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8 pages, 218 KiB

Open AccessEditorial

Hydrological Processes under Climate Change and Human Activities: Status and Challenges

by Qianfeng Wang, Haijun Deng and Jinshi Jian

Water 2023, 15(23), 4164; https://doi.org/10.3390/w15234164 - 1 Dec 2023

Cited by 3 | Viewed by 3296

Abstract

Climate change, driven by the intricate interplay between natural variability and anthropogenic activities, emerges as one of the paramount challenges of the 21st century [...] Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

Research

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20 pages, 5419 KiB

Open AccessEditor’s ChoiceArticle

Historical Drought Events in the Early Years of Qing Dynasty in Shanxi Based on Hydrological Reconstructions

by Yanping Qu, Xuejun Zhang, Jingyu Zeng, Zhe Li and Juan Lv

Water 2023, 15(5), 995; https://doi.org/10.3390/w15050995 - 6 Mar 2023

Cited by 7 | Viewed by 2606

Abstract

Droughts are serious natural disasters that adversely affect water resources, agriculture, the economy, and the environment. Reconstructing historical drought records is necessary to assess the impact of droughts and their evolution and has become a top priority to support and improve sustainable water [...] Read more.

Droughts are serious natural disasters that adversely affect water resources, agriculture, the economy, and the environment. Reconstructing historical drought records is necessary to assess the impact of droughts and their evolution and has become a top priority to support and improve sustainable water management decisions. In this study, we used Shanxi Province as the research area, and meteorological data from the early years of Guangxu in the Qing Dynasty were reconstructed using historical rain and snow records. The Variable Infiltration Capacity (VIC) model is driven by the reconstruction of historical meteorological data. The study area’s monthly runoff and soil water sequence from 1875 to 1879 were simulated, and the hydrology and soil of the ancient historical period were reproduced in the absence of data. The results show the following: (1) The idea of reconstructing hydrological parameters using historical data is feasible and the VIC model can be used to study drought characteristics under specific scenarios. (2) The proportions of areas with runoff depths less than 10 mm throughout Shanxi from 1875 to 1879 were 55%, 48%, 58%, 19%, and 30%. The annual runoff depth in each region from 1875 to 1877 was less than 60 mm. The hydrological drought from 1875 to 1877 was very serious, and the area covered by the drought was relatively large. (3) The annual average soil water content of various regions was stable between 150 and 510 mm from 1875 to 1879. The soil water content had no apparent interannual variation. The area with soil water content less than 180 mm accounted for ratios as high as 31%. This research provides new ideas for ancient drought research and a scientific basis for regional drought prevention, mitigation, and water resources management, and ensures the orderly progress of agricultural production activities. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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24 pages, 25347 KiB

Open AccessArticle

Effects of Climate Change on Streamflow in the Ayazma River Basin in the Marmara Region of Turkey

by Khaja Haroon Seddiqe, Rahmatullah Sediqi, Osman Yildiz, Gaye Akturk, Jakub Kostecki and Marta Gortych

Water 2023, 15(4), 763; https://doi.org/10.3390/w15040763 - 15 Feb 2023

Cited by 4 | Viewed by 2298

Abstract

This study investigates the effects of climate change on streamflow in the Ayazma river basin located in the Marmara region of Turkey using a hydrological model. Regional Climate Model (RCM) outputs from CNRM-CM5/RCA4, EC-EARTH/RACMO22E and NorESM1-M/HIRHAM5 with the RCP4.5 and RCP8.5 emission scenarios [...] Read more.

