Trend Analysis of Climatic and Hydrological Parameters in Ajora-Woybo Watershed, Omo-Gibe River Basin, Ethiopia

Abstract BackgroundIdentifying hydro-meteorological trends is basic for assessing change in climate and river discharge at watershed level. This study examined the long-term trends of rainfall, temperature, and discharge in the annual, monthly and seasonal time scale of Ajora-Woybo watershed in Ethiopia. The data span of rainfall and temperature is between 1990 and 2020 and that of discharge is between 1990 and 2015. Homogeneity test was performed by using Pettit and SNHT tests. Then Mann-Kendall and Sen's slope test for trend analysis and different variability measures were used. ResultsResults indicate that inhomogeneity was detected in annual rainfall data of Angacha and Areka stations. On annual basis, rainfall and discharge exhibited insignificant trends over time while showing a general decreasing pattern. On monthly basis, February and March were found to have significantly decreasing trend for rainfall. During the Kiremt season, rainfall increases and discharge decreases insignificantly. In contrast, maximum, minimum and mean annual temperatures exhibited significant trends with annual increment of 0.04oC, 0.01oC, and 0.025 oC per year respectively. Correlations of discharge with both temperature and rainfall have found to be weak in this study.ConclusionsThis trend, combined with population growth and increasing demand of water for agricultural activities exacerbates competing demands for water resources. Caution is therefore required when it comes to developing appropriate measures for the planning and sustainable development of the water resources in the watershed.

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Advanced Rainfall Trend Analysis of 117 Years over West Coast Plain and Hill Agro-Climatic Region of India

Atmosphere ◽

10.3390/atmos11111225 ◽

2020 ◽

Vol 11 (11) ◽

pp. 1225

Author(s):

Atul Saini ◽

Netrananda Sahu ◽

Pankaj Kumar ◽

Sridhara Nayak ◽

Weili Duan ◽

...

Keyword(s):

Trend Analysis ◽

West Coast ◽

Winter Season ◽

Recurrence Interval ◽

Annual Rainfall ◽

Rainfall Trend ◽

Climatic Region ◽

Monotonic Trend ◽

Slope Test ◽

The Impact

In this paper, the rainfall trend of the West Coast Plain and Hill Agro-Climatic Region is analyzed for 117 years (1901–2017). This region is a globally recognized biodiversity hotspot and known for one of the highest rainfall receiving regions in India. Rainfall grid dataset is used for the analysis of rainfall trends on monthly, seasonal, and decadal time scales. Modified Mann–Kendall’s test, Linear Regression, Innovative Trend Analysis, Sen’s Slope test, Weibull’s Recurrence Interval, Pearson’s Coefficient of Skewness, Consecutive Disparity Index, Kurtosis, and some other important statistical techniques are employed for trend analysis. Results indicate that the rainfall trend is significant in January, July, August, September as well as the Winter season. Among all the significant trends, January and July showed a decreasing rainfall trend. July has the highest contribution (30%) among all the obtained monotonic trend to annual rainfall and coincidentally has the highest trend magnitude. August and September months with a combined contribution of 30% to annual rainfall, show an increasing monotonic trend with high magnitude whereas Winter season shows a monotonic decreasing rainfall trend with comparatively low magnitudes. Decadal analysis along with the study of recurrence interval of excess and deficit years helps to understand the decadal rhythm of trend and the magnitude of extreme monthly and seasonal events. Skewness reveals that rainfall dataset of all the periodic results is right-skewed and the recurrence interval also supports the skewness results. Sharply decreasing rainfall in July and rising rainfall in August and September is predictive of the impact on agriculture, biodiversity and indicates the rainfall regime shift in the region.

