Controls of infiltration–runoff processes in Mediterranean karst rangelands in SE Spain

Semiarid karst landscapes represent an important ecosystem surrounding the Mediterranean Basin for which little is known on runoff generation. Knowledge of the sources and patterns of variation in infiltration–runoff processes and their controls is important for understanding and modelling the hydrological functions of such ecosystems. The objectives of this paper are to determine the infiltration rates and their controls in a representative mountain karst area (Sierra de Gádor, SE Spain) at micro-plots and to investigate the integrated response of rainfall on a typical hillslope. Rainfall simulations in micro-plots and natural rainfall-runoff monitoring on a hillslope were carried out complementarily. We investigated the role of soil surface components (vegetation, rock outcrop, fracture, and soil crust), topographic position, antecedent soil moisture, and rainfall characteristics in regulating infiltration–runoff processes. Results of rainfall simulation revealed the importance of vegetation cover and the presence of rock fractures in promoting the infiltration in the limestone karst landscape, while bare patches and rock outcrops acted as sources for runoff. All plots with > 50% vegetation cover had no runoff with up to 55 mm h^− 1 of simulated rain. In contrast, nearly all bare plots had runoff under the same simulated rain, with runoff coefficients ranging from 3.1 to 20.6% on dry soil surface conditions, and from 2.0 to 65.4% on wet soil surfaces. Runoff coefficients amounted to 59.0–79.5% for rock outcrops without cracks, but were drastically reduced by the presence of cracks. The surfaces with rock fragments resting on the soil (generally located in the middle of the slopes) prevented more effectively the runoff generation than those surfaces where rock fragments were embedded in the top soil. Antecedent soil moisture had significant impact on runoff generation, with wet soil having doubled runoff coefficient, shortened time to runoff, and increased runoff rate compared to the same but dry soil. Linear regressions indicated that the main controls for constant infiltration rate were the cover percentages of vegetation and litter, plus rainfall intensity; while the major controls for runoff coefficient were the bare soil and vegetation coverage, plus rainfall intensity. High infiltration rates measured at the micro-plots agreed with low intra-event runoff coefficients (mostly below 1%) observed under natural rainfalls at the hillslope. Runoff depth and coefficient at the hillslope was significantly correlated with rainfall depth, maximum hourly rainfall intensity and antecedent precipitation over 20 days (AP₂₀). During the 1.5-year monitoring period from Sep-2003 to Mar-2005, the overall infiltration was 41% of the total rainfall amount and the maximum infiltration rate was almost 94% of the largest single rainfall event. The results from this study contribute to improved understanding of the magnitude and controls of the surface runoff in semiarid karst mountain areas.     

Heterogeneity in soil hydrological response from different land cover types in southern Spain

This paper reports results from the analysis of the soil hydrological response to simulated rainfall in a cork oak forest in Los Alcornocales Natural Park (SW Spain). Four different soil/vegetation units were selected for the field experiments: [1] cork oak woodland, [2] heathland, [3] grassland, and [4] cork oak/olive tree mixed forest. Rainfall simulations tests were performed on circular plots of 1256.6 cm² at an intensity of 56.5 mm h^− 1 for 30 min.Marked differences in the hydrological behavior of the studied vegetation types were observed after the rainfall simulations. The soils under woodland showed low runoff rates and coefficients. The highest runoff rates were measured on the heath and grass-covered parts of the hillslope. Water repellency of the soil, measured from water drop penetration tests, reduced infiltration (especially under the heathland), and seems to be the cause of fast ponding and runoff generation during the first stages of rainstorms.The mosaic of different patterns of hydrological response to rainfall, such as runoff generation or infiltration, is governed by the spatial distribution of vegetation and its influence on the soil surface.     

坡地开垦的径流泥沙响应

Land use and land cover change is a key driver of environmental change. To investigate the runoff and erosion responses to frequent land use change on the steep lands in the Three Gorges area, China, a rainfall simulation experiment was conducted in plots randomly selected at a Sloping Land Conversion Program site with three soil surface conditions: existing vegetation cover, vegetation removal, and freshly hoed. Simulated rainfall was applied at intensities of 60 (low), 90 (medium), and 120 mm h 1 (high) in each plot. The results indicated that vegetation removal and hoeing significantly changed runoff generation. The proportion of subsurface runoff in the total runoff decreased from 30.3% to 6.2% after vegetation removal. In the hoed plots, the subsurface runoff comprised 29.1% of the total runoff under low-intensity rainfall simulation and the proportion rapidly decreased with increasing rainfall intensity. Vegetation removal and tillage also significantly increased soil erosion. The average soil erosion rates from the vegetation removal and hoed plots were 3.0 and 10.2 times larger than that in the existing vegetation cover plots, respectively. These identified that both the runoff generation mechanism and soil erosion changed as a consequence of altering land use on steep lands. Thus, conservation practices with maximum vegetation cover and minimum tillage should be used to reduce surface runoff and soil erosion on steep lands.     