This study investigates the effects of climate change on streamflow in the Ayazma river basin located in the Marmara region of Turkey using a hydrological model. Regional Climate Model (RCM) outputs from CNRM-CM5/RCA4, EC-EARTH/RACMO22E and NorESM1-M/HIRHAM5 with the RCP4.5 and RCP8.5 emission scenarios were utilized to drive the HBV-Light (Hydrologiska Byråns Vattenbalansavdelning) hydrological model. A trend analysis was performed with the Mann–Kendall trend test for precipitation and temperature projections. A meteorological drought assessment was presented using the Standardized Precipitation–Evapotranspiration Index (SPEI) method for the worst-case scenario (i.e., RCP8.5). The calibrated and validated hydrological model was used for streamflow simulations in the basin for the period 2022–2100. The selected climate models were found to produce high precipitation projections with positive anomalies ranging from 22 to 227 mm. The increase in annual mean temperatures reached up to 1.8 °C and 2.6 °C for the RCP4.5 and RCP8.5 scenarios, respectively. The trend results showed statistically insignificant upward and downward trends in precipitation and statistically significant upward trends in temperatures at 5% significance level for both RCP scenarios. It was shown that there is a significant increase in drought intensities and durations for SPEI greater than 6 months after mid- century. Streamflow simulations showed decreasing trends for both RCP scenarios due to upward trend in temperature and, hence, evapotranspiration. Streamflow peaks obtained with the RCP8.5 scenario were generally lower than those obtained with the RCP4.5 scenario. The mean values of the streamflow simulations from the CNRM-CM5/RCA4 and NorESM1-M/HIRHAM5 outputs were approximately 2 to 10% lower than the observation mean. On the other hand, the average value obtained from the EC-EARTH/RACMO 22E outputs was significantly higher than the observation average, up to 32%. The results of this study can be useful for evaluating the impact of climate change on streamflow and developing sustainable climate adaptation options in the Ayazma river basin. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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17 pages, 1806 KiB

Open AccessArticle

Ecological Health Assessment with the Combination Weight Method for the River Reach after the Retirement and Renovation of Small Hydropower Stations

by Feng Cai, Zhinan Hu, Beihan Jiang, Weifang Ruan, Shujuan Cai and Huiling Zou

Water 2023, 15(2), 355; https://doi.org/10.3390/w15020355 - 14 Jan 2023

Cited by 2 | Viewed by 2495

Abstract

This study aimed to effectively evaluate the ecological restoration of the river reach where a small hydropower station was retired or renovated. An ecological health index system was constructed based on the environmental characteristics of the upstream and downstream of the small hydropower [...] Read more.

This study aimed to effectively evaluate the ecological restoration of the river reach where a small hydropower station was retired or renovated. An ecological health index system was constructed based on the environmental characteristics of the upstream and downstream of the small hydropower station after its retirement and renovation. Based on the combination weighting concept of game theory, the combination weights were obtained by the comprehensive analytic hierarchy process (subjective weight) and entropy method (objective weight). This ecological health assessment with fuzzy comprehensive evaluation was applied to assess the health status of Shimen (dam removal) and Changqiao (renovation in ecological flow) reaches of the Tufang River in Changting County, China. The results showed that the ecological health assessment index system proposed in this study was comprehensive and reasonable, and the revision degree of the hydropower station obviously influenced the process of ecological river restoration. The findings from this study would benefit for the rational utilization of water resources and the river ecological health maintenance in mountainous areas. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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19 pages, 3098 KiB

Open AccessArticle

Development of an Integrated Water Resource Scheduling Model Based on Platform Plug-In: A Case Study of the Wudu Diversion and Irrigation Area, China

by Beihan Jiang, Long Pan, Genquan Qin, Xiaolin Su, Feng Cai and Yue Liang

Water 2022, 14(22), 3671; https://doi.org/10.3390/w14223671 - 14 Nov 2022

Cited by 1 | Viewed by 2467

Abstract

Integrated water resource scheduling is a key strategy for controlling river floods as well as for promoting the benefits and abolishing the harmful aspects of water conservancy projects. It is necessary to explore an effective development mode to address the current issues of [...] Read more.

Integrated water resource scheduling is a key strategy for controlling river floods as well as for promoting the benefits and abolishing the harmful aspects of water conservancy projects. It is necessary to explore an effective development mode to address the current issues of long development times and poor outcomes for integrated water resource scheduling models. Drawing on the concept of software reuse, a development mode for an integrated water resource scheduling model is offered based on “platform system + model plug-in”, the cores of which are plug-in modules and interface integration. The boundaries and connection relations of each plug-in module are formed based on the logical analysis of the model plug-in. A web application mode is used to implement a standardized interface, which can be quickly and seamlessly connected to the system platform. The model is explored and applied in the Wudu diversion and irrigation area in China. The generated model is eventually verified using data obtained from two flood periods. According to the simulation results, the gate operation will be convenient, and the target water level will be attained in the allocated time with a satisfactory peak-clipping effect. It shows both good coordination and great utilization value of the plug-in modules. The concept of designing a plug-in database is eventually taken into consideration for combining and generating an optimization model of each river. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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15 pages, 8959 KiB

Open AccessArticle

Monitoring and Analysis of Water Surface Slope of the Yarlung Zangbo River Based on Remote Sensing

by Shidong Wang, Dunyue Cui and Jiahui Xu

Water 2022, 14(20), 3304; https://doi.org/10.3390/w14203304 - 19 Oct 2022

Cited by 3 | Viewed by 2768

Abstract

Global warming has led to an increase in interest in river hydrology. Water surface slope is a basic parameter of river morphology and is critical in understanding riverine ecosystems. The Yarlung Zangbo River is an important international river. Scientific understanding of its hydrology [...] Read more.

