Risk reduction of extreme hydrological events with sustainable land use and soil management

The limited water resources and the increasing frequency of extreme hydrological events (flood, water-logging, over-moistening and drought) due to the high territorial and temporal variability of atmospheric precipitation; the heterogeneous (micro and meso) relief; and the unfavourable physical/hydrophysical characteristics of soils are pressing to improve agricultural water use efficiency and necessitates an efficient control of soil moisture regime in the Carpathian Basin.Another reason of the necessity of soil moisture control is water quality and its ecohydrological consequences. During the periods of high atmospheric precipitation, especially of quick, high intensity rainfalls a considerable amount of plant nutrients and potentially harmful (or even toxic) chemicals and other compounds are transported to the surface and subsurface water resources by surface runoff, filtration and seepage in the unsaturated zone and by groundwater movement. Efficient soil moisture control may considerably reduce this pollutant and/or “nutrient” transport and its undesirable hydroecological consequences.Soil is the largest potential natural water reservoire: 350–400 mm/0-100 cm soil layer. But in many cases this huge water storage capacity is not used efficiently, mainly due to four reasons: “filled bottle effect”, “frozen bottle effect”, “closed bottle effect”, “leaking bottle effect”. Consequently, the aim of an efficient soil moisture control to help infiltration into, and water storage within the soil in plant available form. For those “actions” adequate information are required on land/soil characteristics. These information are provided by a comprehensive soil/land survey-analysis-categorization-mapping- monitoring system which was developed in Hungary and served as a scientific basis for sustainable land use and soil management including ecosystem management and risk reduction of extreme hydrological events.