scholarly journals Hydroclimatic Variability in the Bilate Watershed, Ethiopia

Climate ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 98
Author(s):  
Yoseph Arba Orke ◽  
Ming-Hsu Li
Keyword(s):  
Water Resource Management ◽  
Significant Rise ◽  
Maximum Temperature ◽  
Trend Test ◽  
Adaptation Measures ◽  
Crucial Information ◽  
Slope Estimator ◽  
Hydroclimatic Variability ◽  
Increasing Temperature ◽  
Point Detection

It is important to understand variations in hydro-meteorological variables to provide crucial information for water resource management and agricultural operation. This study aims to provide comprehensive investigations of hydroclimatic variability in the Bilate watershed for the period 1986 to 2015. Coefficient of variation (CV) and the standardized anomaly index (SAI) were used to assess the variability of rainfall, temperature, and streamflow. Changing point detection, the Mann–Kendell test, and the Sen’s slope estimator were employed to detect shifting points and trends, respectively. Rainfall and streamflow exhibited higher variability in the Bega (dry) and Belg (minor rainy) seasons than in the Kiremt (main rainy) season. Temperature showed an upward shift of 0.91 °C in the early 1990s. Reduction in rainfall (−11%) and streamflow (−42%) were found after changing points around late 1990s and 2000s, respectively. The changing points detected were likely related to the ENSO episodes. The trend test indicated a significant rise in temperature with a faster increase in the minimum temperature (0.06 °C/year) than the maximum temperature (0.02 °C/year). Both annual mean rainfall and streamflow showed significant decreasing trends of 8.32 mm/year and 3.64 mm/year, respectively. With significant increase in temperature and reduction in rainfall, the watershed has been experiencing a decline in streamflow and a shortage of available water. Adaptation measures should be developed by taking the increasing temperature and the declining and erratic nature of rainfall into consideration for water management and agricultural activities.

scholarly journals Analysis of spatio-temporal climate variability of a shallow lake catchment in Tanzania

2020 ◽  
Author(s):  
Latifa O. Nyembo ◽  
Isaac Larbi ◽  
Mwemezi J. Rwiza
Keyword(s):  
Water Productivity ◽  
Standardized Precipitation Index ◽  
Negative Influence ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Adaptation Measures ◽  
Distance Weighting ◽  
Spatio Temporal ◽  
Slope Estimator ◽  
Lake Catchment

Abstract This study analyzed the trends and spatio-temporal variability in rainfall and temperature, and the length of the rainy season (LRS) in the Lake Manyara catchment, Tanzania, covering a period between 1988 and 2018 using stations and satellite climate product. The Mann-Kendall statistical test, Sen's slope estimator, and inverse distance weighting interpolation techniques were used to detect the trends, magnitude of trends and spatial distribution of rainfall and temperature. A modified Stern's method and water balance concept were used for rainfall onset, cessation and LRS analysis, while a standardized precipitation index (SPI) was used to investigate the wetness or dryness of the area. The results showed high variability and decreasing trend (4 mm/y) in annual rainfall, and non-significant increasing trend for minimum and maximum temperature. Rainfall increased from the western to the northern part of the catchment whereas a reversal pattern was noticed for temperature. The SPI shows a signal of normal condition (about 65%) for all stations – with few years showing evidence of wetter and drier conditions. The LRS showed a decreasing trend indicating a potential negative influence on rain-dependent activities. There is a need, therefore, for adaptation measures such as improving water productivity and irrigation at the farm and catchment level.

scholarly journals Spatiotemporal Trend Analysis of Temperature and Rainfall over Ziway Lake Basin, Ethiopia

Hydrology ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 2
Author(s):  
Aster Tesfaye Hordofa ◽  
Olkeba Tolessa Leta ◽  
Tane Alamirew ◽  
Abebe Demissie Chukalla
Keyword(s):  
21St Century ◽  
Water Resource Management ◽  
Climate Model ◽  
Mapping Method ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Cmip5 Models ◽  
Trend Test ◽  
Lake Basin ◽  
Climate Data