Global warming has led to an increase in interest in river hydrology. Water surface slope is a basic parameter of river morphology and is critical in understanding riverine ecosystems. The Yarlung Zangbo River is an important international river. Scientific understanding of its hydrology has been severely limited by its harsh topography and the sparse distribution of measurement stations. This paper describes the first attempt to use ICESat-2 satellite altimetry data to calculate river water slope and introduces a new technique for studying river hydrology. Water level data for different stretches of the Yarlung Zangbo River were obtained from high spatial resolution ICESat-2 altimetry data. The data were analyzed to determine the water surface slope of the Yarlung Zangbo River, and variation in the water surface slope was examined for several river sections. The water surface slope of the Yarlung Zangbo River was greatest in summer and autumn and least in winter and spring. There may be seasonal cyclic changes in the water surface slope. The range for water surface slope was large and the difference in extremes is significant; the maximum average water surface slope was 1935.17 cm/km and the minimum water surface slope was 0.08 cm/km. The water surface slope of the Yarlung Zangbo River can be characterized as small in the upper and middle reaches and large in the lower reaches; it is related to dry and wet conditions determined by topography and climate. The upper and middle reaches of the Yarlung Zangbo River are semi-arid and the lower reaches of the Yarlung Zangbo River span three climate zones: semi-arid, semi-humid and humid. In addition, the water level information measured by ICESat-2 data is basically similar to the water level information measured by Hydroweb data, except that the water level information of individual virtual stations is quite different due to special reasons. It was found that ICESat-2 data had higher-accuracy water level data results and more river location information. Therefore, ICESat-2 satellite altimetry data can provide a baseline reference for the study of the Yarlung Zangbo River hydrology, and the technique used is applicable to other rivers. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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16 pages, 4097 KiB

Open AccessArticle

Lake Changes in Inner Mongolia over the Past 30 Years and the Associated Factors

by Jiao Guo, Jiansheng Shi, Yilong Zhang, Zhongwu Wang and Wei Wang

Water 2022, 14(19), 3137; https://doi.org/10.3390/w14193137 - 5 Oct 2022

Cited by 7 | Viewed by 2830

Abstract

Lakes are important water resources in Inner Mongolia and play essential roles in flood storage, water source maintenance, aquaculture, water volume regulation, and the regional ecological balance. However, most lakes in Inner Mongolia have undergone significant shrinkage over the past few decades. In [...] Read more.

Lakes are important water resources in Inner Mongolia and play essential roles in flood storage, water source maintenance, aquaculture, water volume regulation, and the regional ecological balance. However, most lakes in Inner Mongolia have undergone significant shrinkage over the past few decades. In order to quantify the lake changes in Inner Mongolia and analyze the factors associated with these changes, information about 546 lakes in seven years (1990, 1995, 2000, 2005, 2010, 2015, and 2018) was retrieved using 30 m resolution Landsat images taken of the entire region over 29 years (1989–2018). In addition, water census data from 2010 and 1:250,000 geological maps were used as references. The analysis revealed that the lakes in Inner Mongolia exhibited rapidly decreasing trends during the past three decades, with both the area and the number of lakes decreasing to a minimum by 2010. The number of lakes with areas of >1 km² decreased from 384 in 1990 to 301 in 2018; the total area of lakes with individual areas of >1 km² decreased from 4905.74 km² in 1990 to 4187.45 km² in 2018. With respect to the lake distribution among different geomorphological units, the analysis revealed that the lake shrinkage was most pronounced on the West Liaohe Plain, followed by the northern Inner Mongolian Plateau. Furthermore, in relation to different climatic zones, lake shrinkage primarily occurred in the mid-temperate semi-arid zone, wherein the lake area decreased by 776.6 km². We hypothesize that the changes in the lake number and area in Inner Mongolia resulted from the combined effects of natural conditions and anthropogenic disturbances; possibly, lake shrinkage was mainly driven by the rising temperature and decreasing precipitation, along with water regulation projects, agricultural irrigation, mining development, and population growth that also had non-negligible effects on the lakes. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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20 pages, 8395 KiB

