Research

20 pages, 9220 KiB

Open AccessArticle

Research on the Characteristics of Raindrop Spectrum and Its Water Vapour Transport Sources in the Southwest Vortex: A Case Study of 15–16 July 2021

by Ting Wang, Maoshan Li, Ming Gong, Yuchen Liu, Yonghao Jiang, Pei Xu, Yaoming Ma and Fanglin Sun

Water 2024, 16(6), 837; https://doi.org/10.3390/w16060837 - 14 Mar 2024

Viewed by 558

Abstract

This study investigated the convective weather features, precipitation microphysical characteristics, and water vapour transport characteristics associated with a southwest vortex precipitation event that occurred on the eastern edge of the Qinghai–Tibet Plateau, coinciding with a southwest vortex event, from 15 to 16 July [...] Read more.

This study investigated the convective weather features, precipitation microphysical characteristics, and water vapour transport characteristics associated with a southwest vortex precipitation event that occurred on the eastern edge of the Qinghai–Tibet Plateau, coinciding with a southwest vortex event, from 15 to 16 July 2021, using conventional observations of raindrop spectra, ERA5 reanalysis data, CMORPH precipitation data, and the HYSPLIT_v4 backward trajectory model. The findings aim to provide theoretical insights for improving the forecasting and numerical simulations of southwest vortex precipitation events. The findings revealed that the precipitation event induced by the southwestern vortex at Emeishan Station on 15–16 July 2021 was characterised by high rainfall intensity and significant precipitation accumulation. The raindrop spectrum exhibited a broad distribution with a notable bimodal structure. Both the Sichuan Basin and the Tibetan Plateau were dominated by the South Asian high pressure at higher altitudes, while a pronounced low-pressure system developed at mid and low altitudes within the basin, establishing a meteorological context marked by upper-level divergence and lower-level convergence. Throughout the event, notable vertical uplift velocities were recorded across the Sichuan Basin and Tibetan Plateau, along with distinct positive vorticity zones in the lower and middle strata of the Sichuan Basin, indicating that the atmosphere was in a state of thermal instability. The majority of moisture was in the mid and lower troposphere with evident convergence movements, which played a crucial role in the southwest vortex’s development. WRF numerical simulations of the Emeishan precipitation event more accurately modelled the weather conditions for this precipitation but tended to overestimate the level of precipitation. It was observed that the region around Emei Mountain primarily received moisture influx from the southern Bay of Bengal and the South China Sea, with moisture transport chiefly originating from the Sichuan Basin and in a south-westward trajectory. Full article

(This article belongs to the Special Issue Climate and Water: Impacts of Climate Change on Hydrological Processes and Water Resources)

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19 pages, 7514 KiB

Open AccessArticle

Assessing Changes in Exceptional Rainfall in Portugal Using ERA5-Land Reanalysis Data (1981/1982–2022/2023)

by Luis Angel Espinosa, Maria Manuela Portela and Salem Gharbia

Water 2024, 16(5), 628; https://doi.org/10.3390/w16050628 - 20 Feb 2024

Viewed by 875

Abstract

This research examines the intricate changes in the number of occurrences and cumulative rainfall of exceptional events in Portugal spanning 42 hydrological years (from 1981/1982 to 2022/2023). The study has two primary objectives: assessing the hydrological spatial dynamics of a region susceptible to [...] Read more.

This research examines the intricate changes in the number of occurrences and cumulative rainfall of exceptional events in Portugal spanning 42 hydrological years (from 1981/1982 to 2022/2023). The study has two primary objectives: assessing the hydrological spatial dynamics of a region susceptible to climate-induced variations in exceptional rainfall and evaluating the proficiency of a ERA5-Land reanalysis rainfall dataset in capturing exceptional rainfall. Confronting methodological and data-related challenges (e.g., incomplete record series), the investigation uses continuous daily ERA5-Land rainfall series. Validation against the Sistema Nacional de Informação de Recursos Hídricos (SNIRH) and the Portuguese Institute for Sea and Atmosphere (IPMA) ensures the reliability of ERA5-Land data. Empirical non-exceedance probability curves reveal a broad consensus between reanalysis data and observational records, establishing the dataset’s suitability for subsequent analysis. Spatial representations of occurrences, cumulative rainfall, and rainfall intensity of events above thresholds throughout the overall 42-year period and two subperiods (late: 1981/1982–2001/2002; and recent: 2002/2003–2022/2023) are presented, illustrating spatial and temporal variations. A noteworthy shift in the spatial distribution of intense events from south to north is observed, emphasising the dynamism of such hydrological processes. The study introduces a novel dimension with a severity heat map, combining some key findings from the occurrences and cumulative rainfall through subperiods. This study significantly contributes to the understanding of hydrological dynamics in Portugal, providing valuable insights for risk management and the development of sustainable strategies tailored to the evolving patterns of exceptional rainfall. Full article