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Homogenization and Trend Analysis of Canadian Near-Surface Wind Speeds

Journal of Climate ◽

10.1175/2009jcli3200.1 ◽

2010 ◽

Vol 23 (5) ◽

pp. 1209-1225 ◽

Cited By ~ 126

Author(s):

Hui Wan ◽

Xiaolan L. Wang ◽

Val R. Swail

Keyword(s):

Wind Speed ◽

Trend Analysis ◽

Surface Wind ◽

Surface Wind Speed ◽

The United States ◽

Homogeneity Test ◽

Near Surface ◽

Wind Speeds ◽

Long Term Trends

Abstract Near-surface wind speeds recorded at 117 stations in Canada for the period from 1953 to 2006 were analyzed in this study. First, metadata and a logarithmic wind profile were used to adjust hourly wind speeds measured at nonstandard anemometer heights to the standard 10-m level. Monthly mean near-surface wind speed series were then derived and subjected to a statistical homogeneity test, with homogeneous monthly mean geostrophic wind (geowind) speed series being used as reference series. Homogenized monthly mean near-surface wind speed series were obtained by adjusting all significant mean shifts, using the results of the statistical test and modeling along with all available metadata, and were used to assess the long-term trends. This study shows that station relocation and anemometer height change are the main causes for discontinuities in the near-surface wind speed series, followed by instrumentation problems or changes, and observing environment changes. It also shows that the effects of artificial mean shifts on the results of trend analysis are remarkable, and that the homogenized near-surface wind speed series show good spatial consistency of trends, which are in agreement with long-term trends estimated from independent datasets, such as surface winds in the United States and cyclone activity indices and ocean wave heights in the region. These indicate success in the homogenization of the wind data. During the period analyzed, the homogenized near-surface wind speed series show significant decreases throughout western Canada and most parts of southern Canada (except the Maritimes) in all seasons, with significant increases in the central Canadian Arctic in all seasons and in the Maritimes in spring and autumn.

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Trend Analysis and Variability of Air Temperature and Rainfall in Regional River Basins

Civil Engineering Journal ◽

10.28991/cej-2021-03091692 ◽

2021 ◽

Vol 7 (5) ◽

pp. 816-826

Author(s):

Benjamin Nnamdi Ekwueme ◽

Jonah Chukwuemeka Agunwamba

Keyword(s):

Water Resources ◽

Trend Analysis ◽

Air Temperature ◽

Temporal Trends ◽

Kendall Test ◽

River Basins ◽

Annual Rainfall ◽

Eastern Region ◽

South Eastern ◽

Mann Kendall Test

Global warming and climate variability are emerging as the foremost environmental problems in the 21st century, especially in developing countries. Full knowledge of key climate change variables is crucial in managing water resources in river basins. This study examines the variability of air temperature and rainfall in the five states of South-Eastern region of Nigeria, using the trend analysis approach. For this purpose, temporal trends in annual rainfall and temperature were detected using non-parametric Mann-Kendall test at 5% significance level. The time series rainfall and temperature data for the period 1922-2008 were analyzed statistically for each state separately. The results of Mann Kendall test showed that there is trend in rainfall in all the capital cities in South-East except Owerri and Awka. It is also observed that the trend of rainfall is decreasing for all the study areas in South-East with the lowest trend rate of -0.1153 mm rainfall occurring in Umuahia. In the case of air temperature, it is observed that the trend is increasing for all the study areas in South-East with the highest trend rate of 0.04698 oC/year occurring in Enugu. These findings provide valuable information for assessing the influence of changes on air temperature and rainfall on water resources and references for water management in the South-Eastern river basin of Nigeria. It also proved that Mann-Kendall technique is an effective tool in analyzing temperature and rainfall trends in a regional watershed. Doi: 10.28991/cej-2021-03091692 Full Text: PDF

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Evaluation the Performance of Several Gridded Precipitation Products over the Highland Region of Yemen for Water Resources Management

Remote Sensing ◽

10.3390/rs12182984 ◽

2020 ◽

Vol 12 (18) ◽

pp. 2984

Author(s):

