Groundwater resources for agricultural purposes in the Brazilian semi-arid region

ABSTRACT Exploitation of groundwater resources with no proper characterization of water reserves jeopardizes the quantity and quality of water available in the future. A major challenge is finding appropriate methods or coefficients to evaluate the carrying capacity of the aquifer. The objective of this study was to quantitatively and qualitatively characterize water reserves to provide information and management strategies for the rational use of available water resources in an alluvial aquifer in the Brazilian Northeastern semi-arid region. Shallow and medium-depth wells were analyzed. Water tables were monitored in the dry and wet seasons to calculate water reserves. Groundwater samples were collected for the determination of water quality for irrigation purposes. The increase in agricultural activities is jeopardizing the sustainability of the aquifer’s water, as reserves are not sufficient to meet this demand. Groundwater quality is not limiting for agricultural use. Converting surface irrigation into localized methods will potentially increase water productivity and consequently the irrigated area. This study provides data and makes it possible to recommend appropriate strategies for the exploitation of groundwater resources for the maintenance of agricultural activities under semi-arid conditions, and to avoid overexploitation.

摘要 若未对地下水储量开展合理表征便开发地下水资源，会危及未来可用水资源的数量与质量。当前一大挑战在于，亟需找到适宜的方法或系数以评估含水层的承载能力。本研究旨在对巴西东北部半干旱地区的冲积含水层的地下水储量开展定量与定性表征，为该区域合理利用现有水资源提供信息依据与管理策略。本研究分析了浅井及中深井，于旱季与雨季监测地下水位以计算地下水储量，并采集地下水样本以测定其农业灌溉用水质。农业活动的扩张正危及该含水层水资源的可持续性，因现有储量已无法满足相关需求；而地下水水质未对农业灌溉使用构成限制。将地面灌溉改造为局部灌溉方式，有望提升水资源利用效率，进而扩大灌溉面积。本研究提供了相关数据，可为半干旱条件下维持农业活动的地下水资源开发推荐适宜策略，并避免过度开采。