Analysis of sampling interval for monitoring of agricultural non-point sources based on runoff events
The Wulongchi small watershed in Danjiangkou Reservoir area was selected as the object,and the real value of runoff process was taken from the High-frequency monitoring data of typical rainfall runoff events.The error of pollution load flux estimation was analyzed by simulating sampling at different time intervals and water intervals,and the effective sampling interval was determined.The results showed that the rainfall runoff event in Wulongchi Basin had obvious peak characteristics(initial discharge 55m3/h,peak discharge 977.3m3/h),the total phosphorus concentration was highly synchronized with the runoff(initial concentration 0.05mg/L,peak concentration 0.25mg/L),and the total nitrogen did not decrease significantly after reaching the peak with the runoff(initial concentration 2mg/L,peak concentration 8mg/L).In the simulated sampling with interval 5,10,15,20,30,60,120,240,480,720min,the number of sampling points reduced from 1957 t0 14.In the simulated sampling with interval 16,32,64,128,256,384,576,800,1600,3200m3,the number of sampling points reduced from 2893 to 14.The ability of water interval sampling to capture peak runoff is obviously higher than that of time interval sampling.Load estimation error showed that the fluctuation of total phosphorus error is greater than that of total nitrogen error.Taking±5％as the allowable error range,the effective time interval of rainfall runoff event sampling was 120min,and the effective water interval was 1600m3.
万方数据
维普
