| 1. |
- Wang, Jie, et al.
(författare)
-
Impacts of Summer Monsoons on flood characteristics in the Lancang-Mekong River Basin
- 2022
-
Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 604
-
Tidskriftsartikel (refereegranskat)abstract
- The impact of monsoon on rainfall in the Lancang-Mekong River Basin (LMRB) has been well understood, but its impact on flood characteristic across the basin is still unclear. To investigate this impact, the Variable Infiltration Capacity (VIC) hydrological model was used to generate the basin-wide discharge and extract flood characteristics. Indian Summer Monsoon (ISM), Western North Pacific Monsoon (WNPM), and their combined effect (ISWN) were considered and represented by monsoon index. The monsoon impact area was firstly obtained based on the monsoon impact on rainfall, followed by the anomaly analyses of flood characteristics within the impact area to quantify the monsoon impact on floods at local and spatial scales. The results show that the ISM and WNPM (or ISWN) can significantly modulate up to 20% of the rainfall interannual variability in the western and eastern parts of the basin, respectively. The monsoon impact on flood is regionally distributed with impact in tributary larger than mainstream. Over half of the monsoon impact areas show the flood start date averagely advances (delays) 8–12 days, flood volume averagely increases (decreases) by 9%–17.5% and Q10 averagely increases (decreases) by 7.4%–14.4% during the strong (weak) monsoon years. Also, the comparisons between monsoon local and spatial impacts reveal that the trade-off of water from different areas can disturb the monsoon impact on flood, suggesting that more stations should be used when using the observed data to analyze the monsoon impact. More importantly, the ISM tends to cause the severe flood in northern Thailand, while WNPM and ISWN mainly induce the severe flood in the southeastern part of the LMRB. This study could help to increase the knowledge of the impact of climate change on flood and help with the regional flood managements.
|
|
| 2. |
- Kreibich, Heidi, et al.
(författare)
-
Panta Rhei benchmark dataset : Socio-hydrological data of paired events of floods and droughts
- 2023
-
Ingår i: Earth System Science Data. - : Copernicus Publications. - 1866-3508 .- 1866-3516. ; 15:5, s. 2009-2023
-
Tidskriftsartikel (refereegranskat)abstract
- As the adverse impacts of hydrological extremes increase in many regions of the world, a better understanding of the drivers of changes in risk and impacts is essential for effective flood and drought risk management and climate adaptation. However, there is currently a lack of comprehensive, empirical data about the processes, interactions, and feedbacks in complex human-water systems leading to flood and drought impacts. Here we present a benchmark dataset containing socio-hydrological data of paired events, i.e. two floods or two droughts that occurred in the same area. The 45 paired events occurred in 42 different study areas and cover a wide range of socio-economic and hydro-climatic conditions. The dataset is unique in covering both floods and droughts, in the number of cases assessed and in the quantity of socio-hydrological data. The benchmark dataset comprises (1) detailed review-style reports about the events and key processes between the two events of a pair; (2) the key data table containing variables that assess the indicators which characterize management shortcomings, hazard, exposure, vulnerability, and impacts of all events; and (3) a table of the indicators of change that indicate the differences between the first and second event of a pair. The advantages of the dataset are that it enables comparative analyses across all the paired events based on the indicators of change and allows for detailed context- and location-specific assessments based on the extensive data and reports of the individual study areas. The dataset can be used by the scientific community for exploratory data analyses, e.g. focused on causal links between risk management; changes in hazard, exposure and vulnerability; and flood or drought impacts. The data can also be used for the development, calibration, and validation of socio-hydrological models. The dataset is available to the public through the GFZ Data Services (Kreibich et al., 2023, 10.5880/GFZ.4.4.2023.001).
|
|
| 3. |
- Kreibich, Heidi, et al.
(författare)
-
The challenge of unprecedented floods and droughts in risk management
- 2022
-
Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 608:7921, s. 80-86
-
Tidskriftsartikel (refereegranskat)abstract
- Risk management has reduced vulnerability to floods and droughts globally, yet their impacts are still increasing. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change.
|
|
| 4. |
- Maghrebi, Mohsen, et al.
