Numerical and Analytical modelling of ground water flow in delta structures

Next to air, water is the most essential of Man’s requirements for life. The amount of water necessary to society has increased as population and urbanisation have increased. Today, conflicting interest on water issues appear frequently. All people in the world compete for less than 1% of earth’s water supply. This is enough fresh water to supply all the people on the earth, but the problem rise as both people and fresh water is unevenly distributed over the world. The access to water resources is of vital importance for a broad spectrum of human activities, and a careful management of the water resources is of great concern to society and the environment. It is of major importance that investigation and management of the water supply aim to optimise the utilisation of a common resource. Groundwater is defined as all the water contained in spaces within bedrock and regolith (Skinner and Porter 1995). Less than 1 % of the water on the Earth is groundwater, although the volume of groundwater sounds small, it is 40 times larger than the volume of all the water in freshwater lakes or flowing in streams and nearly a third as large as the water contained in all the world’s glaciers and polar ice (Skinner and Porter 1995). In the work of mapping, managing and investigation of the water resources in the different part of the world modelling is an important tool to understand and optimise the use of water resources that are available. The greatest part of the freshwater that is available is found as groundwater. The major part of the worlds population are dependent on the groundwater supply in the area they live in. Administration of the groundwater resources is therefore vital. Today groundwater modelling is a common practise in groundwater management. Modelling increase the value of observations and makes it easier to understand physical and geochemical responses. In the investigations of groundwater supply there has been used for instance finite mathematics and computer technology to make numerical modeling of these problems. These numerical solutions need a lot of data and a great deal of effort to get a simulation that is realistic enough. Analytical solutions of the same problems can be useful because they don’t need the same amount of data and details as the numerical solutions, but can still give an understanding of the physical conditions in the area and how they affect the groundwater flow.