Ali Hamoud AL-Falahi ◽

Naeem Saddique ◽

Uwe Spank ◽

Solomon H. Gebrechorkos ◽

Christian Bernhofer

Keyword(s):

Climate Change ◽

Water Resources ◽

Rainfall Variability ◽

Annual Rainfall ◽

Climate Data ◽

Average Deviation ◽

Monthly Basis ◽

Highland Region ◽

Single Station ◽

Trmm 3B42

Management of water resources under climate change is one of the most challenging tasks in many arid and semiarid regions. A major challenge in countries, such as Yemen, is the lack of sufficient and long-term climate data required to drive hydrological models for better management of water resources. In this study, we evaluated the accuracy of accessible satellite and reanalysis-based precipitation products against observed data from Al Mahwit governorate (highland region, Yemen) during 1998–2007. Here, we evaluated the accuracy of the Climate Hazards Group Infrared Precipitation with Station (CHIRPS) data, National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR), Tropical Rainfall Measuring Mission (TRMM 3B42), Unified Gauge-Based Analysis of Global Daily Precipitation (CPC), and European Atmospheric Reanalysis (ERA-5). The evaluation was performed on daily, monthly, and annual time steps by directly comparing the data from each single station with the data from the nearest grid box for each product. At a daily timescale, CHIRPS captures the daily rainfall characteristics best, such as the number of wet days, with average deviation from wet durations around 11.53%. TRMM 3B42 is the second-best performing product for a daily estimate with an average deviation of around 34.7%. However, CFSR (85.3%) and PERSIANN-CDR (103%) and ERA-5 (−81.13%) show an overestimation and underestimation of wet days and do not reflect rainfall variability of the study area. Moreover, CHIRPS is the most accurate gridded product on a monthly basis with high correlation and lower bias. The average monthly correlation between the observed and CHIRPS, TRMM 3B42, PERSIANN-CDR, CPC, ERA-5, and CFSR is 0.78, 0.56, 0.53, 0.15, 0.20, and 0.51, respectively. The average monthly bias is −2.9, −5.25, 7.35, −25.29, −24.96, and 16.68 mm for CHIRPS, TRMM 3B42, PERSIANN-CDR, CPC, ERA-5, and CFSR, respectively. CHIRPS displays the spatial distribution of annual rainfall pattern well with percent bias (Pbias) of around −8.68% at the five validation points, whereas TRMM 3B42, PERSIANN-CDR, and CFSR show a deviation of greater than 15.30, 22.90, and 66.21%, respectively. CPC and ERA-5 show Pbias of about −88.6% from observed data. Overall, in absence of better data, CHIRPS data can be used for hydrological and climate change studies on the highland region of Yemen where precipitation is often episodical and measurement records are spatially and temporally limited.

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Climate and land use change impacts on water resources in Sardinia (Italy)

10.5194/egusphere-egu21-10894 ◽

2021 ◽

Author(s):

Dario Ruggiu ◽

Salvatore Urru ◽

Roberto Deidda ◽

Francesco Viola

Keyword(s):