野外模拟降雨条件下坡面降雨入渗、产流试验研究

利用野外模拟降雨试验,研究了植被类型、降雨强度、地表结皮、覆盖杂草等对荒草地和裸地降雨入渗、产流的影响。结果表明:裸地因降雨易产生地表结皮,产流时间主要取决于降雨强度,两者的关系可用幂函数描述,达显著水平;荒草地由于植被覆盖度较高,产流时间主要取决于土壤初始含水量,两者的关系可用线性公式描述,达极显著水平;与裸地相比,荒草地能延缓产流,并有效拦蓄径流;裸地形成地表结皮后,产流提前,平均入渗率降低,但坡面覆盖杂草(尤其是坡中下部覆盖杂草)能有效拦蓄径流、延缓产流、增加入渗,并促进土壤水分向深层的运移,而雨后采用抑制蒸发的措施能起到类似的效果     

Predicting runoff from semi-arid hillslopes as source areas for water harvesting in the Sierra de Gador, southeast Spain

The effectiveness of water harvesting systems collecting surface runoff form rangeland hillslopes in semi-arid regions is difficult to predict, since the hydrological response at the outlet depends on the heterogeneity of hydrological processes. The lack of continuous runoff pathways, due to the irregular spatial patterns of soil properties and the variety of antecedent soil moisture conditions directly influence runoff generation and control discharge into the water harvesting cisterns. The aim of this paper is to evaluate the effectiveness of semi-arid hillslopes in generating runoff for water harvesting systems. Runoff was estimated by the STREAM expert-based model which was applied to three semi-arid hillslopes (0.4 to 6 ha). On the one hand the STREAM model rules were adapted to the regional conditions i.e. an antecedent precipitation index was adjusted to local soil moisture conditions and the rainfall duration was defined as the total rainfall event quantity and the effective rainfall duration (P_tot/t_eff). On the other hand, the distribution of rock outcrop and vegetation cover along the slopes was used to define homogeneous hydrological units. Final infiltration capacities were attributed to these hydrological units based on values found in the literature. The prediction performances are acceptable for the three water harvesting systems with an RMSE of 13.9 m³. It was shown that the rainfall/runoff model was more sensitive to the duration of the storm than to the antecedent soil moisture conditions. The use of a unique set of hydrological parameters for the three water harvesting systems on representative hillslopes allows the runoff prediction from any rangeland hillslope within the same region. Furthermore, the spatial patterns of soil surface characteristics are crucial for collecting runoff at the outlet of the system. Model runs demonstrated that degradation of vegetation and sealing of very small areas within flow paths can lead to an increase of annual runoff by as much as a factor two.     

Effect of vegetation cover on the hydrology of reclaimed mining soils under Mediterranean-Continental climate

Vegetation cover plays a major role in the restoration and stabilization of disturbed systems. The analysis of relationships between restored vegetation and soil hydrology has special relevance for the evaluation and operation of mining reclamation, particularly in Mediterranean-Continental environments, where climatic conditions restrict the development of continuous vegetation cover. The effect of herbaceous vegetation cover on soil hydrology was analysed by means of rainfall simulation (63 mm h^− 1; 0.24 m²) in reclaimed soils derived from opencast coal mining (a non-saline and clay-loam textured spoil) in central-eastern Spain. A total of 75 simulation experiments were conducted at three different times throughout the year (late winter, summer and autumn) to control the influence of seasonal climatic fluctuations. Sediment concentrations in runoff and the runoff coefficient decreased exponentially with vegetation cover, while increases in steady infiltration rates were obtained with vegetation cover. Additional delays in runoff responses (longer time to runoff start and stabilization) and increases in the wetting front depth were observed with vegetation cover. Seasonal variations in soil surface state and moisture strongly influenced hydrological responses; although the influence of season on the analysed hydrological responses was attenuated by vegetation cover, especially in the case of infiltration rates. We also determined a practical ground cover threshold for site restoration and evaluation of over 50% vegetation cover, which could help achieve an optimum biological control of hydrological soil responses in the studied environment.     

