Impact of karstic flow on Chalk aquifer function and water quality

白垩纪白垩纪含水层是英国最重要的地下水资源，也是白垩流生态系统的重要生态系统。类似的含水层存在于法国、比利时、荷兰和以色列。白垩岩含水层在多大程度上表现出岩溶特征(由于地下水的溶解而扩大的裂缝和管道的发展)是令人感兴趣的，因为在岩溶特征将污染源直接连接到钻孔提取物的地方，水质可能很差。由于喀斯特发育程度较低且规模较小，水流分布较广的地方，水质一般较好。岩溶通常与独特的、往往是壮观的地貌相联系，包括洞穴，并导致地下溪流和河流中的地下水快速流动，以及通过较小的溶洞流动，尽管后者由于难以进入而不太为人所知。白垩岩通常不被认为是岩溶含水层，因为洞穴很少，地表岩溶地貌很小，直到最近才有很好的记录。最近的工作强调了白垩岩中岩溶的潜在重要性，使地下水能够在长距离内快速流动，但白垩岩溶的性质及其如何影响地下水流动和污染物迁移还没有被很好地了解。示踪剂测试技术的最新进展为研究岩溶含水层中较小尺寸的溶洞提供了机会，无论是在传统的岩溶含水层中还是在白垩岩中。如噬菌体(小到足以穿透裂隙含水层系统的无害病毒颗粒)等示踪剂的开发和对岩溶网络发育的模拟，使我们能够通过系统调查白垩纪白垩纪关键地区岩溶发育的程度，结合岩溶网络发育的数值模拟，开辟一条新的前进道路。使用这种方法将检验关于控制岩溶发育的关键因素、岩溶含水层中不同孔洞类型之间的相互作用以及这些因素对水质的影响的假设。

The Cretaceous Chalk aquifer represents the most important groundwater resource in the UK and is also important ecologically for chalk stream ecosystems. Similar aquifers exist in France, Belgium, Netherlands, and Israel. The extent to which chalk aquifers show development of karstic features (widened fractures and conduit development due to dissolution by groundwater flow) is of interest because where karstic features connect sources of contaminants directly to borehole abstractions, water quality may be poor. Where flow is more distributed because karst features less developed and smaller, water quality is generally better. Karst is generally associated with distinctive and often spectacular landforms, including caves, and results in rapid groundwater flow in subsurface streams and rivers, as well as flow through smaller solutional voids, although the latter are less well understood due to their inaccessibility. The Chalk is often not considered a karst aquifer because caves are rare, and surface karst features are small and until recently not well documented. Recent work has highlighted the potential importance of karst in the Chalk enabling rapid groundwater flow over long distances, but the nature of chalk karst and how it impacts groundwater flow and contaminant transport is not well understood. Recent advances in tracer testing techniques offer the opportunity to study the smaller sized solutional voids in karst aquifers, both in classical karst aquifers and in the Chalk. The development of tracers such as bacteriophage (non-harmful virus particles small enough to pass through fractured aquifer systems) and in modelling the development of karst networks enable a new way forward via systematic investigation of the extent of karst development in key areas of the Cretaceous Chalk coupled with numerical simulations of karst network development. Using this approach will test hypotheses about the key factors controlling karst development, the interactions between different void types in karst aquifers, and the impact of these on water quality.