Trend Analysis of Stream Flow of Ramganga River Catchment

2017 ◽  
Vol 10 (3) ◽  
pp. 327
Author(s):  
Rajesh Kumar ◽  
P.R. Ojasvi ◽  
V.K. Chandola ◽  
A.K. Nema
Keyword(s):  
Trend Analysis ◽  
Stream Flow ◽  
River Catchment ◽  
Ramganga River

Wavelet-based trend analysis of hydrological processes at different timescales

2015 ◽  
Vol 6 (3) ◽  
pp. 414-435 ◽  
Author(s):  
Vahid Nourani ◽  
Nasrin Nezamdoost ◽  
Maryam Samadi ◽  
Farnaz Daneshvar Vousoughi
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Stream Flow ◽  
Discrete Wavelet ◽  
Precipitation Data ◽  
Short Term ◽  
Mk Test ◽  
Starting Point ◽  
Annual Time Series ◽  
Annual Time

This study analyzes involved trends in stream flow and precipitation data at monthly, seasonal and annual timescales observed at six precipitation and four stream flow stations of Tampa Bay using non-parametric Mann–Kendall (MK) and discrete wavelet transform (DWT) methods. The MK test and sequential MK analysis were applied to different combinations of DWT after removing the effect of significant lag-1 serial correlation to calculate components responsible for trend of the time series. Also, the sequential MK test was used to find the starting point of changes in annual time series. The results showed that negative trend is prevalent in the case study; generally, short-term periods were important in the involved trend at original time series. Thus, the precipitation data at three scales showed short-term periods of 2 months, 6 months and 2 years in monthly, seasonal and annual scales, respectively. In the greatest stream-flow time series at three timescales, wavelet-based detail at level 2 plus the approximations time series was conceded as the dominant periodic component. Finally, the results of Sen's trend analysis, applied to the original annual time series, also confirmed the results of the proposed wavelet-based MK test in most cases.

scholarly journals Trend  Analysis of Climate variables, Stream flow and their Linkage at Modjo River Watershed, Central Ethiopia

2020 ◽  
Author(s):  
Kokeb Zena ◽  
Tamene Adugna ◽  
Fekadu Fufa
Keyword(s):  
Climate Variability ◽  
Trend Analysis ◽  
Stream Flow ◽  
Management Practices ◽  
River Flow ◽  
Pearson Correlation ◽  
Kendall Test ◽  
Precipitation Series ◽  
River Watershed ◽  
The Mean

Abstract Background: Trend and variability analysis of precipitation and stream flow series provides valuable information to understand hydrological changes associated with climate variability. In this study, annual and seasonal trends of precipitation and stream flow series and their relationship was investigated over the Modjo river watershed. The Mann-Kendall test and Sen’s slope estimator were used for trend analysis and evaluation of its magnitude respectively, with an approach that corrects the serial correlation. The Pearson correlation analysis was also applied to evaluate the relationships between river flow and precipitation series.Results: the mean and maximum stream flow series showed downward trends at the annual and kiremt time series, whereas no significant trend was observed for the minimum flow over the Modjo watershed. The study indicated that the mean annual and kiremt (monsoon) stream flow decreased significantly at a rate of 8.262 and 6.528 m3s-1per year respectively. In contrary to the river flow, there is no positive or negative trend in the annual and seasonal precipitation series although the tendency was towards increasing trends. It was evidenced that the annual, and kiremt season river flow series was affected abruptly since 2000, however for the same analysis period there was no evidence of changes in precipitation events, which is also not related significantly with the variability of river flow during the analysis period.Conclusions: the river flow decreased dramatically in the Modjo watershed during the analysis period (1981-2015), however it was not primarily associated significantly with climate variability (precipitation & temperature). The result suggests the need of considering the unplanned water extraction and the poor land use management practices to sustain and restore river flow trend observed in the watershed.

scholarly journals Effects of Climate Variability on Normalized Difference Vegetation Index (NDVI) in the Gojeb River Catchment, Omo-Gibe Basin, Ethiopia

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Melku Dagnachew ◽  
Asfaw Kebede ◽  
Awdenegest Moges ◽  
Adane Abebe
Keyword(s):  
Climate Variability ◽  
Trend Analysis ◽  
Vegetation Dynamics ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Rainfall Variability ◽  
Time Lag ◽  
Rainfall Time Series ◽  
River Catchment ◽  
Vegetation Degradation

