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

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.

scholarly journals Rainfall trend and variability over Opak River basin, Yogyakarta, Indonesia

2020 ◽  
Vol 1000 (1000) ◽  
Author(s):  
Wakhidatik Nurfaida ◽  
Hendra Ramdhani ◽  
Takenori Shimozono ◽  
Indri Triawati ◽  
Muhammad Sulaiman
Keyword(s):  
River Basin ◽  
Water Resource ◽  
Rainfall Intensity ◽  
Kendall Test ◽  
Rainfall Data ◽  
Positive Trend ◽  
Sen’S Slope Estimator ◽  
Sen’S Slope ◽  
Slope Estimator

Rainfall intensity seems to be increasing nowadays due to climate change as presented in many studies of both global and regional scale. Consequently, cities worldwide are now more vulnerable to flooding. In Indonesia, increasing frequency of floods was reported for the past decades by The National Agency for Disaster Countermeasure (BNPB). To understand the rainfall changes, long-term trend evaluation over a specific area is then crucial due to the large variability of spatial and temporal rainfall distribution. This study investigates the homogeneity and trend of rainfall data from 20 stations over the Opak River basin, Yogyakarta, Indonesia. A long-term ground observation rainfall data whose period varies from 1979 to 2019 were analyzed. Non-parametric Mann – Kendall test was applied to assess the trend, while the magnitude was calculated using the Sen’s slope estimator. An increasing annual maximum of daily rainfall intensity was observed at four stations on a 0.95 confidence level based on the Mann – Kendall test, while the Sen’s slope estimator shows a positive trend at almost all stations. The trend of heavy rainfall frequency was also found to be significantly increased, with only one station showed a decreasing trend. Furthermore, this paper also described the spatial and temporal rainfall variability. Positive trend was mostly found during the rainy season, while the negative trend occurred during the dry season. This could pose a challenge for water resource management engineering and design, such as water supply systems or reservoir management. Understanding this phenomena will benefit hydrologists in preparing future water resource engineering and management.

scholarly journals Análise de não Homogeneidades de Séries de Vazão de Captações de Nascentes na Bacia Hidrográfica do Rio Gramame, PB, Brasil

2020 ◽  
Vol 13 (6) ◽  
pp. 2896
Author(s):  
Adriana Moura Martins ◽  
Hamilcar José Almeida Filgueira ◽  
Azamor Cirne de Azevedo Filho ◽  
Tarciso Cabral da Silva ◽  
Marcelo Henriques Da Silva Júnior
Keyword(s):  
Time Series ◽  
River Basin ◽  
Statistical Tests ◽  
Local Communities ◽  
Rainfall Data ◽  
South Coast ◽  
Change Points ◽  
Data Series ◽  
The South ◽  
Perennial Springs

A bacia hidrográfica do rio Gramame, no litoral sul paraibano, apresenta diversas nascentes perenes de água com vazões significativas que atendem a comunidades locais para diversos usos. Este trabalho teve como objetivo analisar quatro séries de vazões de captações de nascentes na região sudoeste da bacia e de dados pluviométricos, quanto à sua homogeneidade, entre os anos de 2010 e 2013. A questão motivadora da análise foi a suposta diminuição das vazões de captação das nascentes por consequência da construção de estradas e desmatamentos em áreas do entorno dessas nascentes. Para a análise da homogeneidade das séries, foram empregados testes estatísticos para determinação dos possíveis pontos de ruptura e de verificação da estacionariedade. Foi constatado que houve ruptura em todas as séries de vazões analisadas.  Analysis of non-homogeneities of time series of flow in sources in the Gramame River basin, Paraíba State, Brazil A B S T R A C TThe Gramame river basin on the south coast of Paraiba State, has several perennial springs with significant flows that serve local communities for various uses. However, the construction of roads, in areas around the springs, and recent deforestation indicated to have caused the decrease in flows captured from sources in the basin. This work aimed at analyzing four data series of flows captured from sources in the southwestern basin and the rainfall data series searching to verify their homogeneity, between the years 2010 and 2013. To analyze the homogeneity of the series, statistical tests were used to find significant change points and to verify the stationarity. It was found that rupture occurred in all series of flow analyzed.Keywords: flow from springs, hydrometeorological time series, groundwater.

