黄土丘陵区生物结皮—植被坡面的产流过程

发布时间：2018-07-03 09:28

本文选题：生物结皮 + 植被格局　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：生物结皮是黄土丘陵区坡面水土流失不可忽略的影响因素,目前生物结皮对坡面产流过程的影响仍不明确。本文采用放水试验和模拟降雨试验相结合的方法,研究生物结皮-植被坡面对产流时间、水流深、径流流速以及径流系数等产流特征参数的影响,探讨生物结皮-植被坡面的产流过程,旨在为科学认识生物结皮的水文效应和该区水土保持工作提供科学依据。得到的主要结论如下:1、生物结皮是坡面产流过程的重要影响因素,主要通过影响产流时间、径流流速及径流在坡面的分布而影响坡面产流过程,影响程度与生物结皮的发育阶段和生物组成有关。1)浅色藻结皮、深色藻结皮和混合结皮较裸地显著降低了初始产流时间,三者的初始产流时间较裸地分别减少89.0%、96.2%和96.0%;藓结皮较裸地显著增加了初始产流时间。浅色藻结皮和混合结皮较裸地显著延长了退水持续时间,而深色藻结皮的退水持续时间与裸地差异不显著。2)深色藻结皮和藓结皮的径流流速较裸地分别降低了29.1%和67.3%;藓结皮的径流流速显著低于其它生物结皮小区;浅色藻结皮的径流深显著高于深色藻结皮。3)不同类型的生物结皮较裸地明显改变了坡面产流过程;浅色藻结皮小区的径流系数显著高于裸地,深色藻结皮和混合结皮小区的径流系数较裸地差异不显著;放水时段内,藓结皮小区没有径流流出。2、生物结皮坡面的产流过程与生物结皮与植被在坡面的分布格局和放水流量有关。1)随着放水流量增大,相同植被格局的坡面初始产流时间显著减少,退水持续时间、径流流速和水流深显著增加。三种流量下,生物结皮斑块的水流深均显著低于植被斑块的水流深。2)同一流量下,坡顶聚集格局的初始产流时间较无植被小区无显著差异,而坡底聚集、坡中聚集和带状格局的初始产流时间显著高于无植被小区。坡底聚集格局的退水持续时间显著高于无植被小区。3)植被小区较无植被小区显著地降低了径流流速。坡顶聚集和坡底聚集格局较无植被小区显著地延缓了坡面的径流流速,而坡中聚集和带状格局较无植被小区无显著差异。4)不同植被格局对坡面瞬时径流量的变化过程的影响存在较大差异,且这种差异随着放水流量的增加而减小。三种放水流量下,坡顶聚集格局的径流系数较无植被小区差异均不显著,而在2、4L/min流量下,坡底聚集、坡中聚集和带状格局的径流系数较无植被小区显著减小。3、野外模拟降雨条件下,植被格局、降雨强度、坡长和坡度等因素均可影响生物结皮-植被坡面的产流过程。1)同一处理小区中植被斑块的开始积水时间和水流深均显著大于生物结皮斑块,径流流速均显著小于生物结皮斑块。试验条件下,植被格局对坡面产流过程的影响不明显。2)生物结皮与植被茎基面积比与径流流速和区域水流深均呈正相关的关系。生物结皮与植被茎基面积比增加,植被斑块的水流深变化大于生物结皮斑块。3)同一雨强下,随机格局较对照区延长了坡面的初始产流时间、减缓了径流流速,降低了坡面的径流系数。随着雨强增大,随机格局和对照区的初始产流时间减少,径流流速、水流深和径流系数均有所增加。4)随着坡长增加,径流流速、水流深和径流系数曲线均呈先增加后减少的单峰变化,临界坡长均为8m。坡度为25°时的径流流速和水流深均显著小于16°坡度。
[Abstract]:The biological crust is an important factor which can not be ignored in the loess hilly area. At present, the effect of biological crust on the runoff process is still not clear. In this paper, the runoff time, flow depth, flow velocity and runoff coefficient are studied by the combination of water release test and simulated rainfall experiment. The effect of characteristic parameters on the flow process of biological crust vegetation slope is discussed in order to provide scientific basis for the scientific understanding of the hydrologic effect of biological crust and the work of soil and water conservation in this area. The main conclusions are as follows: 1, biological crust is an important factor affecting the flow process of slope surface, mainly through the influence of runoff time, flow velocity and diameter. The distribution of the flow on the slope affects the flow process of the slope, the degree of influence is related to the growth stage of the biological crust and the biological composition of the.1) light alga crust, and the crusts and mixed crusts of the alga are significantly lower than those of the bare land. The initial production time of the three is 89%, 96.2% and 96%, respectively, and the moss crust is significantly higher than that of the bare land. With the addition of the initial flow time, the shallow algae crust and the mixed crust significantly prolonged the duration of water withdrawal, while the duration of water withdrawal from the crust of the dark algae was not significantly different from that of bare land.2) the runoff velocity of the crust and the moss crust decreased by 29.1% and 67.3%, respectively, and the flow velocity of the moss crust was significantly lower than that of other biological crusts. The runoff depth of the shallow algae crust was significantly higher than that of the dark algae crust.3). The runoff coefficient of different types of biological crust changed the runoff process obviously, the runoff coefficient of the light alga crust cell was significantly