<pre><code>                     &lt;p&gt;(1) Runoff observation: the general runoff field and simple runoff field only observe the total runoff (muddy water) generated by precipitation once, and the starting and ending time and process of runoff are also measured in the key runoff field. The highest water level of the runoff pool was observed after the precipitation stopped. If there is sediment deposition in the bearing channel and the water diversion channel, it should be scraped into the pool first and then observed. The runoff process is calculated by the water level process. The water level process is generally observed every two minutes. Self recording water level meter is installed in part of the runoff pool of the runoff field to automatically record the water level process. (2) Sediment Observation: the general runoff field and simple runoff field only observe the total sediment generated by precipitation once, and the sediment concentration process is measured in the key runoff field. There are three sampling methods for the average sediment concentration of runoff: 1) mixing method: firstly, the slurry in the runoff pool is extracted and mixed evenly, and then the water sample is taken; 2) stratified sampling method, after mixing the slurry evenly, three to five water samples of one cubic decimeter are taken out in layers and mixed together, and then 1 to 3 water samples of 0.5 cubic decimeter are taken out as treatment water samples; 3) pump method, using pump or tubular sampler Draw out a column of water for water sample. When there is a large amount of sediment in the runoff and a lot of sludge at the bottom of the pool, alum is used to precipitate the fine mud, and then the upper clean water is sucked out, and then the mud sample is taken for treatment. In the process of sediment concentration measurement, the water sample with sediment concentration is taken from the water tongue of the measuring tank or the water diversion channel, and the time is the same as that of the water level observation, once every two minutes. Water samples are usually treated by drying method and sometimes by displacement method. (3) Flow calculation: the total runoff is calculated according to the maximum water level of the runoff pool and the water level volume relationship of the runoff pool determined in advance. (4) Calculation of sediment concentration: the total sediment content is obtained by multiplying the total runoff with the average sediment concentration. &lt;/p&gt;