Search Results (13)

As a critical link connecting groundwater and vegetation, the vadose zone’s lithological structural heterogeneity directly influences soil water distribution and vegetation growth. A comprehensive understanding of the ecological effects of the vadose zone can provide scientific evidence for groundwater ecological protection and natural vegetation conservation in arid regions. This study, taking the Minqin Basin in the lower reaches of China’s Shiyang River as a case, reveals the constraining effects of vadose zone lithological structures on vegetation water supply, root development, and water use strategies through integrated analysis, field investigations, and numerical simulations. The findings highlight the critical ecological role of the vadose zone. This role primarily manifests through two mechanisms: regulating capillary water rise and controlling water-holding capacity. They directly impact soil water supply efficiency, alter the spatiotemporal distribution of water deficit in the root zone, and drive vegetation to develop adaptive root growth patterns and stratified water use strategies, ultimately leading to different growth statuses of natural vegetation. During groundwater level fluctuations, fine-grained lithologies in the vadose zone exhibit stronger capillary water response rates, while multi-layered lithological structures (e.g., “fine-over-coarse” configurations) demonstrate pronounced delayed water release effects. Their effective water-holding capacities continue to exert ecological effects, significantly enhancing vegetation drought resilience. Full article

Soil organic carbon (SOC) is a crucial component for investigating carbon cycling and global climate change. Accurate data exhibiting the temporal and spatial distributions of SOC are very important for determining the soil carbon sequestration potential and formulating climate strategies. An important scheme of mapping SOC is to establish a link between environmental factors and SOC via different methods. The Shiyang River Basin is the third largest inland river basin in the Hexi Corridor, which has closed geographical conditions and a relatively independent carbon cycle system, making it an ideal area for carbon cycle research in arid areas. In this study, 65 SOC samples were collected and 21 environmental factors were assessed from 2011 to 2021 in the Shiyang River Basin. The linear regression (LR) method and two machine learning methods, i.e., support vector machine regression (SVR) and random forest (RF), are applied to estimate the spatial distribution of SOC. RF is slightly better than SVR because of its advantages in the comparison of classification. When latitude, slope, and the normalized vegetation index (NDVI) are used as predictor variables, the best SOC performance is shown. Compared with the Harmonized World Soil Database (HWSD), the optimal scheme improved the accuracy of the SOC significantly. Finally, the spatial distribution of SOC tended to increase, with a total increase of 135.94 g/kg across the whole basin. The northwestern part of the middle basin decreased by 2.82% because of industrial activities. The SOC in Minqin County increased by approximately 62.77% from 2011 to 2021. Thus, the variability of the spatial SOC increased. This study provides a theoretical basis for the spatial and temporal distributions of SOC in inland river basins. In addition, this study can also provide effective and scientific suggestions for carbon projects, offer a key scientific basis for understanding the carbon cycle, and support global climate change adaptation and mitigation strategies. Full article

Groundwater overexploitation for agricultural irrigation is prone to lead to numerous ecological concerns. This study delved into the present distribution and recent trend of groundwater levels in the plain areas of the Hexi Corridor in Northwest China according to the groundwater level depth (GWD) data from 264 monitoring wells in the Shiyang River Basin (SYB) and 107 in the Shule River Basin (SLB), recorded annually in April from 2019 to 2023. The key findings include the following: (1) Over the five-year span, the SYB’s GWD experienced change rates (CRs) ranging from −12.17 to 9.11 m/a (average: −0.13 m/a), with the number of monitoring wells showing increased and decreased GWDs accounting for 50% and 50%, respectively. By contrast, the SLB’s GWD exhibited CRs ranging from −1.87 to 2.06 m/a (average: 0.01 m/a), with the number of monitoring wells showing increased and decreased GWDs accounting for 52% and 48%, respectively; (2) the Wuwei (CR = 0.09 m/a) and Changning (0.58 m/a) basins in the SYB and the Yumen (0.06 m/a), Guazhou (0.05 m/a), and Huahai (0.03 m/a) basins in the SLB, witnessed rising groundwater levels. In contrast, the Minqin Basin (0.09 m/a) in the SYB and the southern Dunhuang Basin (0.04 m/a) in the SLB witnessed declines in the groundwater levels; (3) The groundwater sustainability assessment showed that the groundwater is still extremely unsustainable. This study’s insights are instrumental in targeted treatment, as well as the preparation and adjustment of sustainable groundwater protection strategies. Full article

