This research report summaries and details the first year of work on a multi-year karst modeling project organized to develop enhanced groundwater modeling capabilities that can be used to effectively manage karst aquifers. Discussed are the three key considerations for modeling karst systems were identified: representation of conduits in flow models, representation of flow dynamics in conduits, and representation of partially filled conduits and the numerical experiments used to identify the limitations and advantages of the three general representations of conduits within groundwater models. A new dual-conductivity MODFLOW-2000 package (DCM) was developed for testing the dual-conductivity approach. A turbulence model was added, the software was validated using simple benchmark problems, and code documentation was completed. Simultaneous demonstrations showed that the modeling tool can be successfully applied in complex applications.

This practical training guidebook makes an important contribution to karst hydrogeology. It presents supporting material for academic courses worldwide that include this and similar topics. It is an excellent sourcebook for students and other attendees of the International Karst School: Characterization and Engineering of Karst Aquifers, which opened in Trebinje, Bosnia & Herzegovina in 2014 and which will be organized every year in early summer. As opposed to more theoretical works, this is a catalog of possible engineering interventions in karst and their implications. Although the majority of readers will be professionals with geology/hydrogeology backgrounds, the language is not purely technical making it accessible to a wider audience. This means that the methodology, case studies and experiences presented will also benefit water managers working in karst environments.

Understanding the karst aquifer response to precipitation and contaminants transport, especially in arid to semi-arid areas, is a very important issue and a challenge due to the unique and heterogeneous characteristics of karst aquifers. Monitoring the water travel time through karst aquifers and the response to precipitation events can provide good information about the characteristics of water and pollutant flow through the aquifer. This can subsequently help provide proper protection for the aquifer against pollution to sustain the water resources for the coming generations. Within this ...

This book is a printed edition of the Special Issue "Environmental Tracers" that was published in Water

"One of the world's great karstic aquifer systems, the Edwards aquifer system supplies water for more than 2 million people and for agricultural, municipal, industrial, and recreational uses. This volume reviews the current state of knowledge, current and emerging challenges to wise use of the aquifer system, and some technologies that must be adopted to address these challenges"--

This book presents an overview of techniques that are available to characterize sedimentary aquifers. Groundwater flow and solute transport are strongly affected by aquifer heterogeneity. Improved aquifer characterization can allow for a better conceptual understanding of aquifer systems, which can lead to more accurate groundwater models and successful water management solutions, such as contaminant remediation and managed aquifer recharge systems. This book has an applied perspective in that it considers the practicality of techniques for actual groundwater management and development projects in terms of costs, technical resources and expertise required, and investigation time. A discussion of the geological causes, types, and scales of aquifer heterogeneity is first provided. Aquifer characterization methods are then discussed, followed by chapters on data upscaling, groundwater modelling, and geostatistics. This book is a must for every practitioner, graduate student, or researcher dealing with aquifer characterization .

Filling a gap in the karst literature, this book describes methods most appropriate for use in karst terrains. These include methods that are basic to all hydrogeological studies, such as hydraulic investigations, hydrochemistry, geophysics, isotope chemistry and modelling, with the emphasis placed on their application to karst systems. The various chapters of this book are written by experts in all the different methods. Most of the chapters are multi-authored, and the authors include hydrogeologists who are experienced in evaluating a variety of karst environments and who together, provide a balanced view of all the karst methods.

The Edwards Aquifer in south-central Texas is the primary source of water for one of the fastest growing cities in the United States, San Antonio, and it also supplies irrigation water to thousands of farmers and livestock operators. It is also is the source water for several springs and rivers, including the two largest freshwater springs in Texas that form the San Marcos and Comal Rivers. The unique habitat afforded by these spring-fed rivers has led to the development of species that are found in no other locations on Earth. Due to the potential for variations in spring flow caused by both human and natural causes, these species are continuously at risk and have been recognized as endangered under the federal Endangered Species Act (ESA). In an effort to manage the river systems and the aquifer that controls them, the Edwards Aquifer Authority and stakeholders have developed a Habitat Conservation Plan (HCP). The HCP seeks to effectively manage the river-aquifer system to ensure the viability of the ESA-listed species in the face of drought, population growth, and other threats to the aquifer. The National Research Council was asked to assist in this process by reviewing the activities around implementing the HCP. Review of the Edwards Aquifer Habitat Conservation Plan: Report 1 is the first stage of a three-stage study. This report reviews the scientific efforts that are being conducted to help build a better understanding of the river-aquifer system and its relationship to the ESA-listed species. These efforts, which include monitoring and modeling as well as research on key uncertainties in the system, are designed to build a better understanding of how best to manage and protect the system and the endangered species. Thus, the current report is focused specifically on a review of the hydrologic modeling, the ecological modeling, the water quality and biological monitoring, and the Applied Research Program. The fundamental question that Review of the Edwards Aquifer Habitat Conservation Plan: Report 1 addresses is whether the scientific initiatives appropriately address uncertainties and fill knowledge gaps in the river-aquifer system and the species of concern. It is hoped that the successful completion of these scientific initiatives will ultimately lead the Edwards Aquifer Authority to an improved understanding of how to manage the system and protect these species.

At hundreds of thousands of commercial, industrial, and military sites across the country, subsurface materials including groundwater are contaminated with chemical waste. The last decade has seen growing interest in using aggressive source remediation technologies to remove contaminants from the subsurface, but there is limited understanding of (1) the effectiveness of these technologies and (2) the overall effect of mass removal on groundwater quality. This report reviews the suite of technologies available for source remediation and their ability to reach a variety of cleanup goals, from meeting regulatory standards for groundwater to reducing costs. The report proposes elements of a protocol for accomplishing source remediation that should enable project managers to decide whether and how to pursue source remediation at their sites.