Gully incision as a key factor in desertification in an and environment, the Negev highlands, Israel
Gully incision as a key factor in desertification in an and environment, the Negev highlands, Israel
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DOI：
10.1016/j.catena.2005.06.004
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发表时间：
2005-10-31
期刊：
影响因子：
6.2
通讯作者：
Avni, Y
中科院分区：
文献类型：
--
作者：
Avni, Y
在以色列干旱和半干旱地区，冲沟下切侵蚀着沿着河谷沉积和发育的冲积物和黄土。这一现象在内盖夫高地的一些地区极为严重，因为这些地区的农田、主要的植物生物量和具有最高放牧价值的地区仅限于狭窄的山谷，山谷中充满了再沉积的黄土沉积物。1990年至2001年期间，在三个有代表性的流域（Zipporim，Revivim和Sekher）在该地区的头切迁移和冲沟的发展进行了研究。在洪水事件期间，径流穿透山谷的冲积层，形成垂直的水头，逐渐后退到山谷。径流被引入狭窄的冲沟，防止洪水前沿蔓延到整个山谷的宽度。灌溉效率的变化沿着山谷反映在急剧下降的估计70-90%的花卉生物量，导致范围值减少了83- 99%。在1990-2001年的监测时间间隔内，研究区的线性沟头后退范围为12.3 - 250 m，平均速度为1.12-22.7年（-1）。这一过程伴随着土壤的侵蚀，具有很高的农业和牧场价值。这些地点的土壤流失总量在800 - 9000 m（3）之间，仙人掌沟头的平均流失率为81-818 m（3）年（-1），相当于121-1227 Mg年-1。在监测期间，在所研究的仙人掌盆地中，大约有0.11-0.87公顷的土地失去了农业和牧场价值，平均速度为0.01-0.079公顷/年（-1）。自拜占庭时期（公元前1400年）以来，约6.5公顷，这是10%的土地，具有高农业和范围价值的Zipporim山谷，失去了价值，由于沟侵蚀。在附近地区没有发现冲沟的恢复效果。土壤侵蚀是由末次冰期结束以来流域内土壤/岩石比的长期自然动态变化产生的。黄土沉积物，最初在晚更新世冰期沉积在流域内，在现在的全新世气候下，在几个侵蚀阶段正在被移除。这一持续存在的现象正在造成土壤和生物量的退化，并严重减少该区域的农业和牧场潜力。这些参数表明，内盖夫高地的土地和环境正在发生荒漠化，而且荒漠化进程与该地区的水头后退速度成比例地加剧。在过去的几千年里，内盖夫高地的土壤侵蚀和头切撤退一直很活跃。如果这些进程在未来继续下去，内盖夫高地地区将在几千年内失去其农业潜力。然而，该地区的古代居民在3000年前就成功地实施了长期的土地保护技术，这意味着可持续的土地管理政策可以适应内盖夫高地以及中东其他半干旱地区。(c)2005 Elsevier B. V.保留所有权利。
Gully incision has been eroding the alluvial sediments and loess soils deposited and developed along the valleys in the and and semiarid regions of Israel. This phenomenon is critical in the and regions of the Negev Highlands where the agricultural fields, the main floral biomass and the areas which have the highest grazing value, are limited to narrow valleys filled with redeposited loessial sediments. The headcut migration and gully development in the region were studied between 1990 and 2001 in three representative drainage basins (Zipporim, Revivim and Sekher). During flood events, the runoff penetrates the alluvial cover of the valleys, forming vertical headcuts, which gradually retreat Lip the valley. The runoff is channeled into narrow gullies, preventing the floodwater front spreading over the whole width of the valley. The change in irrigation efficiency along the valleys is reflected in a sharp estimated drop of 70-90% in the floral biomass, causing the reduction of the range value by 83-99%. During the monitoring time interval (1990-2001), the linear gully retreat in the study area ranged between 12.3 and 250 m an average rate of 1.12-22.7 in year(-1) for each gully head. The process is accompanied by erosion of soil, which has high agricultural and range value. The total soil losses in these sites ranged between 800 and 9000 m(3) at an average rate of 81-818 m(3) year(-1) for cacti gully head, which is equivalent to 121-1227 Mg year-1. During the monitoring period, approximately 0.11-0.87 ha of land lost its agricultural and range value in cacti basin understudy, at an average rate of 0.01-0.079 ha year(-1). Since the Byzantine period (1400 BP), approximately 6.5 ha, which is 10% of the land that had high agricultural and range value in the Zipporim valley, lost its value due to gully erosion. No recovery effects of the gully channels were found in the nearby region. The soil erosion is generated by a long-term natural dynamic change in the soil/rock ratio evolving within the drainage basins through time since the termination of the last glacial phase. The loessic sediments, originally deposited within the drainage basins during the late Pleistocene glacial stage, are being removed under the present Holocene climate in several erosion stages. This ongoing phenomenon is causing degradation of soil and biomass and is severely reducing the agricultural and range potential of the region. These parameters indicate that an ongoing process of desertification is active in the and environment of the Negev Highlands, and is advancing in proportion to the headcut retreat rates in the region. The soil erosion and headcut retreat have been active in the Negev Highlands for the last few millennia. If these processes continue in the future, the Negev Highlands region will lose its agricultural potential within a few millennia. However, the fact that the ancient inhabitants of the region implemented successful long-term land conservation techniques already 3000 years ago, implies that a sustainable land management policy can be adapted to the Negev Highlands, as well as to other semi-arid regions in the Middle East. (c) 2005 Elsevier B.V. All rights reserved.