Water

Editorial

Jump to: Research

4 pages, 164 KiB

Open AccessEditorial

Hydrological Impact of Typhoon on Rivers

by Jr-Chuan Huang and Tsung-Yu Lee

Water 2021, 13(8), 1009; https://doi.org/10.3390/w13081009 - 07 Apr 2021

Viewed by 2512

Abstract

Rivers link terrestrial and marine ecosystems, not only transporting numerous substances downstream but also shaping landscapes and fostering aquatic ecosystems through physical interactions and biogeochemical processes with numerous agents. On the other hand, hydraulic facilities, such as reservoirs, hydropower plants, and banks are [...] Read more.

Rivers link terrestrial and marine ecosystems, not only transporting numerous substances downstream but also shaping landscapes and fostering aquatic ecosystems through physical interactions and biogeochemical processes with numerous agents. On the other hand, hydraulic facilities, such as reservoirs, hydropower plants, and banks are deployed to utilize water resources for sustaining human society. In the river network systems, rainstorms, as episodic/periodic strong triggers, can induce mass wasting from hillslopes, accelerating nutrient transport, which causes sequential effects. In recent decades, global warming has been accelerating water cycling via thermodynamics, and thus, the frequency and intensity of extreme rainstorms are increasing in intensity. In the West Pacific, typhoons (alias tropical cyclones in Asia) characterized by strong wind and torrential rainfall are evidenced to be getting stronger. The intensified typhoons inevitably stimulate the response of river systems through sediment and nutrient transport and threaten the safe operation of the hydraulic facilities and even coastal communities through storm surge flooding. These strong impacts on river systems should be comprehensively explored. This issue aims to improve the understanding of typhoon effects in river systems. Inter- and cross-disciplinary studies on different watershed scales, linking ecosystem services and watershed management, are particularly addressed. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

Research

Jump to: Editorial

20 pages, 46357 KiB

Open AccessArticle

Interaction among Controlling Factors on Riverine DIN Export in Small Mountainous Rivers of Taiwan: Inseparable Human-Landscape System

by Wen-Shiuan Lee, Jr-Chuan Huang, Chung-Te Chang, Shih-Chien Chan, Ying-San Liou, Chien-Sen Liao, Li-Chin Lee, Jun-Yi Lee, Yu-Ting Shih, Meng-Chang Lu and Pei-Hao Chen

Water 2020, 12(11), 2981; https://doi.org/10.3390/w12112981 - 23 Oct 2020

Cited by 4 | Viewed by 2617

Abstract

Increasing anthropogenic nitrogen (N) emission via different pathways has shown prominent impact on aquatic ecosystems for decades, but the effects of interaction among climate-, landscape- and human-associated variables on riverine DIN (dissolved inorganic nitrogen, mainly NO₃⁻ and NH₄⁺) [...] Read more.

Increasing anthropogenic nitrogen (N) emission via different pathways has shown prominent impact on aquatic ecosystems for decades, but the effects of interaction among climate-, landscape- and human-associated variables on riverine DIN (dissolved inorganic nitrogen, mainly NO₃⁻ and NH₄⁺) export are unclear. In this study, the data of 43 watersheds with a wide range of climate-, landscape- and human-associated gradients across Taiwan were evaluated with partial redundancy analysis (pRDA) to examine their interactive controls on riverine DIN export. Results show that the annual riverine DIN export in Taiwan is approximately 3100 kg-N km⁻² yr⁻¹, spanning from 230 kg-N km⁻² yr⁻¹ in less disturbed watersheds (eastern and central Taiwan) to 10,000 kg-N km⁻² yr⁻¹ in watersheds with intensive human intervention (southwestern and northern Taiwan). NO₃⁻ is generally the single dominant form of DIN, while NH₄⁺ renders significance in disturbed watersheds. Nearly all environmental variables display a positive correlation with DIN export, except for landscape setting variables (e.g., slope, area, channel length), which show a negative relationship. In terms of seasonal pattern, climate and human-landscape variables are related to NO₃⁻ export independently in the wet season, yet in the dry season climate-human variables jointly dominate NO₃⁻ export. Meanwhile, human-landscape (LH) variables (λ₁ of LH > 0.60) control NH₄⁺ exports in both seasons, and human-associated (H) variables (λ₁ of H = 0.13) have a minor effect on NH₄⁺ exports in dry season. Precisely, the contribution of controlling variables on DIN export vary with species and seasons, indicating water quality management could be time-dependent, which should be taken into consideration for designing mitigation strategies. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Figure 1

