Dr. Wael Mahmod obtained his Ph.D. degree in water resources management since 2013. He works as an Assistant Professor in Assiut University, Egypt. He researches in fields of Hydraulics, Hydrology, Groundwater Modeling, developing and using new techniques to overcome uncertainty of numerical models, etc. He supervises of many postgraduate students.

Management of complex groundwater systems has been difficult to be properly performed due to the limited availability of hydrogeological data. Numerical models have become effective and powerful management tools for simulating groundwater flow to improve development strategies. However, the lack of basic data often limits the implementation of these models introducing a problem for model calibration and validation. This book therefore provides a newly developed model named as Modified Grey Model (MGM) to overcome these difficulties of data limitation and uncertainty of hydrogeological conditions. As a case study of complex groundwater system, groundwater flow in Nubian Sandstone Aquifer System (NSAS) under Kharga Oasis was analyzed. To check the performance of the MGM model, supplemental comparison between MGM and other models was done for spatial variation of groundwater table and sensitivity analysis. This book should be useful mainly for engineers and geologists. Moreover, it can play an important role with the decision makers to develop a new management and monitoring strategy not only for groundwater but also for other problems have the fingerprint of uncertainty