(författare)
-
Iran's Agriculture in the Anthropocene
- 2020
-
Ingår i: Earth's Future. - : John Wiley & Sons. - 2328-4277. ; 8:9
-
Tidskriftsartikel (refereegranskat)abstract
- The anthropogenic impacts of development and frequent droughts have limited Iran's water availability. This has major implications for Iran's agricultural sector which is responsible for about 90% of water consumption at the national scale. This study investigates if declining water availability impacted agriculture in Iran. Using the Mann‐Kendall and Sen's slope estimator methods, we explored the changes in Iran's agricultural production and area during the 1981‐2013 period. Despite decreasing water availability during this period, irrigated agricultural production and area continuously increased. This unsustainable agricultural development, which would have been impossible without the over‐abstraction of surface and ground water resources, has major long‐term water, food, environmental, and human security implications for Iran.
|
|
| 5. |
- Noori, Roohollah, et al.
(författare)
-
Anthropogenic depletion of Iran's aquifers
- 2021
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 118:25
-
Tidskriftsartikel (refereegranskat)abstract
- Global groundwater assessments rank Iran among countries with the highest groundwater depletion rate using coarse spatial scales that hinder detection of regional imbalances between renewable groundwater supply and human withdrawals. Herein, we use in situ data from 12,230 piezometers, 14,856 observation wells, and groundwater extraction points to provide ground-based evidence about Iran’s widespread groundwater depletion and salinity problems. While the number of groundwater extraction points increased by 84.9% from 546,000 in 2002 to over a million in 2015, the annual groundwater withdrawal decreased by 18% (from 74.6 to 61.3 km3/y) primarily due to physical limits to fresh groundwater resources (i.e., depletion and/or salinization). On average, withdrawing 5.4 km3/y of nonrenewable water caused groundwater tables to decline 10 to 100 cm/y in different regions, averaging 49 cm/y across the country. This caused elevated annual average electrical conductivity (EC) of groundwater in vast arid/semiarid areas of central and eastern Iran (16 out of 30 subbasins), indicating “very high salinity hazard” for irrigation water. The annual average EC values were generally lower in the wetter northern and western regions, where groundwater EC improvements were detected in rare cases. Our results based on high-resolution groundwater measurements reveal alarming water security threats associated with declining fresh groundwater quantity and quality due to many years of unsustainable use. Our analysis offers insights into the environmental implications and limitations of water-intensive development plans that other water-scarce countries might adopt.
|
|
| 6. |
- Noori, Roohollah, et al.
(författare)
-
Complex dynamics of water quality mixing in a warm mono-mictic reservoir
- 2021
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 777
-
Tidskriftsartikel (refereegranskat)abstract
- Cycling of water quality constituents in lakes is affected by thermal stratification and homo-thermal conditions and other factors such as oligotrophication, eutrophication, and microbial activities. In addition, hydrological variability can cause greater differences in water residence time and cycling of constituents in man-made lakes (reservoirs) than in natural lakes. Thus, investigations are needed on vertical mixing of constituents in new impounded reservoirs, especially those constructed to supply domestic water. In this study, sampling campaigns were conducted in the Sabalan reservoir, Iran, to investigate vertical changes in constituent concentrations during the year in periods with thermal stratification and homo-thermal conditions. The results revealed incomplete mixing of constituents, even during cold months when the reservoir was homo-thermal. These conditions interacted to create a bottom-up regulated reservoir with sediment that released settled pollutants, impairing water quality in the Sabalan reservoir during both thermal stratification and homo-thermal conditions. Analysis of total nitrogen and total phosphorus concentrations revealed that the reservoir was eutrophic. External pollution loads, internal cycling of pollutants diffusing out from bottom sediments, reductions in inflow to the reservoir, and reservoir operations regulated vertical mixing and concentrations of constituents in the Sabalan reservoir throughout the year.
|
|
| 7. |
- Xi, Qiaojuan, et al.