20 pages, 3064 KiB

Open AccessArticle

Investigating Sediment Dynamics in a Landslide-Dominated Catchment by Modeling Landslide Area and Fluvial Sediment Export

by Tse-Yang Teng, Jr-Chuan Huang, Tsung-Yu Lee, Yi-Chin Chen, Ming-Young Jan and Cheng-Chien Liu

Water 2020, 12(10), 2907; https://doi.org/10.3390/w12102907 - 18 Oct 2020

Cited by 3 | Viewed by 3337

Abstract

Few models are capable of simultaneously simulating the sequences of landslide occurrence and sediment export. Quantification of the temporarily stored sediment within the watershed plays a key role to link hillslope landslides with fluvial sediment export. In this study, two coupled models were [...] Read more.

Few models are capable of simultaneously simulating the sequences of landslide occurrence and sediment export. Quantification of the temporarily stored sediment within the watershed plays a key role to link hillslope landslides with fluvial sediment export. In this study, two coupled models were proposed to simulate time-series total landslide area and the subsequent sediment export on a daily basis with only the inputs of rainfall and runoff. The landslide model considers per-existing and models new landslide, and the sediment transport model incorporates a sediment storage variable. The landslide and sediment transport model were well evaluated with Nash-Sutcliffe efficiency (EC) of 0.89 and logarithmic Nash-Sutcliffe efficiency (EC_log) of 0.90, respectively, in the Tsengwen Reservoir watershed in southern Taiwan by using long-term observed data (2005–2015). It is found that reactivated landslides were up to 72% of the pre-landslide area, which contributed sediment comparable to the new landslide. Besides, the landslide model indicates that pre-landslide area controls the total landslide area but when rainfall is large it takes control in turn. With the simulation of sediment storage, the sediment transport model can well simulate the sediment export after the catastrophic event (typhoon Morakot in 2009). During the post-Morakot period, small rainfall and runoff can lead to high sediment export owing to the storage of Morakot-triggered landslide. This model will be a useful tool to diagnose the sediment dynamics in the watershed. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Figure 1

18 pages, 1886 KiB

Open AccessArticle

Effects of Land Cover and Atmospheric Input on Nutrient Budget in Subtropical Mountainous Rivers, Northeastern Taiwan

by Chung-Te Chang, Yu-Ting Shih, Li-Chin Lee, Jun-Yi Lee, Tsung-Yu Lee, Teng-Chiu Lin and Jr-Chuan Huang

Water 2020, 12(10), 2800; https://doi.org/10.3390/w12102800 - 09 Oct 2020

Cited by 3 | Viewed by 2264

Abstract

The nutrient budget, the difference between the nutrient output via stream and input via precipitation, can provide insights into how environmental processes affect forested ecosystem biogeochemistry. In this study, field measurements of the nutrient budgets—including Na⁺, Cl⁻, K⁺ [...] Read more.

The nutrient budget, the difference between the nutrient output via stream and input via precipitation, can provide insights into how environmental processes affect forested ecosystem biogeochemistry. In this study, field measurements of the nutrient budgets—including Na⁺, Cl⁻, K⁺, Mg²⁺, Ca²⁺, NO₃⁻, and SO₄²⁻—of 19 sites were conducted in Feitsui Reservoir Watershed (FRW) of northeastern Taiwan. A series of power-law regressions were developed to establish the relationship of the nutrient budget to the discharge, nutrient input, agricultural land cover, and slope. The result show that the weekly nutrient budget is significantly affected by agricultural land and input via precipitation (R² of regression models ≥ 0.90), yet the relationship varies among different nutrient elements. The agricultural land cover is the major factor, while the input via precipitation plays a relatively minor role in the budget of Cl⁻, Mg²⁺, Ca²⁺, and SO₄²⁻. These nutrients could be provisioned abundantly from the system, and thus the input via precipitation is not the predominant controlling factor. By contrast, the Na⁺ and K⁺ inputs via precipitation are indispensable for accurately estimating the riverine exports. Because weathering is a limited source of K⁺, the roles of agricultural activities and input via precipitation are likely decisive for transport. Besides, the NO₃⁻ budget reveals a strong interplay between the atmospheric input and agricultural land, as expected. Because the nutrient budget model of NO₃⁻ is strongly improved, the R² changes from 0.34 to 0.99 when a larger coefficient in exponent term (10.2) for agricultural land cover (showing that NO₃⁻ export is strongly hydrologically controlled) and precipitation input are included. Our analysis is based on one year of data, so extrapolating the result to a long-term period should be done with caution, as there could be substantial inter-annual variation. The nutrient budget approach provides a preliminary assessment to evaluate the impacts of agriculture and atmospheric deposition on nutrient export, which can provide a precursory reference for watershed management for improving water quality and mitigating eutrophication. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Figure 1

