Assessing the Impacts of Climate Change and Land Use/Cover Change on Runoff Based on Improved Budyko Framework Models Considering Arbitrary Partition of the Impacts

Spatio-temporal pattern change of LULC and its response to climate in the Loess Plateau, China

Exploring land use/cover (LULC) change is essential for the sustainable development of ecologically fragile areas. The main objective of this study was to clarify the characteristics and differences in the spatiotemporal changes of LULC on the Loess Plateau (LP) based on the transfer matrix and land use dynamics and to quantitatively describe the impact of natural factors on LULC using a geodetector. The results indicated that the overall LULC change in the LP was characterized by a decrease in the area of cropland, grassland, and bare land, and an increase in the area of woodland and built-up land. This trend shows a clear phase-change characteristic around 2000. LULC changes were primarily affected by human activities in the southeastern agricultural region. The project of returning farmland to forest and grassland had a great impact on LULC change in the central region. Vegetation was sensitive to temperature and precipitation, and the impact of LULC change was significantly higher than that in the humid region in the northwest arid region. NDVI, PRE, and TEM were determined to be the main contributors to LULC changes in the LP. These results provide a scientific basis for the sustainable development of LP.

Evaluation and Analysis of Influencing Factors of Ecosystem Service Value Change in Xinjiang under Different Land Use Types

Based on the data on land-use change in Xinjiang from 1990 to 2020, this study uses a combination of land-use dynamics, the equivalence factor method, the sensitivity index, and a spatial correlation study to quantitatively analyze the spatial and temporal distribution of land-use change and ecosystem service values in the study area from 1990 to 2020. We also use a geographic probe model to explore the driving mechanism of the spatial variation of ecosystem service values in Xinjiang. The following conclusions were drawn: (1) land use in the Xinjiang region from 1990 to 2020 shows a more drastic change, with the main characteristics being an increase in the area of arable land and construction land, and a decrease in the area of forest and grassland, water, and unused land; and (2) with the change in the land-use types, the total value of the ESV in the Xinjiang region from 1990 to 2020 showed an increasing and then decreasing trend, with an average annual contribution value of about 13,730.33 × 108 yuan and a cumulative loss of about 1741.00 × 108 yuan in the last 30a. The value of each individual ecosystem service was dominated by functions such as waste treatment and water connotation. Based on the analysis of the geographic probe model, we found that the single factor influence degree of the ESV was HAI > NDVI > precipitation > GDP > temperature > elevation > population density > slope, and the overall ecosystem service value in the Xinjiang region showed a decreasing trend due to the interaction coefficients of natural factors and socio-economic factors.

Attribution Assessment and Prediction of Runoff Change in the Han River Basin, China

The ecological environment and water resources of the Han River Basin (HRB) are incredibly susceptible to global warming. Naturally, the analysis of future runoff in HRB is believed to offer a theoretical basis for water resources management and ecological protection in HRB. The purpose of this study is to investigate and forecast the effects of climate change and land use change on runoff in the HRB. This study uses CMIP6 data to simulate three future climate change scenarios (SSP126, SSP245 and SSP585) for changes in precipitation and temperature, a CA-Markov model to simulate future land use change scenarios, and the Budyko framework to predict future runoff changes. The results show that: (1) Between 1974 and 2014, annual runoff (R) and annual precipitation (P) in the HRB decline not so significantly with a rate of 1.3673 mm/a and 1.2709 mm/a, while maximum temperature (Tmax) and minimum temperature (Tmin) and potential evapotranspiration (E0) show a non-significantly increasing trend with 0.0296 °C/a, 0.0204 °C/a and 1.3313 mm/a, respectively. Precipitation is considered as main contributor to the decline in Han River runoff, accounting for 54.1%. (2) In the HRB, overall precipitation and temperature are estimated to rise in the coming years, with all other hydrological variables. The comparison of precipitation rise under each scenario is as follows: SSP126 scenario > SSP585 scenario > SSP245 scenario. The comparison of the temperature increase under each scenario is as follows: SSP585 scenario > SSP245 scenario > SSP126 scenario. (3) In the HRB, farmland and grassland land will continue to decline in the future. The amount of forest acreage is projected to decline but not so significantly. (4) The future runoff of the HRB shows an increasing trend, and the future runoff varies in different scenarios and periods. Under the land use scenarios of maintaining LUCC1992-2014 and LUCC2040 and LUCC2060, the R change rates in 2015-2040 are 8.27-25.47% and -8.04-19.35%, respectively, and the R in 2040-2060 are 2.09-13.66% and 19.35-31.52%. At the same time, it is very likely to overestimate the future runoff of the HRB without considering the changes in the land use data of the underlying surface in the future.