Impact of projected climate change on the hydrology in the headwaters of the Yellow River basin

Abstract

Located in the northeast of the Tibetan Plateau, the headwaters of the Yellow River basin (HYRB) are very vulnerable to climate change. In this study, we used the Soil and Water Assessment Tool (SWAT) model to assess the impact of future climate change on this region's hydrological components for the near future period of 2013-2042 under three emission scenarios A1B, A2 and B1. The uncertainty in this evaluation was considered by employing Bayesian model averaging approach on global climate model (GCM) multimodel ensemble projections. First, we evaluated the capability of the SWAT model for streamflow simulation in this basin. Second, the GCMs' monthly ensemble projections were downscaled to daily climate data using the biascorrection and spatial-disaggregation method and then were utilized as input into the SWAT model. The results indicate the following: (1) The SWAT model exhibits a good performance for both calibration and validation periods after adjusting parameters in snowmelt module and establishing elevation bands in sub-basins. (2) The projected precipitation suggests a general increase under all three scenarios, with a larger extent in both A1B and B1 and a slight variation for A2. With regard to temperature, all scenarios show pronounced warming trends, of which A2 displays the largest amplitude. (3) In the terms of total runoff from the whole basin, there is an increasing trend in the future streamflow at Tangnaihai gauge under A1B and B1, while the A2 scenario is characterized by a declining trend. Spatially, A1B and B1 scenarios demonstrate increasing trends across most of the region. Groundwater and surface runoffs indicate similar trends with total runoff, whereas all three scenarios exhibit an increase in actual evapotranspiration. Generally, both A1B and B1 scenarios suggest a warmer and wetter tendency over the HYRB in the forthcoming decades, while the case for A2 indicates a warmer and drier trend. Findings from this study can provide beneficial reference to water resource and eco-environment management strategies for governmental policymakers.

Assessment on the Effect of Climate Change on Streamflow in the Source Region of the Yangtze River, China

“…As indicted in Figure 11a, precipitation performed a substantial increase in winter season (December-February) more than other seasons, meaning that there would be more snow accumulation in winter. However, as energy in the arid zone is sufficient for forcing evapotranspiration [34], thus the increased precipitation would be mostly dissipated by increasing evapotranspiration and contribute to relatively little change of streamflow during this period in this study area.…”

“…Different temporal scale outputs (daily or monthly) of GCMs have been used by various studies to assess climate change effects on hydrology [29][30][31][32]. However, some studies pointed out that the daily outputs of GCM could not be directly used [15] and monthly GCMs outputs were widely used in the northwest China [33,34]. Thus, the monthly outputs of GCMs and LARS-WG method were applied to project the future climate change scenarios.…”

Responses of Ecosystem Service to Land Use Change in Qinghai Province

“…At the same time, the Qinghai-Tibet Plateau is also the area with the most fragile ecological system. It suffers from the multiple effects of global drying and warming [23,24], massif uplifts [25,26] and human activities (such as over-grazing, tourism development and engineering construction). As a result, many ecological deterioration phenomena have been noted, such as rising snow lines [27], glacier recession [28][29][30], loss of soil organic matter [31,32] and desertification [33][34][35][36][37][38].…”

Assessing Climate Change Impacts on Water Resources in the Songhua River Basin

“…It is a physically based, semi-distributed and continuous time-step hydrologic model that is used for rainfall-runoff modeling as well as for predicting the impacts of land use and land management practices, and of climate change on the hydrology and water quality of watersheds or river basins. SWAT has been successfully applied to many parts of the world and proved to adequately reproduce hydrological processes of watersheds across a range of geographical regions and climates [31][32][33]. The water cycle simulated by ArcSWAT is based on a water balance, given as:…”