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A better understanding of the effects of climate change and land use/cover change (LUCC) on streamflow promotes the long-term water planning and management in the arid regions of northwestern China. In this paper, the Soil and Water Assessment Tool (SWAT) and a separation approach were used to evaluate and separate the effects of climate change and LUCC on streamflow in the Xiying River basin. The SWAT model was calibrated by the hydro-meteorological data from 1980-1989 to obtain the optimum parameters, which were validated by the subsequent application to the period between 1990-2008. Moreover, streamflow under several scenarios with different climate change and land use conditions in 1990-2008 and 2010-2069 were further investigated. Results indicate that, in the period of 1990-2008, the streamflow was dominated by climate change (i.e., changes in precipitation and temperature), which led to a 102.8% increase in the mean annual streamflow, whereas LUCC produced a decrease of 2.8%. Furthermore, in the future period of 2010-2039, the mean annual streamflow will decrease by 5.4% and 4.5% compared with the data of 1961-1990 under scenarios A2 and B2, respectively, while it will decrease by 21.2% and 16.9% in the period of 2040-2069, respectively. [ABSTRACT FROM AUTHOR]

The effects of global climate change and human activities are anticipated to significantly impact ecosystem services (ESs), particularly in urban agglomerations of arid regions. This paper proposes a framework integrating the dynamic Bayesian network (DBN), system dynamics (SD) model, patch generation land use simulation (PLUS) model, and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model for predicting land use change and optimizing ESs spatial patterns that is built upon the SSP-RCP scenarios from CMIP6. This framework is applied to the oasis urban agglomeration on the northern slope of the Tianshan Mountains in Xinjiang (UANSTM), China. The findings indicate that both the SD model and PLUS model can accurately forecast the distribution of future land use. The SD model shows a relative error of less than 2.32%, while the PLUS model demonstrates a Kappa coefficient of 0.89. The land use pattern displays obvious spatial heterogeneity under different climate scenarios. The expansion of cultivated land and construction land is the main form of land use change in UANSTM in the future. The DBN model proficiently simulates the interactive relationships between ESs and diverse factors. The classification error rates for net primary productivity (NPP), habitat quality (HQ), water yield (WY), and soil retention (SR) are 20.04%, 3.47%, 4.45%, and 13.42%, respectively. The prediction and diagnosis of DBN determine the optimal ESs development scenario and the optimal ESs region in the study area. It is found that the majority of ESs in UANSTM are predominantly influenced by natural factors with the exception of HQ. The socio-economic development plays a minor role in such urban agglomerations. This study offers significant insights that can contribute to the fields of ecological protection and land use planning in arid urban agglomerations worldwide. • An integrated framework combining DBN, SD, PLUS and InVEST models was proposed. • Impact of natural and socioeconomic factors on ESs was determined under climate scenarios. • The spatial pattern of ESs was optimized and partitioned using DBNs. • ESs in arid oasis urban agglomerations are mainly affected by natural factors. [ABSTRACT FROM AUTHOR]

Land-use change in oases of arid zones play a significant role in the sustainable development and stability of oases. This paper presents a typical case of successful efforts to mitigate land-use change, its drivers and effects on the oasis eco-environment at Keriya Oasis in the western arid zone of China using remotely-sensed data, official statistics, and data collected by field investigation. Mathematical models were developed to quantify important elements related to land-use change, including net change and total change. The results indicate that: (1) approximately 17% of land-use types of Keriya Oasis changed between 1991 and 2002; (2) socioeconomic development, climate change, and economic polices contributed to land-use change in the oasis; (3) inappropriate human activities were the main cause of land-use change and eco-environmental degradation in the oasis; and (4) the stability of the oasis is threatened by land-use change and unexpected eco-environmental changes in the oasis and oasis-desert ecotone. The study suggests irrational human activity in arid zones, and that caution should be exercised to maintain stability and sustainable development of oases. [ABSTRACT FROM AUTHOR]

The effects of land-use changes on the runoff process in the midstream plain of this arid inland river basin are a key factor in the rational allocation of water resources to the middle and lower reaches. The question is whether and by how much increasingly heavy land use impacts the hydrological processes in such an arid inland river basin. The catchment of the Heihe River, one of the largest inland rivers in the arid region of northwest China, was chosen to investigate the hydrological responses to hind-use change. Flow duration curves were used to detect trends and variations in runoff between the upper and lower reaches. Relationships among precipitation, upstream runoff, and hydrological variables were identified to distinguish the effects of climatic changes and upstream runoff changes on middle and downstream runoff processes. The quantitative relation between midstream cultivated land use and various parameters of downstream runoff processes were analysed using the four periods of land-use data since 1956. The Volterra numerical function relation of the hydrological non-linear system response was utilized to develop a multifactor hydrological response simulation model based on the three factors of precipitation, upstream runoff, and cultivated land area. The results showed that, since 1967, the medium- and high-coverage natural grassland area in the midstream region has decreased by 80.1%, and the downstream runoff has declined by 27.32% due to the continuous expansion of the cultivated land area. The contribution of cultivated land expansion to the impact on the annual total runoff is 14-31%, on the annual, spring and winter base flow it is 44-75%, and on spring and winter discharge it is 23-64%. Once the water conservation plan dominated by kind-use structural adjustments is implemented over the next 5 years, the mean annual discharge in the lower reach could increase by 8.98% and the spring discharge by 26.28%. This will significantly alleviate the imbalance between water supply and demand in both its quantity and temporal distribution in the middle and lower reaches. [ABSTRACT FROM AUTHOR]

Aeolian deposits from the Hulun Buir Desert of northeastern China are studied with optically stimulated luminescence dating methods to establish the chronology of dune building phases and climatic changes since the last deglaciation. Our results indicate that wet climate, marked by dune stabilization and soil development in the Hulun Buir Desert, commenced at ∼ 11 ka ago, and this early episode of dune stabilization lasted until ∼ 4.4 ka ago. This optimum climate between ∼ 11 and ∼ 4.4 ka ago is mostly the response to the strengthened monsoon circulation and increased precipitation in the Northern Hemisphere. The environment generally became arid after ∼ 4.4 ka ago, but the dry climate was interrupted by three phases of weak soil development occurring at ∼ 1.8–1.4, ∼ 1.2–1.0 and ∼ 0.84–0.5 ka ago, respectively. Such short events of dune stabilization were associated with the warm and humid climate in historical time. However, the present dune mobilization in the Hulun Buir Desert is mainly the result of poor land-use practices (land cultivation and overgrazing) since about 300 years ago. [ABSTRACT FROM AUTHOR]