| Dsite is formed in the process of open pit mining platform-slope huge artificial loose accumulation,open coal mining to promote surface disturbance,form different landform unit,dump is the most serious soil erosion area,due to the surface subsidence produce soil cracks,intensify soil erosion and nutrient loss,make land productivity damage and intensify non-point source pollution to water contribution.In order to deeply explore the influence of soil cracks on land productivity and nutrient loss,Haizhou open-pit coal mine,study the crack width and different rainfall intensity of soil erosion and nutrient loss rule,the results can not only reveal the land productivity decline,but also provide scientific basis for the prevention of dump nutrient loss.The main research contents and results are as follows:(1)Under the rainfall intensity of 60,90 and 120 mm/h,the runoff of the platform slope system of the waste dump presents the state of first increase,decrease and stability.Under the rainfall intensity of 60 mm/h,the total runoff with the crack width of 15 cm is 13.15,45.76 and96.54L/min respectively.The overall runoff of different crack widths is 15cm>12.5cm>10cm>control.Under the rainfall intensity of 120mm/h,the crack width of 15 cm is 2.45 times of the total runoff without crack.The crack width of 15 cm is more likely to increase the runoff of waste dump.When the crack width is 15 cm,the average sediment yield of 60,90 and 120mm/h rainfall intensity is 118.78,185.09 and 420.73g/min respectively;The sediment yield increases with the increase of rainfall intensity.The sediment yield of waste dump platform slope system with different crack width is 15cm>12.5cm>10cm>control,and no crack has the least effect on the sediment yield of waste dump.The average contribution rate of different soil cracks to runoff and sediment yield is more than 55%.When the crack width is 15 cm,the overall width depth ratio of the platform is120mm/h>90mm/h>60mm/h;The overall aspect ratio of slope is 90mm/h>60mm/h>120mm/h.With the increase of rain intensity and crack width,the average ditch depth and width increase.(2)Under different rainfall intensities,the nutrient concentration of nitrogen,phosphorus and potassium gradually decreases and tends to be stable with the increase of rainfall intensity.The overall performance is 60mm/h>90mm/h>120mm/h.The larger the crack width is,the greater the nutrient concentration is,and the potassium concentration is the largest compared with nitrogen and phosphorus.At 120mm/h,the maximum concentration peaks of rainfall intensity are 6.79mg/L and5.28mg/L respectively.The precipitation directly determines the amount of runoff,thus affecting the nutrient concentration;When the rain intensity is 120mm/h and the crack width is 15 cm,the total loss of TN,TP and TK are 421.80mg/L,322.94mg/L and 536.22mg/L respectively,which shows that total potassium>total nitrogen>total phosphorus.Soil sediment nutrients in the slope of waste dump decrease with the increase of rainfall intensity,and the average sediment loss increases with the increase of rainfall intensity.The nutrient loss is mainly caused by surface sediment loss.The enrichment coefficient of nitrogen in the lost sediment is more than 1,and the rest is less than 1;The enrichment rates of soil sediment nutrients in the platform slope system of waste dump increase with the increase of rainfall intensity,and the enrichment degree has an obvious relationship with rainfall intensity.(3)The nutrient concentration of runoff from different soil cracks is the highest in the micro developed(10cm)cracks.The total TN nutrient concentration reaches the maximum(0.85mg/L)when the crack width is 10 cm under the condition of 60mm/h rain intensity,which is most likely to cause nitrogen loss and bring water environment pollution.The loss of nitrogen,phosphorus and potassium in runoff water increased with the increase of crack width,and the loss showed as total potassium>total nitrogen>total phosphorus.The soil sediment nutrients in the slope of waste dump decrease with the increase of soil crack width,and the nutrient concentrations of sediment are greater than those in runoff water body.The enrichment coefficient of total nitrogen and total potassium is greater than 1.The influence of soil crack width on phosphorus enrichment rate is not obvious.(4)Rainfall intensity has a very significant relationship with total nitrogen,total phosphorus and total potassium nutrient loss(P<0.01),and there is no significant correlation between different soil cracks and total nitrogen,total phosphorus and total potassium nutrient loss(P>0.05).The regression model between rainfall intensity and runoff nutrient loss is very significant,which is well fitted by quadratic function,and the determination coefficients are more than 0.95.There is no significant difference between crack width and nutrient loss. |
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