21 pages, 5028 KiB

Open AccessArticle

Characterizing Density Flow Regimes of Three Rivers with Different Physicochemical Properties in a Run-Of-The-River Reservoir

by Ingu Ryu, Soonju Yu and Sewoong Chung

Water 2020, 12(3), 717; https://doi.org/10.3390/w12030717 - 06 Mar 2020

Cited by 13 | Viewed by 3006

Abstract

Inflow mixing affects the spatiotemporal heterogeneity of water quality in reservoirs. Reservoir water quality management requires accurate prediction of density flow regimes to understand the spatiotemporal distribution of dissolved and particulate nutrients and organics. This study aims to characterize the mixing and circulation [...] Read more.

Inflow mixing affects the spatiotemporal heterogeneity of water quality in reservoirs. Reservoir water quality management requires accurate prediction of density flow regimes to understand the spatiotemporal distribution of dissolved and particulate nutrients and organics. This study aims to characterize the mixing and circulation of three rivers with different physicochemical properties in a run-of-the-river (ROR) reservoir, using high-frequency monitoring and three-dimensional (3D) hydrodynamic modeling. The Aquatic Ecosystem Model (AEM3D) was constructed for the reservoir and calibrated with high-frequency data obtained from May–June 2016, accurately reproducing the observed spatiotemporal variations of flow velocity, water temperature, and electrical conductivity (EC) in the reservoir. High-frequency data and 3D model results showed that mixing of the rivers in the ROR reservoir is governed by density flow regimes formed by influent water temperature differences. At the confluence, colder and warmer river influents formed underflows and surface buoyant overflows, respectively. The spatial arrangement of flow direction, water residence time, and EC concentration were largely controlled by the buoyancy-driven flow. Stagnant areas with long residence times corresponded with areas of observed algal blooms and hypoxia. High-frequency sensor technology, combined with 3D hydrodynamic modeling, is effective for understanding the complex flow regimes and associated water quality characteristics in ROR-type reservoirs. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Graphical abstract

24 pages, 6184 KiB

Open AccessArticle

Analysis of Environmental Factors Associated with Cyanobacterial Dominance after River Weir Installation

by Sungjin Kim, Sewoong Chung, Hyungseok Park, Youngcheol Cho and Heesuk Lee

Water 2019, 11(6), 1163; https://doi.org/10.3390/w11061163 - 03 Jun 2019

Cited by 23 | Viewed by 4507

Abstract

Following the installation of 16 weirs in South Korea’s major rivers through the Four Rivers Project (2010–2012), the water residence time increased significantly. Accordingly, cyanobacterial blooms have occurred frequently, raising concerns regarding water use and the aquatic ecosystem health. This study analyzed the [...] Read more.

Following the installation of 16 weirs in South Korea’s major rivers through the Four Rivers Project (2010–2012), the water residence time increased significantly. Accordingly, cyanobacterial blooms have occurred frequently, raising concerns regarding water use and the aquatic ecosystem health. This study analyzed the environmental factors associated with cyanobacterial dominance at four weirs on the Nakdong River through field measurements, and parametric and non-parametric data mining methods. The environmental factors related to cyanobacterial dominance were the seven-day cumulative rainfall (APRCP7), seven-day averaged flow (Q7day), water temperature (Temp), stratification strength (ΔT), electrical conductivity (EC), dissolved oxygen (DO), pH, and NO₃–N, NH₃–N, total nitrogen (TN), total phosphorous (TP), PO₄–P, chlorophyll–a, Fe, total organic carbon (TOC), and SiO₂ content, along with biological and chemical oxygen demands. The results indicate that site-specific environmental factors contributed to the cyanobacterial dominance for each weir. In general, the physical characteristics of EC, APRCP7, Q7day, Temp, and ΔT were the most important factors influencing cyanobacterial dominance. The EC was strongly associated with cyanobacterial dominance at the weirs because high EC indicated persistent low flow conditions. A minor correlation was obtained between nutrients and cyanobacterial dominance in all but one of the weirs. The results provide valuable information regarding the effective countermeasures against cyanobacterial overgrowth in rivers. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Graphical abstract