桂西北喀斯特峰丛不同土地利用方式坡面产流产沙特征

由于缺乏长期定位观测资料,西南喀斯特山区坡地水土流失规律一直不明确,严重影响了该区石漠化综合治理和水土流失防治工作的成效和进程。该文基于13个大型径流小区(宽20m、投影面积>1000m2)5a(2006-2010年)的定位观测资料,分析了桂西北喀斯特峰丛洼地不同利用方式坡面降雨产流规律和地表侵蚀产沙特征。结果表明:观测期内年降雨量为1300～2000mm,无论平水年还是丰水年,不同利用方式坡面次降雨径流系数<5%,地表产流很少,降雨几乎全部入渗。不同利用方式地表侵蚀产沙模数虽有较大差异,但土壤侵蚀以微度(<30t/(km2a))为主,部分甚至只有0～5t/(km2a)。植被类型、土地利用方式对坡面降雨产流的影响较小,但人为干扰会增加地表侵蚀产沙量。该文为喀斯特坡地植被恢复重建和水土流失防治提供参考。     

Impact of afforestation on hydrological response and sediment production in a small Calabrian catchment

Extensive afforestation using Pinus and Eucalyptus has taken place in Calabria since the early 1960's to control expansion of calanchi and biancane. In 1978 three small catchments were established near Crotone to monitor the effect of afforestation on hydrological response and sediment yield. In 1992, rainfall simulation experiments were carried out on plots in these catchments to determine more precisely the effect of tree and ground vegetation on surface runoff and erosional response. Most experiments were carried out in a logged catchment with slopes ranging from 20 to 30° and aspects from SW to NE. Results showed complex runoff generation and sediment production, reflecting the effect of microclimate and subtle variations in vegetation on infiltration characteristics. On south-facing slopes with little ground vegetation runoff generation was rapid with runoff coefficients from 27 to 37% and peak sediment concentrations reaching 83.7 g · 1⁻¹. On north-facing slopes with good tree cover, little grass, but continuous leaf litter, runoff coefficients reached 21%, but peak sediment concentration was only 3.6 g · 1⁻¹, while on recently logged north-facing slopes with dense grass cover the highest runoff coefficient was only 5.5% runoff coefficient, and there was virtually no sediment production. Implications of results for forest management and soil conservation are discussed.     

The impact of vegetation and soil on runoff regulation in headwater streams on the east Qinghai–Tibet Plateau,China

Vegetation type is one of many factors that affect watershed hydrology and is an especially important influence on surface hydrological processes. Canopy and ground cover vegetation provide a natural cushion against the impact energy of rainfall in headwater portions of a stream basin, increasing water filtration into the soil and reducing surface runoff, but effects of different vegetation types are not fully understood. We sought to evaluate the capacity of different vegetation communities to regulate surface runoff in an alpine landscape. We collected water samples for stable hydrogen and oxygen isotopic analyses from precipitation, throughfall, soils, streams, and rivers and compared their isotopic signatures. Results indicated that different vegetation types had different capacities for water conservation. Forested vegetation types were best able to regulate surface runoff. Land use changes have dramatically affected water conservation in the study area in the past several decades; if forested land cover existed at the levels present in 1986 or 1974, the ability of the watershed to intercept surface runoff would increase by about 7% and 3%, respectively, over its capacity in 2000.     

重庆四面山植被类型对坡面产流的影响

 为研究长江三峡库区植被类型对坡面产流的影响,在重庆四面山布设针阔混交林、阔叶林、楠竹林、灌丛和农耕地5种不同植被类型的标准径流小区。对天然降雨过程和由降雨产生的地表径流进行观测。结果表明:不同植被类型林地地表径流量的平均值,从大到小依次为农地、灌丛、楠竹林、阔叶林和针阔混交林,分别是6·45、4·12、2·91、2·34和1·57mm。3种以乔木为主的林地地表径流量,均小于农地的地表径流量,不同乔木林地地表径流量差异不显著。不同植被类型林地地表径流量与降雨量存在显著的相关关系,与降雨强度也存在极显著的相关关系,并且都表现为多项式或幂函数关系。在同一降雨条件下,不同植被类型林地(包括农地),地表径流变化趋势存在一定差异,且均是农地地表径流量最大。     

