Flow distribution and trends in the Das Velhas River Basin

In the management of water resources, it is necessary to balance the demands of multiple uses of water and water availability, while enabling use in an environmentally sustainable way. Probability distributions of flow rates are essential tools for assessing water availability. The objectives of this work were to analyze the best probability distribution that conforms to the annual minimum daily average discharge for periods of seven consecutive days (Q7) for 14 stream gauging stations in the Das Velhas River Basin and to identify possible trends in Q7 time series and in bi monthly and annual sets of daily discharges in three key stream gauging stations. The quality of fit was verified by the Anderson-Darling test (A-D). The selection of the models that presented the best fit was done according to the Bayesian Information Criterion (BIC). The Mann-Kendall test was used to verify trends in time series of discharge. In general, better measures of quality of fit were obtained for the probability distributions Gumbel and Rayleigh. Negative trends in discharge distributions were verified in the three stations. For the Várzea da Palma station, the closest to the river mouth, negative and significant trends were found for the Q7 data and daily average discharge for every bimester except the first.

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Assessment of the impact of climate change on the freshwater availability of Kaduna River basin, Nigeria

Journal of Water and Land Development ◽

10.2478/jwld-2018-0047 ◽

2018 ◽

Vol 38 (1) ◽

pp. 105-114 ◽

Cited By ~ 2

Author(s):

Gloria C. Okafor ◽

Kingsley N. Ogbu

Keyword(s):

Climate Change ◽

River Basin ◽

Water Availability ◽

Hydrological Cycle ◽

Temporal Trends ◽

Kendall Test ◽

Well Being ◽

Trend Test ◽

Climate Indices ◽

The Impact

AbstractChanges in runoff trends have caused severe water shortages and ecological problems in agriculture and human well-being in Nigeria. Understanding the long-term (inter-annual to decadal) variations of water availability in river basins is paramount for water resources management and climate change adaptation. Climate change in Northern Nigeria could lead to change of the hydrological cycle and water availability. Moreover, the linkage between climatic changes and streamflow fluctuations is poorly documented in this area. Therefore, this study examined temporal trends in rainfall, temperature and runoff records of Kaduna River basin. Using appropriate statistical tools and participatory survey, trends in streamflow and their linkages with the climate indices were explored to determine their amplifying impacts on water availability and impacts on livelihoods downstream the basin. Analysis indicate variable rainfall trend with significant wet and dry periods. Unlike rainfall, temperature showed annual and seasonal scale statistically increasing trend. Runoff exhibit increasing tendency but only statistically significant on annual scale as investigated with Mann–Kendall trend test. Sen’s estimator values stood in agreement with Mann–Kendall test for all variables. Kendall tau and partial correlation results revealed the influence of climatic variables on runoff. Based on the survey, some of the hydrological implications and current water stress conditions of these fluctuations for the downstream inhabitants were itemized. With increasing risk of climate change and demand for water, we therefore recommend developing adaptive measures in seasonal regime of water availability and future work on modelling of the diverse hydrological characteristics of the entire basin.

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Using Naave Forecasts to Assess Limits to Forecast Accuracy and the Quality of Fit of Forecasts to Time Series Data

SSRN Electronic Journal ◽

10.2139/ssrn.2515072 ◽

2014 ◽

Author(s):

Paul Goodwin

Keyword(s):

Time Series ◽

Time Series Data ◽

Forecast Accuracy ◽

Series Data ◽

Quality Of Fit

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ESTUDO DA QUALIDADE DA ÁGUA DO CÓRREGO DA CASCATA E/OU TABUINHA DE PRESIDENTE PRUDENTE

Colloquium Exactarum ◽

10.5747/ce.2018.v10.nesp.000179 ◽

2018 ◽

Vol 10 (Especial) ◽

pp. 191-196

Author(s):

Carolina Gomes de Melo ◽

Danielle Elis Garcia Furuya ◽

Ireli Cristina Luz ◽

Lucas Flávio Thomaz ◽

Nayara de Jesus Figueiredo ◽

...

