Inland River Research Articles

Landscape Ecological Risk Assessment and Driving Force Analysis of the Heihe River Basin in the Zhangye Area of China

Watershed ecosystems are crucial to the overall sustainable development of a region, and a scientific and effective grasp of the characteristics of land-use change in a watershed, and the factors affecting land change, is an important prerequisite for the high-quality construction of watershed ecology, which needs to be emphasized. As the second largest inland river in the arid zone of Western China, the Heihe River Basin (HRB) has been affected by human and natural factors in recent years, and the ecological environment is relatively fragile, and there is an urgent need to analyze the ecological characteristics of the basin and to explore the relevant influencing factors in order to provide a basis for subsequent ecological management. Therefore, this article applies the landscape index, the landscape ecological risk index (ERI) model and the geodetector tools to analyze the land-use data from 2000 to 2020 in the Zhangye area of the HRB to study the characteristics of the ecological risk evolution and the driving forces affecting the ecological risk differentiation. The results show the following: (1) the area of the regional land-use change accounts for 4.99% of the total area, and the landscape pattern as a whole shows an increasing degree of fragmentation and a decreasing trend of aggregation; (2) the distribution of the ERI in the region shows a trend of being low in the center and high in the periphery, with an increase of 2.11% in the area of the lowest and lower risk and a decrease of 1.77% in the highest and higher, and the temporal change shows an increase followed by a significant decrease; (3) the human interference degree is the dominant factor influencing the spatial differentiation of the ERI in the basin area. There are significant differences between social factors, climate factors and land factors.

Hybrid Path Planning for Unmanned Surface Vehicles in Inland Rivers Based on Collision Avoidance Regulations.

In recent years, with the continuous advancement of the construction of the Yangtze River's intelligent waterway system, unmanned surface vehicles have been increasingly used in the river's inland waterways. This article proposes a hybrid path planning method that combines an improved A* algorithm with an improved model predictive control algorithm for the autonomous navigation of the "Jinghai-I" unmanned surface vehicle in inland rivers. To ensure global optimization, the heuristic function was refined in the A* algorithm. Additionally, constraints such as channel boundaries and courses were added to the cost function of A* and the planned path was smoothed to meet the collision avoidance regulations for inland rivers. The model predictive control algorithm incorporated a new path-deviation cost while imposing a cost constraint on the yaw angle, significantly minimizing the path-tracking error. Furthermore, the improved model predictive control algorithm took into account the requirements of rules in the cost function and adopted different collision avoidance parameters for different encounter scenarios, improving the rationality of local path planning. Finally, the proposed algorithm's effectiveness was verified through simulation experiments that closely approximated real-world navigation conditions.

Interaction, Adhesion and Aggregation of Microplastic/Nanoplastic Particles: Effects of Plastic Polymer Type

Microplastics (MP; <5 mm) and nanoplastics (NP; <1000 nm) are now ubiquitous in nature as they have been released into inland water, lakes, rivers, and marine water through direct discharge, runoff from upland watersheds, and other terrestrial environments. To understand the aggregation of MP and NP in the last decade, surveys and analytical efforts were undertaken. The MP and NP particles in the soil and water environments interact with other natural and engineered nanoparticles, which in turn form aggregates. These plastic particles could form homoaggregates and/or heteroaggregates depending on pH, ionic type, ionic valence, salt concentration, shape and size of the plastic particles, and the polymer type of MP. Differences in MP aggregation due to differences in plastic polymer type are not yet well documented. This review is conducted to investigate the effect of polymer type on the aggregation of MP and NP particles in the presence of various aggregation conditions.