Land Use ◽

Water Resources ◽

Land Use Change ◽

Hydrological Cycle ◽

Potential Evapotranspiration ◽

Regional Scale ◽

Annual Runoff ◽

Annual Rainfall ◽

Land Use Scenarios ◽

Near Future

The assessment of climate change and land use modifications effects on hydrological cycle is challenging. We propose an approach based on Budyko theory to investigate the relative importance of natural and anthropogenic drivers on water resources availability. As an example of application, the proposed approach is implemented in the island of Sardinia (Italy), which is affected by important processes of both climate and land use modifications. In details, the proposed methodology assumes the Fu&#8217;s equation to describe the mechanisms of water partitioning at regional scale and uses the probability distributions of annual runoff (Q) in a closed form. The latter is parametrized by considering simple long-term climatic info (namely first orders statistics of annual rainfall and potential evapotranspiration) and land use properties of basins.In order to investigate the possible near future water availability of Sardinia, several climate and land use scenarios have been considered, referring to 2006-2050 and 2051-2100 periods. Climate scenarios have been generated considering fourteen bias corrected outputs of climatic models from EUROCORDEX&#8217;s project (RCP 8.5), while three land use scenarios have been created following the last century tendencies.Results show that the distribution of annual runoff in Sardinia could be significantly affected by both climate and land use change. The near future distribution of Q generally displayed a decrease in mean and variance compared to the baseline. &#160;&#160;The reduction of&#160; Q is more critical moving from 2006-2050 to 2051-2100 period, according with climatic trends, namely due to the reduction of annual rainfall and the increase of potential evapotranspiration. The effect of LU change on Q distribution is weaker than the climatic one, but not negligible.

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Climatologia da pluviometria do município de Teresina, Piauí, Brasil

Revista Verde de Agroecologia e Desenvolvimento Sustentável ◽

10.18378/rvads.v11i4.4609 ◽

2016 ◽

Vol 11 (4) ◽

pp. 135

Author(s):

Hudson Ellen Alencar Menezes ◽

Raimundo Mainar de Medeiros ◽

José Lucas Guilherme Santos

Keyword(s):

Water Resources ◽

Rainfall Variability ◽

Intertropical Convergence Zone ◽

Atmospheric Dynamics ◽

Rainfall Data ◽

Annual Rainfall ◽

Convergence Zone ◽

Northeast Brazil ◽

Urban Structures ◽

Urbanized Areas

As variações nas precipitações refletem claramente a dinâmica atmosférica da região, marcada pela intensa variabilidade, onde se observa a atuação da Zona de Convergência Intertropical (ZCIT) com sua atuação entre os meses de janeiro a março, sendo esse período mais chuvoso. As variabilidades espaço temporal no comportamento das chuvas tem sido analisadas e diagnosticadas por vários autores no Nordeste do Brasil (NEB), portanto objetivou-se diagnosticar a variabilidade dos índices pluviométricos em Teresina no Estado do Piauí no período de 1913 a 2010. A análise do comportamento da precipitação nas cidades de grande e médio porte é de extrema importância para o gerenciamento dos recursos hídricos, uma vez que se trata de áreas densamente urbanizadas. Muitas vezes, sem uma estruturação urbana adequada, estas cidades se encaixam perfeitamente nesse contexto. Foram utilizados dados mensais observados e anuais de precipitação pluviométrica no período de 1913 a 2010, com 97 anos de observações. Os resultados mostraram a recorrência de valores máximos de precipitação anual dentro de um intervalo de 18, 11 e 8 anos. Na análise dos desvios-padrões, os resultados mostraram predominância dos desvios negativos em relação aos desvios positivos.Climatology of rainfall in the Teresina city, Piauí state, BrazilVariations in precipitation clearly reflect the atmospheric dynamics of the region, marked by intense variability, where we observe the performance of the Intertropical Convergence Zone (ITCZ) with his performance in the months of January-March, this being more rain tem period. The timeline of rainfall variability in behavior has been analyzed and diagnosed by several authors in Northeast Brazil (NEB), so let's study this variability between the periods 1913 to 2010 of Teresina city. The behavior of rainfall in cities large and medium sized is of utmost importance to the managerial of water resources, since it is densely urbanized areas. Often without adequate urban structures these cities fit perfectly in this context. We used observed monthly and annual rainfall data for the period 1913-2010, 97 years of observations. The results showed recurrence of maximum values of annual precipitation an interval of 18, 11 and 8 years. In the analysis of standard deviations, the results showed a predominance of negative deviations from the positive deviations.

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Hydrogeology of a Complex Aquifer System in Semi-Arid Mountainous Region: The Eastern Upper Guir Basin in the High Atlas (Morocco)

Water ◽

10.3390/w12102849 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2849

Author(s):

Fatima Abdelfadel ◽

Mohamed Hilali ◽

Claude Fontaine ◽

Abderrazak El Albani ◽

Abderahman Mahboub ◽

...