higher than that of the bare land, and the runoff coefficient of the dark algae crust and the mixed crust was not significant. The flow process of runoff is.2, the flow process of biological crust slope is related to the distribution pattern of biological crust and vegetation on the slope distribution and the flow rate of.1). With the increase of the discharge flow, the initial flow time of the slope surface of the same vegetation pattern is significantly reduced, the retreating duration, the flow velocity and the depth of water flow increase significantly. Under the three kinds of flow, the biological crust patch The depth of water flow is significantly lower than the depth of water depth.2 of vegetation patches. The initial flow time of the top slope aggregation pattern is not significantly different from that of no vegetation, but the initial runoff time in the slope bottom is significantly higher than that in the non vegetation plot. The duration of water retreat in the slope bottom aggregating grid is significantly higher than that of the non vegetation plot. 3) the flow velocity of runoff was significantly reduced in the vegetation plot than in the non vegetation plot. The slope top aggregation and the slope bottom aggregation pattern significantly delayed the runoff velocity of the slope, while the aggregation and banded pattern in the slope had no significant difference.4 from that of the non vegetation plot. The influence of different vegetation patterns on the change process of the instantaneous runoff of the slope was larger. The difference is decreased with the increase of the discharge flow. Under the three kinds of discharge flow, the runoff coefficient of the top of the slope is not significant compared with that of the non vegetation plot, but under the 2,4L/min flow, the slope bottom is aggregated. The runoff coefficient in the sloping and banded pattern is significantly reduced by.3 than that in the small vegetation area, and the vegetation is vegetation under the simulated rainfall conditions. The pattern, rainfall intensity, slope length and slope can affect the flow process of the biological crust and vegetation slope.1). The initial water accumulation time and the depth of water flow in the same treatment area are significantly greater than that of the biological crusts, and the flow velocity is significantly smaller than that of the biological crusts. The relationship between the area ratio of the biological crust and the stem base of vegetation is positively correlated with the flow velocity and the depth of water flow in the region. The ratio of the area ratio of the biological crust to the stem base of the vegetation is increased, the depth of the water flow in the vegetation patch is greater than that of the.3 of the biological crust. The random pattern prolongs the initial flow time of the slope surface and slows down the.2. With the increase of rainfall intensity, the initial runoff time of the random pattern and the control area decreased, the flow velocity, the flow depth and the runoff coefficient increased.4 with the increase of the rainfall intensity. The flow velocity, the flow depth and the runoff coefficient curves were first and then decreased with the increase of the slope length, and the critical slope length was 8m. gradient. The runoff velocity and flow depth at 25 degrees are significantly less than 16 degree slope.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157

【共引文献】