(författare)
-
中国主要流域灰-绿-蓝蓄水能力时空演变 : [Spatio-temporal variation of gray-green-blue storage capacity in nine major basins of China]
- 2021
-
Ingår i: Chinese Science Bulletin-Chinese. - 0023-074X .- 2095-9419. ; 66:34, s. 4437-4448
-
Tidskriftsartikel (refereegranskat)abstract
- Most of China's territory is influenced by the East Asia monsoon, and thus, the spatio-temporal distribution of surface water resources in China is extremely uneven, causing many water-related issues, e.g.. water scarcity and flooding. As the basis and essential condition of economic and social development, water-related infrastructures provide the material basis and guarantee for regulating and storing surface water resources and solving multi-dimensional water problems. The infrastructures that play an important role in surface water resource regulation and storage mainly include three types: Gray (such as dams), green (such as forests), and blue infrastructures (such as lakes). Gray infrastructures can reduce the flood peak and increase water supply during dry seasons by regulating and storing water so that the seasonal and inter-annual fluctuation of runoff is reduced, which plays an important role in water storage, water supply, flood control, and disaster mitigation. However, excessive gray infrastructures would have adverse effects on the social economy and environmental ecology. Unlike gray infrastructures, green and blue infrastructures can not only benefit water resource management but also have ecological functions, such as improving water quality and enhancing ecosystem services. Thus. it is significant to couple gray, green, and blue infrastructures to regulate the spatio-temporal distribution of water resources. However, research on the spatial distribution and temporal variation of water storage capacity is still lacking, which hinders the coordinated regulation and comprehensive management of surface water resources. Therefore, in the present study, the spatio-temporal distribution of the three aforementioned infrastructures was compared and analyzed on basin scale, based on the latest data of darns, root zone storage capacity, natural lakes, and so on. Results indicated the following: (1) Gray water storage capacity has exceeded that of the natural terrestrial surface ecosystem in the Yangtze River Basin and the Southeast Basins, where human activities are intense. (2) Gray water storage capacity has increased significantly in nine major basins from 1955 to 2020, but the timing of construction varies in different basins. (3) Green water storage capacity did not change much, the Songhua-Liaohe River Basin and the Huaihe River Basin increased slightly. (4) Blue water storage capacity shows a constantly increasing trend on the whole, in which the water storage capacity in the inland river basin (including the endorheic basin on the Tibetan Plateau) significantly increased. Our study revealed the basic information and spatio-temporal variation of gray-green-blue water storage capacities in nine major basins of China, which could lead to better coordination between natural and artificial water infrastructures and provide support for multidimensional optimization of water resource allocation.
|
|
| 8. |
- Yun, Xiaobo, et al.
(författare)
-
Impacts of climate change and reservoir operation on streamflow and flood characteristics in the Lancang-Mekong River Basin
- 2020
-
Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 590
-
Tidskriftsartikel (refereegranskat)abstract
- © 2020 Elsevier B.V. The Lancang-Mekong River Basin (LMRB) is one of the most important transboundary river basins in Asia. While climate change perturbs the streamflow and affects flood events, reservoir operation may mitigate or aggravate this impact. Therefore, quantitative assessment of the climate change impact and reservoir effect on the LMRB is a vital prerequisite for future hydropower development and environmental protection. This study aimed to estimate the variation of the streamflow and flood characteristics affected by climate change and reservoir operation within the LMRB. A reservoir module was incorporated into the Variable Infiltration Capacity (VIC) model to simulate the streamflow susceptible to the reservoirs. It was found that the reservoirs had a substantial influence on the streamflow during 2008–2016, when many reservoirs were constructed in the LMRB. The reservoirs across the Lancang River (the upper Mekong River located in China) reduced the annual average streamflow by 5% at Chiang Sean station (northern Thailand) in 2008–2016, whereas their influence became undetectable downstream of Vientiane station (northern Laos). The streamflow changes downstream of Mukdahan station at southern Laos (including the stations in Cambodia and southern Vietnam) were mainly attributed to the local reservoirs and climate change. Compared with the baseline period of 1985–2007, the upstream reservoir operation dramatically affected streamflow at the midstream stations with higher dry season streamflow (+15% to +37%), but lower wet season streamflow was less affected (−2% to −24%) in 2008–2016. Climate change increased the magnitude and frequency of the flood by up to 14% and 45%, respectively, whereas the reservoir operation reduced them by 16% and 36%, respectively. Our findings provide insights into the interaction between climate change and reservoir operation and their integrated effects on the streamflow, informing and supporting water management and hydropower development in the LMRB.
|
|
| 9. |
- Zhang, Chi, et al.