Monitoring of chlorophyll-a and suspended sediment concentrations in optically complex inland rivers using multisource remote sensing measurements

In recent decades, phytoplankton proliferation and sediment input to rivers (especially urban rivers) have become more dramatic under the compound pressure of climate change and human activities. Given the generally narrow width of rivers and current high spatial resolution satellites, which are limited by band settings, bandwidth, and the signal-to-noise ratio, UAVs with their exceptional spatiotemporal resolution can be used as a useful tool for river environmental monitoring and inversion uncertainty assessment. In this study, UAV-based hyperspectral (X20P) and multispectral (P4M) images, along with Sentinel-2 MultiSpectral Instrument (MSI), Landsat-8 Operational Land Imager (OLI) and Landsat-9 OLI2 data, were used to assess the uncertainty in retrieving chlorophyll-a (Chla) and suspended sediment (SS) concentrations in rivers. Chla and SS models based on UAV and satellite data were constructed using stepwise multiple regression and typical Chla and SS retrieval algorithms, respectively, and the performance of the models was the focus of our research. The results demonstrated that in the Chla concentration inversion, each sensor performed as follows: X20P > P4M > Landsat9 OLI2 > Sentinel-2 MSI > Landsat8 OLI, and the performance in the SS concentration inversion was as follows: X20P > Sentinel-2 MSI > P4M > Landsat9 OLI2 > Landsat8 OLI. In addition, the uncertainty of high spatial resolution satellite retrievals was analyzed with the assistance of the UAV-based model. Results showed that narrow bandwidths and finely tuned band settings are more essential for the Chla inversion. The typical Chla retrieval algorithm, NDCI, is only effective in certain bands (band 1 from 684 to 724 nm and band 2 from 660 to 680 nm). It is also noted that Landsat8 and Landsat9 lack some key band settings (e.g., the red-edge band of 700–710 nm), severely limiting practical application in relation to Chla. However, specific variances in different sensor bands have a relatively small impact on SS inversion, for example, the correlation between SS and the R/B (a typical SS retrieval algorithm) constructed by each sensor ranged from 0.68 to 0.77. Chla monitoring, on the other hand, necessitates a higher spatial resolution than SS monitoring. The accuracy decreased markedly when UAV images were resampled to 10 m and 30 m spatial resolution. However, it is not as crucial for the SS inversion, images with the original spatial resolution (RMSE<30cm = 6.28 mg/L) were resampled to 10 m resolution (RMSE10m = 5.85 mg/L) and 30 m resolution (RMSE30m = 4.08 mg/L) while using P4M for SS inversion, and the accuracy increased. Our results demonstrated and highlighted various options for future monitoring of Chla and SS, while exploiting the synergy between UAVs and satellites to achieve more precise observations at greater spatial and temporal scales, which will benefit aquatic environment management and protection.

Assessing the evolution and attribution of watershed resilience in arid inland river basins, Northwest China

Water scarcity significantly limits the sustainable development of oasis economies in arid inland river basins. Quantifying watershed resilience and its drivers is a major focus in the fields of hydrology and water resources. In this study, the resilience indicator pi represents watershed resilience, while meteorological, hydrological, socioeconomic, and ecological factors are used to investigate the spatial and temporal patterns of resilience and important driving factors in the Hotan River Basin from 1958 to 2020 by combining principal component analysis and random forest model. Results show that the overall resilience of the Hotan River Basin is low, decreasing from the upper (upstream) to the middle and lower (downstream) reaches, and that the intensity of human activities has a negative impact on resilience. Rivers are more likely to reach maximum resilience after experiencing periods of wet and dry conditions, although there is a lag in this progress. The random forest machine learning algorithm was used to accurately predict the resilience levels of the two upstream tributaries Yurungkash and Karakash Rivers, and the downstream Hotan River, with classification accuracies of 84.2 %, 71.4 %, and 87 %, respectively. The factors affecting the resilience of the Yurungkash River are the 30-day maximum, base flow index, low pulse duration, median streamflow in May, median streamflow in August, median streamflow in October, and 7-day maximum. The set of factors used to classify the resilience of the Karakash River include the 7-day maximum, 1-day maximum, median streamflow in June, 30-day maximum, 3-day maximum, median streamflow in February, and autumn temperature. The factors affecting the resilience of the Hotan River are the watershed inflow, Xiaota station runoff, population growth rate, and effective irrigated area. The findings of this study provide a theoretical basis for integrated water resource management and the sustainable development of the oasis economy in the Hotan River Basin.

