喀斯特溶槽岩-土界面优势流及其对土壤水分动态的影响
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摘要
通过对两个典型溶槽剖面的野外入渗实验,结合对入渗锋面的红外成像和染色示踪,分析溶槽中土壤湿润锋运移受岩—土界面优势流、初始水分状态(干湿程度和不均匀分布)及植被根系的影响程度。其结果表明:岩—土界面优势流增加入渗锋面到达处的土壤含水率是溶槽中部的1.1～14.5倍,但岩—土界面优势流形成的侧向水势梯度可降低优势流锋面下移;初始入渗中表土湿润锋运移主要受植被根系大孔隙优势流的影响,岩—土界面优势流作用不显著,但随着入渗深度的加大,岩—土界面优势流侧向弥散对湿润锋运移和土壤水分的影响加强。
Karst grike and troughs are widely developed in epi-karst zone, in which the soil water and fissure water are important sources for vegetation. The preferential flow through rock-soil(R-S) interface and plant roots are important sources of groundwater recharge. In this paper, two typical fresh limestone karst trough profiles(A and B) in the Puding karst experiment area were selected, where the filled soil were yellow soil clay and yellow calcareous soil, respectively. Especially, the upper and middle parts of profile B contain more plant roots. The field infiltration experiments on the two typical karst profiles were done(profile A:3 times; profile B:1 time), and the soil moisture content at the R-S interface and intermediate soil(SZ) were measured with TDR. Meanwhile, combined with the infrared imaging and dyeing tracer of the infiltration front of the profile, the influence of the dominant rock-soil interface flow, the initial moisture state(degree of wetness and non-uniform distribution) and the vegetation root system on the movement of the soil moisture front in the trough with different initial moisture content was analyzed. The results show that the rapid dominant flow at R-S interface significantly affects the infiltration and water movement in the soil of the karst troughs, and the degree of its influence is related to the size and distribution of the initial soil moisture content. The increase of soil moisture content in the vicinity of R-S interface where the infiltration front reaches during infiltration is 1.1 to 14.5 times of that in the middle of karst trough; but the lateral water potential gradient formed by the preferential flow in the R-S interface can reduce the downward velocity of the dominant flow front. Whereas, in the middle part of the soil far away from the R-S interface, the wetting front moving down speed in infiltration mainly depends on the degree of soil moisture at the initial stage. The lower the soil moisture content, the greater the wetting front matrix potential gradient and the faster the wetting front moving down. For another, the macro-pore dominant flow of vegetation root system mainly acted on the surface soil moist front movement in the initial infiltration and the preferential flow of the R-S interface is not significant. Then, with the increase of infiltration depth, the lateral dispersion of preferential flow in the R-S interface has a stronger influence on wetting front migration and soil moisture content.
Karst grike and troughs are widely developed in epi-karst zone, in which the soil water and fissure water are important sources for vegetation. The preferential flow through rock-soil(R-S) interface and plant roots are important sources of groundwater recharge. In this paper, two typical fresh limestone karst trough profiles(A and B) in the Puding karst experiment area were selected, where the filled soil were yellow soil clay and yellow calcareous soil, respectively. Especially, the upper and middle parts of profile B contain more plant roots. The field infiltration experiments on the two typical karst profiles were done(profile A:3 times; profile B:1 time), and the soil moisture content at the R-S interface and intermediate soil(SZ) were measured with TDR. Meanwhile, combined with the infrared imaging and dyeing tracer of the infiltration front of the profile, the influence of the dominant rock-soil interface flow, the initial moisture state(degree of wetness and non-uniform distribution) and the vegetation root system on the movement of the soil moisture front in the trough with different initial moisture content was analyzed. The results show that the rapid dominant flow at R-S interface significantly affects the infiltration and water movement in the soil of the karst troughs, and the degree of its influence is related to the size and distribution of the initial soil moisture content. The increase of soil moisture content in the vicinity of R-S interface where the infiltration front reaches during infiltration is 1.1 to 14.5 times of that in the middle of karst trough; but the lateral water potential gradient formed by the preferential flow in the R-S interface can reduce the downward velocity of the dominant flow front. Whereas, in the middle part of the soil far away from the R-S interface, the wetting front moving down speed in infiltration mainly depends on the degree of soil moisture at the initial stage. The lower the soil moisture content, the greater the wetting front matrix potential gradient and the faster the wetting front moving down. For another, the macro-pore dominant flow of vegetation root system mainly acted on the surface soil moist front movement in the initial infiltration and the preferential flow of the R-S interface is not significant. Then, with the increase of infiltration depth, the lateral dispersion of preferential flow in the R-S interface has a stronger influence on wetting front migration and soil moisture content.
引文
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[21] 刘金涛,张文平,宋慧卿,等.影响山坡土壤入渗速率及路径的染色示踪研究[J].中国农村水利水电,2016(5):77-80.
[22] Flury M,Flühler H,Jury W A,et al.Susceptibility of soils to preferential flow of water:A field study[J].Water Resources Research,1994,30(7):1945-1954.
[23] Mei X,Zhu Q,Ma L,et al.Effect of stand origin and slope position on infiltration pattern and preferential flow on a loess hillslope[J].Land Degradation & Development,2018,29(5):1353-1365.
