This book is aimed at developing methodologies for optimal monitoring of groundwater contamination. The detection and remediation of groundwater contamination involves monitoring of the contaminant plume in groundwater systems. Design of optimal monitoring network remains a challenging task due to various associated uncertainties and budgetary limitations. A simulation-optimization based algorithm is presented here. A geostatistical based Kriging algorithm is used and then linked with Simulated Annealing (SA) as optimization tool. Two broad scenarios are considered, when the groundwater contaminant source characteristics (location, magnitude and direction) are known and when it is not possible to identify the actual source characteristics. This book also presents SA based methodology using feedback information on concentration measurements at designed monitoring locations for sequential characterization of contaminant plume. An example study area located in a district of the Indian state is chosen for testing the performance of the developed methodologies. This book will serve the need of the postgraduate students for doing research work in the area of groundwater.