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首页> 外文期刊>Catena: An Interdisciplinary Journal of Soil Science Hydrology-Geomorphology Focusing on Geoecology and Landscape Evolution >Abandonment of soil and water conservation structures in Mediterranean ecosystems: a case study from south east Spain.
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Abandonment of soil and water conservation structures in Mediterranean ecosystems: a case study from south east Spain.

机译：地中海生态系统中水土保持结构的废弃：以西班牙东南部为例。

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Traditional rainfed agriculture in semi-arid regions heavily relies on soil and water conservation (SWC) structures to supplement the sparse rainfall. As referring to the ecosystem functions of these constructions, when extensive such systems prevent any runoff into the fluvial system. The extent to which these dams and terraces resist major events is variable, and earthen dams can be major sediment sources. Extensification and increasing mechanization of rainfed agriculture in marginal areas have led to a change in cropping systems. Large-scale almond and olive plantations with widely spaced trees do not rely on runoff water, but draw the soil water from a large soil volume of bare soil maintained by regular shallow tillage. The high density of terraces has now become a nuisance to the farmers. The aim of this paper is to (i) demonstrate the degradation of SWC structures and the relative importance of the driving forces, (ii) assess the limits of the protection that earthen dams can provide by surveying their resistance during a heavy storm (return period 8.2 years) and (iii) demonstrate the implications of the abandonment of SWC structures over the period 1956-2005 for the hydrological connectivity between croplands and the ephemeral rivers system. The headwaters of a marl catchment with a continuous area treated with SWC structures in Murcia region (Spain) already had a very high density of step terraces and check dams (182 m ha-1) in 1956. This density decreased by 27% in the period 1956-2005. Furthermore, many terraces have not been maintained and flow traces indicate that they no longer retain water. This is particularly true for the check dams in abandoned lands. The distance between the step terraces has increased over time, making them vulnerable to erosion. The mean drainage area of the dams that failed during the heavy storm was significantly (3.16 ha) higher than that of the ones that remained intact (1.11 ha). The probability of failure increases with drainage area from P=0.16 for an area of 1.8 ha to P=0.8 for an area of 20 ha. The percentage of cropland draining directly on the river system without interference of a check dam has increased from just 9% in 1956 to 31% in 2005 and 40% after the storm in November 2006.
机译：半干旱地区的传统雨养农业严重依赖水土保持（SWC）结构来补充稀疏的降雨。关于这些结构的生态系统功能，在广泛使用时，此类系统可防止径流进入河流系统。这些水坝和阶地抵抗主要事件的程度是可变的，土坝可能是主要的沉积物来源。边缘地区雨养农业的集约化和机械化程度提高，导致了耕作制度的变化。大型杏仁和橄榄种植园的树木分布较宽，它们不依赖径流水，而是从通过定期浅耕而保持的大量裸土中汲取土壤水。梯田的高密度现在已成为困扰农民的麻烦。本文的目的是（i）证明SWC结构的退化和驱动力的相对重要性;（ii）通过调查大坝在暴风雨中（返回期）的阻力来评估土坝可提供的保护极限。 8.2年）和（iii）展示了1956-2005年期间废弃SWC结构对农田和短暂河流系统之间的水文联系的影响。 1956年，在西班牙穆尔西亚地区，一个用SWC结构处理过的，具有连续面积的泥炭流域的源头，已经有很高的阶梯阶地和止水坝密度（182 m ha -1 ）。 1956-2005年期间，人口密度下降了27％。此外，许多阶地没有得到维护，流动痕迹表明它们不再保留水。对于废弃土地上的止水坝尤其如此。梯阶之间的距离随着时间的推移而增加，使其容易受到侵蚀。在暴风雨中倒塌的大坝的平均排水面积（3.16公顷）比保持完好的大坝的平均排水面积（1.11公顷）高。随着排水面积从1.8公顷的 P = 0.16到20公顷的区域的 P = 0.8，失败的可能性增加。在没有防洪坝干扰的情况下，直接在河流系统上排水的农田所占百分比已从1956年的9％增加到2005年的31％和2006年11月暴风雨后的40％。

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