The effects of human intervention in the water regime

Water tables in the Netherlands have fallen due to human interventions in the water regime, causing hydrological degradation, particularly over the last 50 Sears, Factors responsible for this hydrological degradation are increased agricultural crop production, changes in land use, increased drainage, lowering of the drainage base, and increased ground water abstractions. Additionally, variations in the water regime have been caused by differences in meteorological conditions over a number of Sears. The physically based ground water and surface water model SIRIGRO was used to predict the effect of these human interventions. The analysis was carried out in three regions in the Netherlands and various scenarios were defined to represent the man-induced changes over the last 50 Sears, Changes in natural recharge of ground water and mater tables were used as indicators for the hydrological degradation, The calculations show that the natural recharge increases when water tables are deep. Variations in meteorological conditions over the last 50 years have a pronounced effect on the natural recharge, and the effect is greater than the changes caused by any of the human influences. The lowering of the drainage base causes the greatest change in ground mater tables.