A dataset of water, heat, and carbon fluxes of an oasis agroecosystem in the middle areas of the Hexi Corridor (2012–2015)

The exchange of water, heat, and carbon dioxide between the terrestrial ecosystems and the atmosphere is a fundamental process that underlies mass and energy transfer at the Earth’s surface. The eddy covariance technique has become one of the preferred and state-of-the-art approaches for measuring and calculating the exchange of water, heat, and carbon between the land surface and the atmosphere. This dataset covers the fluxes of water, heat, and carbon dioxide in an oasis agroecosystem, as well as the auxiliary micrometeorological variables in the middle areas of the Hexi Corridor during 2012–2015. The experimental observation campaign was carried out by the Linze Inland River Basin Research Station, a member station of the China Flux Observation and Research Network (ChinaFLUX). The dataset serves as a fundamental source of data, enabling in-depth comprehension water transfer, energy exchange, carbon cycle processes in the oasis agroecosystem in arid regions, and even their environmental and vegetation controlling mechanisms. It offers valuable insights into better understanding hydrological processes, ecosystem-hydrology reaction and discovering the coupling between carbon, water and heat in the context of climate change. Furthermore, the dataset holds significant scientific value in addressing chronic practical challenges related to fragile environment and shortage of water resource, such as water and land resources management, the preservation of oasis stability and sustainable development, the conservation of oasis ecosystems, etc.

Impact of Ecological Restoration Project on Water Conservation Function of Qilian Mountains Based on InVEST Model—A Case Study of the Upper Reaches of Shiyang River Basin

Scientifically evaluating the influence of ecological restoration projects on the water conservation function (WCF) of regional ecosystems is the foundation for formulating regional ecological restoration policies and optimizing and adjusting ecological restoration projects. In this paper, we considered fully the runoff generation and confluence process in the Qilian Mountains with the actual situation of the basin and re-rated the parameter Z to improve the simulation accuracy of InVEST model. On this basis, the impact of ecological restoration project on the WCF in the upper reaches of Shiyang River Basin (SRB) in the eastern part of Qilian Mountains was quantified. The results showed that, on the whole, the water conservation depth (WCD) of forest land was the largest (138.5 mm) and that of cultivated land was the smallest (24.78 mm), while the water conservation coefficient of forest land was also the largest (93.36%) and that of unused land was the smallest (16.67%). From 1986 to 2018, the WCD showed an increasing trend in the upper reaches of SRB, among them, the WCD in the western tributaries increased faster than that in the eastern tributaries from 1986 to 2000. The significantly increased areas were mainly distributed in the middle reaches of the western tributaries and the river source areas of the eastern tributaries, while the significantly decreased areas were mainly distributed in the river source areas of the western tributaries and the cultivated land expansion area in the middle reaches of the eastern tributaries. From 2000 to 2018, the WCD of the eastern tributaries increased more than that of the western tributaries. The significantly increased areas were mainly distributed in the four eastern tributaries, and the significantly decreased areas were scattered in the middle and lower reaches of each tributary. From 1986 to 2000, the overall influence of land use change on the increase in WCD was negative, while the influence of climate and land use change on the increase in water conservation were both positive from 2000 to 2018. The influence of land use change on WCD was different in different tributaries. Among them, that of the western tributaries (except the Dongda River) was positive in two different periods, while that of the eastern tributaries (except the Xiying River) was changed from negative to positive. The implementation of ecological restoration project was one of the main reasons for the improvement of WCF in Qilian Mountains from 2000 to 2018, with a contribution of 9.04%. In the future, the protection and restoration of decreased areas of WCF should be strengthened, and the Z value determined in this paper is expected to be applied in the arid inland river basins of northwest China.

Ecological Water Requirement of Vegetation and Water Stress Assessment in the Middle Reaches of the Keriya River Basin