Open AccessFeature PaperArticle

Spatial-Temporal Evolution Characteristics and Driving Force Analysis of NDVI in the Minjiang River Basin, China, from 2001 to 2020

by Junyi Wang, Yifei Fan, Yu Yang, Luoqi Zhang, Yan Zhang, Shixiang Li and Yali Wei

Water 2022, 14(18), 2923; https://doi.org/10.3390/w14182923 - 18 Sep 2022

Cited by 11 | Viewed by 2861

Abstract

Monitoring vegetation growth and exploring the driving force behind it is very important for the study of global climate change and ecological environmental protection. Based on Normalized Difference Vegetation Index (NDVI) data from Moderate-Resolution Imaging Spectroradiometer (MODIS), meteorological and nighttime lights data from [...] Read more.

Monitoring vegetation growth and exploring the driving force behind it is very important for the study of global climate change and ecological environmental protection. Based on Normalized Difference Vegetation Index (NDVI) data from Moderate-Resolution Imaging Spectroradiometer (MODIS), meteorological and nighttime lights data from 2001 to 2020, this study uses the Theil–Sen slope test, Mann–Kendall significance test, Rescaled Range Analysis and partial correlation analysis to investigate the evolution of NDVI in the Minjiang River Basin, China, from three aspects: the spatial-temporal variation characteristics and future trend prediction of NDVI, the variation of climate and human activities in the basin, and the influences of different driving forces on NDVI. The results show that the average NDVI in the growing season was 0.60 in the Minjiang River Basin in the past twenty years, with a growth rate of 0.002/a. The area with high NDVI growth accounts for 66.02%, mainly distributed in the southeast, the central and the northern low-altitude areas of the basin. Combined with the Hurst index, the NDVI in the Minjiang River Basin exhibits an anti-sustainable tendency, with 63.22% of the area changing from improvement to degradation in the future. Meanwhile, the spatial differentiation of NDVI in the Minjiang River Basin is mainly affected by topography and climate factors, followed by human activities. This study not only provides scientific guidelines for the vegetation restoration, soil and water conservation and sustainable development of the Minjiang River Basin, but also provides a scientific basis for making informed decisions on ecological protection under the impacts of climate change and human activities. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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25 pages, 10349 KiB

Open AccessFeature PaperArticle

Evidence and Implications of Hydrological and Climatic Change in the Reno and Lamone River Basins and Related Coastal Areas (Emilia-Romagna, Northern Italy) over the Last Century

by Matteo Meli and Claudia Romagnoli

Water 2022, 14(17), 2650; https://doi.org/10.3390/w14172650 - 28 Aug 2022

Cited by 7 | Viewed by 3701

Abstract

Climate change and human activities have consequences on coastal areas as they affect hydrological processes in the related river basins. The riverine sediment supply to the beaches of the Emilia-Romagna coast, a highly urbanized area with high economic and naturalistic value, has been [...] Read more.

Climate change and human activities have consequences on coastal areas as they affect hydrological processes in the related river basins. The riverine sediment supply to the beaches of the Emilia-Romagna coast, a highly urbanized area with high economic and naturalistic value, has been heavily impacted by human activities throughout the catchment, reducing solid transport to the coast and increasing the threat of coastal erosion and flooding. Despite the introduction of safeguard policies in the early 1980s and the consequent stoppage of such activities, the expected return in solid transport has not yet been reflected at the coast. To better understand the various processes acting at the river basin scale, we utilized empirical mode decomposition to analyze the variability in different parameters (river discharge, rainfall, air temperature, and sea level) from the headwaters to the coast of the Reno and Lamone rivers over the last century. The anthropogenic footprint, linked to the large-scale dimming/brightening phenomenon, is visible in the long-term trends. Moreover, natural signals with variable periodicity are evident and partially correlated with two major climate modes (North Atlantic Oscillation and Atlantic Multidecadal Oscillation). The coupled interactions among these processes, combined with the changes in land use and evapotranspiration during the last century, have resulted in the prolonged scarcity of river sediment supply and a long-term trend of erosion of the coastal area. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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18 pages, 3097 KiB

Open AccessArticle

Realizing Sustainable Development of Yellow River Basin by Horizontal Eco-Compensation Based on Integrated Water Rights (IWRs) Transactions

by Yuxi Xie, Weihua Zeng, Yinglan Xue and Yue Zhuo

Water 2022, 14(17), 2646; https://doi.org/10.3390/w14172646 - 27 Aug 2022

Cited by 2 | Viewed by 1943

Abstract

Horizontal/interregional eco-compensation is an important policy to promote regional ecological and environmental cooperation and realize sustainable development for river basins. To solve these problems, a horizontal compensation framework based on integrated water rights (IWRs) transaction has been established. Taking the Yellow River basin [...] Read more.

