Hydrological regionalization of streamflows for the Tocantins River Basin in Brazilian Cerrado biome

The Brazilian Cerrado biome is the largest and richest tropical savanna in the world and is among the 25 biodiversity hotspots identified worldwide. However, the lack of adequate hydrological monitoring in this region has led to problems in the management of water resources. In order to provide tools for the adequate management of water resources in the Brazilian Cerrado biome region, this paper develops the regionalization of maximum, mean and minimum streamflows in the Tocantins River Basin (287,405.5 km2), fully located in the Brazilian Cerrado biome. The streamflow records of 32 gauging stations in the Tocantins River Basin are examined using the Mann-Kendall test and the hydrological homogeneity non-parametric index-flood method. One homogeneous region was identified for the estimate of the streamflows Qltm (long-term mean streamflow), Q90% (streamflow with 90% of exceeding time), Q95% (streamflow with 95% of exceeding time) and Q7,10 (minimum annual streamflow over 7 days and return period of 10 years). Two homogeneous regions were identified for maximum annual streamflow estimation and the Generalized Extreme Value distribution is found to describe the distribution of maximus events appropriately within the both regions. Regional models were developed for each streamflow of each region and evaluated by cross-validation. These models can be used for the estimation of maximum, mean and minimum streamflows in ungauged basins within the Tocantins River Basin within the area boundaries identified. Therefore, the results provided in this paper are valuable tools for practicing water-resource managers in the Brazilian Cerrado biome. Keywords: l-moments, statistical hydrology, water use rights concessions.

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Estimation of dry events duration in Northern Tunisia – Analysis of extremes trends

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-384-195-2021 ◽

2021 ◽

Vol 384 ◽

pp. 195-201

Author(s):

Majid Mathlouthi ◽

Fethi Lebdi

Keyword(s):

Extreme Value Distribution ◽

Kendall Test ◽

Generalized Extreme Value Distribution ◽

Data Series ◽

Positive Trend ◽

Wet Season ◽

Northern Tunisia ◽

Dry Spells ◽

Agricultural Potential ◽

Anderson Darling

Abstract. Modeling of extremes dry spells in Northern Tunisia, in order to detect the severity of the phenomenon, is carried out. Dry events are considered as a sequence of dry days (below a threshold) separated by rainfall events from each other. The maximum dry event duration follows the Generalized Extreme Value distribution. The data series adherence to the probability distribution was verified by the Anderson-Darling test. The positive trend and non-stationarity of dry spells was verified respectively by the Mann–Kendall test and Dickey–Fuller and augmented Dickey–Fuller tests. The irregular distribution of rainfall in the growing season for Sidi Abdelbasset station has increased the number of dry spells. The increase of rainy days in Ghézala dam and Sidi Salem gauge stations resulted in a decrease of dry spells in this area. Regarding the return period of one year (wet season), dry events occurred from 14 to 27 d in this region constitute an agricultural potential risk. The Southern region was the most vulnerable.

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Spatial Characteristics of Flooded Areas in the Mun and Chi River Basins in Northeastern Thailand

Journal of Disaster Research ◽

10.20965/jdr.2019.p1337 ◽

2019 ◽

Vol 14 (9) ◽

pp. 1337-1345 ◽

Cited By ~ 1

Author(s):

Shingo Zenkoji ◽

Shigehiko Oda ◽

Taichi Tebakari ◽

Boonlert Archevarahuprok ◽

◽

...

Keyword(s):

Extreme Value Distribution ◽

Kendall Test ◽

Generalized Extreme Value Distribution ◽

Annual Rainfall ◽

Spatial Characteristics ◽

Significance Level ◽

Inundation Area ◽

Inundation Depth ◽

Rainfall Change

The objectives of this study are to conduct an analysis on rainfall change tendencies, calculate the inundation in the basins of Mun and Chi Rivers in the northeastern region of Thailand, and clarify the flood risk in the long term, taking the spatial characteristics of flooding into consideration. To grasp the rainfall change tendencies, two statistical analyses are conducted using the Mann-Kendall test and the generalized extreme value distribution. The inundation analysis is conducted using the Rainfall-Runoff-Inundation (RRI) model. As a result of the statistical analysis on the rainfall characteristics, it can be observed that the annual rainfall has significant increasing tendencies at the significance level of 5% in a wide area of the upper reaches. In addition, inundation calculation indicates that the maximum inundation depth and inundation area have increased in recent years.

