Alluvial corridors of ephemeral river systems provide viable opportunities for natural water storage in dry lands. Whilst alluvial corridors are widely recognized as water buffers, particularly for areas experiencing constant water scarcity, little research has been undertaken in Sub-Saharan Africa to explore their hydrological variability and water resource potential as alternative water sources for nearby communities. This study investigated the water flow behavior and storage potential of an ephemeral river system in the Mara Basin of Kenya for purposes of supporting water resources development and ecological sustainability. The water flow processes – including the recharge rates and water loss processes – from existing sand storage systems were established through monitoring of ground and surface water levels. Water samples along the alluvial corridor were collected and analyzed for major ions and isotopic signatures required to establish the water storage dynamics. The storage potential was estimated through Probing and Electrical Resistivity Tomography techniques, augmented with in-situ measurements of hydraulic conductivities and channel bed porosities. The mean annual storage volume in the alluvium of the study reach was estimated at 1.1 Mm3, potentially capable of providing for the annual domestic and livestock water demands of the area. Transmission losses into the alluvium beneath the ephemeral channel-bed were noted to attenuate the flood peak discharges, depending on the level of saturation of the alluvial bed. However, water storage in the alluvium was subject to losses through evapotranspiration and seepage through fractured bedrocks. The study demonstrated the potential of alluvial corridors as water storage buffers providing alternative water sources to communities within the dry land regions with water scarcity, thereby to supporting ecosystem sustainability.

中文翻译：

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肯尼亚马拉盆地半干旱短命河流系统的水流行为和蓄水潜力

短暂河流系统的冲积走廊为旱地的自然蓄水提供了可行的机会。虽然冲积走廊被广泛认为是水缓冲区，特别是对于经常缺水的地区，但在撒哈拉以南非洲开展的研究很少，以探索其水文变化和水资源作为附近社区替代水源的潜力。本研究调查了肯尼亚马拉盆地短暂河流系统的水流行为和蓄水潜力，以支持水资源开发和生态可持续性。通过监测地下水位和地表水位，建立了来自现有沙子储存系统的水流过程——包括补给率和失水过程。沿冲积走廊的水样被收集并分析了建立蓄水动态所需的主要离子和同位素特征。通过探测和电阻率层析成像技术估计存储潜力，并通过对水力传导率和通道床孔隙度的原位测量进行增强。研究范围内冲积层的年平均蓄水量估计为 1.1 Mm3，可能能够满足该地区的年度家庭和牲畜用水需求。根据冲积层饱和度的不同，临时河道床下冲积层的传输损失会减弱洪水峰值流量。然而，冲积层中的水储存会因蒸发蒸腾和裂缝基岩渗漏而损失。