Wind erosion is a key global environmental problem. As an important protective measure to provide services to the ecosystems in wind-eroded areas, the wind erosion prevention service is of great significance to the management of wind and sand hazards and ecological environment restoration in the wind-eroded areas and the neighboring areas. Taking the Shiyang River basin as the study area, the quality of supplies for wind erosion prevention services was estimated using the RWEQ model for the years 2005, 2010, 2015, and 2020; the trajectories of air masses at wind speeds higher than the sand-causing wind speeds were simulated based on the forward trajectory module of the HYSPLIT model for a 24 h period; the spatial simulation of the flow of wind erosion prevention services on a daily scale with Minqin Station as the sand source was carried out; and the beneficiary areas of wind erosion prevention services were identified. Based on the RWEQ model, the spatial patterns of potential wind erosion, actual wind erosion, and wind and sand stabilization services were obtained, and the supply areas were divided. From 2005 to 2020, the wind erosion prevention service flow in the Shiyang River basin was distributed along a northwest–southeast direction, with a radial decrease from the center to the periphery, and with an extremely strong extraterritorial effect. The amount of wind erosion in the basin has a variable downward tendency over time and a spatial distribution pattern of high in the north and low in the south. The area of higher sand fixation is distributed in the eastern oasis area and desert junction zone. The HYSPLIT model was used to simulate the transport paths of wind and sand within 24 h during 2005–2020, the transmission paths of the wind erosion prevention service flow were obtained to be 59–134, and the flows were 2.55 × 10⁴–3.85 × 10⁶ t, displaying a changing trend of first decreasing, then increasing, and then decreasing. Gansu Province, Ningxia Hui Autonomous Region, and Inner Mongolia Autonomous Region are the most important areas benefiting from the wind erosion prevention service flow in the Shiyang River basin. The wind erosion prevention service flows in the basin benefit 47 cities in 9 provinces. Full article

Although we are in an era of enormous global commitments to ecological restoration (the UN Decade on ER; the Bonn Challenge), little attention has been paid to the importance of sustained commitment to individual restoration initiatives and few resources have been dedicated to monitoring, especially the long-term and broad-scale evaluations that would allow us to understand how basin-scale restoration can result in complex spatiotemporal patterns. Remote sensing offers a powerful tool for evaluating restoration initiatives focused on water management in arid regions, where changes in vegetation growth can be tracked visually with measures like the generalized difference vegetation index (GDVI). In this paper, we evaluate the Comprehensive Treatment Program of the Shiyang River Basin (CTSRB), a landscape restoration initiative in China’s northwest, using a widely available remote sensing tool, showing how it can reveal the causes of fluctuating changes in restoration success. We focus on spatiotemporal variation, studying a time series from 2001 to 2020 using regression, trend, and stability analyses for six different divisions of the study region (the study area as a whole, the irrigated areas, the periphery of the irrigated regions, and the districts of Ba, Quanshan, and Hu) to evaluate the effects of the restoration initiative. The study period was divided into four equal-length phases based on the implementation timeline of the CTSRB, which includes one pre- and post-intervention interval and two stages of the CTSRB. We found that the CTSRB has played a positive role in the restoration of vegetation in the Minqin Basin, especially desert vegetation. However, the positive effects were not obvious in the first CTSRB period, which was characterized by a decline in vegetation growth likely caused by the strategy of “close the pumping-wells, transform the land”, which reversed a greening trend caused by the unsustainable irrigation of wasteland prior to the project’s initiation. During the second phase of the CTSRB, vegetation in the regions of “transform the land” gradually improved, and the growth of desert vegetation gradually improved and expanded as a result of more water flowing out of agricultural zones. The rate of vegetation recovery slowed down during the final phase of the CTSRB, and some areas even experienced a decline in the GDVI. Overall, our findings show that the CTSRB, by integrating water management and allowing for uninterrupted ecological restoration, drove complex regional changes in the GDVI, including successful restoration of desert vegetation. The spatiotemporal variable we observed underscores the importance of long-term commitment to arid land restoration initiatives and the importance of even longer-term monitoring using tools like remote sensing. Full article

