Impacts of landscape management on the hydrological behaviour of small agricultural catchments

Changes of agricultural land use often induce changes of the hydrological behaviour of catchments. Because only the effects on a few processes are measurable, modelling and simulating the hydrological processes can help to estimate the impact of land use changes on distinct hydrological quantities (e.g. evapotranspiration, groundwater recharge, runoff production, channel runoff). While selecting management measures hydrological models can serve as tools for decision making. Possible aims are the reduction of flood events, guaranteeing the supply of drinking water (amount and quality) and optimising use of irrigation water in agriculture. In order to forecast the effects of management on hydrology a physically based, deterministic model system is applied which consists of two model parts, an one dimensional soil-vegetation-atmosphere-transfer model (SVAT) and a distributed catchment model. The sensitivity of the model and its parameters is shown by scenarios whose quantitative model results are transferred to qualitative statements concerning effects of landscape management on hydrology. Especially the effect of land use changes due to EC policy (applying different fallow practices) on the catchment water balance and on the channel runoff (flood events) is investigated, additionally the reestablishment of channels and the impact of plant growth in channels. (C) 1999 Elsevier Science Ltd. All rights reserved.