Simulation Research On Migration Of Phosphorus In Slope Soil In The Granite Works At Sichuan Erlang Mountain Area

Phosphorus(P)is one of the essential nutrient elements for plant growth and one of the important factors causing eutrophication of water.Surface runoff formed by rainfall is the main driving force of phosphorus migration.A large amount of granite gravel is embedded in the engineering slope in Erlang mountain area of sichuan,with a low vegetation coverage rate and a large slope.Under the complex rainfall conditions,soil phosphorus is easily lost along with surface runoff and sediment migration.To explore granite mountain area in sichuan engineering slope soil p migration mechanism,the indoor simulation rainfall experiments and methods of artificial soil configuration,analysis on three kinds of slope(30 °,40 °,50 °)and four kinds of rainfall intensity(25 mm/h,45 mm/h,85 mm and 65 mm/h)granite project under the condition of slope runoff sediment total phosphorus(TP),total phosphorus(STP),changes of migration of dissolved phosphorus(DP)and its relationship with soil erosion conditions and hydrodynamic parameters.The main achievements of the paper include:(1)The initial flow production time of the engineering slope decreases to different degrees with the increase of rainfall intensity,but it has significant difference with the increase of slope.The runoff rate of engineering slope increases with the increase of rain intensity.Engineering of slope runoff water can section unit(E)and runoff power(omega)were increased along with the increase of rainfall intensity in different degree,runoff shear force(tau)along with the increase of rainfall intensity has significant difference;Under the condition of four kinds of rainfall intensity granite engineering slope runoff runoff power(omega)increased with the increase of the slope,flow shear force washed section unit(tau)and(E)with the change of the slope has the remarkable difference.(2)When the rain intensity is 25 mm / h and 45 mm / h,the soil erosion rate of the engineering slope is low on the whole and does not change significantly with the duration of rainfall under the conditions of 30 ° and 40 ° slopes.When the rain intensity is 65 mm / h and 85 mm / h,the erosion rate of the engineering slope is high and tends to be stable or slow down after rapidly increasing to the peak with the duration of rainfall.Under the condition of 50 ° slope,when the rainfall intensity is 25 mm / h,overall engineering slope soil erosion rate is low and with slowly rising rainfall,when the rainfall intensity is 45 mm / h,engineering slope soil erosion rate increased significantly with the rainfall and rapid growth to slow upward trend after peak,when the rainfall intensity is 65 mm / h and 85 mm / h,the engineering slope soil erosion rate with present a rapid increase to peak after rainfall the wave continues to decline trend.(3)The phosphorus loss of engineering slope is mainly STP(99%),but DP loss is the main form of available phosphorus loss.The overall DP concentration was lower,and the variation amplitude was smaller with the rainfall intensity.Under low rain and strong conditions,STP loss rate showed a trend of slow increase with time.Under the condition of high rainfall intensity,the STP loss rate showed a trend of increasing rapidly at the beginning of rainfall and then leveling off or decreasing slowly.The overall DP loss rate of granite engineering slope showed a trend of continuous slow growth or stabilization after rapid growth at the early stage of rainfall.The total DP loss of granite engineering slope runoff increased with the increase of rainfall intensity.The variation of the total amount of STP with the gradient and rain intensity was significant.(4)The soil erosion characteristics and hydrodynamic parameters of the engineering slope have an important influence on the phosphorus migration of the slope.The TP loss rate of the engineering slope increases as a power function with the increase of the runoff rate,while the TP loss rate increases as a linear function with the increase of the erosion rate.The DP loss rate of engineering slope increases as a power function with the increase of runoff rate.The loss rate of engineering slope DP increases with the increase of erosion rate in the form of power function.