(författare)
-
Fate and Changes in Moisture Evaporated From the Tibetan Plateau (2000–2020)
- 2023
-
Ingår i: Water Resources Research. - 0043-1397 .- 1944-7973. ; 59
-
Tidskriftsartikel (refereegranskat)abstract
- Total evaporation from the vast terrain of the Tibetan Plateau (TP) may strongly influence downwind regions. However, the ultimate fate of this moisture remains unclear. This study tracked and quantified TP-originating moisture using an extended Eulerian model. The findings reveal that the involvement of moisture from the TP in the downwind precipitation is most pronounced near the eastern boundary of the TP and gradually diminishes eastward. Consequently, the TP moisture ratio in precipitation reaches the highest of over 30% over the central-eastern TP. 44.9%–46.7% of TP annual evaporation is recycled over the TP, and 65.1%–66.8% of the TP evaporation is reprecipitated over terrestrial China. Moisture recycling of TP origin shows strong seasonal variation, with seasonal patterns largely determined by precipitation, evaporation and wind fields. High levels of evaporation and precipitation over the TP in summer maximize local recycling intensity and recycling ratios. Annual precipitation of TP origin increased mainly around the northeastern TP during 2000–2020. This region consumed more than half of the increased TP evaporation. Further analyses showed that changes in reprecipitation of TP origin were consistent with precipitation trends in nearby downwind areas: when intensified TP evaporation meets intensified precipitation, more TP moisture is precipitated out. The model estimated an annual precipitation recycling ratio (PRR) of 26.9%–30.8% in forward moisture tracking. However, due to the non-closure issue of the atmospheric moisture balance equation, the annual PRR in backward tracking can be ∼6% lower.
|
|
| 10. |
- Zhang, Chi, et al.
(författare)
-
Moisture source differences between the 2020 and 1998 super Meiyu-flood events in the Yangtze River Valley
- 2024
-
Ingår i: Weather and Climate Extremes. - 2212-0947. ; 43
-
Tidskriftsartikel (refereegranskat)abstract
- Two historic Meiyu events in 1998 and 2020 hit the Yangtze River Valley (YRV), causing catastrophic damage to the socio-economy. By tracking moisture supplies to the extreme precipitation events using Water Accounting Model-2Layers and ERA5 reanalysis, the moisture origins and their differences in feeding the YRV precipitation were revealed. Climatologically, the southwest monsoon channel is the most important moisture channel with the Indian Ocean contributing ∼45% and the Indo-China Peninsula contributing ∼16% of the YRV precipitation. During the two super Meiyu events, the Indian Ocean and the Indo-China Peninsula dominated the excessive moisture supply, which together contributed more than 65% of the extra precipitation. Moisture supply anomalies in 1998 and 2020 showed a robust spatial pattern of “west increase-east decrease”. When the YRV precipitation is higher than the normal, moisture mainly comes from the southwest sources, and moisture contribution from the northwestern Pacific is relatively small. We also found that the intensity of the western Pacific subtropical high is a major influencing factor that explained ∼47% of the YRV precipitation variation during 1991–2020. When it intensifies, an anomalous anticyclone is formed in the mid-lower troposphere around the tropical Northwest Pacific. In its northwestern flank, a strong southwesterly in the upwind of the YRV helps bring in more moisture through the southwest monsoon. In the downwind, it inhibits moisture supply from the northwestern Pacific Ocean. Compared with 2020, a drier condition over Indo-China Peninsula and YRV in 1998 led to a substantially less (∼29%) moisture supply to the YRV precipitation, resulting in a less strong Meiyu event in 1998.
|
|