Rainfall and river flow trends using Mann–Kendall and Sen’s slope estimator statistical tests in the Cobres River basin

2015 ◽  
Vol 77 (2) ◽  
pp. 1205-1221 ◽  
Author(s):  
Richarde Marques da Silva ◽  
Celso A. G. Santos ◽  
Madalena Moreira ◽  
João Corte-Real ◽  
Valeriano C. L. Silva ◽  
...  
Keyword(s):  
River Basin ◽  
River Flow ◽  
Statistical Tests ◽  
Sen’S Slope Estimator ◽  
Sen’S Slope ◽  
Slope Estimator

scholarly journals Integrating Satellite Rainfall Estimates with Hydrological Water Balance Model: Rainfall-Runoff Modeling in Awash River Basin, Ethiopia

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 800 ◽  
Author(s):  
Girma Berhe Adane ◽  
Birtukan Abebe Hirpa ◽  
Belay Manjur Gebru ◽  
Cholho Song ◽  
Woo-Kyun Lee
Keyword(s):  
Water Resources ◽  
Water Balance ◽  
River Basin ◽  
Pearson Correlation ◽  
Hydrologic Model ◽  
Water Balance Model ◽  
Rainfall Data ◽  
Balance Model ◽  
Awash River Basin ◽  
Satellite Rainfall

Hydrologic models play an indispensable role in managing the scarce water resources of a region, and in developing countries, the availability and distribution of data are challenging. This research aimed to integrate and compare the satellite rainfall products, namely, Tropical Rainfall Measuring Mission (TRMM 3B43v7) and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR), with a GR2M hydrological water balance model over a diversified terrain of the Awash River Basin in Ethiopia. Nash–Sutcliffe efficiency (NSE), percent bias (PBIAS), coefficient of determination (R2), and root mean square error (RMSE) and Pearson correlation coefficient (PCC) were used to evaluate the satellite rainfall products and hydrologic model performances of the basin. The satellite rainfall estimations of both products showed a higher PCC (above 0.86) with areal observed rainfall in the Uplands, the Western highlands, and the Lower sub-basins. However, it was weakly associated in the Upper valley and the Eastern catchments of the basin ranging from 0.45 to 0.65. The findings of the assimilated satellite rainfall products with the GR2M model exhibited that 80% of the calibrated and 60% of the validated watersheds in a basin had lower magnitude of PBIAS (<±10), which resulted in better accuracy in flow simulation. The poor performance with higher PBIAS (≥±25) of the GR2M model was observed only in the Melka Kuntire (TRMM 3B43v7 and PERSIANN-CDR), Mojo (PERSIANN-CDR), Metehara (in all rainfall data sets), and Kessem (TRMM 3B43v7) watersheds. Therefore, integrating these satellite rainfall data, particularly in the data-scarce basin, with hydrological data, generally appeared to be useful. However, validation with the ground observed data is required for effective water resources planning and management in a basin. Furthermore, it is recommended to make bias corrections for watersheds with poorlyww performing satellite rainfall products of higher PBIAS before assimilating with the hydrologic model.

scholarly journals Qualitative Approach for Assessing Runoff Temporal Dependence Through Geometrical Symmetry

2020 ◽  
Author(s):  
Santiago Zazo Del dedo ◽  
Hector Macian-Sorribes ◽  
Cristina Maria Sena Fael ◽  
Ana-María Garía-Martín ◽  
Jose-Luis Molina ◽  
...  
Keyword(s):  
Time Series ◽  
Water Resources ◽  
Iberian Peninsula ◽  
River Basin ◽  
Causal Reasoning ◽  
Qualitative Approach ◽  
Time Step ◽  
Temporal Dependence ◽  
Temporal Behaviour ◽  
Runoff Change