[24] Bauters T W J,Dicarlo D A,Steenhuis T S,et al.Soil water content dependent wetting front characteristics in sands[J].Journal of Hydrology,2000,231(22):244-254.
[25] Cammeraat E L H,Cerdà A,Imeson A C.Ecohydrological adaptation of soils following land abandonment in a semi-arid environment[J].Ecohydrology,2010,3(4):421-430.
[26] 孙玉龙,郝振纯,陈启慧,等.土壤电导率及土壤溶液电导率与土壤水分之间关系[J].河海大学学报,1997,25(6):71-75.
[2] 曹建华,袁道先,潘根兴.岩溶生态系统中的土壤[J].地球科学进展,2003,18(1):37-44.
[3] Tzavaras J,K?hne M,Vogel H J.From pore scale to continuum scale modeling of infiltration[J].Advances in Water Resources,2017,103:108-118.
[4] Liu Z,Li Y,Xiao Y,et al.Effects of riverbed and lake bottom sediment thickness on infiltration and purification of reclaimed water [J].Environmental Earth Sciences,2017,76(1):37.
[5] Homolák M,Pichler V,G?m?ryová E,et al.Effect of surface humus on water infiltration and redistribution in beech forest stands with different density [J].Central European Forestry Journal,2017,63(2-3):73-78.
[6] Schlüter S,Vogel H,Ippisch O,et al.Combined impact of soil heterogeneity and vegetation type on the annual water balance at the field scale [J].Vadose Zone Journal,2013,12(4):1742-1751.
[7] Abrahams A D,Parsons A J.Relation between infiltration and stone cover on a semiarid hillslope,southern Arizona[J].Journal of Hydrology,1991,122(1-4):49-59.
[8] Bergkamp G.A hierarchical view of the interactions of runoff and infiltration with vegetation and microtopography in semiarid shrublands[J].Catena,1998,33(3-4):201-220.
[9] Cantón Y,Solé-Benet A,De Vente J,et al.A review of runoff generation and soil erosion across scales in semiarid south-eastern Spain[J].Journal of Arid Environments,2011,75(12):1254-1261.
[10] Sohrt J,Ries F,Sauter M,et al.Significance of preferential flow at the rock soil interface in a semi-arid karst environment [J].Catena,2014,123:1-10.
[11] Li S,Birk S,Xue L,et al.Seasonal changes in the soil moisture distribution around bare rock outcrops within a karst rocky desertification area (Fuyuan County,Yunnan Province,China)[J].Environmental Earth Sciences,2016,75(23):1482.
[12] Arbel Y,Green Baum N,Lange J,et al.Infiltration processes and flow rates in developed karst vadose zone using tracers in cave drips.[J].Earth Surface Processes & Landforms,2010,35(14):1682-1693.
[13] 陈洪松,邵明安,王克林.土壤初始含水率对坡面降雨入渗及土壤水分再分布的影响[J].农业工程学报,2006,22(1):44-47.
[14] Liu H,Lei T W,Zhao J,et al.Effects of rainfall intensity and antecedent soil water content on soil infiltrability under rainfall conditions using the run off-on-out method[J].Journal of Hydrology,2011,396(1/2) :24-32.
[15] Green W H.Studies on soil physics,I Flow of water and air through soils[J].Journal of Agricultural,1911,4:1-24.
[16] Pietro L D.Application of a lattice-gas numerical algorithm to modelling water transport in fractured porous media[J].Transport in Porous Media,1996,22(3):307-325.
[17] Nitao J J,Buscheck T A.Infiltration of a Liquid Front in an Unsaturated,Fractured Porous Medium[J].Water Resources Research,1991,27(8):2099-2112.
[18] 章程.贵州普定后寨地下河流域地下水脆弱性评价与土地利用空间变化的关系[D].北京:中国地质科学院,2003.
[19] 朱书法,刘丛强,陶发祥,等.贵州喀斯特地区棕色石灰土与黄壤有机质剖面分布及稳定碳同位素组成差异[J].土壤学报,2007,44(1):169-173.
[20] 刘斐,陈军,慕军营,等.土壤温度检测及其与含水率关系研究[J].干旱地区农业研究,2013,31(3):95-99,117.
[21] 刘金涛,张文平,宋慧卿,等.影响山坡土壤入渗速率及路径的染色示踪研究[J].中国农村水利水电,2016(5):77-80.
[22] Flury M,Flühler H,Jury W A,et al.Susceptibility of soils to preferential flow of water:A field study[J].Water Resources Research,1994,30(7):1945-1954.
[23] Mei X,Zhu Q,Ma L,et al.Effect of stand origin and slope position on infiltration pattern and preferential flow on a loess hillslope[J].Land Degradation & Development,2018,29(5):1353-1365.
[24] Bauters T W J,Dicarlo D A,Steenhuis T S,et al.Soil water content dependent wetting front characteristics in sands[J].Journal of Hydrology,2000,231(22):244-254.
[25] Cammeraat E L H,Cerdà A,Imeson A C.Ecohydrological adaptation of soils following land abandonment in a semi-arid environment[J].Ecohydrology,2010,3(4):421-430.
[26] 孙玉龙,郝振纯,陈启慧,等.土壤电导率及土壤溶液电导率与土壤水分之间关系[J].河海大学学报,1997,25(6):71-75.