Riverine floods cause increasingly severe damages to human settlements and infrastructure. Ecosystems have a natural capacity to decrease both severity and frequency of floods. Natural flood regulation processes along freshwaters can be attributed to two different mechanisms: flood prevention that takes place in the whole catchment and flood mitigation once the water has accumulated in the stream. These flood regulating mechanisms are not consistently recognized in major ecosystem service (ES) classifications. For a balanced landscape management, it is important to assess the ES flood regulation so that it can account for the different processes at the relevant sites. We reviewed literature, classified them according to these mechanisms, and analysed the influencing ecosystem characteristics. For prevention, vegetation biomass and forest extent were predominant, while for mitigation, the available space for water was decisive. We add some aspects on assessing flood regulation as ES, and suggest also to include flood hazard into calculations.

Groundwater (GW) in many regions is essential for agricultural productivity, especially during drought periods. The shrinking of GW is an important but rarely documented component of the recent global environmental crisis and may threaten food security. The problem cannot be put in proper perspective, because we rarely have datasets long and detailed enough to scrutinise the unfolding effects at regional scales. To address this knowledge gap, we used a 50-y long (1961-2010) and spatially extensive (283 GW wells) dataset from Hungary to examine the GW trends and the sensitivity of the yields of two important crops to GW fluctuations. During 1986-2010, GW levels were significantly (0.21-0.60 m) lower than during 1961-1985 in every region of Hungary and every month of the year. The decrease was 2.24 cm y-1 at the country level. Linear and bootstrap resampling tests indicated weak relationship between GW levels and wheat yields but decreasing GW levels accounted for 18-38% of maize yield variability during the 'climate change affected' period of 1986-2010. Calculating the impact of GW on potential food production, a 100 mm higher GW levels would have increased annual maize yields by 0.23 t ha-1 on the Hungarian Plain. However, the registered GW decrease caused an estimated maize yield loss of 0.65 t ha-1, i.e. 11.6% of the average annual yield during 1986-2010. GW level fluctuations on the plain showed a significant correlation with August-October soil moisture gridded data over much of the agricultural landscapes of Central and Western Europe, indicating a similar situation in a wider European context. To mitigate the cumulative negative impact of GW decrease and the rising temperature, GW recharge via infiltration of retained water would be an adequate solution. Areas of former floodplains with low agroecological suitability, amounting to almost a quarter of the Hungarian Plain could serve as such water retention areas.

Maintaining and, where possible, improving the ecological status of our water resources are of particular importance for the future. So, one of the main drivers of landscape design must be to protect our waters. In this study, we carried out an evaluation of four hydrologic ecosystem services (HES) in the Zala River catchment area, the largest tributary of Lake Balaton (more than half of the lake’s surface inflow comes from the Zala River), Hungary. The lake has great ecological, economic and social importance to the country. We used the cell-based InVEST model to quantify the spatial distribution of flood control, erosion control and nutrient retention ecosystem services for phosphorus and nitrogen; then, we carried out an aggregated evaluation. Thereby, we localized the hot spots of service delivery and tested the effect of focused land use changes in critical areas of low performance on the examined four HES. Forests proved to have the best aggregated result, while croplands near the stream network performed poorly. The modelled change in land use resulted in significant improvement on nutrient filtration and moderate to minimal but improving change for the other HES in most cases. The applied method is suitable as a supporting tool at the watershed level for decision-makers and landscape designers with the aim of protecting water bodies.

Climate change and water scarcity increase the vulnerability of crop production and other ecosystem services (ES) in flood-protected lowlands under a continental climate. Restoration of wetlands leads to a higher water-buffering capacity of the landscape, strengthening various ecosystem services, and fostering adaptation to climatic, ecological, and agricultural challenges. Such restoration efforts require extensive land-use change, leading to trade-offs in provisioning and regulating ES. However, knowledge is limited about these situations, especially in the case of lowland areas. Here, we introduce a hydrological analysis in a 243 km² flood-protected catchment in the Great Hungarian Plain, mapping the potential hydrological effects of water-retention scenarios on groundwater levels. We point out how the simulated groundwater levels will be used for estimating the changes in crop yields and tree growth (provisioning services). The introduced hydrological analysis and preliminary results for crop-yield estimates suggest a significant and scalable capacity for a nature-based hydrological adaptation: the extent of inundated areas could be increased stepwise and water retention could locally compensate dry periods due to the buffering effect of inundated meanders.

Central and Eastern Europe (CEE) is a pillar of global wheat and maize production. However, certain areas within the CEE region have become climate change hotspots, experiencing intensifying water deficits and drought pressure, rising mean and maximum temperatures. This study focuses on the long-term statistical relationships between climatic factors and rain-fed wheat and maize yields for different landscape types in Hungary over 30-year time windows between 1921 and 2010. The relationship between the variances of the detrended climatic parameters and crop yields was tested employing both simple and multifactorial linear models according to landscape types and periods. The sensitivity of wheat yields to spring–summer mean temperature shifted dynamically from the western part of the country to east (from cooler and wetter hilly landscapes to plains) between the periods 1921–1950 and 1981–2010. The cooling observed in summer temperature between the periods 1921–1950 and 1951–1980 supported an increase in wheat yields by an estimated 0.11–0.43 t ha⁻¹ year⁻¹, while the 0.9–1.2 °C warming of May–July temperature may have cut wheat yields by an estimated 0.44–0.56 t ha⁻¹ year⁻¹ in various regions over 1981–2010. That being said, the regional sensitivity of wheat yields to May–July mean temperature did not display substantial differences between the periods 1921–1950 and 1981–2010. Besides negative effects, climate change had a positive impact on wheat yields, since increasing January–March mean temperatures mitigated the negative impact of warming summer temperatures on wheat yields by an estimated 16–34% over 1981–2010. In this 30-year period, increasing mean temperature together with decreasing precipitation explained 46–75% of the variances in maize yields reducing annual maize harvests by an estimated 11.1–12.4% year⁻¹.

Historical trends in water management and recent climatic variations put wetlands in the Carpathian basin under strong pressure and led to their degradation. The lack of extended site specific environmental data series inhibits the understanding of long-term eco-hydrological processes. This undermines the success of restoration and/or management efforts. As a precedent we analyzed a recently degraded Hungarian lowland wetland, the Nyárjas fen in order to identify the main cause of its drying. Our method is based on one-dimensional simulations of a variably saturated soil column representing the dominant hydrological conditions of the wetland. To properly define the necessary soil hydraulic parameters, soil sampling, laboratory measurements and inverse modelling were carried out. The hydrological simulations for the 1961-2010 period clearly suggest that (i) the wetland degraded due to a temporal unfavorable combination of regional groundwater depletion and decreased precipitation, (ii) and could not recover afterwards despite the improvement of hydrological conditions. The ecological water demand of the Nyárjas fen can be explicitly expressed in terms of groundwater level. However, water availability is a necessary, but not sufficient criteria of good habitat status. The elaborated methodology provides the basis of bottom-up type environmental water demand estimation on a regional/national scale.