[PULA Project] Extreme rainfall and floods in arid regions: replenishment or contamination of water resources?

【PULA项目】干旱地区的极端降雨和洪水：水资源的补充还是污染？

基本信息

批准号：
NE/R002568/1
负责人：
Jean-Christophe Comte
金额：
$ 7.15万
依托单位：
University of Aberdeen
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FR002568%2F1
关键词：
PULA Project Extreme rainfall floods

项目摘要

While recent research suggests that recharge of groundwater resources in arid regions, including Sub-Saharan Africa, only occurs during extreme rainfall events, these conditions are also associated with the mobilisation of contaminants into surface water and aquifers. Scarcity of clean surface water has already put tremendous pressures on water resources in arid developing countries. Projections of growing populations and more pronounced climatic extremes suggest that sustainable approaches to water resources are urgently needed, but there are key deficiencies in understanding of 1/the mechanisms and timing by which water stores (surface and ground) recharge and get contaminated as a result of heavy rainfall and 2/the associated trade-off between increasing water storage but also potentially of poorer water quality.The current exceptional ongoing rainy season in Botswana provides an urgent opportunity to study the effects of heavy rainfall on water resources in arid countries. The last heavy rainfall occurred nearly two decades ago and the exceptionally wet conditions have activated potential migratory routes for leachate from dumpsites to ground and surface water. Such point source pollution provides ideal opportunistic conditions for large-scale tracing of flow and contaminant pathways in arid environments.The proposed work aims to take advantage of this unique prospect to monitor the immediate effect of heavy rainfall and floods on water resources and their transitional hydrologic readjustment towards the dry period, and elucidate whether these events support either or both resources replenishment and contamination. The densely populated Gaborone reservoir catchment is of particular interest because water demand and pollution sources are high and preferential flow pathways in the fractured bedrock result in fast groundwater recharge and contamination. Erosion of shallow soils affects sediment and contaminant transport, as well as geomorphological conditions which in turn impact on recharge patterns.We will utilise the unique opportunity to evaluate the crucial link between water quantity and quality, often investigated separately, through an integrated approach that combines hydrologic monitoring, temporal geophysical imaging, geomorphological mapping and natural tracer experiments (leachate and stable water isotopes) with modelling. Experiments will span the ongoing wet season and its transition to the following dry season. Water monitoring and sampling will focus on existing ground and surface water points across the catchment as well as dams and potential pollution sources at different spatial and temporal scales. Integrating the datasets into the modelling framework will allow for characterising and quantifying the contribution of extreme rainfall events to water resources replenishment and contamination.The project team is composed of UK and African scientists with specialisations in hydrogeology, surface water hydrology, geophysics and sedimentology and water governance stakeholders. Research will benefit from a hydrometric monitoring in place and in-kind sample collection pre-award, which will be expended during the project.The overall research outcomes will be 1/a greater understanding of the key processes governing flood-induced water resources replenishment and contamination in arid developing regions and 2/an increased ability of water resources stakeholders to adapt management and policy to the foreseeable increase in hydrological extreme events.The new science generated will impact both the academic community interested in new methods and knowledge with regards to hydrological processes under changes, and the governance sector in arid (sub-Saharan) regions in need of adaptive water management strategies able to cope with both short and long term effects of climate change. Students and project partners will receive training and early career researchers will build their research portfolio.

虽然最近的研究表明，包括撒哈拉以南非洲在内的干旱地区地下水资源的补给仅发生在极端降雨事件期间，但这些条件也与污染物迁移到地表水和含水层有关。清洁地表水的稀缺已经给干旱发展中国家的水资源带来了巨大压力。对不断增长的人口和更加明显的极端气候的预测表明，迫切需要对水资源采取可持续的方法，但在理解1/水储存（地表和地下）补给并因此受到污染的机制和时间方面存在重大缺陷2/增加蓄水量和潜在较差的水质之间的相关权衡。博茨瓦纳当前持续的异常雨季为研究强降雨对干旱国家水资源的影响提供了一个紧迫的机会。上一次强降雨发生在近二十年前，异常潮湿的条件激活了渗滤液从垃圾场到地下水和地表水的潜在迁移路线。这种点源污染为大规模追踪干旱环境中的流量和污染物路径提供了理想的机会条件。拟议的工作旨在利用这一独特的前景来监测强降雨和洪水对水资源及其过渡水文的直接影响向干旱期进行重新调整，并阐明这些事件是否支持资源补充和污染。人口稠密的哈博罗内水库流域特别令人感兴趣，因为需水量和污染源都很高，而且裂隙基岩中的优先流动路径导致地下水快速补给和污染。浅层土壤的侵蚀会影响沉积物和污染物的迁移，以及地貌条件，进而影响补给模式。我们将利用这一独特的机会，通过综合方法来评估水量和水质之间的关键联系，通常单独进行调查，该方法结合了水文监测、时间地球物理成像、地貌测绘和自然示踪剂实验（渗滤液和稳定水同位素）与建模。实验将涵盖正在进行的雨季及其向下一个旱季的过渡。水监测和采样将重点关注流域内现有的地下水和地表水点以及不同时空尺度的水坝和潜在污染源。将数据集整合到建模框架中将能够描述和量化极端降雨事件对水资源补给和污染的影响。该项目团队由英国和非洲科学家组成，他们的专业领域包括水文地质学、地表水水文学、地球物理学、沉积学和水学。治理利益相关者。研究将受益于项目期间进行的现场水文监测和实物样本收集预授。总体研究成果将是 1/更好地了解控制洪水引起的水资源补给和控制的关键过程。干旱发展中地区的污染和2/水资源利益相关者调整管理和政策以适应可预见的水文极端事件增加的能力。产生的新科学将影响对水文过程新方法和知识感兴趣的学术界变革和治理干旱（撒哈拉以南）地区的部门需要能够应对气候变化的短期和长期影响的适应性水管理战略。学生和项目合作伙伴将接受培训，早期职业研究人员将建立他们的研究组合。