Horizontal/interregional eco-compensation is an important policy to promote regional ecological and environmental cooperation and realize sustainable development for river basins. To solve these problems, a horizontal compensation framework based on integrated water rights (IWRs) transaction has been established. Taking the Yellow River basin as an example, the IWRs scheme realizes sustainable development, to a certain extent, improving the current issues of shortages, the low utilization efficiency of water resources, and weak water environmental carrying capacity. Evidence for this improvement includes: (1) an increased revenue of USD 244.71; (2) the water use efficiency in the middle and upper streams (Qinghai, Gansu, Ningxia, Neimenggu, Shanxi) and the overall river basin being obviously improved (the maximum improvement value is 0.1273 m³/USD); (3) the overload situation of water resource carrying status being relieved in some subareas (Ningxia, Neimenggu, Henan, Shandong) and improved in the whole basin (from 0.6366 to 0.6124); (3) the water environmental carrying rate (COD and NH₄⁺-N) of the middle and upper streams (Qinghai, Gansu, Ningxia, Neimenggu, Shanxi) and the whole river basin obviously decreasing (with maximum decreasing values of 0.43 and 1.14, respectively). Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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16 pages, 2101 KiB

Open AccessArticle

Developing Water-Quality Model for Jingpo Lake Based on EFDC

by Zihan Qin, Zhengwei He, Guozheng Wu, Gula Tang and Qian Wang

Water 2022, 14(17), 2596; https://doi.org/10.3390/w14172596 - 23 Aug 2022

Cited by 6 | Viewed by 2740

Abstract

Water-quality model simulation is the key to understanding hydrological processes and water-quality dynamic(s). In this study, Jingpo Lake, which is the most typical lake in the northern cold region of China, was selected as the research object. A numerical simulation model for transporting [...] Read more.

Water-quality model simulation is the key to understanding hydrological processes and water-quality dynamic(s). In this study, Jingpo Lake, which is the most typical lake in the northern cold region of China, was selected as the research object. A numerical simulation model for transporting and diffusing the chemical oxygen demand (COD_Mn) and ammonia nitrogen (NH₃N) with ice-covered and open-water periods was constructed and calibrated using the Environmental Fluid Dynamics Code (EFDC). Parameters such as the bottom roughness, ice roughness, diffusion coefficient, horizontal momentum diffusivity, molecular eddy viscosity, molecular diffusivity, buoyancy influence coefficient, COD_Mn decay rate and NH₃N decay rate were validated. The research findings show that there were differences in the hydrodynamic water-quality changing process during the ice-covered and open-water periods, as well as for the seasonal ice-covered waterbody. The key parameter decay rates of the COD_Mn and NH₃N in the ice-covered periods were lower than those in the open-water periods due to the water-temperature decline. The R² of the COD_Mn and NH₃N reached 90.71% and 79.79%, respectively. Thus, it may be concluded that the EFDC model could well reflect changes in the water level of Jingpo Lake, as well as the transport and diffusion of the COD_Mn and NH₃N in Jingpo Lake. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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34 pages, 8544 KiB

Open AccessArticle

Zoning Strategy for Basin Land Use Optimization for Reducing Nitrogen and Phosphorus Pollution in Guizhou Karst Watershed

by Xu Zhou, Wenbin Zhang, Yu Pei, Xiao Jiang and Shengtian Yang

Water 2022, 14(16), 2589; https://doi.org/10.3390/w14162589 - 22 Aug 2022

Cited by 4 | Viewed by 2152

Abstract

Eutrophication caused by excessive total nitrogen (TN) and total phosphorus (TP) emissions is of wide concern for society at large. Studies have revealed certain relationships among land use, TN, and TP. However, the relationships among land use compound topographic position, TP, and TN [...] Read more.

