地块质量特征对西南山区梯田撂荒的影响——以贵州剑河县白都村为例北大核心CSCDCSSCI     

牟艳  赵宇鸾  李秀彬  任红玉  刘艳 《地理研究》2022,41(3):903-916

为分析西南山区梯田撂荒地块质量特征及影响因素,厘清山区梯田撂荒与可持续利用机制,本文以贵州省剑河县白都村为例,综合运用农户调查数据与无人机高分辨率影像数据探讨梯田的撂荒规模、空间分布情况及地块质量特征;构建二元Logistic回归模型,对影响梯田撂荒的各地块质量因素作用大小进行定量分析。结果表明:①白都村样本农户的梯田面积为62.518 hm^(2),多集中分布于耕作高差、坡度和耕作距离较大区域,其撂荒面积为21.354 hm^(2),撂荒率为34.16%。②梯田的地块质量因素对其撂荒的贡献程度表现为:灌溉条件>动力使用状况>田埂坍塌状况>耕作面积>综合地形条件,其中灌溉条件、动力使用状况、耕作面积与梯田撂荒均呈负相关,田埂坍塌状况和综合地形条件与梯田撂荒呈正相关。研究结果对于推进西南山区梯田的可持续利用与管理具有重要的理论及实践意义。  相似文献   

Joint exploration of regional importance of possibilistic and probabilistic uncertainty in stability analysis     

《Computers and Geotechnics》2014

Stability analysis generally relies on the estimate of failure probability P. When information is scarce, incomplete, imprecise or vague, this estimate is imprecise. To represent epistemic uncertainty, possibility distributions have shown to be a more flexible tool than probability distributions. The joint propagation of possibilistic and probabilistic information can rely on more advanced techniques such as the classical random sampling of the cumulative probability distribution F and of the intervals from the possibility distributions π. The imprecise probability P is then associated with a random interval, which can be summarized by a pair of indicators bounding it. In the present paper, we propose a graphical tool to explore the sensitivity on these indicators. This is conducted by means of the contribution to sample probability of failure plot based on the ordering of the randomly generated levels of confidence associated with the quantiles of F and to the α-cuts of π. This presents several advantages: (1) the contribution of both types of uncertainty, aleatoric and epistemic, can be compared in a unique setting; (2) the analysis is conducted in a post-processing step, i.e. at no extra computational cost; (3) it allows highlighting the regions of the quantiles and of the nested intervals which contribute the most to the bounds of P. The method is applied on two case studies (a mine pillar and a steep slope stability analysis) to investigate the necessity for extra data acquisition on parameters whose imprecision can hardly be modelled by probabilities due to the scarcity of the available information (respectively the extraction ratio and the cliff geometry).  相似文献   

海平面及海平面变化综述   总被引：3，自引：0，他引：3  

李祥辉  张洁 《沉积与特提斯地质》1999,19(4):61-72,41

本文从沉积相、岩性和测井相入手,分析了下白垩统登娄库组三段岩性发育及相类型,并划分了层序旋回,识别出各旋回体系域归属。并对上述划分用Ｆｉｓｃｈｅｒ点图进行检验,证明上述分析是合理的。同时,本文指出,Ｆｉｓｃｈｅｒ点图在旋回识别上有独到之处。  相似文献   

Flow resistance equation for rills   总被引：1，自引：0，他引：1       下载免费PDF全文

Costanza Di Stefano  Vito Ferro  Vincenzo Palmeri  Vincenzo Pampalone 《水文研究》2017,31(15):2793-2801

In this paper, a new flow resistance equation for rill flow was deduced applying dimensional analysis and self‐similarity theory. At first, the incomplete self‐similarity hypothesis was used for establishing the flow velocity distribution whose integration gives the theoretical expression of the Darcy–Weisbach friction factor. Then the deduced theoretical resistance equation was tested by some measurements of flow velocity, water depth, cross section area, wetted perimeter, and bed slope carried out in 106 reaches of some rills shaped on an experimental plot. A relationship between the velocity profile, the channel slope, and the flow Froude number was also established. The analysis showed that the Darcy–Weisbach friction factor can be accurately estimated by the proposed theoretical approach based on a power–velocity profile.  相似文献   