Keyword(s):

Water Resources ◽

Annual Rainfall ◽

High Atlas ◽

Aquifer System ◽

Water Demands ◽

Aquifer Systems ◽

Drastic Increase ◽

Eastern Border ◽

Eastern Morocco ◽

Semi Arid

The eastern part of Morocco, surrounded by the High Atlas chain close to Errachidia, represents a very sensitive area in a semi-arid context. Average annual rainfall does not exceed 300 mm/year. Most of the regional water resources are linked to the aquifer systems in the Atlas area. The study site coincides with the Eastern Upper Guir Basin, one of the main rivers in Eastern Morocco. This basin is located close to the eastern border of the Moroccan High Atlas. The geology of the basin consists mainly of Jurassic and Cretaceous formations. The structure of the basin is strongly affected by the Atlasian tectonics. This results in successive large synclines separated by major W-E faults. The hydrogeological system of the basin is accordingly constituted by sub-basins associated with each syncline and separated by faulted anticlines, whose overlapping faults act as semi-impermeable barriers. This compartmentalization causes the very complex functioning of the whole system. The study undertaken, based on structural, meteorological, hydrogeological, hydrochemical and isotopic data, allowed us to advance significantly in the understanding of this system. The compartments behave as hydrogeological sub-units but remain interdependent on each other. The recharge of the aquifer system is essentially associated with the rains and snowfalls at high altitudes. This is consistent with the stable isotope results. Important development projects are planned in this region, associated with a drastic increase in water demands. Groundwater suitability was assessed using the WHO standards for drinking purposes and the SAR (sodium adsorption ratio) for irrigation. Complementary investigations should be considered to further the results presented here and move towards a quantitative assessment and management of the water resources.

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Hydrologic impact of climate change on Murray–Hotham catchment of Western Australia: a projection of rainfall–runoff for future water resources planning

Hydrology and Earth System Sciences ◽

10.5194/hess-18-3591-2014 ◽

2014 ◽

Vol 18 (9) ◽

pp. 3591-3614 ◽

Cited By ~ 17

Author(s):

S. A. Islam ◽

M. A. Bari ◽

A. H. M. F. Anwar

Keyword(s):

Climate Change ◽

Water Resources ◽

Western Australia ◽

Water Availability ◽

Rainfall Data ◽

Annual Rainfall ◽

Emission Scenarios ◽

Runoff Reduction ◽

The Mean ◽

Hydrologic Impact

Abstract. Reduction of rainfall and runoff in recent years across southwest Western Australia (SWWA) has attracted attention to the climate change impact on water resources and water availability in this region. In this paper, the hydrologic impact of climate change on the Murray–Hotham catchment in SWWA has been investigated using a multi-model ensemble approach through projection of rainfall and runoff for the periods mid (2046–2065) and late (2081–2100) this century. The Land Use Change Incorporated Catchment (LUCICAT) model was used for hydrologic modelling. Model calibration was performed using (5 km) grid rainfall data from the Australian Water Availability Project (AWAP). Downscaled and bias-corrected rainfall data from 11 general circulation models (GCMs) for Intergovernmental Panel on Climate Change (IPCC) emission scenarios A2 and B1 was used in LUCICAT model to derive rainfall and runoff scenarios for 2046–2065 (mid this century) and 2081–2100 (late this century). The results of the climate scenarios were compared with observed past (1961–1980) climate. The mean annual rainfall averaged over the catchment during recent time (1981–2000) was reduced by 2.3% with respect to the observed past (1961–1980) and the resulting runoff reduction was found to be 14%. Compared to the past, the mean annual rainfall reductions, averaged over 11 ensembles and over the period for the catchment for A2 scenario are 13.6 and 23.6% for mid and late this century respectively while the corresponding runoff reductions are 36 and 74%. For B1 scenario, the rainfall reductions were 11.9 and 11.6% for mid and late this century and the corresponding runoff reductions were 31 and 38%. Spatial distribution of rainfall and runoff changes showed that the rate of changes were higher in high rainfall areas compared to low rainfall areas. Temporal distribution of rainfall and runoff indicate that high rainfall events in the catchment reduced significantly and further reductions are projected, resulting in significant runoff reductions. A catchment scenario map has been developed by plotting decadal runoff reduction against corresponding rainfall reduction at four gauging stations for the observed and projected periods. This could be useful for planning future water resources in the catchment. Projection of rainfall and runoff made based on the GCMs varied significantly for the time periods and emission scenarios. Hence, the considerable uncertainty involved in this study though ensemble mean was used to explain the findings.