Desertification is a global eco-environmental hazard exacerbated by environmental and anthropogenic factors. However, comprehensive quantification of each driving factor’s relative impact poses significant challenges and remains poorly understood. The present research applied a GIS-based and geographic detector model to quantitatively analyze interactive effects between environmental and anthropogenic factors on desertification in the Shiyang River Basin. A MODIS-based aridity index was used as a dependent variable, while elevation, near-surface air temperature, precipitation, wind velocity, land cover change, soil salinity, road buffers, waterway buffers, and soil types were independent variables for the GeoDetector model. A trend analysis revealed increased aridity in the central parts of the middle reach and most parts of the Minqin oasis and a significant decrease in some regions where ecological rehabilitation projects are underway. The GeoDetector model yielded a power determinant (q) ranging from 0.004 to 0.270, revealing elevation and soil types as the region’s highest contributing factors to desertification. Precipitation, soil salinity, waterway buffer, and wind velocity contributed moderately, while near-surface air temperature, road buffer, and land cover dynamics exhibited a lower impact. In addition, the interaction between driving factors often resulted in mutual or non-linear enhancements, thus aggravating desertification impacts. The prominent linear and mutual enhancement occurred between elevation and soil salinity and between elevation and precipitation. On the other hand, the results exhibited a non-linear enhancement among diverse variables, namely, near-surface air temperature and elevation, soil types and precipitation, and land cover dynamics and soil types, as well as between wind velocity and land cover dynamics. These findings suggest that environmental factors are the primary drivers of desertification and highlight the region’s need for sustainable policy interventions. Full article

The relationship between soil and vegetation is an essential scientific issue in surface environment change. (1) Background: Since the implementation of the Shiyang River Basin governance plan, it has become necessary to quantitatively evaluate the impact of ecological restoration on soil–vegetation spatial coupling. (2) Methods: A coupled model and a coupled coordination model are adopted in order to investigate the spatial coupling characteristics of soil–vegetation systems. Additionally, we explore the influences of climate factors and soil properties on the level of spatial coupling and coordination. (3) Results: From 2015 to 2020, the soil–vegetation spatial coupling coordination in the lower reaches of the Shiyang River Basin was poor, and the average annual proportion of areas with medium and low degrees of uncoordination reached 79.3%. The level of spatial coupling coordination is differed under different vegetation coverage scenarios, and the bare land mainly showed low and moderate imbalances, accounting for 90.3% of the annual average area. The annual average proportions of short coverage and canopy coverage coordinated areas were 53.4% and 49.3%, respectively. In particular, vegetation in the Minqin hinterland is highly sensitive to environmental changes. With the implementation of ecological water conveyance, the spatial coupling coordination between soil and vegetation has improved slightly; however, the effect is not obvious. (4) Conclusions: Precipitation, temperature, and potential evaporation affect the level of coupling coordination between soil and vegetation, with the former having a positive effect and the latter two having negative effects. In addition, soil enriched with sulfate and sand contributed to the disharmony of soil–vegetation relationships in the study area. Full article

