The Hirmand transboundary river basin is a complex system and a focal point of environmental, political, and social challenges. This research investigates the combined impacts of land use and climate change on water allocation patterns and hydropolitical tensions. Utilizing remote sensing techniques, radiometric and atmospheric corrections were applied to Landsat imagery (from 2012, 2020, and 2024) to create land use datasets. To analyze the interactions between hydrological, climatic, and socio-economic factors, a system dynamics model was developed in Vensim software, simulating the upstream basin as interconnected hydrological and socio-economic subsystems. Future climate projections were incorporated using CMIP6 data under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios for 2021–2050. The analysis revealed extensive land use changes between 2012–2020 and 2020–2024, particularly near Afghanistan's Kajaki and Kamal Khan dams, driven by agricultural expansion and water diversion to the Godzareh Depression. Climate simulations project a significant 10-21% reduction in annual water inflow to the Sistan region in Iran during the near future (2021-2050) compared to the baseline. This decreased inflow, compounded by rising upstream water demand from socio-economic growth, will substantially reduce downstream water availability. The research concludes that climate change and human activities specifically dam construction and land use change will intensify water scarcity and exacerbate existing hydropolitical tensions within the basin.