(This article belongs to the Special Issue Climate and Water: Impacts of Climate Change on Hydrological Processes and Water Resources)

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16 pages, 3698 KiB

Open AccessArticle

Impact of Soil Surface Temperature on Changes in the Groundwater Level

by Mukhamadkhan Khamidov, Javlonbek Ishchanov, Ahmad Hamidov, Ermat Shermatov and Zafar Gafurov

Water 2023, 15(21), 3865; https://doi.org/10.3390/w15213865 - 06 Nov 2023

Cited by 1 | Viewed by 1997

Abstract

The relationship between the soil surface temperature and groundwater level is complex and influenced by various factors. As the soil surface temperature increases, water evaporates quickly from the soil, which can lead to a decrease in the groundwater level. In this study, we [...] Read more.

The relationship between the soil surface temperature and groundwater level is complex and influenced by various factors. As the soil surface temperature increases, water evaporates quickly from the soil, which can lead to a decrease in the groundwater level. In this study, we analyzed the impact of soil surface temperature on changes in the groundwater level in the Bukhara region of Uzbekistan using data from 1991 to 2020. The Bukhara region experiences regular water shortages, increased soil salinization, and inefficient energy in lift-irrigated areas, which is a typical constellation of challenges to the water–energy–food–environment (WEFE) nexus. The soil surface temperature data were collected from the Hydrometeorological Service Agency, whereas groundwater level data were obtained from the database of the Amelioration Expedition under the Amu-Bukhara Basin Irrigation Systems Authority. We used linear regression analysis and Analysis of Variance (ANOVA) tests to establish the significance of the relationship between the soil surface temperature and groundwater level, as well as the impact of the location of the groundwater level measurements. The results indicate that the model was a good fit to the data, and both the intercept and the soil surface temperature were significant factors that affected groundwater level. The results further suggest that the strength of the relationship between solar radiation and soil surface temperature is very high, with a correlation coefficient of 0.840. This means that when solar radiation increases, soil surface temperature also tends to increase. The analysis also showed that 53.5% of the changes in groundwater level were observed by the regression model, indicating a moderately correlated relationship between the groundwater level and soil surface temperature. Finally, higher solar radiation leads to higher soil surface temperature and higher evapotranspiration rates, which can lead to a decrease in groundwater level. As a result, we observe that the soil surface temperature determines changes in the groundwater level in the study region. Full article

(This article belongs to the Special Issue Climate and Water: Impacts of Climate Change on Hydrological Processes and Water Resources)

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25 pages, 5557 KiB

Open AccessArticle

A General Method to Improve Runoff Prediction in Ungauged Basins Based on Remotely Sensed Actual Evapotranspiration Data

by Ziling Gui, Feng Zhang, Da Chang, Aili Xie, Kedong Yue and Hao Wang

Water 2023, 15(18), 3307; https://doi.org/10.3390/w15183307 - 19 Sep 2023

Viewed by 2449

Abstract

The availability of remotely sensed (RS) actual evapotranspiration (ET) provides a possibility for improving runoff prediction in ungauged basins. To develop a general practical method to improve runoff prediction by directly incorporating RS-ET into rainfall-runoff (RR) models, two modeling schemes are proposed: (i) [...] Read more.

The availability of remotely sensed (RS) actual evapotranspiration (ET) provides a possibility for improving runoff prediction in ungauged basins. To develop a general practical method to improve runoff prediction by directly incorporating RS-ET into rainfall-runoff (RR) models, two modeling schemes are proposed: (i) using RS-ET as direct input; and (ii) using RS-ET as partial direct input. The principle is to use RS-ET in cases where the runoff prediction can be improved. The two schemes are compared in over 200 basins using three RR models (Xinanjiang model, SIMHYD, and GR4J) and RS-ET inverted from AVHRR, and the modeling results in ungauged basins are assessed using the spatial proximity method. Results show that: (i) it is beneficial to incorporate RS-ET into the Xinanjiang model for over 85% of the basins, but this is not the case for SIMHYD and GR4J models; (ii) further model improvements can be obtained by using RS-ET as partial direct input, and are achieved in 91.1%, 59.0%, and 53.2% of the basins for Xinanjiang, SIMHYD, and GR4J, respectively; and (iii) incorporation of RS-ET is more applicable for Xinanjiang while less so for GR4J, and the efficacy is superior for basins that are relatively arid and were originally poorly simulated. Overall, using RS-ET as partial direct input is recommended. Full article