Qingtu Lake is located between Tengger Desert and Badain Jilin Desert, Gansu Province, Northwest China. It is the terminal lake of Shiyang River. In recent years, Qingtu lake has maintained a certain area of water surface and vegetation by artificial water conveyance. It is of great significance in preventing the convergence of the two deserts and restraining the trend of ecological deterioration of Shiyang River Basin. The relationship between the water surface area and the ecological water conveyance have not been thoroughly investigated. This study analyzed the spatial and temporal distribution of water surface area of Qingtu Lake and surrounding reeds by interpreting remote sensing data; the change of water surface area under the influence of meteorological factors and water conveyance by linear regression; the water conveyance to maintain current water surface area by water balance method, as well as the reasonable ecological water delivery in high flow year, normal flow year and low flow year by the means of analyzing the upstream inflow and water consumption in Minqin Basin. The results showed that there is a significant correlation between the water surface area of Qingtu Lake, evaporation and ecological water conveyance, and the minimum and maximum water surface areas generally appear before and after water delivery, indicating that the ecological water delivery and evaporation are the two main factors affecting the water surface area change of Qingtu Lake. The result calculated by linear regression indicated that the ecological water delivery volume to maintain current water surface area of Qingtu Lake is 3.146 × 10⁷ m³/yr, while the value was 3.136 × 10⁷ m³/yr calculated by water balance method. These two results are similar and can be verified with each other. Reasonable ecological water conveyance of Qingtu Lake in high flow year, normal flow year and low flow years were 4 × 10⁷ m³/yr, 3.2 × 10⁷ m³/yr and 2.3 × 10⁷ m³/yr, respectively. Full article

This study was conducted to explore the distribution and changes of groundwater resources in the research area, and to promote the application of geographic information system (GIS) technology and its deep learning methods in chemical type distribution and water quality prediction of groundwater. The Shiyang River Basin in Minqin County was selected as the research object for analyzing the natural components distribution and its preliminary forecast in partial areas. With the priority control of groundwater pollutants, the concentration changes of four indicators (including the permanganate index) in different spatial distributions were analyzed based on the GIS technology, so as to provide a basis for the groundwater quality prediction. Taking the permanganate as a benchmark, this study evaluated the prediction effects of the conventional back propagation (BP) neural network (BPNN) model and the optimized BPNN based on the golden section (GBPNN) and wavelet transform (WBPNN). The algorithm proposed in this study is compared with several classic prediction algorithms for analysis. Groundwater quality level and distribution rules in the research area are evaluated with the proposed algorithm and GIS technology. The results reveal that GIS technology can characterize the spatial concentration distribution of natural indicators and analyze the chemical distribution of groundwater quality based on it. In contrast, the WBPNN has the best prediction result. Its average error of the whole process is 3.66%, and the errors corresponding to the six predicated values are all below 10%, which is dramatically better than the values of the other two models. The maximal prediction accuracy of the proposed algorithm is 97.68%, with an average accuracy of 96.12%. The prediction results on the water quality level are consistent with the actual condition, and the spatial distribution rules of the groundwater water quality can be shown clearly with the GIS technology combined with the proposed algorithm. Therefore, it is of great significance to explore the distribution and changes of regional groundwater quality, and this studywill play a critical role in determining the groundwater quality. Full article

The Chinese government hopes to implement groundwater table control to realize the sustainable utilization of groundwater resources based on controlling the current groundwater exploitation amount. In this study, a method to determine the control index of the groundwater table is proposed. In the method, the reasonable relationship between the groundwater table and groundwater exploitation amount is ensured using the groundwater numerical simulation model. The operability of the index determination is improved using a surrogate numerical model, and the annual hydrological dynamic is simplified to three scenarios of dry, flat, and wet. To verify this method, the Minqin Basin in Northwest China was chosen as a typical study area. It is assumed that the control index of groundwater exploitation in 2020 is 85,000 × 10³m³. Then, the preset annual water table index is calculated as [−0.70, 0.62, 1.13, −1.25, 1.36, 3.09] m [−0.77, 0.53, 1.05, −1.33, 1.27, 2.96] m, and [−0.83, 0.46, 0.99, −1.40, 1.20, 2.85] m for the chosen six monitoring wells, varying over the years with wet, flat, and dry scenarios. This method can ensure high precision, operability, and dynamic management when determining the control index of the groundwater table and satisfy the demand of managers. Full article