Currently, noticeable changes in traditional hydrological patterns are being observed on the short and medium-term. These modifications are adding a growing variability on water resources behaviour, especially evident in its availability. Consequently, for a better understanding/knowledge of temporal alterations, it is crucial to develop  new analytical strategies which are capable of capturing these modifications on its temporal behaviour. This challenge is here addressed via a purely stochastic methodology on annual runoff time series. This is performed through the propagation of temporal dependence strength over the time, by means of Causality, supported by Causal Reasoning (Bayes’ theorem), via the relative percentage of runoff change that a time-step produces on the following ones. The result is a dependence mitigation graph, whose analysis of its symmetry provides an innovative qualitative approach to assess time-dependency from a dynamic and continuous perspective against the classical, static and punctual result that a correlogram offers. This was evaluated/applied to four Spanish unregulated river sub-basins; firstly on two Douro/Duero River Basin exemplary case studies (the largest river basin at Iberian Peninsula) with a clearly opposite temporal behaviour, and subsequently applied to two watersheds belonging to Jucar River Basin (Iberian Peninsula Mediterranean side), characterised by suffering regular drought conditions. Keywords: Causal reasoning, Theorem of Bayes, Temporal dependence propagation, Runoff time series, Water resources management

scholarly journals Long–term spatio–temporal warming tendency in the Vietnamese Mekong Delta based on observed and high–resolution gridded datasets

2019 ◽  
pp. 01-16
Author(s):  
Dang Nguyen Dong Phuong ◽  
Dang Kien Cuong ◽  
Duong Ton Dam ◽  
Nguyen Kim Loi
Keyword(s):  
High Resolution ◽  
Statistical Tests ◽  
Mekong Delta ◽  
Kendall Test ◽  
Trend Detection ◽  
Homogeneity Test ◽  
Spatio Temporal ◽  
Temperature Records ◽  
Slope Estimator ◽  
Increasing Trends

The Vietnamese Mekong Delta is among the most vulnerable deltas to climate–related hazards across the globe. In this study, the annual mean and extreme temperatures from 11 meteorological stations over the Vietnamese Mekong Delta were subjected to normality, homogeneity and trend analysis by employing a number of powerful statistical tests (i.e. Shapiro–Wilk, Buishand Range test, classical/modified Mann–Kendall test and Sen’s slope estimator). As for spatio–temporal assessment, the well–known (0.5° × 0.5°) high–resolution gridded dataset (i.e. CRU TS4.02) was also utilized to examine trend possibilities for three different time periods (i.e. 1901–2017, 1951–2017 and 1981–2017) by integrating spatial interpolation algorithms (i.e. IDW and Ordinary Kriging) with statistical trend tests. Comparing the calculated test–statistics to their critical values (a = 0.05), it is evident that most of the temperature records can be considered to be normal and non–homogeneous with respect to normality and homogeneity test respectively. As for temporal trend detection, the outcomes show high domination of significantly increasing trends. Additionally, the results of trend estimation indicate that the magnitude of increase in minimum temperature was mostly greater than mean and maximum ones and the recent period (1981–2017) also revealed greater increasing rates compared to the entire analyzed period and second half of the 20th century. In general, these findings yield various evident indications of warming tendency in the Vietnamese Mekong Delta over the last three decades.

scholarly journals IWRM as a System Approach to Water Security: Evidence from the Awash River Basin of Ethiopia

2018 ◽  
Author(s):  
Reta Hailu ◽  
Degefa Tolossa ◽  
Getnet Alemu
Keyword(s):  
Water Resources ◽  
River Basin ◽  
Water Resources Management ◽  
System Approach ◽  
Water Security ◽  
Integrated Water Resources Management ◽  
System Thinking ◽  
Multiple Sources ◽  
Resources Management ◽  
Awash River Basin

Integrated Water Resources Management (IWRM) is one of the system thinking approaches emerged in the 1990s. Since then it has been applied in various countries and contexts. However, the implementation of the IWRM is contested. There are paucity of literature and guidelines as to how the concept can be operationalized. In Ethiopia, there is no evidence that IWRM is successfully instituted. Particularly, IWRM has never been implemented in the Awash River Basin. The study generated data from household and institutional surveys, in-depth interviews, focused group discussions, workshops, and secondary sources. Multiple sources of data were triangulated and thematically summarized. We found that pragmatic water resources management through system approach helps to recognize river basin as a bigger system in which the natural and human systems function. This resolves the problem of fragmentations among among various actors, sectors, interest and priorities. That it facilitates the coordination of various subsystems. The operationalization of IWRM as a system to secure water resources require the establishment and/or strengthening of the interactions of various systems, subsystems, and the elements within the entire basin system. Finally, enabling institutional environments should be considered as a medium of realizing IWRM.

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