21 pages, 1655 KiB

Open AccessArticle

Variation and Driving Factors of Water Discharge and Sediment Load in Different Regions of the Jinsha River Basin in China in the Past 50 Years

by Shang-Wu Liu, Xiao-Feng Zhang, Quan-Xi Xu, De-Chun Liu, Jing Yuan and Miao-Lin Wang

Water 2019, 11(5), 1109; https://doi.org/10.3390/w11051109 - 27 May 2019

Cited by 16 | Viewed by 3942

Abstract

The Jinsha River is the main source of sediment in the Yangtze River Basin. The variation of water discharge and sediment load not only affects the operation of the cascade reservoirs in the basin but also change the water and sediment conditions into [...] Read more.

The Jinsha River is the main source of sediment in the Yangtze River Basin. The variation of water discharge and sediment load not only affects the operation of the cascade reservoirs in the basin but also change the water and sediment conditions into the Three Gorges Reservoir. The Jinsha River Basin is divided into six regions based on the measured data of hydrological stations. Herein, the variation regularity and driving factors of water discharge and sediment load in the Jinsha River Basin are analyzed in the past 50 years using the Mann–Kendall and Rank Sum Test. Results show that the source of water and sediment in the Jinsha River Basin is different, and the abrupt and trend changes of water discharge and sediment load in different regions are evident different. Changes in precipitation, water and soil conservation projects, and the construction of reservoirs are the main driving factors of sediment load variation. The average annual sediment reduction load in the Jinsha River from 1998 to 2015 is approximately 99.57 × 10⁶ t/y, of which the contributions of water discharge change and human activities to sediment load are 18.9% and 81.1%, respectively. The reduction of sediment load in the Jinsha River Basin can result in evident decrease in the sedimentation of cascade reservoirs, erosion of the downstream channel of the river, and considerable reduction of sediment load into the Three Gorges Reservoir. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Figure 1

17 pages, 6307 KiB

Open AccessArticle

Investigating Influence of Hydrological Regime on Organic Matters Characteristic in a Korean Watershed

by SangSoo Baek, Hyuk Lee, Jongkwan Park and Kyung Hwa Cho

Water 2019, 11(3), 512; https://doi.org/10.3390/w11030512 - 12 Mar 2019

Cited by 8 | Viewed by 3237

Abstract

Source tracking of dissolved organic matter (DOM) is important to manage water quality in rivers. However, it is difficult to find the source of this DOM because various DOMs can be added from the river watershed. Moreover, the DOM composition can be changed [...] Read more.

Source tracking of dissolved organic matter (DOM) is important to manage water quality in rivers. However, it is difficult to find the source of this DOM because various DOMs can be added from the river watershed. Moreover, the DOM composition can be changed due to environmental conditions. This study investigated the change of organic matter characteristics in the Taewha River of Ulsan City, Korea, before and after rainfall. A Soil and Water Assessment Tool (SWAT) was used to simulate water flow from various sources, and dissolved organic matter characterization was conducted in terms of molecular size distribution, hydrophobicity, fluorescence excitation and emission, and molecular composition. From the results, it was found that lateral flow transported hydrophobic and large-molecule organic matter after rainfall. According to the orbitrap mass spectrometer analysis, the major molecular compound of the DOM was lignin. Coupling the SWAT model with organic matter characterization was an effective approach to find sources of DOM in river. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Figure 1

22 pages, 6284 KiB

Open AccessArticle

Modeling Sediment Yields and Stream Stability Due to Sediment-Related Disaster in Shihmen Reservoir Watershed in Taiwan

by Yu-Jia Chiu, Hong-Yuan Lee, Tse-Lin Wang, Junyang Yu, Ying-Tien Lin and Yeping Yuan

Water 2019, 11(2), 332; https://doi.org/10.3390/w11020332 - 15 Feb 2019

Cited by 15 | Viewed by 4336

Abstract

Accurate and reliable estimates of sediment yields from a watershed and identification of unstable stream reaches due to sediment-related disaster are crucial for watershed management, disaster prevention, and hazard mitigation purposes. In this study, we added hydrodynamic and sediment transport modules in a [...] Read more.

