The global hydrological cycle is susceptible to climate change (CC), particularly in underdeveloped countries like Pakistan that lack appropriate management of precious freshwater resources. The study aims to evaluate CC impact on stream flow in the Soan River Basin (SRB). The study explores two general circulation models (GCMs), which involve Access 1.0 and CNRM-CM5 using three metrological stations (Rawalpindi, Islamabad, and Murree) data under two emission scenarios of representative concentration pathways (RCPs), such as RCP-4.5 and RCP-8.5. The CNRM-CM5 was selected as an appropriate model due to the higher coefficient of determination (R²) value for future the prediction of early century (2021–2045), mid-century (2046–2070), and late century (2071–2095) with baseline period of 1991–2017. After that, the soil and water assessment tool (SWAT) was utilized to simulate the stream flow of watersheds at the SRB for selected time periods. For both calibration and validation periods, the SWAT model’s performance was estimated based on the coefficient of determination (R²), percent bias (PBIAS), and Nash Sutcliffe Efficiency (NSE). The results showed that the average annual precipitation for Rawalpindi, Islamabad, and Murree will be decrease by 43.86 mm, 60.85 mm, and 86.86 mm, respectively, while average annual maximum temperature will be increased by 3.73 °C, 4.12 °C, and 1.33 °C, respectively, and average annual minimum temperature will be increased by 3.59 °C, 3.89 °C, and 2.33 °C, respectively, in early to late century under RCP-4.5 and RCP-8.5. Consequently, the average annual stream flow will be decreased in the future. According to the results, we found that it is possible to assess how CC will affect small water regions in the RCPs using small scale climate projections.

Soil water infiltration is a key mechanism for meeting plant water demand and groundwater recharge cycles; however, unreasonable land use practices cause reduced infiltration capacity and greater soil erosion. To date, differences in the properties of aeolian sandy soil and Pisha sandstone soil under different utilization methods as well as in soil properties, aggregates, and infiltration among kind of soil types, remain poorly understood. In this work, 54 soil samples of cropland and grassland were selected to identify the unique characteristics of soil infiltration processes under transition from cropland to grassland and contributions of soil properties to soil infiltrability in the Loess Plateau of China. The results showed that converting cropland to grassland could enhance the stable infiltration capacity of shallow soils of aeolian sandy soil and loess soil by 43.6% and 35.7%, respectively. Compared with cropland, the root properties and soil aggregate formation of the three soil types increased during grassland use, with the largest increase in soil organic matter content (32.14%) and total porosities (6.4%). As determined by the ring knife method, the saturated infiltration capacity of Pisha sandstone soil was significantly lower than in aeolian sandy soil and loess soil (p < 0.5). Moreover, its saturated infiltration capacity of cropland was better than grassland. Spearman’s correlation analysis and structural equation modeling (SEM) revealed that soil infiltration capacity appeared to be the most influenced by soil organic matter, and aggregate structure. These results highlight that fifteen years of returning cropland to grassland is not enough to affect the infiltration ability of deep soil (≥20 cm), and this improvement requires longer term maintenance.

Soil degradation and erosion pose significant threats to agricultural sustainability in fragile ecosystems, such as the Loess Plateau in northern China. This study examines the long-term impacts of fertilization regimes and land-use systems on soil health, focusing on soil aggregate stability, fertility, and crop productivity. Six treatment combinations were evaluated in our study, including three continuous alfalfa fields (AL-CK, AL-P, and AL-NPM) and three continuous wheat fields (WH-NPM, WH-NP, and WH-P), each representing a combination of land use and three fertilization treatments: (1) no fertilization (CK), (2) inorganic fertilization (120 kg ha⁻¹ N, 60 kg ha⁻¹ P-NP), and (3) a combination of organic and inorganic fertilization (75 t ha⁻¹ cow manure-NPM). Soil samples were collected from three depths (0–10 cm, 10–20 cm, and 20–30 cm) to assess physical and chemical properties. We evaluated the long-term effects of different fertilization treatments on soil stability, fertility, and crop yield to explore the interactions among soil’s physical and chemical properties under two land-use types and to assess the effectiveness of combined organic and inorganic fertilization strategies in improving soil health and mitigating erosion in vulnerable landscapes. The study revealed significant depth-specific variations with surface layers (0–10 cm) showing the greatest improvement under NPM treatments, particularly in continuous alfalfa fields, which exhibited higher soil fertility, improved soil structure, and crop yield. In contrast, continuous wheat fields with minimal fertilization demonstrated significantly lower soil quality and productivity. Using the combination of mineral fertilizers and organic amendments, such as cow manure, proved to be the most effective strategy for significantly enhancing nutrient availability and overall soil health. Partial Least Squares Modeling (PLS-M) and Mantel analysis highlighted the critical role of fertilization management in maintaining soil quality, boosting crop productivity, and mitigating erosion in high-risk areas. This study emphasizes the importance of integrated nutrient management for sustainable land use and soil conservation in erosion-prone regions.