Rainfall and temperature trends detection is vital for water resources management and decision support systems in agro-hydrology. This study assessed the historical (1983–2005) and future (2026–2100) rainfall, maximum temperature (Tmax), and minimum temperature (Tmin) trends of the Ziway Lake Basin (Ethiopia). The daily observed rainfall and temperature data at eleven stations were obtained from the National Meteorological Agency (NMA) of Ethiopia, while simulated historical and future climate data were obtained from the Coupled Model Intercomparison Project 5 (CMIP5) datasets under Representative Concentration Pathways (RCP) of 4.5 and 8.5. The CMIP5 datasets were statistically downscaled by using the climate model data for hydrologic modeling (CMhyd) tool and bias corrected using the distribution mapping method available in the CMhyd tool. The performance of simulated rainfall, Tmax, and Tmin of the CMIP5 models were statistically evaluated using observation datasets at eleven stations. The results showed that the selected CMIP5 models can reasonably simulate the monthly rainfall, Tmax, and Tmin at the majority of the stations. Modified Mann–Kendall trend test were applied to estimate the trends of annual rainfall, Tmax, and Tmin in the historical and future periods. We found that rainfall experienced no clear trends, while Tmax, and Tmin showed consistently significant increasing trends under both RCP 4.5 and 8.5 scenarios. However, the warming is expected to be greater under RCP 8.5 than RCP 4.5 by the end of the 21st century, resulting in an increasing trend of Tmax and Tmin at all stations. The greatest warming occurred in the central part of the basin, with statistically significant increases largely seen by the end of the 21st century, which is expected to exacerbate the evapotranspiration demand of the area that could negatively affect the freshwater availability within the basin. This study increases our understanding of historic trends and projected future change effects on rainfall- and evapotranspiration-related climate variables, which can be used to inform adaptive water resource management strategies.

Diurnally Alternating Temperatures Stimulate Sprouting of Purple Nutsedge (Cyperus rotundus) Tubers

Weed Science ◽  
1996 ◽  
Vol 44 (1) ◽  
pp. 122-125 ◽  
Author(s):  
Joel E. Miles ◽  
Roy K. Nishimoto ◽  
Osamu Kawabata
Keyword(s):  
High Temperature ◽  
Cyperus Rotundus ◽  
Maximum Temperature ◽  
Temperature Cycle ◽  
Purple Nutsedge ◽  
Tuber Temperature ◽  
Tuber Sprouting ◽  
Alternating Temperature ◽  
Increasing Temperature ◽  
Temperature Responses

Experiments were conducted to determine the response of purple nutsedge tuber sprouting to diurnally alternating temperature. These experiments compared the response to alternating and constant temperatures and determined the effect of the amplitude of alternation and time of exposure to the maximum temperature. Tuber sprouting was more rapid and complete with alternating temperatures than with constant temperatures. Increasing temperature fluctuation from 0 to 6 C for 12 h daily linearly increased total tuber sprouting. As little as 30 min exposure to high temperature per day provided nearly the same level of sprouting as a 12 h alternating temperature cycle. This phenomenon should be considered when conducting studies to describe tuber temperature responses or when predicting tuber sprouting and emergence.

scholarly journals Long-Term Trends and Seasonality Detection of the Observed Flow in Yangtze River Using Mann-Kendall and Sen’s Innovative Trend Method

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1855 ◽  
Author(s):  
Ali ◽  
Kuriqi ◽  
Abubaker ◽  
Kisi
Keyword(s):  
Trend Analysis ◽  
Yangtze River ◽  
Winter Season ◽  
Trend Test ◽  
Analysis Method ◽  
Adaptation Measures ◽  
Minimum Flow ◽  
Mk Test ◽  
Innovative Trend Analysis ◽  
Increasing Trend