Accurate and reliable estimates of sediment yields from a watershed and identification of unstable stream reaches due to sediment-related disaster are crucial for watershed management, disaster prevention, and hazard mitigation purposes. In this study, we added hydrodynamic and sediment transport modules in a recently developed model to estimate sediment yields and identify the unstable stream reaches in a large-scale watershed (> 100km²). The calibrated and verified models can well reproduce the flow discharge and sediment discharge at the study site, the Shihmen Reservoir Watershed in Taiwan, during several typhoon events. For the scenario applications, the results revealed that the contribution (> 96%) of landslides on sediment supply is much more significant than compared to soil erosion (< 4%). The sediment contribution from the upstream of the hydrological station-Yufeng is approximately 36–55% of the total sediment supply for the rainfall events of 25, 50, 100, and 200 years return period. It also indicates that 22–52% of sediment still remain at foot of the slope and the streams, which become a potential source for sediment hazards in the future. Combining with the bed erosion and deposition depths, flow-induced shear stress from the SRH-2D model, and probability of slope failure within 250 m of stream reaches, the relatively stability of stream reaches can be identified. The results could provide the water resource authorities for reference to take precautionary measures in advance on the stream reaches with high-degree instability. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Figure 1

18 pages, 8826 KiB

Open AccessArticle

Topographical Analysis of the 2013 Typhoon Haiyan Storm Surge Flooding by Combining the JMA Storm Surge Model and the FLO-2D Flood Inundation Model

by Lea Dasallas and Seungsoo Lee

Water 2019, 11(1), 144; https://doi.org/10.3390/w11010144 - 15 Jan 2019

Cited by 10 | Viewed by 4941

Abstract

The floods associated with the effects of an incoming tropical cyclone have an immense effect in the Philippines, especially with respect to agriculture, industry, livelihood, and public safety. Knowledge of how such storm surge flooding can affect the community is therefore of great [...] Read more.

The floods associated with the effects of an incoming tropical cyclone have an immense effect in the Philippines, especially with respect to agriculture, industry, livelihood, and public safety. Knowledge of how such storm surge flooding can affect the community is therefore of great importance. In this study, the mechanisms behind Typhoon Haiyan’s anomalous storm surge flooding in 2013, which resulted in more than 6300 casualties and 2.86 billion USD worth of damage in the Philippines, were investigated. The Japan Meteorological Agency (JMA) storm surge model and the FLO-2D flood model were used to simulate Typhoon Haiyan’s storm surge height and the extent of inundation, respectively. The storm surge input data were obtained from JMA typhoon data, and the digital terrain models used were gathered from the airborne interferometric synthetic aperture radar data. The model’s accuracy was also validated using field validation data of the extent of the observed storm surge in affected coastal areas. Topographical analysis of the inundated regions showed the effects of coastal shape, elevation, and position relative to the typhoon’s approach angle on storm surge flow depth and velocity. Storm surge maximum velocity appears to increase as the fluid flows to an increasingly elevated area. Observing fluid velocity in a coastal area with uniform storm surge discharge from all directions also showed that flow velocity tends to increase at the center. Greater flood depths were experienced in areas with lower coastal elevation and not directly located at the coast, compared to higher elevation coastal areas. Greater extents of storm surge flooding are expected in coastal areas that have a concave shape, as fluid is more likely to be dispersed when hitting a convex coast. Extents are likewise observed to be greater in coastal regions that are located perpendicular to the direction of the typhoon. The research also validated the option of using a combination of typhoon and flood models to simulate the inundation flooding caused by extreme weather events. Full article

(This article belongs to the Special Issue Hydrological Impact of Typhoon on Rivers)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Hydrological Impact of Typhoon on Rivers

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (10 papers)

Editorial

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI