In a similar context for many areas, groundwater is the major source of surface water, and in other areas, surface water infiltration is a major source of recharge. Consequently, understanding the interaction of groundwater and surface water is important to the understanding of groundwater dynamics. Recharge rates are relatively well known for several agricultural crops in some regions, but much less so for many types of natural vegetation. Recharge may be estimated from unsaturated zone tracer studies, and hydrometric measures of soil water content, groundwater levels, and micrometeorological measurements. Impact of human activity on groundwater quantity Groundwater level fluctuations result from the combined effect of climatic fluctuations, processes of soil water transport in the unsaturated zone, hydrogeological properties of the aquifer, and numerous human influences.
Human activities have an increasing effect on groundwater levels.
Statistical and physical analysis of groundwater level fluctuations provides insight in the hydrogeological system and the effects of natural and non-natural influences. Papers are welcomed dealing with developments in the simulation of groundwater level fluctuations, time series analysis and identification of separate components. Impact of land use change on water quality Groundwater quality is determined by the quality of the infiltrating water, which is susceptible to pollution derived for example from atmospheric deposition, solid and liquid waste disposal, agricultural practice, urbanisation, and deforestation. In some cases, changes in land use may result in improved water quality. For example, land conversion from agriculture to natural vegetation may decrease nutrient load.