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Data Assimilation in Groundwater Modeling
Published in Surendra Kumar Chandniha, Anil Kumar Lohani, Gopal Krishan, Ajay Krishna Prabhakar, Advances in Hydrology and Climate Change, 2023
Groundwater models are set of mathematical equations that mimic the natural groundwater system. Models help water managers in multiple ways to help understand the natural processes and enabling impact assessments. Models are useful to investigate the response of groundwater system under certain conditions, or to predict/hindcast the system behavior under anthropogenic or natural changes in groundwater recharge/abstraction, land scape, climate and hydrogeology. A verity of groundwater models have been developed in the past. Among these models, the physically based process-driven models remain the most widely used. These models use simplified laws of fluid dynamics and mimic the natural groundwater system utilizing various properties and parameters of the aquifer system. These models allow to handle the heterogeneity and anisotropy by discretizing the study domain into several spatial grids. Similarly, the temporal variations of aquifer stress can be considered by discretizing the temporal domain into several stress periods. The complex multidimensional flow equations are typically solved in these models utilizing numerical solution techniques, such as finite-difference method (FDM) and finite-element method (FEM).
Hydrogeology
Published in Mohammad Albaji, Introduction to Water Engineering, Hydrology, and Irrigation, 2022
Hydrogeology is a branch of geology that studies the distribution and movement of groundwater in the soil and rocks of the Earth's crust. Hydrogeology is an interdisciplinary subject that needs knowledge in several various fields in both the theoretical and the experimental area because it can be complex to determine the chemical, physical, biological, and legal interactions between soil, water, nature, and society.
Fate and Transport in the Subsurface
Published in Benjamin Alter, Environmental Consulting Fundamentals, 2019
Water enters the subsurface as part of the hydrogeologic cycle. A schematic diagram of the hydrogeologic cycle is shown in Figure 5.5. In the hydrogeologic cycle, water is deposited on the earth’s surface as precipitation or condensation, evaporating or transpiring (which is similar to evaporation, but from flora) back into the atmosphere only to fall back to earth as precipitation or condensation, restarting the whole cycle. When water falls to earth, it either becomes part of a surface water body, such as an ocean or a lake, or it lands on an unsaturated surface and infiltrates into the earth. The water that does not return to the atmosphere percolates through the soils, first manifesting itself as soil moisture in the unsaturated zone, and eventually becoming groundwater in the saturated zone. The groundwater eventually discharges to a surface water body, once again becoming a part of the never-ending hydrogeologic cycle.
Groundwater governance under climate change in India: lessons based on evaluation of World Bank interventions
Published in International Journal of Water Resources Development, 2023
Bekele A. Shiferaw, V. Ratna Reddy, Bharat Sharma
Sustainable management of groundwater often requires transdisciplinary approaches involving hydrogeology, biophysical sciences and socio-economics to address demand and supply-side constraints. Successful groundwater governance also involves a combination of instruments or approaches (e.g., incentive or market-based and regulatory instruments; Molle & Closas, 2019a, 2019b; Msangi, 2021). The actual combinations of interventions or instruments to address groundwater depletion may vary depending on the hydrogeology, bio-physical, socio-economic and policy contexts. The World Bank projects often deploy different interventions that aim to address supply- and/or demand-side constraints. The evaluation of these interventions in India was conceived using transdisciplinary approaches in an effort to better understand their effectiveness, the drivers of success and the constraints. Given the growing challenges of groundwater depletion and the policy interest to address it, the evaluation aimed to offer lessons that could help improve future policies and programmes in India.
The United Nations World Water Development Report 2022 on groundwater, a synthesis
Published in LHB, 2022
The scientific knowledge of hydrogeology and the methods and tools available are sufficient to address most groundwater management issues, like siting wells, optimising abstraction and predicting its effects at the local and regional scale, preventing contamination, etc. The challenge lies more in the scarcity of reliable data for area-specific groundwater assessments and scenario analyses, especially in low-income countries, and in the limited dissemination of data, information and knowledge among researchers, practitioners and decision makers (144). Groundwater models nowadays are also used as one component in much more complex hydro-economic modelling frameworks, where scenario analyses encompass the outcomes of various models, addressing a diversity of topics and issues (152).
State-of-the-art review of transboundary water governance in the Euphrates–Tigris river basin
Published in International Journal of Water Resources Development, 2019
The Inventory of Shared Water Resources in Western Asia is a systematic effort to catalogue and characterize ‘shared’ surface water and groundwater systems throughout the Middle East (UN-ESCWA & BGR, 2013). It analyzes the Euphrates and Tigris river basins separately with their geographical, hydrological characteristics as well as water resources management patterns, with specific emphasis on water development and use in Turkey, Syria, Iraq and Iran. It particularly highlights water quality and environmental issues. The existing agreements, cooperation frameworks and outlook for the future are briefly described. It dedicates particular chapters to the shared tributaries of the Euphrates (the Sajur, Balikh and Khabour) and the Tigris (the Feesh Khabour, Greater Zab, Lesser Zab and Diyala) by looking into their hydrological characteristics, with special attention to transboundary agreements as well as water quality and environmental issues. It devotes separate chapters to less studied shared aquifer systems in the ET basin, such as the Jezira Tertiary Limestone Aquifer System, and the Halabja-Khurmal and Central Diyala Basins in the areas that extend into the Taurus-Zagros mountain range across Iran, northern Iraq and Turkey. It examines hydrogeology (aquifer and groundwater characteristics), groundwater abstraction and use, and groundwater quality issues, as well as agreements, cooperation frameworks and the outlook for the future.