian sediments blown into the Yellow River from the Ulanbuh Desert was 5.56x106 t from 2001 to 2010, most of which occurred in spring （from March to May）; for example, 6.54x10~ tons of aeolian sand were blown into the Yellow River on 25 April, 2010. However, in summer and winter, the saltation process occasionally occurred. This research has supplied some references to prevent blown sand hazards and silting in the Yellow River.

Combating wind erosion through soil stabilization under simulated wind flow condition -Case of Kuwait

The soil survey of Kuwait has revealed the landscapes dominated by loose sandy material, that are vulnerable to wind erosion. Globally three modes of soil particle movement (creep, saltation & sus-pension) by wind have been recognized. To evaluate these modes in the deserts of Kuwait, sixty surface soil samples were collected and analyzed for particle sizes to quantify relative occurrence of modes of particle movement in the deserts of Kuwait. This analysis revealed distribution of particles in the size ranges, as follows: saltation (70%) > Creep (20%) > Suspension (10%) confirming saltation is the main mode of soil movement. This has provided basic information to set up a pilot scale experiment to reduce the wind erosion rate through sand stabilization using various sand binding products in three treat-ments;T1 (native sandy soil);T2 (sand mixed with biochar and animal manure);T3 (sand mixed with biochar, animal manure, Urea Formaldehyde (UF), Sulfonated Naphthalene Formaldehyde (SNF), and Poly Vinyl Alcohol (PVA). The results showed that the erosion rate of native sandy soil (T1) has increased from 3.33, 4.77 to 7.35 g/(m2. min) when wind speed was increased from 5, 10 to 15 m/s, respectively. At the same wind speeds, the measured erosion loss was 1.99, 3.07, 5.32 g/(m2. min) in T2 and 1.17, 2.6, 4.24 g/(m2. min) in T3. From these results, it can be concluded that there is a possibility to reduce wind erosion in the deserts of Kuwait through sand stabilization and save the deserts from further degradation.