Eutrophication caused by excessive total nitrogen (TN) and total phosphorus (TP) emissions is of wide concern for society at large. Studies have revealed certain relationships among land use, TN, and TP. However, the relationships among land use compound topographic position, TP, and TN have seldom been studied. Therefore, the objectives of this paper are to construct optimal zoning of land use and reduce the nutrient load of lakes. Spearman correlation and redundancy analyses were used to reveal the relationship between land use comprehensive topographic position and TN and TP in the lakes of Guizhou Plateau. The results show that the nutritional state of the research area is medium. The trophic level index (TLI) value and TN concentration were high during flood periods, while TP concentration was high in dry periods. The TN concentration in the tributaries was higher than that in the reservoir area. Construction land and valley were the sources of the pollution, whereas forest land and gentle slope were the sink. According to the ”source–sink” effect, once the optimal zoning of land use is completed, the governance of urban land pollution governed areas should be strengthened next. This paper can provide decision support for water environment management and sustainable development decision-making. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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15 pages, 4479 KiB

Open AccessArticle

Temporal Variation of Soil Moisture and Its Influencing Factors in Karst Areas of Southwest China from 1982 to 2015

by Xiaocha Wei, Jixi Gao, Sihan Liu and Qiuwen Zhou

Water 2022, 14(14), 2185; https://doi.org/10.3390/w14142185 - 11 Jul 2022

Cited by 4 | Viewed by 2279

Abstract

Climate change and human activities are two dominating factors affecting soil moisture temporal variation trends, whereas their individual contributions to soil moisture trends still remain uncertain in the karst areas of Southwest China. Based on the linear regression trend analysis, Mann–Kendall mutation detection, [...] Read more.

Climate change and human activities are two dominating factors affecting soil moisture temporal variation trends, whereas their individual contributions to soil moisture trends still remain uncertain in the karst areas of Southwest China. Based on the linear regression trend analysis, Mann–Kendall mutation detection, and residual analysis methods, we quantified the contributions of climate change and human activities to soil moisture temporal variation trends in the karst areas of Southwest China. The results showed that the soil moisture in the study area experienced a drying trend from 1982 to 2015. The mutated year was 1999, and the soil moisture decreasing trend was more evident from 2000 to 2015 than from 1982 to 1999. Human activities and climate change accounted for 59% and 41%, respectively, of soil moisture drying trends. Owing to the spatial heterogeneity of geomorphic features, the individual contributions of climate change and human activities to soil moisture trends exhibited regional differences. Although remarkable regional vegetation restoration was found since applying the Grain for Green Project, the negative impact of vegetation restoration on soil moisture cannot be neglected. This study is a quantitative analysis of the relative impacts of climate change and human activities on soil moisture trends, and our findings provide a theoretical reference for the sustainable use of soil water resources in the karst areas of Southwest China. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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19 pages, 12510 KiB

Open AccessArticle

Extraction of Aquaculture Pond Region in Coastal Waters of Southeast China Based on Spectral Features and Spatial Convolution

by Lin Wang, Yefan Li, Dongzhu Zhang and Zhicai Liu

Water 2022, 14(13), 2089; https://doi.org/10.3390/w14132089 - 29 Jun 2022

Cited by 3 | Viewed by 2624

Abstract

To control the negative effects resulting from the disorderly development of aquaculture ponds and promote the development of the aquaculture industry, rapid and accurate identification and extraction techniques are essential. An aquaculture pond is a special net-like water body divided by complex roads [...] Read more.

To control the negative effects resulting from the disorderly development of aquaculture ponds and promote the development of the aquaculture industry, rapid and accurate identification and extraction techniques are essential. An aquaculture pond is a special net-like water body divided by complex roads and dikes. Simple spectral features or spatial texture features are not sufficient to accurately extract it, and the mixed feature rule set is more demanding on computer performance. Supported by the GEE platform, and using the Landsat satellite data set and corresponding DEM combined with field survey data, we constructed a decision-making model for the extraction of aquaculture ponds in the coastal waters, and applied this method to the coastal waters of Southeast China. This method combined the image spectral information, spatial features, and morphological operations. The results showed that the total accuracy of this method was 93%, and the Kappa coefficient was 0.86. The overlapping proportions of results between the automated extraction and visual interpretation for test areas were all more than 90%, and the average was 92.5%, which reflected the high precision and reliability of this extraction method. Furthermore, in 2020, the total area of coastal aquaculture ponds in the study area was 6348.51 km², which was distributed primarily in the cities of Guangdong and Jiangsu. Kernel density analysis suggested that aquaculture ponds in Guangdong and Jiangsu had the highest degree of concentration, which means that they face higher regulatory pressure in the management of aquaculture ponds than other provinces. Therefore, this method can be used to extract aquaculture ponds in coastal waters of the world, and holds great significance to promote the orderly management and scientific development of fishery aquaculture. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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20 pages, 6284 KiB

