Abstract:【Objective】 In order to study effects of revegetation varying in pattern controlling runoff and sediment yield on slopes of refuse dumps in opencast coal mining fields, a field experiment was conducted on the slope of a refuse dump in the Yongli Coal Mining Area, Inner Mongolia. 【Method】 Five plots different in vegetation pattern were selected on the slope that had been revegetated for four years for the experiment using in-site scouring method. The five plots included Plot C3H7 (Agropyron planted on the upper slope accounting for 30% in area plus Artemisia desertorum on the lower slope accounting for 70% in area), Plot C7H3 (Agropyron planted on the upper slope accounting for 70% in area plus Artemisia desertorum on the lower slope accounting for 30% in area), Plot QC (Agropyron planted on the whole slope), Plot CG (Agropyron mixed with Artemisia desertorum in plantation) and Plot BS (Bare slope) as control, all being 8×1 m in area and 38°in slope gradient. Water flowed down on the top of the slopes or plots at a gradually increasing rate (5-10-15-20 L•min-1). During the flow scouring events, runoff flow velocity was monitored with the dye tracing method. In the first 6 minutes of runoff, samples of runoff were collected once every minute, and afterwards once every 3 minutes for analysis of sediment content, using the oven-drying ied weighing method. 【Result】 (1) At the initial stage of the increase (0～9 min) in flow rate, runoff rate and erosion rate increased sharply, and follow-up-fluctuation decreased. When the flow increased, runoff rate on the slope increased stepwise with the duration of runoff prolonging. Compared to the initial flow at a rate (5 L•min-1), the flow increasing to 10, 15 and 20 L•min-1 made the difference in runoff rate between protected surface and unprotected surface narrower. Meanwhile，the variation of erosion rate with the variation of flow rate was lower in magnitude than that of the variation of runoff rate, and the erosion rate tended to decline in the late phase of the scouring test even when the flow rate was quite high; (2) In Plot C3H7, C7H3, QC and CG, runoff was reduced by 31.99%, 18.72%, 15.29% and 34.36% and sediment was by 81.28%, 87.29%, 84.80% and 58.73%. Plot CG (mixed Agropyron-Hippophae)” and C7H3 (70% Agropyron Hippophae – 30% Artemisia desertorum) was obviously the most effective pattern of vegetation for controlling runoff and sediment yield, respectively; (3) Agropyron Hippophae and Artemisia desertorum are different in root system, i.e. taperoot system and fibrous root system. The vegetation formed of or properly arranged with mixed plants different in root system has better soil and water conserving effects than the one formed of only a type of plant does; (4) In all the slopes, regardless of vegetation pattern, erosion rate and runoff rate formed an extremely significant power function and linear (C7H3) relationship. And (5) Vegetations of all patterns in this experiment had certain functions to resist scouring erosion caused by continuous heavy storms. 【Conclusion】 All the findings in this experiment may serve as scientific a basis for reasonable ecological restoration in the mining area.

Abstract:【Objective】The ecological and environmental problems caused by mining, especially coal mining, have aroused worldwide concerns and attention. It is, therefore, essential to explore rapid and effective ways to rehabilitate the ecological systems in the mining areas. 【Method】Outdoor simulation of rainfall events was conducted with rainfall intensity controlled at 1.0 mm min-1-1Agropyron was formerly planted in the farmlands around the mining and transplanted on the slopes and the fish-scale pits dug temporarily. The rainfall simulator was a trough-type artificial simulator. When the nozzle is 3m above the ground, the raindrops may reach the end point speed. Plots of the artificial slopes were 3m×1 each in area and 35° in slope gradient. Before the start of the experiment, rainfall was calibrated in intensity until it reached 85% or higher in uniformity coefficient. During the rainfall events, runoff flow velocity was measured with the dye tracing method. During the first 3 minutes of rainfall, samples of runoff and sediment were gathered every minute, and after that once every 3 minutes. Sediment samples were oven-dried for weighing. 【Result】（1) Runoff leveled off in rate in 6minutes after the initiation of runoff on all the three types of slopes, regardless of type of control measure. The erosion rate on the slope of gangue tended to fluctuate, while declining and the trend was more obvious than those on the protected slopes. (2) Planting grass reduced runoff by 42.91%~51.21%, 26.28%~55.20% and 10.33% and sediment by 97.54%~97.95%, 41.87%~42.26% and7.80%, respectively, on earthy slopes, rocky slopes and slopes of gangue, while digging fish-scale pits did by 51.89%~72.72%, 22.37%~42.92% and 21.32% and by 98.41%~99.30%, 94.90%~91.84% and 39.50%, respectively. (3) On earthy slopes, digging fish-scale pits was 8.98%~21.51% and 0.46%~1.76%, respectively, higher in runoff and sediment reduction rate than planting grass, while on rocky slopesand slopes of gangue, planting grass was 3.91%~12.28% and 0.28%~3.06% higher and 10.99% and 31.70% higher, respectively. (4) On all the three types of slopes without protection measures taken, linear relationships (R2 = 0.775，p<0.01; R2 = 0.649，p<0.01; R2=0.450，p<0.05) were found between erosion rate and runoff rate, but they were weakened or fading out altered when the protection measures were taken. 【Conclusion】All findings in this study may serve as scientific basis in guiding ecological restoration of slopes of gangue in the mining area.

