Meet Teves – Hungarian Case Study

Meet Teves – Hungarian Case Study

The Tetves case study area is located in the Southern Transdanubia region of Hungary and belongs to the catchment of Lake Balaton (Figure 1). Covering a total of 72 km², it is a rural hilly landscape shaped by both natural features and human activity. The climate is moderately warm and moderately humid, with an average annual precipitation of 689 millimeters and a mean annual temperature of 11.2 °C. More than half of the territory is covered by forests (52%), while arable land accounts for 31%, where wheat, maize, sunflower, rapeseed, and winter barley are cultivated in crop rotation.

Figure 1. Location of the Tetves case study (Hungary)

In many places, erosion has removed the upper soil layers, leaving the loess parent material exposed at the surface. These conditions contribute to several environmental challenges (Figure 2): extreme weather events, with droughts occurring more frequently, high erosion rates, decreasing soil quality, and a stream whose ecological status requires improvement.

Figure 2. Environmental issues in the Tetves case study area

Based on suggestions of the Multi-Actor Reference Group (Figure 3) – major, farm advisor and local farmers the following natural water retention measures (NSWRMs) were selected for SWAT+ modelling:

–      forested riparian buffers,

–      field dividing forest buffers,

–      no-till with cover crops,

–      cropland-to-grassland conversion.

Figure 4 show the allocation of these measures.

Figure 3. Local stakeholder consultation in the Tetves catchment at the Somogybabod Municipal Office

Figure 4. Locations of the selected NSWRMs in the Tetves case study area

SWAT+ modelling results indicate that no-till farming with cover crops has a strong positive effect on all analyzed indicators, especially in reducing sediment-related phosphorus loss and overall sediment loss, while enhancing soil moisture.

Forested riparian buffers are very effective in reducing phosphorus load, mitigating sediment loss, and controlling high flows, although their effect on other indicators is negligible. An additional advantage is their low land requirement, covering only 1% of the catchment area.

Field-dividing forest buffers also effectively reduce phosphorus loss associated with sediments and sediment loss, but their impact is limited due to the small implementation area, covering only 1% of cropland.

Converting cropland to grassland effectively decreases sediment load, sediment loss, and high flows. However, it significantly reduces the area of arable land, and soil moisture is projected to decrease.

Table 1. Effectiveness of NSWRMS at catchment scale based on SWAT+

The optimization of land use allocation in the Tetves case study was carried out using the multi-objective approach – CoMOLA, with the goal of identifying the best possible combination of the selected NSWRMs within the study area. The optimization focused on four key objectives: minimizing nitrogen load at the catchment outlet (measured as the average annual sum in kg N), maximizing soil moisture content in cropland (average annual value in mm), minimizing the implementation and maintenance costs of the NSWRMs (average annual sum in EUR), and maximizing agricultural production (average annual sum in grain units).

The optimization resulted in 192 Pareto optimal solutions, from which the stakeholder-preferred solutions were identified.

The selected scenario – which minimizes nitrogen load and NSWRM implementation costs while maximizing soil moisture in cropland and agricultural production – mainly includes no-till practices, some land use changes from cropland to grassland, and implementation of riparian buffers in a few sensitive areas (Figure 5). Further optimization analyses are in progress, considering other set of environmental indicators. The results of these optimization runs will be presented at the final Multi-Actor Reference Group event.

Figure 5. The most optimal solution based on the local stakeholder consultation