Keyword(s):

Water Quality ◽

Population Growth ◽

Natural Resources ◽

Environmental Impacts ◽

River Basin ◽

Environmental Degradation ◽

Natural Resource ◽

Water Availability ◽

Rapid Population Growth

The conservation of the watercourses are essential because they enable the accomplishment of activities that need this natural resource and determine the characteristics of the microbasin in which they are inserted. Rapid population growth requires increased use of natural resources, such as water in streams. In addition to the use, incorrect treatment and environmental impacts are increasingly decreasing the water availability of rivers and tributaries in each river basin. The microcatchment of the Cascata stream and / or Tabuinha shows signs of environmental degradation, since the depth and quantity of water in the stream is scarce. In this context, the objective of this study was to analyze parameters that determine the water quality of the stream, as well as to analyze the interference of a tannery.

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Assessment of streamflows in the Hornád river basin and analysis of trends

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1209/1/012022 ◽

2021 ◽

Vol 1209 (1) ◽

pp. 012022

Author(s):

P Nagy

Keyword(s):

Climate Change ◽

Water Management ◽

Time Series ◽

River Basin ◽

Extreme Rainfall ◽

Dry Season ◽

Trend Test ◽

Surface And Groundwater ◽

Daily Flows

Abstract Climate change is a global phenomenon. The more frequent occurrence of dry periods, which last longer but also extreme rainfall, needs to be reduced for better water management. During the dry season, the quantity and quality of surface and groundwater decreases. Water is important for agriculture, agriculture and ecosystems. This study was focused on the occurrence of trends in daily flows in the Hornád basin at selected hydrological stations for the period 1960-2011. The Mann-Kendall trend test is used to evaluate trends in hydrometeorological time series.

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A Transient Stochastic Rainfall Generator for Climate Changes Analysis at Hydrological Scales in Central Italy

Atmosphere ◽

10.3390/atmos11121292 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1292

Author(s):

Davide Luciano De Luca ◽

Andrea Petroselli ◽

Luciano Galasso

Keyword(s):

Climate Change ◽

Time Series ◽

Climate Changes ◽

Probability Distributions ◽

Central Italy ◽

Kendall Test ◽

Rain Gauge ◽

Rainfall Series ◽

Rainfall Time Series ◽

Climate Change Effects

In this work, a comprehensive methodology for trend investigation in rainfall time series, in a climate-change context, is proposed. The crucial role played by a Stochastic Rainfall Generator (SRG) is highlighted. Indeed, SRG application is particularly suitable to obtain rainfall series that are representative of future rainfall series at hydrological scales. Moreover, the methodology investigates the climate change effects on several timescales, considering the well-known Mann–Kendall test and analyzing the variation of probability distributions of extremes and hazard. The hypothesis is that the effects of climate changes could be more evident only for specific time resolutions, and only for some considered aspects. Applications regarded the rainfall time series of the Viterbo rain gauge in Central Italy.

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Water Appropriation on the Agricultural Frontier in Western Bahia and Its Contribution to Streamflow Reduction: Revisiting the Debate in the Brazilian Cerrado

Water ◽

10.3390/w13081054 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1054

Author(s):

Andréa Leme da Silva ◽

Saulo Aires de Souza ◽

Osmar Coelho Filho ◽

Ludivine Eloy ◽

Yuri Botelho Salmona ◽

...

Keyword(s):

Time Series ◽

River Basin ◽

Hydrological Cycle ◽

Land Use Changes ◽

Interdisciplinary Approach ◽

Fold Increase ◽

Kendall Test ◽

Annual Data ◽

Precipitation Time Series ◽

Agricultural Frontier

Over the last three decades, almost half of the Brazilian tropical savanna (Cerrado biome) has been converted into cropland and planted pastures. This study aims to understand the implications of the expansion of the agricultural frontier for water resources in western Bahia state. We use an interdisciplinary approach that combines quantitative and qualitative data (spatial and hydrological analysis, interviews) to tie together land use changes in the Corrente basin, the streamflow and precipitation time series in the Pratudão River sub-basin (part of the Corrente basin), and the perceptions of soybean farmers and smallholder communities about the transformations of the hydrological cycle over the last few years. We observed an almost 10-fold increase in agricultural surface area in the Corrente River basin over the last three decades (1986–2018), going on from 57,090 ha to 565,084 ha, while center-pivot irrigated areas increased from 240 ha to 43,631 ha. Over this period, the streamflow has reduced by 38% in the Pratudão River. Our hydrological analyses, based on the Mann-Kendall test, of seven fluviometric stations and 14 pluviometry stations showed a statistically significant streamflow trend in the Pratudão River sub-basin for both minimum and mean streamflow series (p ≤0.05). Surface runoff coefficient, which relates streamflow and precipitation annual data coefficient, decreased from around 0.4 in the late 1990s to less than 0.2 in 2015. In addition, most precipitation time series analysis (number of annual rainy days) showed no statistically significant trend (p > 0.05). Our results indicate that agricultural changes rather than climate change may be the main driver of downward streamflow trends in the Pratudão River sub-basin that is part of Corrente River basin.