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Flow Indices Variability in Humid Subtropical of Upper Awash River Basin, Ethiopia

10.21203/rs.3.rs-908354/v1 ◽

2021 ◽

Author(s):

Sintayehu Yadete Tola ◽

Amba Shetty

Keyword(s):

Water Resources ◽

River Basin ◽

Decadal Variability ◽

Statistical Tests ◽

Kendall Test ◽

Change Points ◽

Watershed Hydrology ◽

Time Step ◽

Awash River Basin ◽

Slope Estimator

Abstract Investigating the hydrological extremes indices at high resolutions describing the whole stream spectrum is essential for the comprehensive assessment of watershed hydrology. The study focuses on a wide-ranging assessment of river discharge in annual mean, peak, and high and low percentiles flow at the Upper Awash River basin, Ethiopia. Statistical tests such as coefficient of variation, flood variability to characterize the flow regime and Tukey’s test to detect decadal variability. Modified Mann-Kendall test, Sen’s slope estimator, innovative trend analysis and Pettitt’s test were applied to see trends, and change points in time series, respectively. Results showed that the basin was characterized by moderate to high variability. Spatially, main tributaries showed a higher variability, almost in all-time step and characterized by higher flood variability. The large discharge receiving rivers resulted in a moderate to high and lower discharge variability. Test statistics resulted in a positive increasing trend dominating most time scales at a 5% significant level and higher magnitude of slope trend in peak flow. A negative trends were also exhibited. Hombole main outlet site experienced decreasing trend in high percentile flow. In comparison, complete trend direction agreements were observed (except in few series). Flow indices showed an upward shift and downward shift mainly in the year 2000s and the significant decadal variation resulted in comparable with change points. The study provides an understanding of water resources variability, which will be necessary to apply operational water resources strategies and management to restrain the potential impacts of variability nature of the streamflow.

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Spatial Distribution of Precipitation in Huang-Huai-Hai River Basin between 1961 to 2016, China

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16183404 ◽

2019 ◽

Vol 16 (18) ◽

pp. 3404 ◽

Cited By ~ 2

Author(s):

Yong Yuan ◽

Denghua Yan ◽

Zhe Yuan ◽

Jun Yin ◽

Zhongnan Zhao

Keyword(s):

Spatial Distribution ◽

River Basin ◽

Extreme Precipitation ◽

Extreme Value Distribution ◽

Precipitation Intensity ◽

Generalized Extreme Value Distribution ◽

Grid Data ◽

Weighting Method ◽

Distribution Method ◽

Distance Weighting

The Huang-huai-hai River Basin is one of the most economically developed areas, but is also heavily impacted by drought and flood disasters. Research on the precipitation feature of the Huang-huai-hai River Basin is of great importance to the further discussion of the cause of flood disaster. Based on the selected meteorological stations of the study area from 1961–2016, the inverse distance weighting method was used to get daily precipitation grid data. Interannual variation of precipitation intensity and cover area of different precipitation classes was analyzed. The generalized extreme-value distribution method was used to analyze the spatial distribution of extreme precipitation. The results show that: (1) decrease of accumulated precipitation in light precipitation year and moderate precipitation year might be the reason why the precipitation in the whole basin decreased, but the coefficient of variation (CV) of different classes of precipitation and precipitation days does not change significantly; (2) since the cover area of precipitation > 50 mm and precipitation intensity both decreased, the extreme precipitation of the whole basin may be decreasing; (3) extreme precipitation mainly occurred in the loess plateau in the northeast of Huang-huai-hai River Basin, Dabieshan in the middle of Huang-huai-hai River Basin and other areas.

