The impact of fictitious land use changes on water management related ecosystem services in a Hungarian catchment

<p>As a result of climate change, improving the efficiency of our water management has become a key social goal in recent decades. In many regions, water management problems are becoming more common as the result of hydrologic extremes, such as water scarcity, drought or floods.</p><p>Countries and regions dealing with water problems, like some parts of Hungary, could avoid major damage by land use change. The possibility of land use change is obviously not an option in certain instances, especially in populated areas or areas with major infrastructure (roads, railways, airports, factories, etc.). At the same time, non-populated areas (primarily agricultural land) may be transformed in the future, in the hope of better water management.</p><p>Complex, multi-dimensional assessment of ecosystem services can be a step forward in the evaluation and planning of future land use changes with the aim of improving water resources management. The strength of this approach is multi-disciplinarity, which requires the collaboration of representatives of the technical, economic, social and ecological sciences.</p><p>In our study, we quantified and mapped the most important water resources related indicators and services of the Zala River basin in Western Hungary. Zala River is the largest sub-catchment of Lake Balaton, Central-Europe’s largest standing water. The lake has great economic and social importance in Hungary, primarily due to its recreational and cultural services, so it is necessary to have sufficient quantity and quality of water.  The catchment area is 1521 km<sup>2</sup>, land use conditions are dominated by agricultural and forest areas (around 57% and 37% respectively).</p><p>For the quantification of ecosystem services indicators, we used the GIS based, static model package InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs). InVEST is suggested to describe the socio-ecological state of several services, under various periods or land use conditions. The strength of the model lies in its solid data requirements and low computational demand. In our work, we mapped the following services and indicators: annual water yield, seasonal water yield, quickflow, nutrient retention, sediment retention and agricultural crop yields.</p><p>We examined the impact of different interventions on the ecosystem services. We intervened primarily in areas where agricultural land use is not justified due to different environmental conditions. In these areas, we analyzed the introduction of natural surfaces with afforestation and meadows. We built up a reference (based on a novel LULC map representing actual conditions) and some fictive model variants. These model variants differed in the amount and location of the new semi-natural areas. The variants were compared for two temporal periods: 1980-2010 and 2020-2050 (based on climate models).</p><p>We quantified the tradeoffs as a result of a given land use change. As expected, the future negative effects of climate change could be mitigated by increasing semi-natural areas. All ecosystem services would improve except for crop yields. At the same time, however, farmers would be deprived of significant yields in areas, which are excluded from agriculture. Our research highlights that the positive effects or tradeoffs due to land-use change will be needed in the future.</p>