Trend analysis of streamflow provides practical information for better management of water resources on the eve of climate change. Thus, the objective of this study is to evaluate the presence of possible trends in the annual, seasonal, maximum, and minimum flow of Yangtze River at Cuntan and Zhutuo stations in China for the period 1980 to 2015. The assessment was carried out using the Mann–Kendall trend test, and the innovative trend analysis, while Sen’s slope is used to estimate the magnitude of the changes. The results of the study revealed that there were increasing and decreasing trends at Cuntan and Zhutuo stations in different months. The mean annual flow was found to decrease at a rate of −26.76 m3/s and −17.37 m3/s at both stations. The minimum flow was found to significantly increase at a rate of 30.57 m3/s and 16.37 m3/s, at a 95% level of confidence. Maximum annual flows showed an increasing trend in both regions of the Yangtze River. On the seasonal scale, the results showed that stations are more sensitive to seasonal flow variability suggesting a probable flooding aggravation. The winter season showed an increasing flow trend, while summer showed a decreasing trend. The spring flow was found to have an increasing trend by the Mann–Kendall test at both stations, but in the Zhutuo Station, a decreasing trend was found by way of the innovative trend analysis method. However, the autumn flow indicated a decreasing trend over the region by the Mann–Kendall (MK) test at both stations while it had an increasing trend in Cuntan by the innovative trend analysis method. The result showed nonstationary increasing and decreasing flow trends over the region. Innovative trend analysis method has the advantage of detecting the sub-trends in the flow time series because of its ability to present the results in graphical format. The results of the study indicate that decreasing trends may create water scarcity if proper adaptation measures are not taken.

Micro-Chemistry and Mechanical Behaviour of Ti6Al4V-SiCf Composite Produced by HIP for Aeronautical Applications

2011 ◽  
Vol 678 ◽  
pp. 23-47 ◽  
Author(s):  
Paolo Deodati ◽  
Riccardo Donnini ◽  
Saulius Kaciulis ◽  
Majid Kazemian-Abyaneh ◽  
Alessio Mezzi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Turbine Blades ◽  
Hot Isostatic Pressing ◽  
Heat Treatments ◽  
Maximum Temperature ◽  
Indentation Tests ◽  
Service Conditions ◽  
Increasing Temperature

The paper reports the results of an extensive characterization of the Ti6Al4V-SiCfcomposite produced by hot isostatic pressing (HIP) to assess its capability to withstand the in-service conditions of turbine blades operating at middle temperatures in aeronautical engines. The microstructure of composite, in as-fabricated condition and after long-term heat treatments (up to 1,000 hours) in the temperature range 673-873 K, has been investigated by means of different techniques. Particular attention was paid to the micro-chemical evolution of fibre-matrix interface which is scarcely affected also by the most severe heat treatments examined here. This leads to stable mechanical properties as evidenced by hardness, tensile and FIMEC instrumented indentation tests. Therefore, the composite can operate at the maximum temperature (873 K) foreseen for its aeronautical applications without remarkable modifications of its microstructure and degradation of mechanical properties. The mechanical characterization has been completed by internal friction and dynamic modulus measurements carried out both at constant and increasing temperature, from 80 to 1173 K.

scholarly journals Assessing the Impacts of Climate change on Crop Yields in different Agro-Climatic Zones of India

2020 ◽  
Vol 3 (4) ◽  
Author(s):  
Naveen P Singh ◽  
Bhawna Anand ◽  
S K Srivastava ◽  
K V Rao ◽  
S K Bal ◽  
...  
Keyword(s):  
Climate Change ◽  
Crop Yields ◽  
Climate Impact ◽  
Significant Rise ◽  
Agricultural System ◽  
Adaptation Measures ◽  
Climatic Zones ◽  
Emissions Scenarios ◽  
The Impact ◽  
Impacts Of Climate Change

Thestudy attempts to estimateand predict climate impact on crop yieldsusing future temperature projections under two climate emissions scenarios of RCP 4.5 and 8.5 for threedifferent time periods (2030s, 2050s and 2080s) across Agro-climatic zones (ACZ) of India.During the period 1966-2011, a significant rise was observed in both the annual mean maximum and minimum temperature across ACZs. Rainfall recorded an annual decline in Himalayan Regions and Gangetic Plains and a rise in Coastal Regions, Plateau & Hills and Western Dry Region.Our results showedhigh heterogeneity in climate impact onkharif and rabi crop yields (with both negative and positive estimates) across ACZs.It was found that rainfall had a positive effect on most of crop yields, but was not sufficient enough to counterbalance the impact of temperature.Changes in crop yield were more pronounced forhigheremission scenario of RCP 8.5. Thus, it was evident that the relative impacts of climate change and the associated vulnerability varyby ACZs, hence comprehensive crop and region-specific adaptation measures should be emphasized that helps in enhancing resilience of agricultural system in short to medium term. 

