Recharge

To face the threats to the water supply and to maintain sustainable water management policies, detailed knowledge is needed on the surface-to-subsurface transformation link in the water cycle. Recharge flux is covered in this book as well as many other groundwater issues, including a comparison of the traditional and modern approaches to determine groundwater recharge. The authors also explain in detail the fate of groundwater recharge in the subsurface by hydraulic and geologic means, in order to stimulate adapted groundwater-management strategies.

The primary groundwater management issue in many countries today is pollution. This may derive from a point source, perhaps a leaking solvent store at a factory, or it may be diffuse, such as the threat posed by the use of agricultural fertilisers and pesticides. The key to understanding the transport of a pollutant from the ground surface or near surface into an aquifer is an understanding of recharge. In turn, this allows the vulnerability of aquifers to pollution to be classified and appropriate land zones to be defined. Land zonation of different classes of aquifer vulnerability is a valuable tool for management and planning. In this volume the recent developments within the interlinked areas of groundwater pollution, aquifer recharge and vulnerability are set against the current groundwater protection policies of the UK amd Republic Ireland.

The book is an overview of the diversity of anthropogenic aquifer recharge (AAR) techniques that use aquifers to store and treat water. It focusses on the processes and the hydrogeological and geochemical factors that affect their performance. This book is written from an applied perspective with a focus of taking advantage of global historical experiences, both positive and negative, as a guide to future implementation. Most AAR techniques are now mature technologies in that they have been employed for some time, their scientific background is well understood, and their initial operational challenges and associated solutions have been identified. However, opportunities exist for improved implementation and some recently employed and potential future innovations are presented. AAR which includes managed aquifer recharge (MAR) is a very important area of water resources management and there is no recent books that specifically and comprehensively addresses the subject.

Understanding groundwater recharge is essential for successful management of water resources and modeling fluid and contaminant transport within the subsurface. This book provides a critical evaluation of the theory and assumptions that underlie methods for estimating rates of groundwater recharge. Detailed explanations of the methods are provided - allowing readers to apply many of the techniques themselves without needing to consult additional references. Numerous practical examples highlight benefits and limitations of each method. Approximately 900 references allow advanced practitioners to pursue additional information on any method. For the first time, theoretical and practical considerations for selecting and applying methods for estimating groundwater recharge are covered in a single volume with uniform presentation. Hydrogeologists, water-resource specialists, civil and agricultural engineers, earth and environmental scientists and agronomists will benefit from this informative and practical book. It can serve as the primary text for a graduate-level course on groundwater recharge or as an adjunct text for courses on groundwater hydrology or hydrogeology. For the benefit of students and instructors, problem sets of varying difficulty are available at http://wwwbrr.cr.usgs.gov/projects/GW_Unsat/Recharge_Book/

In view of the rapidly expanding urban, industrial and agri cultural water requirements in many areas and the normally associated critical unreliability of surface water supplies in arid and semi-arid zones, groundwater exploration and use is of fundamental importance for logical economic development. Two interrelated facets should be evident in all such groundwater projects : (a) definition of groundwater recharge mechanisms and characteristics for identified geological formations, in order to determine whether exploitation in the long-term involves 'mining' of an es sentially 'fossil' resource or withdrawal from a dynamic supply. A solution to this aspect is essential for development of a re source management policy: (b) determination of recharge variability in time and space to thus enable determination of total aquifer input and to quantify such practical aspects as 'minimum risk' waste disposal locations and artificial recharge potential via (e.g.) devegetation or engi neering works. However, current international developments relating to natural recharge indicate the following 'problems' ; no single comprehensive estimation technique can yet be iden tified from the spectrum of methods available; all are reported to give suspect results.