Open AccessFeature PaperArticle

Metropolis-Hastings Markov Chain Monte Carlo Approach to Simulate van Genuchten Model Parameters for Soil Water Retention Curve

by Xuan Du, Can Du, Jesse Radolinski, Qianfeng Wang and Jinshi Jian

Water 2022, 14(12), 1968; https://doi.org/10.3390/w14121968 - 20 Jun 2022

Cited by 5 | Viewed by 2785

Abstract

The soil water retention curve (SWRC) is essential for assessing water flow and solute transport in unsaturated media. The van Genuchten (VG) model is widely used to describe the SWRC; however, estimation of its effective hydraulic parameters is often prone to error, especially [...] Read more.

The soil water retention curve (SWRC) is essential for assessing water flow and solute transport in unsaturated media. The van Genuchten (VG) model is widely used to describe the SWRC; however, estimation of its effective hydraulic parameters is often prone to error, especially when data exist for only a limited range of matric potential. We developed a Metropolis-Hastings algorithm of the Markov chain Monte Carlo (MH-MCMC) approach using R to estimate VG parameters, which produces a numerical estimate of the joint posterior distribution of model parameters, including fully-quantified uncertainties. When VG model parameters were obtained using complete range of soil water content (SWC) data (i.e., from saturation to oven dryness), the MH-MCMC approach returned similar accuracy as the widely used non-linear curve-fitting program RETC (RETention Curve), but avoiding non-convergence issues. When VG model parameters were obtained using 5 SWC data measured at matric potential of around −60, −100, −200, −500, and −15,000 cm, the MH-MCMC approach was more robust than the RETC program. The performance of MH-MCMC are generally good (R² > 0.95) for all 8 soils, whereas the RETC underperformed for coarse-textured soils. The MH-MCMC approach was used to obtain VG model parameters for all 1871 soils in the National Cooperative Soil Characterization dataset with SWC measured at matric potentials of −60 cm, −100 cm, −330 cm, and −15,000 cm; the results showed that the simulated SWC by MH-MCMC model were highly consistent with the measured SWC at corresponding matric potential. Altogether, our new MH-MCMC approach to solving the VG model is more robust to limited coverage of soil matric potential when compared to the RETC procedures, making it an effective alternative to traditional water retention solvers. We developed an MH-MCMC code in R for solving VG model parameters, which can be found at the GitHub repository. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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18 pages, 4265 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Monitoring Recent Changes in Drought and Wetness in the Source Region of the Yellow River Basin, China

by Yanqun Ren, Jinping Liu, Masoud Jafari Shalamzari, Arfan Arshad, Suxia Liu, Tie Liu and Hui Tao

Water 2022, 14(6), 861; https://doi.org/10.3390/w14060861 - 10 Mar 2022

Cited by 21 | Viewed by 3187

Abstract

The source region of the Yellow River Basin (SRYRB) is not only sensitive to climate change and the vulnerable region of the ecological environment but also the primary runoff generating region of the Yellow River Basin (YRB). Its changes of drought and wetness [...] Read more.

The source region of the Yellow River Basin (SRYRB) is not only sensitive to climate change and the vulnerable region of the ecological environment but also the primary runoff generating region of the Yellow River Basin (YRB). Its changes of drought and wetness profoundly impact water resources security, food production and ecological environment in the middle and downward reaches of YRB. In the context of global warming, based on daily precipitation, maximum and minimum temperature of 12 national meteorological stations around and within SRYRB during 1960–2015, this study obtained standardized precipitation index (SPI) and reconnaissance drought index (RDI) on 1-, 3-, 6- and 12-month scales, and then compared the consistency of SPI and RDI in many aspects. Finally, the temporal and spatial variation characteristics of drought and wetness in the SRYRB during 1960–2015 were analyzed in this study. The results showed that SPI and RDI have high consistency on different time scales (correlation coefficient above 0.92). According to the average distribution and change trend of the RDI, SRYRB presented an overall wetness state on different time scales. We found an increasing trend in wetness since the early 1980s. In terms of wetness events of different magnitudes, the highest frequency for moderate and severe ones was in June (12.7%) and February (5.5%), respectively, and for extreme wetness events, both September and January had the highest frequency (1.8%). Among the four seasons, the change rate of RDI in spring was the largest with a value of 0.38 decade⁻¹, followed by winter (0.36 decade⁻¹) and autumn (0.2 decade⁻¹) and the smallest in summer (0.1 decade⁻¹). There was a greater consistency between RDI values of larger time scales such as annual and vegetation growing seasonal (VGS) scales in SRYRB. There was generally a growing trend in wetness in the VGS time scale. These findings presented in this study can provide data support for drought and wetness management in SRYRB. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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23 pages, 6458 KiB