Abstract:During the processes of development and construction of the Shenfu coalfield, generated were large tracts of disturbed land, and large volumes of translocated soil and waste slag, which, unique in soil constitution and complex in underlying surface layer, have become the major source of serious surface runoff and soil and water loss. An artificially simulated rainfall experiment was carried out to explore effects of rainfall intensity and soil fractal dimension on runoff and sediment yielding from undisturbed land, disturbed land, and piles of translocated soil or waste slag, with undisturbed land as CK. Detailed investigation found that the piles of translocated soils and waste slag had slopes at 40°, their natural angle of repose and the disturbed and undisturbed lands had slopes at 18°. Plots in the experiment field were designed to be 3m × 1m, each, and had two sections, each, set up for monitoring of water flow. Rainfall intensity in the experiment was designed to vary from 1.0 ~ 3.0mm min-1, forming five levels with a interval of 0.5mm min-1 between every two levels. Before the experiment, the rainfall intensity was calibrated repeatedly until uniformity coefficient of the rainfalls reached 85% or higher. Soil particle compositions of the plots were determined with the pipette method. During every rainfall, flow velocity was measured with the dye tracing method and width and depth of the flow with a thin steel rule. For the first 3 minutes of runoff, samples of runoff and sediment were gathered once a minute, and after that once every 3 minutes. Results show that (1) on piles of translocated soil and waste slag, runoff followed the process of spurting-declining-leveling off, while on undisturbed and disturbed lands, it did the process of rising – leveling off. Runoff rate on the underlying surfaces increased with increasing rainfall intensity. (2) Fractal dimension of soil particles on the underlying surfaces of the four plots displayed an order of D1 (abandoned residue) < D2 (abandoned soil) < D3 (disturbed ground) < D4 (undisturbed ground). Volume of runoff caused by a single rainfall event was found to be in a significant linear relationship with rainfall intensity and a significant power function relationship with fractal dimension. Moreover, between D1 and D2 and between D3 and D4 existed two critical fractal dimensions, i.e. 2.229 and 2.479, which can be used to distinguish types of underlying surfaces. (3) Erosion on the pile of waste slag followed the process of fluctuating – leveling off, while on the pile of translocated soil, it was characterized by multiple peaks and valleys. On undisturbed and disturbed lands, erosion increased in rate first and then gradually leveled off under rainfall 1.0 ~ 2.5 mm min – 1 in intensity, and fluctuated drastically under rainfall 3.0 mm min-1 in intensity Erosion rates on all the four underlying surfaces increased with increasing rainfall intensity. (4) Amount of erosion was found to be in a significant power function relationship with rainfall intensity, and with fractal dimension of soil particles, too. (5) Volume of runoff was in significant linear relationships with rainfall intensity and fractal dimension of soil particles (Mw=-147.43Di+123.46Pi 268.96, R2=0.952), while yield of sediment was in significant exponential function relationships with the two (lnMs=-11.32Di 1.32Pi 25.83,R2=0.844). The above findings indicate that disturbed land and piles of translocated soil and waste slag, all formed as a result of mining, differ sharply from undisturbed land in rules of runoff and sediment yield, and underlying surface is an affecting factor of runoff and sediment yield that should not be ignored. Fractal dimension of soil particles, as a quantitative indicator of underlying surface, can be used to effectively predict runoff volume and sediment yield. Obviously this study has some important scientific significance to the establishment of a soil erosion model for mining areas.