(This article belongs to the Special Issue Climate and Water: Impacts of Climate Change on Hydrological Processes and Water Resources)

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15 pages, 4857 KiB

Open AccessArticle

Long-Term Variability of the Hydrological Regime and Its Response to Climate Warming in the Zhizdra River Basin of the Eastern European Plain

by Bing Bai, Qiwei Huang, Ping Wang, Shiqi Liu, Yichi Zhang, Tianye Wang, Sergey P. Pozdniakov, Natalia L. Frolova and Jingjie Yu

Water 2023, 15(15), 2678; https://doi.org/10.3390/w15152678 - 25 Jul 2023

Cited by 1 | Viewed by 876

Abstract

Climate warming globally has a profound effect on the hydrological regime, amplifying evapotranspiration and precipitation and accelerating the processes of snow melt and permafrost thaw. However, in the context of small river basins—those encompassing less than 10,000 km²—the response of the [...] Read more.

Climate warming globally has a profound effect on the hydrological regime, amplifying evapotranspiration and precipitation and accelerating the processes of snow melt and permafrost thaw. However, in the context of small river basins—those encompassing less than 10,000 km²—the response of the hydrological regime to climate change is intricate and has not yet been thoroughly understood. In this study, the Zhizdra River Basin, a typical small river basin in the eastern European plain with a total drainage area of 6940 km², was selected to investigate the long-term variability of the hydrological regime and its responses to climate warming. Our results show that during the period of 1958–2016, the average runoff in the Zhizdra River Basin was approximately 170 mm, with significant fluctuations but no trend. Sensitivity analysis by the Budyko framework revealed that the runoff was more sensitive to changes in precipitation (P) compared to potential evapotranspiration (E₀), implying that the Zhizdra River Basin is limited by water availability and has a slightly dry trend. A comprehensive analysis based on the seasonality of hydrometeorological data revealed that temperature predominantly affects spring runoff, while P mainly controls autumn runoff. Both factors make significant contributions to winter runoff. In response to climate change, the nonuniformity coefficient (C_v) and concentration ratio (C_n) of runoff have noticeably declined, indicating a more stabilized and evenly distributed runoff within the basin. The insights gleaned from this research illuminate the complex hydrological responses of small river basins to climate change, underlining the intricate interrelation among evapotranspiration, precipitation, and runoff. This understanding is pivotal for efficient water resource management and sustainable development in the era of global warming. Full article

(This article belongs to the Special Issue Climate and Water: Impacts of Climate Change on Hydrological Processes and Water Resources)

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18 pages, 12918 KiB

Open AccessArticle

Spatiotemporal Patterns of Hydrological Variables in Water-Resource Regions of China

by Chao Zang, Huan Liu, Guotao Cui and Jing Liu

Water 2023, 15(9), 1643; https://doi.org/10.3390/w15091643 - 23 Apr 2023

Viewed by 1524

Abstract

The spatiotemporal patterns of key hydrological variables across China were illustrated based on the developed Water and Energy Transfer Processes model in China (WEP-CN model). Time series of four key hydrological variables, namely, precipitation (P), runoff (R), infiltration ( [...] Read more.

The spatiotemporal patterns of key hydrological variables across China were illustrated based on the developed Water and Energy Transfer Processes model in China (WEP-CN model). Time series of four key hydrological variables, namely, precipitation (P), runoff (R), infiltration (Inf), and actual evapotranspiration (ET_a), were obtained over 60 years. Then, the temporal trends and spatial differences of these variables were analyzed using the Mann-Kendall and linear methods on a national scale and on the water resource regional scale. Moreover, we explored the drivers and constraints for changes in R, Inf, and ET_a. The results showed: (1) Based on the coefficient of variations of P (5.24%), R (11.80%), Inf (2.57%), and ET_a (3.77%), R was more fluctuating than the other variables. (2) These variables followed a similar trend of gradually decreasing from the southeast coast to the northwest inland. (3) Changes in R and Inf were caused mainly by P, having correlation coefficients with precipitation of 0.74 and 0.73, respectively. The ET_a was constrained by a combination of P and energy. The results improved the refined and quantitative research on hydrological processes in China, identified the differences in hydrological variables between water-resource regions, and provided a useful supplement to the research of the large-scale hydrological process. Full article