A lot of timeseries satellite products have been well documented in exploring changes in ecosystems. However, algorithms allowing for measuring the directions, magnitudes, and timing of vegetation change, evaluating the major driving factors, and eventually predicting the future trends are still insufficient. A novel framework focusing on addressing this problem was proposed in this study according to the temporal trajectory of Normalized Difference Vegetation Index (NDVI) timeseries of Moderate Resolution Imaging Spectroradiometer (MODIS). It divided the inter-annual changes in vegetation into four patterns: linear, exponential, logarithmic, and logistic. All the three non-linear patterns were differentiated automatically by fitting a logistic function with prolonged NDVI timeseries. Finally, features of vegetation changes including where, when and how, were evaluated by the parameters in the logistic function. Our results showed that 87.39% of vegetation covered areas (maximum mean growing season NDVI in the 17 years not less than 0.2) in the Shiyng River basin experienced significant changes during 2001–2017. The linear pattern, exponential pattern, logarithmic pattern, and logistic pattern accounted for 36.53%, 20.16%, 15.42%, and 15.27%, respectively. Increasing trends were dominant in all the patterns. The spatial distribution in both the patterns and the transition years at which vegetation gains/losses began or ended is of high consistency. The main years of transition for the exponential increasing pattern, the logarithmic increasing pattern, and the logarithmic increasing pattern were 2008–2011, 2003–2004, and 2009–2010, respectively. The period of 2006–2008 was the foremost period that NDVIs started to decline in Liangzhou Oasis and Minqin Oasis where almost all the decreasing patterns were concentrated. Potential disturbances of vegetation gradual changes in the basin are refer to as urbanization, expansion or reduction of agricultural oases, as well as measures in ecological projects, such as greenhouses building, afforestation, grazing prohibition, etc. Full article

To deal with the contradictions that are caused by natural conditions and unreasonable water allocations in Minqin County, which are located downstream of the Shiyang River basin in arid northwest China, an optimization-based multi-scale calculation method was proposed for analyzing agricultural water-saving potential. Firstly, an optimization model was developed for allocating water and land resources legitimately with the conjunctive use of surface water and groundwater. Secondly, the groundwater equilibrium was fully considered in developing optimization model to achieve the ecological value of agricultural water savings. Then, multi-scale agricultural water-saving potentials were analyzed based on optimal results under different water-saving levels. These results provide local water managers with satisfactory economic benefit with higher water use efficiency. With reasonable management strategies of water and land resources, the ecosystem of Minqin County could gradually recover in the future. The results of the multi-scale water-saving potential analysis can help decision makers to identify desired water-saving plans that consider the coordinated development of the local economy, society, and ecology. Full article

Ecological migration policy has been proposed and implemented as a means for depopulating ecological restoration areas in the arid Northwest China. Migration intention is critical to the effectiveness of ecological migration policy. However, studies on migration intention in relation to ecological migration policy in China remain scant. Thus this paper aims to investigate the rural residents’ migration intentions and their affecting factors under ecological migration policy in Minqin County, an ecological restoration area, located at the lower terminus of Shiyang River Basin in arid Northwest China. The data for this study come from a randomly sampled household questionnaire survey. Results from logistic regression modelling indicate that most residents do not intend to migrate, despite rigid eco-environmental conditions and governance polices threatening livelihood sustainability. In addition to demographic and socio-economic factors, the eco-environmental factors are also significantly correlated with the possibility of a resident intending to migrate. The implications of the significant independent variables for the sustainability of ecological migration policy are discussed. The paper concludes that ecological migration policies may ultimately be more sustainable when taking into account household interests within complex migration intention contexts, such as household livelihoods dynamics and environmental change. Full article