This study explores the application of the open-source InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) [1] tool to model ecosystem services in Armenia, utilizing a scenario-based approach. By simulating two hypothetical scenarios, where all natural terrestrial land cover classes are replaced with bare ground or croplands, the study emphasizes the critical role of terrestrial ecosystems in ecosystem service provisioning. The results are published through Web GIS platforms powered by open-source framework NextGIS Web (https://github.com/nextgis/nextgisweb), providing an interactive medium for engaging civil society and fostering public awareness. This integration of advanced modeling techniques with accessible web-based dissemination aims to influence strategic policy-making in forest management, water resource allocation, and urban planning. The findings highlight the potential of scenario analysis and Web GIS to support sustainable development by illustrating the value of ecosystem services to both policymakers and the public.

Study scope

Ecosystem services, the benefits humans derive from nature, are crucial for supporting human well-being [2]. In the context of Armenia, a country with diverse landscapes and significant environmental challenges, understanding and sustainable managing these services is vital. The widely discussed bill in Armenia since the beginning of 2025, "On the Launch of the Process of Accession of the Republic of Armenia to the European Union", increases the need to raise public awareness about issues of sustainable use of ecosystems, maintaining ecosystem services and biodiversity protection
This study employs the InVEST tool, an open-source software suite designed for ecosystem service modeling, to assess critical services on example of Sediment Delivery Ratio, Seasonal Water Yield, Urban Cooling, and Urban Flood Risk Mitigation models. By adopting a scenario-based approach, we aim to estimate the physical volume of ES provided by natural ecosystems and changes in it from 2017 and 2023. Our approach involves several key steps: data collection, scenario development, models parametrization, statistics calculations over model outcomes, mapping and results publishing via Web GIS.

Materials and methods

First, we collected geospatial data relevant to the four ecosystem services, including land cover, relief, soil properties, climate data, and urban infrastructure. We used only global public domain datasets and public domain Armenian sources to increase study transparency and reproductivity. Source datasets were transformed to meet different scenarios conditions, for example land cover dataset was recalculated to scenarios “all natural vegetation turns to bare land” and “all terrestrial land cover classes except built-up areas turn to cropland”.
Then, we calibrated four InVEST models to reflect the specific conditions of Armenia, ensuring accurate simulations of each service under different scenarios. Selected InVEST models:
1. Sediment Delivery Ratio (SDR) model evaluates how well a land area can prevent sediment from being eroded and transported, based on factors like terrain, climate, vegetation, and land management practices
2. Seasonal Water Yield model calculates the amount of water generated by a watershed and delivered to streams. Its main outputs are quickflow, local recharge, and baseflow. Quickflow measures rainfall that flows over the land surface immediately or shortly after rain. Local recharge quantifies water that infiltrates the soil, minus what is lost to evaporation or vegetation use. Baseflow accounts for water reaching streams more slowly via underground pathways, including during dry periods. The model relies on inputs such as elevation, soil properties, land cover, rainfall patterns.
3. Urban Cooling model evaluates heat mitigation by calculating an index based on factors like shade, evapotranspiration, surface reflectivity (albedo), and proximity to cooling areas such as parks.
4. Urban Flood Risk Mitigation model estimates the reduction in runoff, or the volume of stormwater retained at each pixel relative to the total storm volume, based on land cover and soil properties.

Outcomes of all models under different scenarios were mapped and published as web maps. Also, statistics for the most significant outputs were calculated for each province and major watershed basin of Armenia.

Results and Discussion

The scenario analysis revealed significant variations in ecosystem service delivery under different hypothetical scenarios. Replacing natural vegetation with bare land, for example, led to increased sediment delivery and reduced baseflow, highlighting the protective role of forests and grasslands in maintaining soil stability and water supply.
The Urban Flood Risk Mitigation model indicated that natural vegetation could lower flood risk, protecting densely populated areas from extreme rain events.
Presented in the form of maps and connected statistical reports, these scenarios are very illustrative of the role of ecosystems and how dramatic the effects of forest destruction or large-scale agricultural expansion can be. So, to maximize the impact of our findings, we utilized the open-source Web GIS framework NextGIS Web to publish the results as interactive web maps. Its advanced integration with desktop tool QGIS, which we used as a primary tool of mapping, data preparation and post-processing, saved a lot of time — once being prepared in QGIS, maps are ready to be published on the web. From the point of view of end-users, this platform allows them to explore the data visually on the web-maps, fostering greater understanding and engagement. By making the results publicly accessible, we aim to raise awareness about the importance of ecosystem services and encourage informed decision-making among policymakers and the general public.

Our study demonstrates the utility of scenario-based modeling and Web GIS in supporting sustainable resource management. The insights gained from the InVEST models can inform policy decisions in several key areas such as forest management, water resource management, agricultural practices and urban planning. Open-source technologies and public domain data as a core of the study open wide prospects for reproducing similar research for any other country.

Source data and modeling outcomes are available for public access here: https://bccarmenia.nextgis.com/resource/113/display?panel=layers