紫色丘陵区不同土地利用类型径流泥沙及氮磷流失特征

Characteristics of Runoff and Sediment,Nitrogen and Phosphorous Losses Under Different Land-use Types in Purple Hilly Area

采用径流小区定位观测法研究紫色丘陵区不同土地利用类型在自然降雨条件下的径流泥沙特征及面源污染物流失特征。结果表明,（1）2014年6-7月共观测到6次产生地表径流降雨事件,其降雨量在14.3~34.3mm之间,不同次降雨条件下产流量均以荒草地最大,其数值在25~35L之间;而产沙量均以顺坡耕作最大,其产沙模数在0.130~2.056g/m2,其次为横坡耕作。（2）各种土地利用类型径流总氮浓度均以6月25日和6月30日较高且以横坡耕作最大,而总磷浓度在观测期间均以顺坡耕作最大,其浓度在2.51~5.90 mg/L之间;顺坡耕作平均总氮流失量比横坡耕作和横坡植物篱耕作分别高9.31%和94.49%,而平均总磷流失量分别为二者的2倍和3倍左右。（3）总氮次产污模数随降雨量增加而增大且前期降雨会导致次产污模数迅速增加;降雨量为27.8mm（6月30日）时各种土地利用类型总氮次产污模数达到最大值;总磷次产污模数与总氮相比较小,数值在0.03~0.51kg/km2之间,与降雨量关系不明显。

The paper mainly studied the loss characteristics of runoff and sediment,nitrogen and phosphorous by runoff plots location observation method at natural rainfall conditions for four land-use types in Purple Hilly Area.The results indicated that（1）there were 6runoff events had been observed with a range of 14.3mm to 34.3mm during June and July in 2014.The runoff yield of wild grass land was the maximum with the range from 25 Lto 35L,the sediment yield of the traditional straight-plowing was the greatest,the modulus of sediment yield varied from 0.130g/m2 to 2.056g/m2,the cross-plowing took the second.（2）The total nitrogen concentration in runoff among four land-use types reached the maximum in June 25 and 30and the cross-plowing took the first place.However,the total phosphorous concentration in runoff during observing period was the highest with a range of concentration from 2.51 mg/L to 5.90 mg/L,the average total amount of runoff nitrogen for straight-plowing was increased by 9.31% and 94.49% respectively,as compared with cross-plowing and cross-plowing type hedgerow,that of runoff phosphorous was about 2and 3times compared with them.（3）Individual pollutant modulus of total nitrogen increased with increasing rainfall and prophase rainfall would cause secondary pollutant modulus increasing rapidly,which reached the maximum under a rainfall of 27.8mm（June 30）among four land-use types,the individual pollutant modulus of total phosphorous was lower than that of total nitrogen and ranged between 0.03kg/km2 and 0.51kg/km2,the relationship between pollutant modulus of total phosphorous and rainfall was not obvious.