Desert oases are vital for maintaining the ecological balance in arid regions’ inland river basins. However, fine-grained assessments of water stress in desert oasis ecosystems are limited. In our study, we aimed to evaluate the water stress in desert oasis ecosystems in the middle reaches of the Keriya River Basin, with a specific focus on their ecological functions and optimizing water resource management. We hypothesized that evapotranspiration has significant effects on ecological water consumption. First, we estimated the actual evapotranspiration (ET) and potential evapotranspiration (PET) based on the SEBS (surface energy balance system) model and remote sensing downscaling model. Then, the ecological water requirement (EWR) and ecological water stress (EWS) index were constructed to evaluate the ecological water resource utilization. Finally, we explored the influencing factors and proposed coping strategies. It was found that regions with higher ET values were mainly concentrated along the Keriya River and its adjacent farmland areas, while the lower values were observed in bare land or grassland areas. The total EWR exhibited the sequence of grassland &gt; cropland &gt; forest, while the EWR per unit area followed the opposite order. The grassland’s EWS showed a distinct seasonal response, with severe, moderate, and mild water shortages and water plenitude corresponding to spring, summer, autumn, and winter, respectively. In contrast, the land use types with the lowest EWS were water areas that remained in a state of water plentitude grade (0.08–0.20) throughout the year. Temperature and vegetation index were identified as the primary influencing factors. Overall, this study provides a reliable method for evaluating the EWR and EWS values of basin scale vegetation, which can serve as a scientific basis for formulating water resource management and regulation policies in the region.

Evaluation of nuclear magnetic resonance spectroscopy for characterisation and quantitation of water-soluble polymers in river water

Water-soluble polymers (WSPs) are commonly used in industrial, commercial, agricultural and pharmaceutical products and their molecular weights and concentrations vary considerably. Methods commonly used in the analysis of WSPs are often for pure products or formulations with only a few other high MW constituents. These methods, like size exclusion chromatography (SEC) or Gel Permeation Chromatography coupled with Mass Spectrometry (MS) can be frustrated by the impact of the necessary separation steps prior to identification and the limitations of MS when identifying and quantifying polymers. To that end, the employment of a Nuclear Magnetic Resonance (NMR) method to identify, characterize and quantify WSPs in the real-world is reported for the first time. Samples were taken from fourteen UK inland river sites, concentrated via air-drying, freeze-drying or vacuum-drying and analyzed using 1D 1H NMR and 2D 1H Diffusion Ordered Spectroscopy (DOSY) NMR analysis. Seven of the river sites showed the presence of polyethylene glycol (PEG) with a range of molecular weights, evidencing the application of these techniques in analysis of WSPs. Soil percolation models evidenced the proof of principle that these techniques can also be used for the detection of polyacrylamide (PAM) and polyacrylic acid (PAA). This work should better enable the evaluation of the biological impact of WSPs on aquatic organisms in future studies.

Coupling Simulation and Prediction of Sustainable Utilization of Water Resources in an Arid Inland River Basin under Climate Change

The arid endorheic basin of northwest China is characterized by rich land resources, water shortage, and a fragile ecological environment. The establishment of a credible coupling model of groundwater and surface water based on multi-source observation data is an effective means to study the change in basin water cycles and the sustainable utilization of water resources in the past and future. Based on the latest understanding of hydrogeological conditions, hydrology and water resource utilization data in the middle reaches of the Heihe River Basin (HRB), this paper constructs an up-to-date coupling model of surface water and groundwater to study the water balance change of the basin. The water resources data series under historical replay and CMIP5 climate model prediction are constructed to predict future changes in water resources. The study shows that, under the joint influence of natural conditions and human activities, the average annual recharge of groundwater in the study area from 1990 to 2020 is 17.98 × 108 m3/a, the average annual discharge is 18.62 × 108 m3/a, and the difference between recharge and discharge is −0.64 × 108 m3/a. The total groundwater storage is −19.99 × 108 m3, of which the groundwater storage from 1990 to 2001 was −17.52 × 108 m3 and from 2002 to 2020 was −2.47 × 108 m3. Abundant water from 2002 to 2020 in the basin significantly improved the loss of groundwater storage. Under the prediction of historical reappearance and the CMIP5 CNRM-CM5 model RCP4.5 and RCP8.5 pathways, the groundwater level of the Heihe River–Liyuanhe River inclined plain falls first because the HRB has just experienced a wet season and then rises according to future climate change. The groundwater level of the inclined plain east of the Heihe River and Yanchi basin decreases continuously because of the change in water cycle caused by human activities. The erosion accumulation plain is located in the groundwater discharge zone, and the water level is basically stable. Under the conditions of water resource development and utilization, the runoff of Zhengyixia hydrological station cannot meet the requirements of the “97 Water Dividing Plan” of the State Council in most years in the future, and the ecological and production water in the lower reaches of HRB cannot be effectively guaranteed. With the implementation of water-saving irrigation under the RCP4.5 and RCP8.5 scenarios, the runoff of Zhengyixia can meet the “97 Water Diversion Plan”. It is suggested to further improve the level of agricultural water savings in the middle reaches of the HRB and control the reasonable scale of cultivated land in order to reduce water consumption in the middle reaches of the HRB and implement sustainable utilization of water resources in the HRB.

