间歇性降雨对黄土坡地水土养分流失的影响
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摘要
坡面水土养分流失是研究农业非点源污染方面的核心问题,涉及土壤侵蚀、坡地水文和环境治理等方面的内容。以黄土坡地为研究对象,利用人工降雨模拟试验,分析间歇降雨时坡地产流-入渗-土壤侵蚀过程,以及通过预先在坡地喷施养分(NH_4~+-N、NO_3~--N、PO_4~(3-)-P),研究间歇降雨时坡面水土流失以及土壤溶质的迁移规律。试验采用针孔式人工模拟降雨器进行模拟降雨,对试验坡地间歇性进行3次降雨,雨强恒为100mm/h,每次降雨历时60min,降雨间隔时间60min。结果表明:(1)3次降雨的初始含水率不同,但产流规律相似,降雨径流率均为先增大后趋于平稳。(2)3次降雨产生的泥沙累积量分别为250.91,100.20,79.76g,第1次降雨的泥沙量远高于第2,3次。泥沙率先迅速增大到峰值然后缓慢减少,平均泥沙率随降雨次数的增多而递减。(3)对于非吸附性的NO_3~-、NH_4~+,3场降雨过程中溶质浓度均呈现由高降低并逐渐平稳的变化趋势;PO_4~(3-)-P浓度的变化规律却略显不同,降雨初期溶质浓度先短暂升高,然后再由高降低并逐渐平稳。(4)3次降雨的NH_4~+-N、NO_3~--N、PO_4~(3-)-P的径流总流失量分别为535.33,1 058.18,400.79mg,其中NO_3~--N流失量最多,PO_4~(3-)-P流失量最少。随着降雨次数的增加,不同降雨次数下的NH_4~+-N、NO_3~--N、PO_4~(3-)-P径流流失量均逐渐减少,流失量较前次降雨分别降低了19%,14%、3%,62%和57%,28.3%。因此,通过对间歇性降雨条件下黄土坡地水土溶质迁移特征的研究,对揭示降雨-径流-土壤相互作用过程和土壤养分迁移机理具有重要意义。
Soil water and nutrient losses have played an important role in the research on the expansion of non-point source pollution,which also involved in soil erosion,hillslope hydrology and environmental management.Based on the simulated rainfall experiments on loess slope with spray-applied fertilizer(NH_4~+-N,NO_3~--N,PO_4~(3-)-P),the process of infiltration,soil erosion,and the solute transport process of soil water and solute on slope under interval rain events were investigated.The simulated rainfall experiments were carried out for three interval rain events.Specifically,rainfall intensity was designed as 100 mm/h,and the rainfall lasted 60 min,the rainfall interval was 60 min.Results were as follows:(1)The initial soil moisture content under the three rainfall events were different,but the runoff processes were similar,and the runoff rate showed an increasing trend at first and then tended to be stable.(2)For three interval rain events,the accumulation amounts of sediment were 250.91,100.20 and 79.76 g,respectively,and the amount of accumulated sediment yield in the 1 st rainfall events was more than those of the 2 nd and 3 rd.The curve of sediment rate increased rapidly to the peak and then decreased slowly,and the average sediment yield decreased with the increase of rainfall frequency.(3)The concentrations of NH_4~+-N,NO_3~--N were changed from high to low and gradually tended to be stable in three rainfalls.Compared with the NH_4~+-N,NO_3~--N,theconcentration of PO_4~(3-)-P increased at the beginning of rainfall,and then lowered and leveled off.(4)The total loss of NH_4~+-N,NO_3~--N and PO_4~(3-)-P in surface runoff of three rainfall were 535.33 mg,1 058.18 mg and 400.79 mg,respectively,and NO_3~--N have the most loss and PO_4~(3-)-P have the least.With the increase of rainfall frequency,NH_4~+-N,NO_3—N and PO_4~(3-)-P loss decreased gradually under different rainfall times,the loss amount were reduced 19% and 14%,3% and 62%,57% and 28.3% than previous rainfalls.The effects of three rain events on yellow soil of loess slope land reveal the interaction of rainfall,surface runoff and soil,and the mechanism of nutrient loss,also provide the scientific basis for control of water and soil erosion.
