Phosphorus forms and fluxes via hydrological pathways in typical rainfall events from different land uses in the hilly area of purple soil had been conducted by in-situ monitoring in some sub-catchments so as to understand“hotspot”and “critical time”for control of non-point-source pollution of phosphorus in a catchment.Rainfall-run-off process along with sediment yield,total phosphorus (TP),dissolved phosphorus (DP)and particulate phos-phorus (PP)concentrations and loadings were monitored in representative rain (small,medium,heavy and storm) events from sub-catchment of residence,forestland and cropland.The results showed that rainfall-runoff processes responded with land uses.In the residence sub-catchment,runoff started while rainfall reached 4mm,whereas, that started in much higher rainfall (20 mm)in the forestland and cropland sub-catchment,respectively.Runoff responded to rainfall rapidly at almost the same peak in the residence sub-catchment in medium,heavy and storm rain,while runoff delayed 20 -90 and 20 -120 min after rainfall in cropland and forestland sub-catchment,re-spectively.The mean runoff depth,runoff coefficient and sediment yield from residence sub-catchment were 22.4 mm,0.36 and 136.2 kg/hm2;while those were 9.5 mm,0.09 and 48.6 kg/hm2 from forestland and 12.3mm, 0.17 and 73.5 kg/hm2 from cropland,respectively.The water and soil loss from the residence is the most serious in the hilly area of purple soil.The concentration of total P (TP)and particulate phosphorus (PP)of runoff water from the residence and forestland sub-catchment reached peak quickly and decreased sharply,whereas,TP and PP of runoff water from cropland turned into a process with multi-peaks.The concentration of dissolved P (DP)of run-off water from the residence sub-catchment decreased when runoff discharge increased.DP of runoff water from the forestland sub-catchment increased during the runoff process.DP and phosphate (PO3-4 -P)concentrations of run-off from cropland were relative low.The TP loss fluxes under small,medium,heavy and storm rain from the resi-dence sub-catchment were 42.6,136.3,190.0 and 1 245.6 g/hm2 with average fluxes of 403.6 g/hm2;while, the TP loss fluxes under medium,heavy and storm rain from forestland and cropland were 3.5,3.9,90.6 g/hm2 (average 32.7 g/hm2)and 6.6,10.2,210.6 g/hm2(average 75.8 g/hm2),respectively.The phosphorus load-ing from the residence sub-catchment was significantly higher than those from the cropland and forestland sub-catch-ment under various rain-type conditions.%通过对居民点、林地、坡耕地等土地利用类型的小型集水区（亚流域）径流磷形态与通量的定位监测，研究了紫色丘陵典型小流域的非点源磷流失特征。结果表明，居民点在降雨量4 mm即可产流，林地与坡耕地的产流临界降雨量为20 mm。居民点的降雨径流响应迅速，径流与降雨峰值基本同步；林地和坡耕地产流时间延迟，径流峰值较降雨延迟20～120 min。居民点、坡耕地和林地的次降雨平均径流深分别为22．4、12．3、9．5 mm，径流系数分别为0．36、0．17和0．09，泥沙流失量分别为136．2、73．5和48．6 kg／hm2。居民点和林地径流的总磷（Total P－TP）、颗粒态磷（Particulate P－PP）浓度在径流过程中迅速达到峰值后陡然下降；坡耕地径流的TP、PP浓度呈多峰变化。居民点径流的可溶性磷（Dissolved P－DP）浓度随径流量增大而减少；林地径流的DP浓度逐渐增加；坡耕地DP、磷酸盐（PO3－4－P）浓度较低且波动较小。居民点小雨、中雨、大雨和暴雨等雨型下的 TP流失负荷分别为42.6、136.3、190.0、1245.6 g／hm2，平均负荷为403.6 g／hm2，林地与坡耕地在中雨、大雨和暴雨等雨型下的TP流失负荷分别为3.5、3.9、90.6和6.6、10.2、210.6 g／hm2，二者的平均负荷为32.7和75.8 g／hm2。降雨量越大，磷流失负荷越高，暴雨条件下的TP流失负荷最高。居民点的磷流失负荷远高于坡耕地和林地，表明居民点的径流污染是非点源污染控制的关键源。
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