Long-term increase in diffuse groundwater recharge following expansion of rainfed cultivation in the Sahel, West Africa
Long-term increase in diffuse groundwater recharge following expansion of rainfed cultivation in the Sahel, West Africa
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DOI：
10.1007/s10040-014-1143-z
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发表时间：
2014-05
影响因子：
2.8
通讯作者：
M. Ibrahim;G. Favreau;B. Scanlon;J. Seidel;M. Coz;J. Demarty;B. Cappelaere
中科院分区：
文献类型：
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作者：
M. Ibrahim;G. Favreau;B. Scanlon;J. Seidel;M. Coz;J. Demarty;B. Cappelaere
撒哈拉以南西非地区人口的快速增长和一些地方相关的农田扩张表明，通过池塘的集中补给增加了地下水位。为了估计扩散补给的变化，在2009至2010年间监测了水分含量和基质势，并使用Hydrus-1D程序对尼日尔西南部的两个田间地点进行了模拟：(1)休耕地和(2)旱作小米农田。上层10米的监测结果表明，旱地(>；2.5m)的含水率和土壤潜势比休耕地(≤；1.0m)增加。模型模拟表明，退耕还田(1)增加了包气带蓄水量，(2)在滞后30-60年后，应增加10m深度的排水通量(∼为25 mm/年，−为1)。因此，观察到的区域地下水储存量的增加可能越来越多地源于扩散补给，这至少可以部分补偿因观察到的灌溉面扩张而导致的地下水抽出；因此，有助于缓解萨赫勒地区的粮食危机。
Rapid population growth in sub-Saharan West Africa and related cropland expansion were shown in some places to have increased focused recharge through ponds, raising the water table. To estimate changes in diffuse recharge, the water content and matric potential were monitored during 2009 and 2010, and modeling was performed using the Hydrus-1D code for two field sites in southwest Niger: (1) fallow land and (2) rainfed millet cropland. Monitoring results of the upper 10 m showed increased water content and matric potential to greater depth under rainfed cropland (>2.5 m) than under fallow land (≤1.0 m). Model simulations indicate that conversion from fallow land to rainfed cropland (1) increases vadose-zone water storage and (2) should increase drainage flux (∼25 mm year−1) at 10-m depth after a 30–60 year lag. Therefore, observed regional increases in groundwater storage may increasingly result from diffuse recharge, which could compensate, at least in part, groundwater withdrawal due to observed expansion in irrigated surfaces; and hence, contribute to mitigate food crises in the Sahel.