(This article belongs to the Special Issue Climate and Water: Impacts of Climate Change on Hydrological Processes and Water Resources)

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20 pages, 25881 KiB

Open AccessArticle

The Impacts of Climate Change on the Hydrological Process and Water Quality in the Three Gorges Reservoir Area, China

by Yidian Sun, Wanshun Zhang, Hong Peng, Feng Zhou, Anna Jiang, Xiaomin Chen and Hao Wang

Water 2023, 15(8), 1542; https://doi.org/10.3390/w15081542 - 14 Apr 2023

Cited by 3 | Viewed by 2549

Abstract

With the intensification of climate change, understanding the impacts of climate change on the water cycle is vital for integrated watershed management. Based on the precipitation and temperature data from 1980 to 2018, the climatic change characteristics of the Three Gorges Reservoir Area [...] Read more.

With the intensification of climate change, understanding the impacts of climate change on the water cycle is vital for integrated watershed management. Based on the precipitation and temperature data from 1980 to 2018, the climatic change characteristics of the Three Gorges Reservoir Area were analyzed. The Soil and Water Assessment Tool (SWAT) was used to simulate the spatial and temporal distribution of runoff and water quality. The result indicated that precipitation showed clear inter-annual fluctuation, and the maximum and minimum temperatures showed an increasing trend with rates of 0.38 °C/10a and 0.29 °C/10a, respectively. The moving averages revealed that the annual averages of runoff, total nitrogen (TN), and total phosphorus (TP) loads showed a decreasing trend followed by an increasing trend, which experienced strong inter-annual fluctuations. The hydrological processes changed significantly at different spatial scales, and the most affected area was the middle and head of reservoir area. The highest correlation was found between precipitation and runoff (0.91), followed by TP (0.81), and TN (0.60), while extreme precipitation could result in a high probability of water pollution events. These findings provide useful information to support the utilization of water resources, especially in the face of strong climate change impacts. Full article

(This article belongs to the Special Issue Climate and Water: Impacts of Climate Change on Hydrological Processes and Water Resources)

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23 pages, 40810 KiB

Open AccessArticle

Long-Term Change of Lake Water Storage and Its Response to Climate Change for Typical Lakes in Arid Xinjiang, China

by Zijin Huang, Jianhua Xu and Lilin Zheng

Water 2023, 15(8), 1444; https://doi.org/10.3390/w15081444 - 07 Apr 2023

Cited by 3 | Viewed by 2008

Abstract

Lakes play a role as the sentinel of climate change. Surrounded by vast expanses of barren land with limited infrastructure, there is also a lack of knowledge about the dynamics of dryland lakes. The change of lake area can be effectively monitored by [...] Read more.

Lakes play a role as the sentinel of climate change. Surrounded by vast expanses of barren land with limited infrastructure, there is also a lack of knowledge about the dynamics of dryland lakes. The change of lake area can be effectively monitored by remote sensing, and multi-source satellite altimetry datasets provide the possibility to obtain long-term lake water level data. Using the Global Surface Water Monthly Historical dataset and altimetry water level dataset (Hydroweb), we reconstructed a time series of lake water storage changes in Xinjiang, Northwestern China, by establishing the empirical models based on the statistical relationship between the surface area and water level of each lake. We further explored lake response to climate change. The results show that the storage of water at Ayakkum Lake, Aqqikkol Lake and Aksayquin Lake have been undergoing an obvious expanding trend from 2000 to 2020, at a rate of

3.59 \times 10^{8} m^{3} / a

,

9.43 \times 10^{8} m^{3} / a

and

0.44 \times 10^{8} m^{3} / a

, respectively. In the plain and transition zone, Ulungur Lake showed an upward tendency (

0.413 \times 10^{8} m^{3} / a

) in water storage, while Manas Lake and Bosten Lake experienced shrinkage with descending rates of

- 0.1 \times 10^{8} m^{3} / a

and

- 0.86 \times 10^{8} m^{3} / a

. Temperature changes significantly affect the lake water storage on plateaus, especially those lakes supplied with a large proportion of glacial meltwater. Precipitation is a key factor for changes of lake storage in the plain and transition zones. Meanwhile, extreme weather and man-made factors also play crucial roles. To reduce the risk of flood and drought disasters, rational regulation of water resources is required, and a large-scale integrated catchment management plan can avoid inadvertent trade-offs. This research provides a new perspective for lake water storage inversion, as well as data support for water resources management in arid areas including Xinjiang. Full article

(This article belongs to the Special Issue Climate and Water: Impacts of Climate Change on Hydrological Processes and Water Resources)

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