华北土石山区土地利用/土地覆被变化的水文响应研究——以张家口云州水库流域为例

以张家口云州水库流域为例研究华北土石山区土地利用/覆被变化的水文响应.收集研究区1968年、1980年和2000年遥感影像.采用MaptGIS解译得到不同时期的土地利用网,采用ArcView分析获得空间数据和属性数据.并利用研究区逐日降水量和径流量数据,分析不同土地利用时期的水文响应.结果表明:华北土石山区土地利用变化对流域年径流具有显著影响.1981-2000年间植被条件较好的土地利用较1968-1980年间产流有所减少,多年平均径流系数下降了22.22%.在相同的降水条件下,根据不同土地利用降水与径流的拟合曲线进行预测,发现1981-2000年间土地利用产流比1968-1980年间减少了15%～3O%.不同土地利用在相同降水条件下的产流仅在生长季节具有明显差异,也就是说土地利用变化对产流的影响具有季节性,在枯水季节无显著影响.植被条件好的时期产流能力明显下降.     

Decoupling effects of driving factors on sediment yield in the Chinese Loess Plateau

Investigations of runoff and sediment yield changes and their relationships with potential driving factors provide good insights for understanding the mechanisms of hydrological processes. This study attempted to present a comprehensive investigation on the spatiotemporal variations of sediment yield in the Loess Plateau using continuous observed data at 46 hydrological stations during 1961–2016, and its responses to changes of precipitation, land use/cover and vegetation cover were analyzed by using the Partial Least Squares-Structural Equation Model (PLS-SEM). The results indicated that sediment yield reduced pronouncedly during 1961–2016 in the Loess Plateau, and 77.9% of this variation was explained by the combined effects of precipitation, land-use change, vegetation dynamics and runoff reduction. Indirect effects of precipitation, land-use change, and vegetation cover on sediment yield were 0.242, ?0.528 and ?0.630 (P < 0.05), respectively, and direct effect of runoff on sediment yield was 0.833 (P < 0.05). According to the Pearson Correlation Coefficient, the strongest positive correlation existed between annual sediment yield and runoff (r = 0.88, P < 0.05), followed by vegetation cover (r = ?0.47, P < 0.05) and land-use change (i.e. forest land and grassland) suggesting their significant trapping effects on soil erosion. However, lower correlations were examined between sediment yield and precipitation indices (?0.14<r < 0.34), and a relatively higher relationship was examined between sediment yield and heavy rainfall (P₂₅) (r = 0.34). Overall, changes in runoff and land-use/vegetation cover well explained variations in sediment yield in the Loess Plateau. The findings are expected to provide scientific and technical support for future soil and water conservation planning in the Loess Plateau, and are valuable for sustainable water resources and sediment load management in the Yellow River Basin.     

雨强和植被覆盖度对红壤坡面产流产沙的影响

为探究雨强和植被覆盖度对花岗岩红壤坡面产流产沙的影响,通过室内人工模拟降雨试验,分析了不同雨强(0.5,1.0,1.5 mm/min)和植被覆盖度(0,20%,40%,60%)下坡面侵蚀的产流、产沙规律及相关关系。结果表明:(1)同一雨强下,初始产流时间随植被覆盖度增加而延迟,并随雨强增大而提前,雨强越大,产流时间提前越明显;(2)各坡面径流率、侵蚀率随植被覆盖度增加而减小,且植被覆盖度越高,径流率和侵蚀率波动范围越小,侵蚀过程越稳定;(3)有植被覆盖的坡面,产沙主要以0.25 mm的水稳性团聚体为主,侵蚀泥沙中0.25 mm水稳性团聚体比重随雨强增大而增加,且增加的幅度随覆盖度的提高而减小;(4)雨强、植被覆盖度均与产流时间、径流率、侵蚀率呈现极显著相关关系(P0.01),且坡面产流过程与雨强变化的相关性大于其与植被覆盖度变化的相关性,坡面产沙过程与植被覆盖度变化的相关性大于其与雨强变化的相关性,不同雨强下植被覆盖坡面累积径流量和累积产沙量关系符合幂函数模型(R~20.98)。研究结果可为南方红壤丘陵区水土流失治理与生态恢复提供科学参考。     