Vegetation dynamics have been visibly influenced by climate variability. The Normalized Difference Vegetation Index (NDVI) has been the most commonly used index in vegetation dynamics. The study was conducted to examine the effects of climatic variability (rainfall) on NDVI for the periods 1982–2015 in the Gojeb River Catchment (GRC), Omo-Gibe Basin, Ethiopia. The spatiotemporal trend in NDVI and rainfall time series was assessed using a Theil–Sen (Sen) slope and Mann–Kendall (MK) statistical significance test at a 95% confidence interval. Moreover, the residual trend analysis (RESTREND) method was used to investigate the effect of rainfall and human induction on vegetation degradation. The Sen’s slope trend analysis and MK significant test indicated that the magnitude of annual NDVI and rainfall showed significant decrement and/or increment in various portions of the GRC. The concurrent decrement and/or increment of annual NDVI and rainfall distributions both spatially and temporarily could be attributed to the significant positive correlation of the monthly (RNDVI-RF = 0.189, P≤0.001) and annual (RNDVI-RF = 0.637, P≤0.001) NDVI with rainfall in almost all portions of the catchment. In the GRC, a strongly negative decrement and strong positive increment of NDVI could be derived by human-induced and rainfall variability, respectively. Accordingly, the significant NDVI decrement in the downstream portion and significant increment in the northern portion of the catchment could be attributed to human-induced vegetation degradation and the variability of rainfall, respectively. The dominance of a decreasing trend in the residuals at the pixel level for the NDVI from 1982, 1984, 2000, 2008 to 2012 indicates vegetation degradation. The strong upward trend in the residuals evident from 1983, 1991, 1998 to 2007 was indicative of vegetation improvements. In the GRC, the residuals may be derived from climatic variations (mainly rainfall) and human activities. The time lag between NDVI and climate factors (rainfall) varied mainly from two to three months. In the study catchment, since vegetation degradations are mainly caused by human induction and rainfall variability, integrated and sustainable landscape management and climate-smart agricultural practices could have paramount importance in reversing the degradation processes.

scholarly journals Water Pollution Assessment of Selected Valuable Rivers in Efon Alaaye, Ekiti State

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
James R Adewumi
Keyword(s):  
Water Pollution ◽  
Water Quality ◽  
River Water ◽  
Stream Flow ◽  
Pollution Assessment ◽  
International Standards ◽  
Quality Analysis ◽  
Human Consumption ◽  
River Catchment ◽  
Quality Water

Pollution in relation to river water is the term used to express the level of contamination and the suitability of such river water to sustain various usage. In many developing countries, the main issue, however, is not the physical scarcity of water but poor management which results in the continuous deterioration of water quality. This study conducted an onsite measurement of seasonal stream flow and quality variation of major valuable streams use for non-potable domestic purposes in Efon-Alaaye, Ekiti state. Stream flow data was obtained using volumetric method and the quality analysis was carried out in accordance with Standard Methods for Examination of Water and Wastewater. The result shows that the average stream flow ranges from 0.120 m3/s to 1.04 m3/s. The physicochemical parameters measured fall short of the national and international standards, which indicates that the water is not fit for human consumption. It was also observed that the self-cleansing of the studied rivers is sufficient to meet the quality requirement for non-potable domestic use. It is recommended that all human activities that could lead to further pollution should be avoided around the river catchment while period public enlightenment should be carried out to sensitize the community on the best hygienic practice within the river catchment to promote good water quality. Keywords: Water quality, water pollution, stream flow, water management.

scholarly journals Challenges to Implementing an Environmental Flow Regime in the Luvuvhu River Catchment, South Africa

2019 ◽  
Vol 16 (19) ◽  
pp. 3694 ◽  
Author(s):  
Pfananani Ramulifho ◽  
Esther Ndou ◽  
Reuben Thifhulufhelwi ◽  
Tatenda Dalu
Keyword(s):  
South Africa ◽  
Flow Regime ◽  
Stream Flow ◽  
Literature Search ◽  
Management Strategies ◽  
Environmental Flow ◽  
Catchment Management ◽  
Natural Ecosystem ◽  
River Catchment ◽  
Water Abstraction

