Was Contemporary Land Use Strategy and Engineering Measures Sufficient for an Integrated Management of Water, Sediment and Carbon in the Semi‐Arid Region? a Modelling Investigation on the Chinese Loess Plateau?

ABSTRACT In the arid and semi‐arid region, traditional land use strategies and engineering measures used for erosion control and water conservation may face challenges, particularly given that carbon management has become a globally critical issue. However, few studies have investigated whether contemporary land use strategy and engineering measures were sufficient for an integrated management of water, sediment, and carbon. This study employed the Terrestrial‐Aquatic Sciences Convergence (TASC) model to address the above question through investigating the impacts of climate change, land use shifts, and engineering measures on streamflow, sediment yield, and total organic carbon (TOC) in a catchment of Chinese Loess Plateau during 1990–2020. Results indicated that TASC effectively simulated monthly streamflow and sediment yield (0.60 < NSE < 0.85, 0.65 < R 2 < 0.90), while NPP simulation results (0.50 ≤ NSE < 0.60, 0.75 ≤ R 2 < 0.80) were also acceptable. Compared with 1990, climate change led to increased streamflow (2.75 m 3 s −1 ), sediment yield (11.50 × 10 6 t year −1 ), and TOC loss (1.31 × 10 3 t year −1 ) during 1991–2020, primarily by increasing surface runoff. Land use change, check dams, and terraces reduced streamflow (0.20–0.32 m 3 s −1 ), sediment yield (2.22–11.34 × 10 6 t year −1 ), and TOC loss (0.24–0.77 × 10 3 t year −1 ) through different hydrological pathways, with land use change and terracing affecting hillslope runoff generation and check dams interrupting channel processes. Climate change exerted a positive and dominant impact on streamflow (approximately 65%), whereas check dams dominated changes in sediment yield and organic carbon losses (around 40%). Under climate change, contemporary land use patterns and engineering measures reduced sediment and enhanced carbon sequestration, while their capacity to maintain water resources remained insufficient.