土壤结皮对黑土区坡面产流产沙的影响

土壤结皮对坡面产流形成和侵蚀过程有重要的影响。基于室内人工模拟降雨试验,研究了土壤结皮对黑土区坡面产流产沙的影响。结果表明:土壤结皮促使坡面产流提前发生,但对坡面产流量的影响不甚明显;对坡面侵蚀产沙量却有明显的作用。试验条件下,5°坡面有土壤结皮处理的坡面侵蚀产沙量较无土壤结皮处理减少了54%。有土壤结皮处理的10°坡面,在降雨过程中结皮尚未破坏前,其坡面侵蚀产沙量较无土壤结皮处理的对照减少了40%;一旦土壤结皮被破坏,之后的坡面侵蚀产沙量较无土壤结皮处理的对照增加了46%;在整个降雨过程中,10°有土壤结皮处理的坡面侵蚀产沙量较无土壤结皮处理增加了16%。表明土壤结皮对坡面侵蚀的影响与地面坡度有密切关系。     

坡面尺度林地植被对地表径流与土壤水分的影响初步研究

通过定位观测以及对两个天然坡面有林地径流场和无林地径流场进行对比,以2003年、2004年实测的降雨、径流数据分析研究区域内降雨特性、地表径流产生的过程和机制,并结合1996～1998年相关数据,初步研究了林地植被对地表径流的影响.结果表明:无论是有林地还是无林地,地表径流系数随降雨量增大而增大.有林地径流系数小于对应的无林地径流系数.植被对地表径流有不同程度的削减作用,径流削减率与降雨量大小并不是单一的线性(递增、递减)关系:当降雨量小于73.04mm时,植被对地表径流系数的削减率随降雨量增加而增加,当降雨量大于73.04mm时,植被对地表径流系数削减率随降雨量增加降低.植被能够削弱地表径流的峰值,延缓峰值出现的时间,使得径流历时加长.植被对地表径流削减率的大小和降雨量大小关系不是单一的线性(递增、递减)关系:当降雨量小于73.04mm时,植被对洪峰的削减率随降雨量增加而增加,当降雨量大于73.04mm时,植被对洪峰的削减率随降雨量增加而呈总体下降趋势.以2004年为例,比较有林地与无林地在三种相同坡位情况下的土壤含水量大小关系,结果:坡上位土壤水分有林地大于无林地,而坡下、坡中无林地土壤水分大于有林地.说明林地植被能够拦蓄、调节径流,起到涵养水源、在空间和时间上合理配置土壤水分、提高生态效益的作用.     

人工模拟降雨条件下不同雨强、坡度对紫色土坡面产流的影响

[目的]研究不同降雨强度和坡度对紫色土坡面产流过程的影响,为紫色土区域的水土流失防治提供科学依据。[方法]基于室内人工模拟降雨试验开展研究。[结果]不同雨强和坡度下的产流过程可大致分为"下凹"型和"上凸"型,且分别可以用指数函数和对数函数描述。随着雨强和坡度的增大,产流时间逐渐减小,产流过程逐渐趋于一致,坡面径流量逐渐增加。坡度和雨强对径流总量的贡献率有着对比消长的关系,小雨强下(雨强为33和54mm/h),坡度是坡面径流总量的主要贡献因子,随着雨强增大(雨强为94和125mm/h),雨强为坡面径流总量的主要贡献因子。[结论]坡度和雨强均为坡面侵蚀的主要影响因子,随着坡度和雨强的增加,坡面侵蚀更加剧烈,主要侵蚀因子也由坡度转变为雨强。     

Impact of small mammal disturbances on sediment yield from grassland and shrubland ecosystems in the Chihuahuan Desert

This study examines water and sediment movement on Summerford bajada in the Jornada Basin, N.M. Forty-five rainfall simulation experiments were conducted on 1- and 2-m² runoff plots in grassland, degraded grassland, and shrubland communities. Within the shrubland community separate experiments were conducted in shrub and intershrub environments. Regression analyses indicate that for a 30-min rainfall at approximately 130 mm h⁻¹, water yields on these environments are negatively related to the percentage of ground covered by vegetation and/or litter. In the degraded grassland and intershrub environments, sediment concentration is positively correlated with the average diameter of small mammal disturbances, suggesting that animal digging is an important factor controlling rates of erosion in these environments. Sediment concentration is not correlated with any surface property in the grassland or shrub environments. An analysis of water yields and sediment concentrations at 5-min intervals during the 30-min simulated rainfall experiments reveals that the influence of the above-mentioned factors on runoff and erosion is established during events as short as 10–15 min.     