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Quantification of Temporal Variations in Base Flow Index Using Sporadic River Data: Application to the Bua Catchment, Malawi

Water ◽

10.3390/w11050901 ◽

2019 ◽

Vol 11 (5) ◽

pp. 901 ◽

Cited By ~ 10

Author(s):

Laura Kelly ◽

Robert M. Kalin ◽

Douglas Bertram ◽

Modesta Kanjaye ◽

Macpherson Nkhata ◽

...

Keyword(s):

Water Resources ◽

River Flow ◽

Temporal Variations ◽

Dry Season ◽

Base Flow ◽

Flow Index ◽

Wet Season ◽

Data Application ◽

Base Flow Index ◽

Long Term Trends

This study investigated how sporadic river datasets could be used to quantify temporal variations in the base flow index (BFI). The BFI represents the baseflow component of river flow which is often used as a proxy indicator for groundwater discharge to a river. The Bua catchment in Malawi was used as a case study, whereby the smoothed minima method was applied to river flow data from six gauges (ranging from 1953 to 2009) and the Mann-Kendall (MK) statistical test was used to identify trends in BFI. The results showed that baseflow plays an important role within the catchment. Average annual BFIs > 0.74 were found for gauges in the lower reaches of the catchment, in contrast to lower BFIs < 0.54 which were found for gauges in the higher reaches. Minimal difference between annual and wet season BFI was observed, however dry season BFI was >0.94 across all gauges indicating the importance of baseflow in maintaining any dry season flows. Long term trends were identified in the annual and wet season BFI, but no evidence of a trend was found in the dry season BFI. Sustainable management of the investigated catchment should, therefore, account for the temporal variations in baseflow, with special regard to water resources allocation within the region and consideration in future scheme appraisals aimed at developing water resources. Further, this demonstration of how to work with sporadic river data to investigate baseflow serves as an important example for other catchments faced with similar challenges.

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Turkey's Water Resources and Hydropower Potential

Energy Exploration & Exploitation ◽

10.1260/0144-5987.23.1.19 ◽

2005 ◽

Vol 23 (1) ◽

pp. 19-29 ◽

Cited By ~ 3

Author(s):

Ayhan Demirbaş ◽

Recep Bakiş

Keyword(s):

Surface Water ◽

Water Resources ◽

Ground Water ◽

Annual Rainfall ◽

Water Reservoirs ◽

Total Potential ◽

Hydropower Potential ◽

Different Types

The aim of this paper is to investigate water resources in Turkey. Annual rainfall varies from 220 mm to 2500 mm with an average of 643 mm, which means total volume of 501 km3 and average annual potential of surface water is 186 km3 and 95 km3 of this amount potential can be feasibly developed. Ground water reservoirs are estimated to be around 12 km3. As a result of construction of 700 dams, with different types, purposes and sizes, 140 km3 of water is being stored in the reservoirs. Total hydropower potential of Turkey is annually 433,000 GWh. Almost 50% of the total potential is technically exploitable, and 29% is (122,322 GWh/year) economically exploitable.

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