Open AccessFeature PaperArticle

Detecting the Quantitative Hydrological Response to Changes in Climate and Human Activities at Temporal and Spatial Scales in a Typical Gully Region of the Loess Plateau, China

by Peng Guo, Jiqiang Lyu, Weining Yuan, Xiawan Zhou, Shuhong Mo, Dengrui Mu and Pingping Luo

Water 2022, 14(2), 257; https://doi.org/10.3390/w14020257 - 16 Jan 2022

Cited by 7 | Viewed by 2218

Abstract

This study examined the Chabagou River watershed in the gully region of the Loess Plateau in China’s Shaanxi Province, and was based on measured precipitation and runoff data in the basin over a 52-year period (1959–2010), land-use types, normalized difference vegetation index (NDVI), [...] Read more.

This study examined the Chabagou River watershed in the gully region of the Loess Plateau in China’s Shaanxi Province, and was based on measured precipitation and runoff data in the basin over a 52-year period (1959–2010), land-use types, normalized difference vegetation index (NDVI), and other data. Statistical models and distributed hydrological models were used to explore the influences of climate change and human activity on the hydrological response and on the temporal and spatial evolution of the basin. It was found that precipitation and runoff in the gully region presented a downward trend during the 52-year period. Since the 1970s, the hydrological response to human activities has become the main source of regional hydrological evolution. Evapotranspiration from the large silt dam in the study area has increased. The depth of soil water decreased at first, then it increased by amount that exceeded the evaporation increase observed in the second and third change periods. The water and soil conservation measures had a beneficial effect on the ecology of the watershed. These results provide a reference for water resource management and soil and water conservation in the study area. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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18 pages, 4942 KiB

Open AccessFeature PaperArticle

Spatio-Temporal Heterogeneity of Climate Warming in the Chinese Tianshan Mountainous Region

by Xuemei Li, Bo Zhang, Rui Ren, Lanhai Li and Slobodan P. Simonovic

Water 2022, 14(2), 199; https://doi.org/10.3390/w14020199 - 11 Jan 2022

Cited by 10 | Viewed by 2292

Abstract

The Chinese Tianshan mountainous region (CTMR) is a typical alpine region with high topographic heterogeneity, characterized by a large altitude span, complex topography, and diverse landscapes. A significant increase in air temperature had occurred in the CTMR during the last five decades. However, [...] Read more.

The Chinese Tianshan mountainous region (CTMR) is a typical alpine region with high topographic heterogeneity, characterized by a large altitude span, complex topography, and diverse landscapes. A significant increase in air temperature had occurred in the CTMR during the last five decades. However, the detailed, comprehensive, and systematical characteristics of climate warming, such as its temporal and spatial heterogeneity, remain unclear. In this study, the temporal and spatial heterogeneity of climate warming across the CTMR had been comprehensively analyzed based on the 10-day air temperature data gathered during 1961–2020 from 26 meteorological stations. The results revealed local cooling in the context of general warming in the CTMR. The amplitude of variation (AV) varied from −0.57 to 3.64 °C, with the average value of 1.19 °C during the last six decades. The lapse rates of the elevation-dependent warming that existed annually, and in spring, summer, and autumn are −0.5 °C/100 m, −0.5 °C/100 m, −0.7 °C/100 m, and −0.4 °C/100 m, respectively. The warming in the CTMR is characteristic of high temporal heterogeneity, as represented by the amplified warming at 10-d scale for more than half a year, and the values of AV were higher than 1.09 °C of the global warming during 2011–2020 (GWV_2011–2020). Meanwhile, the amplitudes of warming differed greatly on a seasonal scale, with the rates in spring, autumn, and winter higher than that in summer. The large spatial heterogeneity of climate warming also occurred across the CTMR. The warming pole existed in the warm part, the Turpan-Hami basin (below 1000 m asl) where the air temperature itself was high. That is, the warm places were warmer across the CTMR. The cooling pole was also found in the Kuqa region (about 1000 m asl). This study could greatly improve the understanding of the spatio-temporal dynamics, patterns, and regional heterogeneity of climate warming across the CTMR and even northwest China. Full article

(This article belongs to the Special Issue The Interrelationship between Climate Change, Human Activities and Hydrological Processes)

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