Evaluation of trace elements in the sediments of intertidal zone around Mahin-Ugbo Area, southwestern Nigeria

This study assessed the spatial distribution of Trace Elements (TE) in the muddy sediments of the Mahin-Ugbo coastal area of Southwestern Nigeria, using Inductively Coupled Plasma-mass spectrometry, (ICP-MS). The physicochemical parameters (pH, EC and TDS) of the sediments were also determined. Results showed that the mean values for pH, E.C and TDS were 5.09, 153.6 μs/cm and 76.8 mg/L, respectively. Further, there was a varying distribution pattern of TE concentrations: Mn&gt; Zn &gt; Ba &gt; Cr &gt; V &gt; Sr &gt; Pb &gt; La &gt; Cu &gt; Ni &gt; Co &gt; As &gt; Th &gt; Sc &gt; Ga. The As, Pb, and Zn concentrations in the sediment with mean values of 11.2, 40.4 and 122.1 ppm, respectively, were significantly higher than the average concentrations of As (10 ppm), Pb (20 ppm) and Zn (90 ppm) in natural shale, suggesting anthropogenic TE enrichment in the study area. To corroborate this, the TE source apportionments in the sediments using correlation coefficient, bi-variant plots and principal component analyses showed that the TE enrichment may have been anthropogenically induced. Pollution status assessments using I-geo, contamination factors and pollution load index indicated that the study area's sediments is slightly to moderately polluted. These findings suggest that although the area is not heavily polluted, increasing human activities, from inland rivers to the coastal area, in the study area will in no time be a cause for concern.

Vegetation responses to ecological water delivery and prolonged droughts in an artificial desert oasis, Northwestern China

Irrational water usage in the middle reaches of inland rivers is detrimental to downstream oases, and the Qingtu Oasis is a typical downstream oasis that is degraded by water resource scarcity. The Qingtu Lake ecological water diversion project (EWDP) has restored the oasis, but the response pattern of different vegetation communities to environmental water and the dominant drivers of vegetation dynamics are not clear. Here, based on ground and satellite observations, this study investigated the spatial and temporal patterns of vegetation distribution and growth in the Qingtu Oasis from 2010 to 2022, and the reasons for the interannual variability in vegetation growth were also explained. The results showed that temporal variations in the distribution area of Phragmites australis (PA) followed a logistic curve after the EWDP, which increased rapidly from 2010 to 2019 and stabilized afterward. Meanwhile, the distribution area of Nitraria tangutorum (NT) presented a linear increase during the study period, with a 121.2% increase. Due to water inundation, the central region was occupied by PA communities, while NT communities moved to the edge. The spatial connectivity of PA patches increased significantly in contrast to the overall fragmentation tendency of NT patches in 2010–2022. The oasis tended to be homogenized and aggregated according to the morphological spatial pattern analysis, along with the landscape diversity and contagion indices. Enhanced vegetation growth, as indicated by the normalized difference vegetation index (NDVI), was observed in 76.1% of the vegetated lands, and the NDVI increasing rate was high near the canal. Using the random forest model, this study found that changes in groundwater depth were the most important driver of NDVI variability. The following influencing factors were atmospheric CO2 concentration, water inundation area and water delivery amount. In the absence of large increases in water delivery amount, oasis vegetation growth was susceptible to prolonged droughts. This study uncovers a nonlinear response of different vegetation communities to climate change and the EWDP in the downstream region of arid endorheic basins and identifies meteorological droughts as a key factor that should be fully considered in water delivery strategies. These findings lay a solid foundation for managing oasis restoration and water resource allocation in arid inland river basins.