scholarly journals Assessment of Spatiotemporal Variability and Trend Analysis of Reference Crop Evapotranspiration for the southern region of Peninsular India

2021 ◽  
Author(s):  
Jayashree Tenkila Ramachandra ◽  
Subba Reddy Nandanavana Veerappa ◽  
Dinesh Acharya Udupi
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Solar Radiation ◽  
Water Resource Management ◽  
Spatiotemporal Variability ◽  
Trend Test ◽  
Accurate Estimation ◽  
Peninsular India ◽  
Climatic Zones ◽  
Statistical Measures

Abstract Accurate estimation of reference evapotranspiration (ET0) is an essential requirement for water resource management and scheduling agricultural activities. Several empirical methods have been employed in estimating ET0 across diverse climate regimes over the past decades. The Python implementation for estimation of daily and monthly ET0 values of representative stations of ten agro-climatic zones of Karnataka from 1979 through 2014 using the standard FAO Penman-Monteith method was carried out. The assessment of temporal and spatial variability of monthly ET0 values across the various agro-climatic zones done by the various statistical measures revealed that the variation in spatial ET0 values was higher than temporal indicating major differentiation of ET0 values was with respect to the stations rather than years under study. The non-parametric Mann-Kendall test conducted at 1% significance level on the annual ET0 values revealed that statistically significant increasing trend was observed for all the ten stations during the study period. The trend test conducted on the climate variables like mean air temperature, wind speed, relative humidity and solar radiation signify their influence the annual ET0 values. The magnitude changes in the trends detected by the Theil Sen’s slope indicated that increasing values of mean temperature, solar radiation and decreasing values of relative humidity predominantly contributed to the annual upward trend in ET0 values for the 10 stations. A trivial impact of wind speed on annual ET0 values was observed for the stations. Kalburgi and Udupi stations exhibited positive ET0 trend with the highest and lowest annual values among ten stations.

scholarly journals Links between the Big Dry in Australia and hemispheric multi-decadal climate variability – implications for water resource management

2013 ◽  
Vol 10 (11) ◽  
pp. 13539-13593 ◽  
Author(s):  
D. C. Verdon-Kidd ◽  
A. S. Kiem ◽  
R. Moran
Keyword(s):  
Southern Hemisphere ◽  
Water Resource Management ◽  
Large Scale ◽  
Economic Effects ◽  
Data Sets ◽  
Climate Data ◽  
Decadal Climate Variability ◽  
Winter Rainfall ◽  
Millennium Drought ◽  
Hydroclimatic Variability

Abstract. Southeast Australia (SEA) experienced a protracted drought during the mid-1990s until early 2010 (known as the Big Dry or Millennium Drought) that resulted in serious environmental, social and economic effects. This paper analyses a range of historical climate data sets to place the recent drought into context in terms of Southern Hemisphere inter-annual to multi-decadal hydroclimatic variability. The findings indicate that the recent Big Dry in SEA is in fact linked to the widespread Southern Hemisphere climate shift towards drier conditions that began in the mid-1970s. However, it is shown that this link is masked because the large-scale climate drivers responsible for drying in other regions of the mid-latitudes since the mid-1970s, did not have the same effect on SEA during the mid to late-1980s and early-1990s. More specifically, smaller-scale synoptic processes resulted in elevated autumn and winter rainfall (a crucial period for SEA hydrology) during the mid to late-1980s and early-1990s, which punctuated the longer term drying. From the mid-1990s to 2010 the frequency of the synoptic processes associated with elevated autumn/winter rainfall decreased, resulting in a return to drier than average conditions and the onset of the Big Dry. The findings presented in this paper have marked implications for water management and climate attribution studies in SEA, in particular for understanding and dealing with "baseline" (i.e. current) hydroclimatic risks.

scholarly journals Assessing traditional irrigation systems in data scarcity conditions, a proposal for a methodological approach.