Rivers are now facing increasing pressure and demand to provide water directly for drinking, farming and supporting industries as a result of rapidly growing global human population. Globally, the most common practice for catchment managers is to limit water abstraction and changes to stream flow by setting environmental flow standards that guard and maintain the natural ecosystem characteristics. Since the development of the environmental flow concept and methods in South Africa, very few studies have assessed the institutional constraints towards environmental flow implementation. This study determined stream flow trends over time by fitting simple linear regression model to mean daily stream flow data at three selected stations in the Luvuvhu River Catchment (LRC). We also conducted a literature search to review, firstly the response of aquatic organisms (fish and macroinvertebrate) to changes in habitat conditions and secondly on local challenges affecting the sustainable implementation of environmental flow regime and related water resources management strategies. All the three stream flow stations show decreasing stream flow volume of 1 and 2 orders of magnitude faster in some stations with the possibility that flow will cease in the near future. Qualitative analyses from both local and international literature search found that the main challenges facing the implementation of sustainable flow strategies and management are absence of catchment management agency, lack of understanding of environmental flow benefits, limited financial budget, lack of capacity and conflict of interest. Rivers with changing stream flows tend to lose sensitive species. The development of scientifically credible catchment-wide environmental flow and abstraction thresholds for rivers within the LRC would make a major contribution in minimizing the declining stream flow volumes. Monitoring and reporting should be prioritized to give regular accounts of the state of our rivers.

scholarly journals Attribution of changes in stream flow to land use change and climate change in a mesoscale tropical catchment in Java, Indonesia

2016 ◽  
Vol 48 (4) ◽  
pp. 1143-1155 ◽  
Author(s):  
Hero Marhaento ◽  
Martijn J. Booij ◽  
Arjen Y. Hoekstra
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Trend Analysis ◽  
Stream Flow ◽  
Potential Evapotranspiration ◽  
Quantitative Measure ◽  
Change Analysis ◽  
Slope Estimator ◽  
Landsat Satellite

Changes in the stream flow of the Samin catchment (277.9 km2) in Java, Indonesia, have been attributed to land use change and climate change. Hydroclimatic data covering the period 1990–2013 and land use data acquired from Landsat satellite imageries for the years 1994 and 2013 were analysed. A quantitative measure is developed to attribute stream flow changes to land use and climate changes based on the changes in the proportion of excess water relative to changes in the proportion of excess energy. The results show that 72% of the increase in stream flow might be attributed to land use change. The results are validated by a land use change analysis and two statistical trend analyses namely the Mann-Kendall trend analysis and Sen's slope estimator for mean annual discharge, rainfall and potential evapotranspiration. The results of the statistical trend analysis are in the same direction as the results of the attribution analysis, where climate change was relatively minor compared to significant land uses change due to deforestation during the period 1994–2013. We conclude that changes in stream flow can be mainly attributed to land use change rather than climate change for the study catchment.

scholarly journals TREND ANALYSIS OF STREAM FLOW AND ITS RELATION TO RAINFALL IN THE LOWER TAMIRAPARANI SUB-BASIN OF TAMILNADU, INDIA

2020 ◽  
Vol 18 (1) ◽  
pp. 863-878
Author(s):  
M. MARTINA ISABELLA ◽  
N.K. AMBUJAM ◽  
P.T. SANTHANA KRISHNAN
Keyword(s):  
Trend Analysis ◽  
Stream Flow

scholarly journals Trend Analysis of Hydrological Drought for Selected Rivers in Iraq

2020 ◽  
Vol 27 (1) ◽  
pp. 51-57
Author(s):  
Ihsan Hasan ◽  
Younis Saeed
Keyword(s):  
Trend Analysis ◽  
Stream Flow ◽  
Drought Index ◽  
Parametric Method ◽  
Hydrological Drought ◽  
Eastern Region ◽  
Hydropower Generation ◽  
The North ◽  
North Eastern ◽  
Increasing Trend

The surface water in study area supports a range of uses such as water supply, irrigation and hydropower generation. Therefore, the assessment and analysis of the hydrological drought are important in the planning and management of the water resources. In this paper, hydrological drought was assessed using stream-flow drought index (SDI) based on observed mean monthly stream-flow data collected from three selected gauging stations at Greater Zab River, Lesser Zab River and Khazir River located in the North-Eastern region of Iraq. Trend analysis of the hydrological drought was investigated using Mann-Kendall non-parametric method to evaluate the significance of trends and Sen\\\’s slope method to determine the magnitude of the slope of trends for 47 years during the period 1965-2011. According to the SDI 3, 6 and 12-month time scales, the recorded drought was severe, and M-K method showed that the decreasing trends in the SDI values were statistically significant at α=0.05 mostly in the Greater Zab River and Lesser Zab River basins, increasing trend in SDI values is insignificant. This indicates that the hydrological drought is increasing over time at the study area.

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