Small Organisms in a Large River: What Provides the High Diversity of Scaled Chrysophytes in the Ob River?

Currents are one of the main factors favoring the dispersal of microscopic planktic organisms over inland lakes and rivers. Large rivers of the northern hemisphere, flowing from south to north, can increase the diversity of northern latitudes with boreal species, while high water levels and floods expand the range of ecotopes and the biodiversity of rivers. We studied the distribution of the taxonomic structure and species richness of scaled chrysophytes downstream of the Ob river—a large river in West Siberia—at the end of the high-water period (June). Methods of scanning and transmission microscopy allowed the determination of a high taxonomic richness of these organisms, 67 species in total. The species were unevenly distributed by stations, with the maximum number of species (54) occurring in a shallow still bay without current and with minimum turbidity and a small number of diatoms. The species diversity in the main current was represented mainly by ubiquitous and cosmopolitan species.Water level fall usually coincides with the end of the vegetation of many scaled chrysophytes and the formation of stomatocysts. The stomatocysts of different species may drift downstream and then germinate when they find suitable conditions at theappropriatetime. Large rivers that are subject to significant changes in water level during their hydrologicalperiodsare able to host ahigh diversity of microscopic planktic organisms. Studying this capacity may reinforce the hypothesis of an omnipresence, i.e., that “everything is everywhere”.

Snow Cover on the Tibetan Plateau and Topographic Controls

Snow cover plays a critical role in global energy and water cycles. Snow cover on the Tibetan Plateau (TP) provides vital water sources in western China and Himalayan regions, in addition to its weather and climate significance. The massive high mountain topography of the TP is the main condition for the presence and persistence of snow cover on the plateau at the mid-low latitudes of the Northern Hemisphere (NH). However, how the mountain topography controls snow-cover distribution on the TP remains largely unclear, and the relationship is not well quantified. Here, the spatial distribution and the topographic controls of snow cover on the TP are examined based on snow cover frequency (SCF) derived from MODIS snow cover product (MOD10A2 v005) and digital elevation model (DEM) data. The results show that snow cover on the TP is spatially unevenly distributed, and that it is characterized by rich snow and high SCF on the interior and the surrounding high mountain ranges, with less snow and low SCF in inland basins and river valleys. Snow cover on the TP presents elevation dependence: the higher the altitude, the higher the SCF, the longer the snow cover duration, and the more stable the intra-annual variation. The annual mean SCF below 3000 m above sea level (m a.s.l) is less than 4%, and it reaches 77% above 6000 m a.s.l. The intra-annual snow cover variation below 4000 m a.s.l features a unimodal distribution, while above 4000 m a.s.l it presents a bimodal distribution. The mean minimum SCF below 6000 m a.s.l occurs in summer, while above 6000 m a.s.l it occurs in winter. Due to differences in solar radiation and moisture condition caused by the mountain slope and aspect, the mean SCF generally increases with mountain slopes, and it is the highest on the north-facing aspect and the lowest on the south-facing aspect.

Ecological Security Assessment and Territory Spatial Restoration and Management of Inland River Basin—Based on the Perspective of Production–Living–Ecological Space

