Remote sensing, hydrological analysis and hydrotopes

Remotely sensed images are used to differentiate complex terrain mapping units, which are based on natural associations of geology, geomorphology and soils. Land cover, also derived by remote sensing, is added. Based on an understanding of the role of terrain characteristics, analysis of existing hydrological data and field observations, a conceptual, hut comprehensive, hydrological model is formulated. In this manner, the effects of spatial variation of hydrological parameters can be taken into account even in data scarce regions. The procedure leads to the recognition of hydrotopes, which are complex units with a specific set of hydrological processes and therefore, a specific water balance. Depending on the nature of the terrain and the purpose of study, modelling approaches are developed which often deviate from routinely used models. A first example deals with the assessment of spatial recharge in a granitic area, which is used as an independent parameter for the calibration of a numerical groundwater model. The second example pertains to a permeable region, where local groundwater flow systems are modelled by quasi-linear tank models.