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Response of Water Resources to Future Climate Change in a High-Latitude River Basin

Sustainability ◽

10.3390/su11205619 ◽

2019 ◽

Vol 11 (20) ◽

pp. 5619 ◽

Cited By ~ 1

Author(s):

Peng Qi ◽

Guangxin Zhang ◽

Yi Jun Xu ◽

Zhikun Xia ◽

Ming Wang

Keyword(s):

Climate Change ◽

Water Resources ◽

Groundwater Recharge ◽

River Basin ◽

High Latitude ◽

Future Climate ◽

Future Climate Change ◽

Annual Streamflow ◽

Dry Conditions ◽

Rcp 8.5

Global water resources are affected by climate change as never before. However, it is still unclear how water resources in high latitudes respond to climate change. In this study, the water resource data for 2021–2050 in the Naoli River Basin, a high-latitude basin in China, are calculated by using the SWAT-Modflow Model and future climate scenarios RCP4.5 and RCP8.5. The results show a decreasing trend. When compared to the present, future streamflow is predicted to decrease by 2.73 × 108 m3 in 2021–2035 and by 1.51 × 108 m3 in 2036–2050 in the RCP4.5 scenario, and by 8.16 × 108 m3 in 2021–2035 and by 0.56 × 108 m3 in 2036–2050 in the RCP8.5 scenario, respectively. Similarly, groundwater recharge is expected to decrease by −1.79 × 108 m3 in 2021–2035 and −0.75 × 108 m3 in 2036–2050 in the RCP 4.5 scenario, and by −0.62 × 108 m3 in 2021–2035 and −0.12 × 108m3 in 2036–2050 in the RCP 8.5 scenario, respectively. The worst impact of climate change on water resources in the basin could be frequent occurrences of extremely wet and dry conditions. In the RCP 4.5 scenario, the largest annual streamflow is predicted to be almost 14 times that of the smallest one, while it is 18 times for the groundwater recharge. Meanwhile, in the RCP 8.5 scenario, inter-annual fluctuations are expected to be more severe. The difference is 17 times between the largest annual streamflow and the lowest annual one. Moreover, the value is 19 times between the largest and lowest groundwater recharge. This indicates a significant increase in conflict between water use and supply.

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Future Hydrologic Extremes of the Red River Basin

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-17-0346.1 ◽

2018 ◽

Vol 57 (6) ◽

pp. 1321-1336 ◽

Cited By ~ 7

Author(s):

Darrian Bertrand ◽

Renee A. McPherson

Keyword(s):

Water Resources ◽

River Basin ◽

Water Resource ◽

Decision Makers ◽

Red River ◽

Severe Drought ◽

Resource Managers ◽

Red River Basin ◽

State History ◽

Hydrologic Extremes

AbstractHydrologic extremes of drought and flooding stress water resources and damage communities in the Red River basin, located in the south-central United States. For example, the summer of 2011 was the third driest summer in Oklahoma state history and the driest in Texas state history. When the long-term drought conditions ended in the spring of 2015 as El Niño brought record precipitation to the region, there were also catastrophic floods that caused loss of life and property. Hydrologic extremes such as these have occurred throughout the historical record, but decision-makers need to know how the frequency of these events is expected to vary in a changing climate so that they can mitigate these impacts and losses. Therefore, the goals of this study focus on how these hydrologic extremes impact water resources in the Red River basin, how the frequency of such events is expected to change in the future, and how this study can aid local water-resource managers and decision-makers. Heavy-precipitation events were defined at the historical 90th and 99th percentiles, and severe-drought events were identified at a threshold of the standardized precipitation evapotranspiration index’s value of less than or equal to −1. The results show an increase in the frequency of severe-drought events in the western Red River basin and a rise in heavy-rainfall events in the east by the end of the century, especially under RCP 8.5. Therefore, decision-makers and water-resource managers will likely need to prepare for both hydrologic extremes depending on their location within the basin.

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