Ecological security evaluation and land space governance are effective ways to ensure regional ecological security and realize sustainable development. This study evaluated the ecological security status at the raster scale and conducted research on the restoration and governance of the national territory, with the aim of implementing accurate restoration, reducing ecological restoration costs, and increasing ecological restoration benefits. Taking the typical arid inland river Shule River Basin as an example, this study selected evaluation factors from production, living, and ecological perspectives, obtained the influencing factors of regional ecological security by spatial principal component analysis, and calculated the ecological security index on the grid scale of production, life and ecological space. The macro-scale national parks, ecological protection red line and other realistic constraints are combined with the grid-scale ecological security evaluation results to achieve accurate land space restoration and governance. The results show that the ecological space accounts for 79.23%, and the production space only accounts for 7.47%, which is similar to other inland river basins in arid areas. The study found that per capita GDP and distance to the road have a significant impact on the ecological security of the study area from the perspectives of production and life, while distance to the water, vegetation coverage, and land cover have a significant impact on ecological security from the ecological perspective. Moderate, moderate low and low ecological security zones account for 72.09% of the total area of the basin, indicating that the ecological security guarantee ability of the Shule River Basin is low. The ecological security level of the living space was the lowest, and the ecological security pattern of the basin area as a whole presented a “higher in the north and south and lower in the middle” characteristic. The land restoration and governance of the Shule River Basin area was divided into five types of ecological control, ecological conservation, ecological enhancement, ecological restoration and ecological management, of which the ecological control area accounted for as much as 35.86%, implying that ecological security in the Shule River Basin has attracted sufficient attention from the government. It is considered that the management of production and living space is more difficult, complex and important, and the proportion of space is relatively small, so it is necessary to focus on the comprehensive management project of ecological protection and restoration. However, the ecological endowment conditions of ecological space in the Shule River Basin are relatively poor, and the distribution area is vast, so natural restoration should be given priority, supplemented by artificial restoration. This study provides a reference for regional ecological security evaluation, ecological civilization construction, and national ecological security research and practice.

Enhancement of Cruise Boat Resilience to Strong Convective Gusts with Global Model Cumulus Variable Prediction

Ship pilots and maritime safety administration have an urgent need for more accurate and earlier warnings for strong wind gusts. This study firstly investigated the “Oriental Star” cruise ship capsizing event in 2015, one of the deadliest shipwreck events in recent years, and explored all related hydro-meteorological components in a global mesoscale model. It was found that rather than the missing signal in raw surface-wind prediction, the cumulus precipitation variable (CP) increased dramatically during the accident occurrence, which significantly corresponds to a sub-grid strong wind gust. The effective lead time could be extended from 24 h (deterministic model) to 48 h (ensemble model). This finding was then verified in another two recent deadly cruise boat accidents. The introduction of the new variable aims to improve the current maritime safeguard system in predicting sub-grid strong wind gusts for small-sized cruise boats offshore and in inland rivers. Finally, an automatic response system was developed to provide economical convection prediction via INMARSAT email communication, aiming to explore operational severe convective gust early warning and appropriate numerical mesoscale model applications.

Optimal allocation for land in an arid inland basin in northwest China: framework and application based on CLUE-S and MCR models.

Reasonable planning of the limited land resources can promote the coordinated development of social economic and ecological protection. It is very important to optimize the rational distribution of land resources in the arid inland river basin because of the scarce land. In this paper, the GIS technologies of spatial analysis, conversion of land use, and its effects at small regional extent (CLUE-S) and minimum cumulative resistance (MCR) model were used to optimize the land allocation. The ecological security pattern (ESP) was constructed through using MCR model, which included ecological source and resistance surface. The dynamics of land use and spatial optimizing allocation of Shiyang River Basin in 2025 and 2030 was simulated under three different optimization scenarios including farmland protection scenario (FPS), free development scenario (FDS), and ecological security pattern scenario (ESPS). It was found that under ESPS, farmland was reduced, but woodland, grassland, and water body were increased significantly. Under FPS, land for construction was controlled effectively, a large part of homestead was converted into farmland, and the potential of unused land was developed vigorously. Furthermore, the current FDS and macro policy guidance should be comprehensively considered. The ESPS was more suitable for the scientific development of Shiyang River Basin on a long view. The combination of CLUE-S and MCR can effectively improve the optimization methods under ecological process and ecological resistance of landscape elements.

Spatial Distribution and Driving Mechanisms of Rural Settlements in the Shiyang River Basin, Western China

