Determination of ecosystem services of the buyuksu river basin and evaluation in terms of landscape restoration

Rivers are dynamic natural systems that play a fundamental role in the continuity of ecosystem services. They directly or indirectly provide many services such as water supply, habitat provision, flood regulation, water quality protection, and support for biological diversity. However, factors such as urbanization, changes in land use, industrial and domestic waste discharge, conversion to sewer lines, climate change, and habitat fragmentation negatively affect these services. As a result, there are significant losses in the quantity and quality of ecosystem services provided by rivers; this situation threatens not only ecological balance but also human well-being. This thesis aims to reveal the status of ecosystem services in the Büyüksu River Basin located within the borders of Bolu Province and to identify areas in need of restoration; in this regard, it aims to develop strategies and area-level recommendations for river landscape restoration. The primary objective of the study is to restore the functionality of river systems that have lost their function due to increasing urbanization, population pressure, changes in land use, and interventions in riverbeds, using nature-based solutions. Within the scope of this thesis study, the natural and cultural landscape characteristics of the study area were first analyzed. In the first phase, ecosystem services were identified based on both landscape functions and land cover capacities, mapped separately, and then combined to create an integrated ecosystem services map. In the second phase, dominant land covers (forest, agriculture, and settlement) were mapped and integrated with the integrated ecosystem services map. This identified areas requiring landscape restoration. The findings indicate that forest areas have high ecosystem service capacity, whereas agricultural and settlement areas have low capacity. In this context, areas with low and medium levels of ecosystem services were prioritized; landscape restoration recommendations specific to forest, agricultural, and settlement land cover were evaluated at the strategy and area levels, focusing on landscape character types. In conclusion, the study demonstrates that considering ecosystem services in conjunction with land cover enables the development of sustainable, local, and nature-based intervention approaches in river basins. The findings contribute to the academic literature and provide a model for institutions, managers, and decision-makers.