Soil water and nutrient losses have played an important role in the research on the expansion of non-point source pollution,which also involved in soil erosion,hillslope hydrology and environmental management.Based on the simulated rainfall experiments on loess slope with spray-applied fertilizer(NH_4~+-N,NO_3~--N,PO_4~(3-)-P),the process of infiltration,soil erosion,and the solute transport process of soil water and solute on slope under interval rain events were investigated.The simulated rainfall experiments were carried out for three interval rain events.Specifically,rainfall intensity was designed as 100 mm/h,and the rainfall lasted 60 min,the rainfall interval was 60 min.Results were as follows:(1)The initial soil moisture content under the three rainfall events were different,but the runoff processes were similar,and the runoff rate showed an increasing trend at first and then tended to be stable.(2)For three interval rain events,the accumulation amounts of sediment were 250.91,100.20 and 79.76 g,respectively,and the amount of accumulated sediment yield in the 1 st rainfall events was more than those of the 2 nd and 3 rd.The curve of sediment rate increased rapidly to the peak and then decreased slowly,and the average sediment yield decreased with the increase of rainfall frequency.(3)The concentrations of NH_4~+-N,NO_3~--N were changed from high to low and gradually tended to be stable in three rainfalls.Compared with the NH_4~+-N,NO_3~--N,theconcentration of PO_4~(3-)-P increased at the beginning of rainfall,and then lowered and leveled off.(4)The total loss of NH_4~+-N,NO_3~--N and PO_4~(3-)-P in surface runoff of three rainfall were 535.33 mg,1 058.18 mg and 400.79 mg,respectively,and NO_3~--N have the most loss and PO_4~(3-)-P have the least.With the increase of rainfall frequency,NH_4~+-N,NO_3—N and PO_4~(3-)-P loss decreased gradually under different rainfall times,the loss amount were reduced 19% and 14%,3% and 62%,57% and 28.3% than previous rainfalls.The effects of three rain events on yellow soil of loess slope land reveal the interaction of rainfall,surface runoff and soil,and the mechanism of nutrient loss,also provide the scientific basis for control of water and soil erosion.
引文
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[2]李裕元,邵明安,郑纪勇,等.降雨强度对黄绵土坡地磷流失特征影响试验研究[J].农业工程学报,2007,23(4):39-46.
[3]姚文艺,陈国祥.雨滴降落速度及终速公式[J].河海大学学报,1993,21(3):21-27.
[4]李长宝,太史怀远.降雨特性对土壤侵蚀影响的研究分析[J].水土保持学报,1990,4(3):21-25.
[5]Ran Q,Su D,Li P,et al.Experimental study of the impact of rainfall characteristics on runoff generation and soil erosion[J].Journal of Hydrology,2012,424/425(6):99-111.
[6]Jiang F,Huang Y,Wang M,et al.Effects of rainfall intensity and slope gradient on steep colluvial deposit erosion in Southeast China[J].Soil Science Society of America Journal,2014,78(5):1741-1752.
[7]田坤.降雨-径流条件下土壤溶质迁移过程模拟[J].农业工程学报,2011,27(4):81-87.
[8]陈晓鹏,周蓓蓓,陶汪海,等.变雨强对黄土坡地水土养分流失机制研究[J].水土保持学报,2016,30(4):33-37.
[9]马琨,王兆骞,陈欣,等.不同雨强条件下红壤坡地养分流失特征研究[J].水土保持学报,2002,16(3):16-19.
[10]王占礼,高素娟,黄鸣斌,等.黄河中游多沙区坡面薄层水流水动力学特性[J].水土保持通报,2010,30(4):11-16.
[11]赵海滨,曹京京,姚文艺,等.黄土坡面径流输沙过程试验研究[J].水土保持研究,2014,21(1):90-94.
[12]杨婷.黄土坡面土壤溶质随地表径流迁移特征试验及数学研究[D].西安:西安理工大学,2013.
[13]王辉,王全九,邵明安.人工降雨条件下黄土坡面养分随径流迁移试验[J].农业工程学报,2006,22(6):39-44.
[14]焦平金,许迪,王少丽,等.自然降雨条件下农田地表产流及氮磷流失规律研究[J].农业环境科学学报,2010,29(3):534-540.
[15]张亚丽,李怀恩,张兴昌,等.间歇降雨条件下黄土坡面土壤溶质的迁移特征[J].中国农业科学,2009,42(4):1299-1305.
[16]周蓓蓓,胡梓超,王全九.一种针孔式防堵塞人工野外模拟降雨装置:中国,ZL201510069492.4[P].2016.
[17]王全九.土壤物理与作物生长模型[M].北京:中国水利水电出版社,2016.
[18]Lightthill M J,Whitham G B.On kinematic waves.1.Flood movement in long rivers.Proceeding of the royal society of London[J].Series A,Mathematical and Physical Sciences,1955,229(1178):281-316.
[19]胡梓超,周蓓蓓,王全九.模拟降雨条件下纳米碳对黄土坡面养分流失的影响[J].水土保持学报,2016,30(4):1-6.
[20]贾莲莲.模拟降雨条件下黄土坡面侵蚀过程与调控试验研究[D].西安:西安理工大学,2010.
[21]吴淑芳,刘政鸿,霍云云,等.黄土坡面细沟侵蚀发育过程与模拟[J].土壤学报,2015,52(1):48-56.