2021 ◽  
Author(s):  
Vladimiro Boselli ◽  
Eleni Maria Michailidi ◽  
Jalal Kassout ◽  
Mhammad Houssni ◽  
Abdeltif El Ouahrani ◽  
...  
Keyword(s):  
System Dynamics ◽  
Water Resource Management ◽  
Driving Forces ◽  
Methodological Approach ◽  
Irrigation Systems ◽  
Adaptation Measures ◽  
Data Scarcity ◽  
Atlas Mountains ◽  
Traditional Irrigation ◽  
Local Initiatives

<p>Traditional irrigation systems, apart from being an important cultural heritage element, are considered vital for sustainable water resource management and climate change adaptation measures. However, these traditional forms of irrigation and agriculture, with direct implications in food security at a local scale, have been suffering from abandonment or degradation worldwide. In light of this, the need to fully comprehend the complex linkage of their abandonment with different driving forces is essential. The identification of these dynamics enables the adoption of appropriate interventions with local initiatives and policies on a larger scale.</p><p>The present scientific contribution aims at presenting a valid methodology to consistently address the multidisciplinarity and the multifacetedness that emerge in studies relating to traditional irrigation systems.</p><p>The methodological approach introduced regards that of system dynamics and is geared to outline a combined framework at the service of stakeholders and policy makers. This approach has been already adopted previously, in different studies to tackle down the complexity stemming from the heterogeneity of drivers in complex water-related and ecosystem modeling problems. Among its advantages there are its ease of implementation in any given scenario and its ability to integrate qualitative and quantitative assessments of multidisciplinary nature that can even be interconnected. Moreover, its applicability in cases affected by data scarcity allows to address issues in those areas of the world which often are more vulnerable, poorer and marginalized and which consequently suffer from a lack of interest in monitoring environmental and social variables, properly.</p><p><span>The abstract is based on </span><strong>Boselli, V., Ouallali, A., Briak, H., Houssni, M., Kassout, J., El Ouahrani, A., & Michailidi, E. M. (2020). System Dynamics Applied to Terraced Agroecosystems: The Case Study of Assaragh (Anti-Atlas Mountains, Morocco). <em>Water</em>, <em>12</em>(6), 1693. doi.org/10.3390/w12061693</strong></p>

scholarly journals Impact of Climate Change on the Hydrology of the Upper Awash River Basin, Ethiopia

Hydrology ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 3
Author(s):  
Nega Chalie Emiru ◽  
John Walker Recha ◽  
Julian R. Thompson ◽  
Abrham Belay ◽  
Ermias Aynekulu ◽  
...  
Keyword(s):  
Climate Change ◽  
Assessment Tool ◽  
Addis Ababa ◽  
Swat Model ◽  
Hydrological Drought ◽  
Global Climate Models ◽  
Mitigation Measures ◽  
Maximum Temperature ◽  
Mean Annual Precipitation ◽  
Trend Test

This study investigated the impacts of climate change on the hydrology of the Upper Awash Basin, Ethiopia. A soil and water assessment tool (SWAT) model was calibrated and validated against observed streamflow using SWAT CUP. The Mann–Kendall trend test (MK) was used to assess climate trends. Meteorological drought (SPEI) and hydrological drought (SDI) were also investigated. Based on the ensemble mean of five global climate models (GCMs), projected increases in mean annual maximum temperature over the period 2015–2100 (compared with a 1983–2014 baseline) range from 1.16 to 1.73 °C, while increases in minimum temperature range between 0.79 and 2.53 °C. Increases in mean annual precipitation range from 1.8% at Addis Ababa to 45.5% over the Hombole area. High streamflow (Q5) declines at all stations except Ginchi. Low flows (Q90) also decline with Q90 equaling 0 m3s−1 (i.e., 100% reduction) at some gauging stations (Akaki and Hombole) for individual GCMs. The SPEI confirmed a significant drought trend in the past, while the frequency and severity of drought will increase in the future. The basin experienced conditions that varied from modest dry periods to a very severe hydrological drought between 1986 and 2005. The projected SDI ranges from modestly dry to modestly wet conditions. Climate change in the basin would enhance seasonal variations in hydrological conditions. Both precipitation and streamflow will decline in the wet seasons and increase in the dry seasons. These changes are likely to have an impact on agricultural activities and other human demands for water resources throughout the basin and will require the implementation of appropriate mitigation measures.

Sign in / Sign up

Export Citation Format

Share Document