Thresholds of land cover to control runoff and soil loss     

Masoud Eshghizadeh  Ali Talebi  MohammadTaghi Dastorani 《水文科学杂志》2018,63(9):1424-1434

This research focused on the determination of land cover thresholds that have a significant impact on runoff generation and soil loss at the pedon scale. For this purpose, six erosion micro-plots were set up on grassland and shrubland types of rangeland in the northeast of Iran, and the amounts of vegetation cover, litter, runoff and soil loss on them were measured. A factorial statistical analysis was carried out on the completely randomized design using land cover and rainfall factors. The results show that the effect of rainfall on soil loss and runoff was greater than that of land cover. Also, the effect of land cover on soil loss was greater than that on runoff generation. Furthermore, two specific thresholds were identified: the first was from 10 to 30% of landcover and the second from 50 to 70%.  相似文献   

Shift from transport limited to supply limited sediment concentrations with the progression of monsoon rains in the Upper Blue Nile Basin          下载免费PDF全文

Haimanote K. Bayabil  Birru Yiftaru  Tammo S. Steenhuis 《地球表面变化过程与地形》2017,42(9):1317-1328

Long‐term erosion monitoring data in the Ethiopian highlands are only available from the Soil Conservation Research Program (SCRP) watersheds including the Anjeni watershed. The 113 ha Anjeni watershed was established in 1984 and fanya juu terraces were installed in 1986. Runoff and erosion data are available from three different plot sizes and at the watershed outlet. The objective of this study was to investigate how erosion processes and sediment rating parameters vary with plot size and the progression of the rainy monsoon phase. We analyzed runoff and sediment loss data from 40 plots and the watershed outlet. The dataset included erosion data from 24 newly constructed plots (3 m length) during the rainy monsoon phase of 2012 and 2013, and 16 long‐term plots (with 12, 16, 22, and 24% slopes and 3, 15 and 30 m lengths) and the watershed outlet during the period between 1986 to 1990. Sediment concentration (C) was fitted to runoff (Q) using a power regression equation (C = aQ^b). Sediment concentration and yield increased with increasing plot length from 3 m to 15 m, but sediment yield decreased as plot length increased to 30 m.The coefficients (a and b) were affected by plot size and the progression of the rainy monsoon phase. As plot size increases, the a value increased, while the b value decreased. Greater a values were observed during the beginning of the monsoon phase, while values of b were greater towards the end of the monsoon phase. Overall findings suggest that erosion from cultivated fields is primarily controlled by transport limitations at the beginning of the monsoon phase, while towards the end of the monsoon phase, as surface covers emerge, sediment availability will be reduced, and thus sediment source would be a limitation. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

一种分析岩土模型地震受力变形的方法          下载免费PDF全文

邹祖银  雷达  蒋关鲁  罗斌  孙诗伟  赵伟豪  王太达 《世界地震工程》2020,(4):185-192

在国内外岩土模型动力试验中,一般以图表形式对监测区域进行逐一动态分析,无法直观形象的掌握试验模型整体受力变形,为深入分析动态响应机理带来一定的不便。以前-后排抗滑桩加固斜坡桥基的大型振动台模型试验为例,通过在岩土体中埋设一定数量的自制磷青铜带和水平加速度计,监测滑坡变形和加速度响应,结合已知测点的水平坐标和竖向坐标,利用Renka Cline随机矩阵生成方法转换为数字矩阵形式,据此绘制坡体变形及PGA放大系数的二维等势图。试验结果显示,二维等势图能合理反映斜坡PGA放大系数的变化规律,揭示振动波作用下斜坡变形破坏的基本特征,研究结论和试验现象保持一致,满足斜坡模型整体受力变形分析的基本要求,可以作为一种实用的试验分析方法。  相似文献