Characteristics Of Nutrient Retention And Its Response To Human Disturbance Of Artificial Pool Geomorphic Structure In An Agricultural Headwater Stream

The retention and regulation ability of nitrogen and phosphorus and other nutrients are different in different types of headwater streams.It is significant to study the retention of nitrogen and phosphorus nutrients to the downstream water after human disturbance.To investigate the regulation of the impacts on nitrogen and phosphorus nutrients in the transient storage and retention of deep pool geomorphic structure in a headwater stream and human disturbance experiment.Using a constant-rate injection of conservative tracer?NaCl?and nutrients?NH₄Cl and KH₂PO₄?launched nine field tracer experiments,including the following four times,which were conducted under the condition of human disturbance in deep pool reach.Based on the analysis of OTIS water quality model,by comparing transient storage metrics and nutrient spiral metrics between deep pool reach and straight reach before and after disturbance to analysis the effects of human disturbance on transient storage and retention of nitrogen and phosphorus,and hydrological parameter sensitivity analysis and hydrological parameters of multivariate statistical analysis,get the following results:?1?For the hydrological parameters,the mean values of D,A,As and a in study reach predominated by deep pool reach were 0.116m² · s^-1,0.357m²,0.380m²,5.86×10^-4s^-1,the mean values of D,A,A,and a in study reach predominated by straight reach were 0.162m² · s^-1,0.167m²,0.071m²,4.11×10^-3s^-1;using perturbation analysis method of parameter sensitivity ranking found that deep pool reach and straight reach of four main parameters,A,As,,D,a parameter sensitivity sorting results were A>As>a>D.?2?under natural conditions,the deep pool reach F200 med mean value was 21.97%,straight reach mean value was 27.97%,and the vast majority of straight reach is higher than that of deep pool,that under natural conditions the straight reach of transient storage capacity than the deep pool reach stronger;after artificial disturbance,deep pool F200 med average is 23.94%,the straight reach F200 med average is 23.19%.The deep pool is relatively straight reach is too large,that human disturbance after the deep pool period of transient capacity significantly enhanced and higher than that of the straight reach.?3?before and after interference,SW-NH⁴⁺ and SW-SRP values are shown as deep pool reach is far less than the straight reach,indicating that deep pool reach for nitrogen and phosphorus retention ability was stronger than straight reach,and the deep pool reach and a straight reach of SW value at home and abroad the same scale of the stream Sw is equivalent to the value of the interference,the deep pool;some streams the nitrogen and phosphorus retention capacity increased significantly,Vf and U value increased,Sw value decreased greatly;the interference test reach of the deep pool,not only improve the retention capacity of deep pools of nitrogen and phosphorus,but also changed the retention capacity of the downstream straight reach of nitrogen and phosphorus nutrients.?4?statistical pool canal and straight canal reach analysis shows that the deep pool in the basic hydraulic parameters of Q and transient storage capacity on stream influence,straight reach in the transient storage index exists between different relationships;in W,A,Ts and Ls,deep pools and flat reach the straight reach of the transient storage had significant differences.