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Trend in river water quality: tracking the overall impacts of climate change and human activities on water quality in the Dez River Basin

Journal of Water and Health ◽

10.2166/wh.2020.123 ◽

2020 ◽

Author(s):

Nariman Mahmoodi ◽

Khaled Osati ◽

Ali Salajegheh ◽

Mohsen Mohseni Saravi

Keyword(s):

Water Quality ◽

River Water ◽

River Basin ◽

Groundwater Resources ◽

Kendall Test ◽

Quality Parameters ◽

Quality Parameter ◽

River Water Quality

Abstract A perceptible degradation in water quality complicates safe water supply for drinking and irrigation purposes. Therefore, this study aims at monitoring water quality changes and effective factors in the Dez River Basin, which are required to manage water resources effectively. To this end, the common influence of flow rate changes on water quality was separated by implementing seasonal Mann–Kendall test on residuals resulting from the LOWESS test. The results show that after adjusting the effects of seasonality and streamflow fluctuations, significant positive trends in most water quality parameters are still observed. It emphasizes the role of other factors controlling river water quality in the basin. Comparison of the trends of modified quality parameter time series (residuals) in different subbasins having natural or mad-made conditions, with or without significant groundwater resources, shows almost the same presented trends in water quality. This supports that, overall, minor changes occurred in land use, groundwater table, and environmental and human factors with no important influences on presented trends in water quality. Our analyses show that overall reduction in precipitation as well as positive trends in temperature and evaporation led to intensified streamflow variations, explaining the main changes in the river water quality of the basin.

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DEVELOPMENT OF STREAMFLOW DROUGHT INDICES IN THE MORAVA RIVER BASIN

Proceedings of the XXVII Conference of the Danubian Countries on Hydrological Forecasting and Hydrological Bases of Water Management ◽

10.15407/uhmi.conference.01.14 ◽

2020 ◽

Author(s):

Ondrej Ledvinka ◽

◽

Pavel Coufal ◽

Keyword(s):

Time Series ◽

Kendall Test ◽

Drought Indices ◽

Drought Period ◽

Left Hand ◽

Low Flows ◽

Current Period ◽

Catchment Size ◽

Morava River ◽

The Stability

The territory of Czechia currently suffers from a long-lasting drought period which has been a subject of many studies, including the hydrological ones. Previous works indicated that the basin of the Morava River, a left-hand tributary of the Danube, is very prone to the occurrence of dry spells. It also applies to the development of various hydrological time series that often show decreases in the amount of available water. The purpose of this contribution is to extend the results of studies performed earlier and, using the most updated daily time series of discharge, to look at the situation of the so-called streamflow drought within the basin. 46 water-gauging stations representing the rivers of diverse catchment size were selected where no or a very weak anthropogenic influences are expected and the stability and sensitivity of profiles allow for the proper measurement of low flows. The selected series had to cover the most current period 1981-2018 but they could be much longer, which was considered beneficial for the next determination of the development direction. Various series of drought indices were derived from the original discharge series. Specifically, 7-, 15- and 30-day low flows together with deficit volumes and their durations were tested for trends using the modifications of the Mann– Kendall test that account for short-term and long-term persistence. In order to better reflect the drivers of streamflow drought, the indices were considered for summer and winter seasons separately as well. The places with the situation critical to the future water resources management were highlighted where substantial changes in river regime occur probably due to climate factors. Finally, the current drought episode that started in 2014 was put into a wider context, making use of the information obtained by the analyses.

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