IMPACTS OF LAND COVER CHANGE SCENARIOS ON STORM RUNOFF GENERATION: A BASIS FOR MANAGEMENT OF THE NYANDO BASIN,KENYA

The effects of conceptual land cover change scenarios on the generation of storm runoffs were evaluated in the Nyando Basin. The spatial scenarios represented alternatives that vary between full deforestation and reforestation. Synthetic storm events of depths 40, 60 and 80 mm were formulated according to the rainfall patterns and assumed to have durations corresponding to the runoff times of concentration. The Natural Resource Conservation Service–Curve Number model was used to generate runoff volumes within the sub‐catchments, which were subsequently routed downstream to obtain effects in the whole basin. The simulated land cover change impacts were evaluated relative to values obtained from the actual land cover state of the basin in the year 2000. From the results, an agricultural land cover scenario constituting of about 86 per cent of agriculture indicated increased runoff volumes in the entire basin by about 12 per cent. An agricultural‐forested land cover scenario with 40 and 51 per cent of forest and agriculture respectively revealed reduced runoff volumes by about 12 per cent. Alternatively, a scenario depicting a largely forested land cover state with about 78 per cent of forests reduced the runoff volumes by about 25 per cent according to the model estimates. Runoff volumes in the basin were also likely to reduce by about 15 per cent if the appropriate land cover scenario for the respective sub‐catchments were to be assumed for runoff management purposes. Considering the prevalent data uncertainty, the study effectively highlights the potential hydrological vulnerability of the basin. The results obtained can form a basis for appropriate catchment management of the area. Copyright © 2012 John Wiley & Sons, Ltd.     

The impact of vegetative cover type on runoff and soil erosion under different land uses

The effects of different vegetation types on runoff generation and soil erosion were investigated. The study was conducted at the Southern part of West Bank, about 10 Km north-west of Hebron city, during 2005, 2006 and 2007. Five treatments were implemented; forests planted with P. halepensis (F), natural vegetation dominated by S. spinosum (W.S), natural vegetation where S. spinosum was removed (W/o.S), cultivated land (C), and deforestation (Df). Three types of data were estimated in each plot: runoff after each rainfall event, sedimentation at the end of the rainy season, and chemical and physical soil properties. The obtained results indicate that there are significant and important differences in runoff generation and sediment production with respect to the different types of vegetative cover. Forest and natural vegetation dominated by S. spinosum treatments exhibited the lowest amounts of runoff, with averages of 2.02 and 1.08 mm, respectively, in comparison to other treatments. The removal of S. spinosum significantly increased the total amount of runoff and sedimentation compared to the forest and S. spinosum treatments. In addition, runoff significantly increased (4.03 mm) for the Df treatment compared to that of the forest site. The greatest amount of sedimentation was observed in cultivated land and with deforestation.     

岔巴沟流域汛期径流模拟及地表产流特征分析

气候变化是影响流域水文循环过程的重要驱动因素,近年来,气候变化导致极端降雨—径流事件的频繁发生对人类社会经济发展构成了严重的威胁。因此,迫切需要开展流域水文模拟和产流特征分析。土壤和水评估工具(SWAT)是一种具有物理机制的分布式水文模型,已被广泛用于评价变化环境下的水文过程。以黄土高原岔巴沟流域为研究区,通过利用与黄土高原地区产流模式更为接近的Green-Ampt下渗法驱动SWAT模型模拟了岔巴沟流域日尺度的水文过程,并以水文响应单元为分析对象,结合4个降雨—径流事件的地表产流量和地表径流系数分析了降雨强度和前期土壤含水量对不同土地覆被产流特征的影响。结果表明：(1)基于Green-Ampt下渗法驱动的SWAT模型率定期和验证期E_NS为0.76,0.74,R²为0.78,0.75,模型能够较好地模拟日尺度流域水文过程;(2)流域不同土地覆被下地表径流系数随最大雨强的增加呈显著上升趋势,且最大降雨强度大于16 mm/h后地表径流系数显著增加,当土地覆被为耕地时降雨转化为地表径流的比例最大,其次为草地和林地;(3)前期土壤含水量的大小可以揭示大...