Slope and rainfall effects on the volume of sediment yield by gully erosion in the Souar lithologic formation (Tunisia)
Slope and rainfall effects on the volume of sediment yield by gully erosion in the Souar lithologic formation (Tunisia)
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DOI：
10.1016/j.catena.2009.04.003
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发表时间：
2009-08
期刊：
影响因子：
6.2
通讯作者：
Hajer Bouchnak;Mennoubi Sfar Felfoul;M. R. Boussema;M. H. Snane
中科院分区：
文献类型：
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作者：
Hajer Bouchnak;Mennoubi Sfar Felfoul;M. R. Boussema;M. H. Snane
半干旱突尼斯的Souar岩性地层正在遭受严重的沟蚀，威胁着土壤和水资源。土壤保持战略更多地侧重于梯田而不是沟道控制技术，因为沟道沉积物在流域总土壤流失中的作用尚不清楚。本文报告了调查所提供的头切，以及侧壁，地板侵蚀的一阶冲沟的缓坡和陡坡集水区强调的Souar岩性地层的产沙量。我们分别测量了位于缓坡和陡坡集水区的10条和9条冲沟的不同溯源河段的平均田间排沙量。建立了切沟长度与切沟排沙量的关系式。处理与地理信息系统（弧视图）的航空照片，从1952年至2000年允许的沉积物量的计算提供的头部切割和沟侧壁，通过后续的8个集水区的沟壑扩展在五个时期分开的日期，这些航班。沟蚀总量平均为1.66 m3 ha −1year− 1（缓坡）和5.603 m3 ha −1year− 1（陡坡）。坡脚对坡面总侵蚀的贡献率，缓坡平均为81.5%，陡坡为77.8%。我们发现，平均年降雨量所产生的40毫米的日降雨量阈值更好地解释了这五个时期的年水头切割产沙量的变化比任何其他年降雨量所产生的较低的日降雨量阈值。在这两个变量之间建立了两个方程的缓坡和陡坡集水区。
The Souar lithologic formation in semi-arid Tunisia is undergoing severe gully erosion which is threatening soil and water resources. Soil conservation strategies have focused more on terracing than on gully control techniques, since the contribution of gully sediment yield in the overall soil loss from watersheds is unknown. The paper reports investigations into the sediment yield provided by head-cut as well as sidewall–floor erosion of first order gullies on gentle and steep slope catchments underlined by the Souar lithologic formation. We measured mean field sediment volumes evacuated by different headward reaches of 10 and 9 gullies located on gentle and steep slope catchments, respectively. Two equations between the length of the gully head cutting and the corresponding volume of evacuated sediment were established. The treatment with a Geographic Information System (Arc View) of air photographs of six flights from 1952 to 2000 allowed the calculation of the volume of sediment provided both by head cutting and gully sidewalls–floor erosion through the following up of gully extension in eight catchments during the five periods separating the dates of these flights. Total gully erosion was on average 1.66 m3ha−1year−1for the gentle slopes and 5.603 m3ha−1year−1for the steep slopes. Sidewalls–floor contribution in total erosion was on average 81.5% for the gentle slopes and 77.8% for the steep slopes. We found out that the mean annual rainfall resulting from 40 mm daily rainfall threshold explained better the variation of annual head cutting sediment yield for these five periods than any other annual rainfall resulting from lower daily rainfall thresholds. Two equations between these two variables were established both for gentle and steep slope catchments.