Advances in thermal tracers for measuring and managing groundwater resources

全球地下水资源正在枯竭，这引起人们对未来水和粮食安全的关切。由于气候变化以及人口重新分布和城市环境中地下水需求增加，预计未来几十年内，目前的情况将进一步恶化。不可持续的地下水开采通常被认为仅限于第三世界国家，但加拿大境内的一些地区最近因干旱而出现地下水短缺。整体地下水管理必须考虑社会和生态系统对地下水的需求，因为地下水排入河流对于调节旱季的温度和维持流量至关重要。可持续地下水管理往往具有挑战性，因为难以测量进出含水层的地下水通量（每单位面积的流量）。使用示踪剂估计这些通量的标准方法通常仅适用于某些环境，需要昂贵的采样和分析，并且具有假设和不确定性的特点。因此，迫切需要开发更好的方法，以廉价和准确地追踪地下水通量。热可用于研究地下水运动，因为水流会引起热平流并干扰地下温度。热量比其他地下水示踪剂具有优势，因为它总是存在于地下，连续监测成本低廉，并且不需要进一步的实验室分析。在水资源管理界，利用热量作为地下水示踪剂的现有分析技术受到限制，因为大多数常用方法仅限于不到一米的深度。该研究计划的总体目标是开发新的综合技术和技术，用于从深层和浅层含水层的温度跟踪地下水，为社会和生态系统需求提供地下水资源的可持续管理信息。这项研究计划，这将培养七名学生，将包括仪器设计，数据收集和模型开发。对浅水环境的研究将提供监测含水层-河流交换的改进方法，以帮助河流恢复和栖息地保护，特别是在加拿大东南部，由于河流变暖，鲑鱼数量下降，地下水对创造鱼类栖息地至关重要。以热示踪为重点的研究将为地下水工程师提供新的工具，以监测地下水补给的长期变化或评估在新地点开发井场的可行性。在这个研究计划中开发的知识将通过期刊出版物，演讲和短期课程转移到其他学者以及更广泛的水资源管理社区。

Global groundwater resources are being depleted, which is eliciting concern over future water and food security. The present situation is expected to be exacerbated in the coming decades due to climate change as well as population redistribution and increased groundwater demand in urban environments. Unsustainable groundwater extraction is often thought to be limited to third world countries, but regions within Canada have recently experienced groundwater shortages due to droughts. Holistic groundwater management must consider both societal and ecosystem groundwater demands because groundwater discharge to rivers is critical for modulating temperatures and sustaining flows during the dry season. Sustainable groundwater management is often challenging due to difficulties associated with measuring groundwater fluxes (flow per unit area) to and from aquifers. Standard approaches to estimate these fluxes using tracers are typically only applicable in certain environments, require expensive sampling and analyses, and are characterized by assumptions and uncertainties. Thus, there is a critical need to develop improved methods to inexpensively and accurately trace groundwater fluxes.******Heat can be used to study groundwater movement because water flow induces heat advection and disturbs subsurface temperatures. Heat offers advantages over other groundwater tracers as it is always present in the subsurface, it is inexpensive to continuously monitor, and it does not require further laboratory analysis. Uptake of existing analytical techniques for using heat as a groundwater tracer has been limited in the water resources management community because most common methods are restricted to depths less than one meter. The overall objective of this research program is to develop new integrated technology and techniques for tracing groundwater from temperature in deep and shallow aquifers to inform the sustainable management of groundwater resources for both societal and ecosystem needs. This research program, which will train seven students, will include instrument design, data collection, and model development. Research focused on shallow environments will provide improved methods for monitoring aquifer-river exchanges to aid in river restoration and habitat conservation, particularly in southeastern Canada where salmon populations are in decline due to river warming and where groundwater is critical for creating fish habitat. Research focused on heat tracing to quantify flows to and from deeper aquifers will provide new tools for groundwater engineers to monitor long-term changes in groundwater recharge or assess the viability of developing well fields in new locations. Knowledge developed in this research program will be transferred to other academics as well as the broader water resources management community via journal publications, presentations, and short courses.********