In the context of the rural revitalization strategy, an accurate grasp of the spatial differentiation characteristics and influencing factors of rural settlements in underdeveloped arid inland river basins is urgently required. Taking the Shiyang River Basin as an example, rural settlements from 2000 to 2019 were examined via visual interpretation using satellite remote sensing data and official statistical data. Following the logic of “state characteristics—evolutionary patterns—influence factors—layout optimization”, the average nearest index, the gravity-center migration model, spatial statistical analysis, and other methods were used in combination with GIS. The spatiotemporal pattern evolution characteristics of rural settlements in the past 20 years were analyzed. The results revealed the following: (1) The distribution pattern of rural settlements in the study area is sheet-like and strip-shaped. The projects in the southeast are mostly distributed in a patchy pattern with high density, while the characteristics in the west and north are exactly opposite. The objects in the south are distributed in an alluvial area of rivers, while settlements in the north are located in an oasis area. (2) From 2000 to 2019, the scale of rural settlements in the Shiyang River Basin, where there is a simultaneous occurrence of newly-built and disappearing phenomena, shows an expansion trend that first increased quickly and then slowed down. Spatially, rural settlements in the basin show a clustering trend toward the southwest. (3) The distribution characteristics of rural settlements are close to water and roads, and they are greatly influenced by urban–rural integration and ecological migration. The results will provide a scientific basis for accelerating the modernization of rural areas and the construction of new rural areas according to local conditions.

Influence of Irrigation on Vertical Migration of Soil Organic Carbon in Arid Area of Inland River

Soil organic carbon is very important to increase crop yield. Understanding the composition changes and migration characteristics of SOC under different irrigation conditions in arid oasis areas is of great significance for the sustainable development of agro-ecosystem and the estimation of carbon balance of farmland ecosystem in arid areas. In this paper, classical statistics and geostatistics were used to study the leaching characteristics and migration laws of soil organic carbon under different irrigation conditions in Minqin Oasis, and the leaching amount and loss process and mechanism of SOC under different irrigation conditions were quantified. The research results showed that: (1) Irrigation increased the average 0–100 cm SOC content. After irrigation, SOC content decreased first and then increased with the increase in soil depth, with the maximum value of 8.56 g/kg and the minimum value of 1.82 g/kg. Compared with that before irrigation, SOC content in 0–30 cm surface layer was in leaching state, SOC content in 30–70 cm surface layer was accumulated, and SOC content in 70–100 cm surface layer had no obvious change. (2) Water was an important factor affecting soil carbon. The greater the irrigation amount, the higher the carbon leaching rate and the greater the migration amount. The SOC content in 0–30 cm soil layer was most significantly affected by irrigation, and the migration amount of SOC gradually decreased with the increase in soil depth. The maximum leaching rate of SOC was 36.8%, the minimum leaching rate was 13.5%, and its average leaching rate was 23.4%. (3) Due to the influence of soil infiltration rate under water, SOC content in different irrigation periods showed that the greatest SOC occurred in the 0–70 cm layer, and SOC content in soil was basically the same as that in non-irrigated areas on the fifth day after irrigation. (4) Precipitation, plastic film mulching, soil physical and chemical properties and other environmental factors were important factors affecting the migration and change in SOC content.

Proposed Z-Source Electrical Propulsion System of a Fuel Cell/Supercapacitor-Powered Ship

The use of green energy to power ships in the marine industry has attracted increasing attention in recent years. This paper presents an inland river cruise ship supplied by a fuel cell (FC) as the main power source and a supercapacitor (SC) as the auxiliary power source. Its propulsion inverter adopts the proposed high-boost Z-source inverter, and the proposed high-voltage-boost Z-source inverter (HVB-ZSI) principle is studied. The advantages of this proposed HVB-ZSI in two cases are verified through simulation. In case 1, it can be seen that the capacitance voltage is only 250 V, and the maximum inductance’s inrush current at the start is less than 200 A. But the capacitance voltage of HVB-ZSI reaches 383 V, and the inrush current is 300 A. While considering different constraints of the propulsion system, four operating modes for the set of the FC and SC are proposed. The small-signal model of the propulsion system is derived, and the control strategy is studied. By controlling the shoot-through duty cycle and modulation factor, the FC power, output power, and state of charge (SOC) of the SC can be controlled. Finally, to verify the performance of the proposed propulsion system, a hybrid power ship prototype equipped with a 7.5 kw propulsion motor is constructed. Four modes of the entire system are simulated by MATLAB/SIMULINK, and its performance is analyzed with experimental results. These results show that the new Z-source propulsion system has a promising application in new energy ships, as it has higher reliability and lower complexity and cost compared to conventional propulsion systems.