scholarly journals Temporal and spatial changes of rainfall and streamflow in the Upper Tekezē–Atbara river basin, Ethiopia

2017 ◽  
Vol 21 (4) ◽  
pp. 2127-2142 ◽  
Author(s):  
Tesfay G. Gebremicael ◽  
Yasir A. Mohamed ◽  
Pieter v. Zaag ◽  
Eyasu Y. Hagos
Keyword(s):  
Change Point ◽  
Statistical Tests ◽  
Catchment Management ◽  
Trend Analyses ◽  
Temporal And Spatial Variability ◽  
Spatial Changes ◽  
Changing Patterns ◽  
Temporal And Spatial ◽  
Using Data ◽  
Streamflow Trends

Abstract. The Upper Tekezē–Atbara river sub-basin, part of the Nile Basin, is characterized by high temporal and spatial variability of rainfall and streamflow. In spite of its importance for sustainable water use and food security, the changing patterns of streamflow and its association with climate change is not well understood. This study aims to improve the understanding of the linkages between rainfall and streamflow trends and identify possible drivers of streamflow variabilities in the basin. Trend analyses and change-point detections of rainfall and streamflow were analysed using Mann–Kendall and Pettitt tests, respectively, using data records for 21 rainfall and 9 streamflow stations. The nature of changes and linkages between rainfall and streamflow were carefully examined for monthly, seasonal and annual flows, as well as indicators of hydrologic alteration (IHA). The trend and change-point analyses found that 19 of the tested 21 rainfall stations did not show statistically significant changes. In contrast, trend analyses on the streamflow showed both significant increasing and decreasing patterns. A decreasing trend in the dry season (October to February), short season (March to May), main rainy season (June to September) and annual totals is dominant in six out of the nine stations. Only one out of nine gauging stations experienced significant increasing flow in the dry and short rainy seasons, attributed to the construction of Tekezē hydropower dam upstream this station in 2009. Overall, streamflow trends and change-point timings were found to be inconsistent among the stations. Changes in streamflow without significant change in rainfall suggests factors other than rainfall drive the change. Most likely the observed changes in streamflow regimes could be due to changes in catchment characteristics of the basin. Further studies are needed to verify and quantify the hydrological changes shown in statistical tests by identifying the physical mechanisms behind those changes. The findings from this study are useful as a prerequisite for studying the effects of catchment management dynamics on the hydrological variabilities in the basin.

scholarly journals Temporal and spatial changes of rainfall and streamflow in the Upper Tekeze–Atbara River Basin, Ethiopia

2016 ◽  
Author(s):  
Tesfay Gebretsadkan Gebremicael ◽  
Yasir Abbas Mohamed ◽  
Pieter van der Zaag ◽  
Eyasu Yazew Hagos
Keyword(s):  
River Basin ◽  
Change Point ◽  
Statistical Tests ◽  
Catchment Management ◽  
Temporal And Spatial Variability ◽  
Spatial Changes ◽  
Changing Patterns ◽  
Temporal And Spatial ◽  
Using Data ◽  
Streamflow Trends

Abstract. The Upper Tekeze–Atbara river basin–part of the Nile basin, is characterized by high temporal and spatial variability of rainfall and streamflow. In spite of its importance for sustainable water use and food security, the changing patterns of streamflow and its association with climate change is not well understood in the basin. This study aims at improving the understanding of the linkages between rainfall and streamflow trends and identifying the drivers of streamflow variabilities in the basin. Trend and change point detections of rainfall and streamflow were analysed using Mann–Kendall and Pettitt tests, respectively, using data records for 21 rainfall and 9 streamflow stations. The nature of changes and linkages between rainfall and streamflow were carefully examined for monthly, seasonal, annual flows as well as Indicators of Hydrological Alterations (IHA). The trend and change point analyses found that 20 of the tested 21 rainfall stations did not show statistically significant changes. In contrast, trend analyses on the streamflow showed a significant increasing/decreasing patterns. A decreasing trend in the dry (October to February), short (March to May), main rainy seasons (June to September) and annual totals is dominant in 6 out of the 9 stations. Only one out of nine gauging stations experienced increasing flow significantly in the dry and short rainy seasons. This increasing trend is attributed to the construction of Tekeze hydropower dam above the station in 2009. Overall, streamflow trends and change point timings were found to be inconsistent among the stations. Changes in streamflow without significant change in rainfall suggests other factors than rainfall to drive the change. Weak linkages between rainfall and streamflow trends indicate that the observed changes in streamflow regimes could be due to changes in catchment characteristics of the basin. Further studies are needed to verify and quantify the hydrological changes shown in statistical tests by identifying the physical mechanisms behind those changes. The findings from this study are useful as a pre-requisite for studying the effects of catchment management dynamics on the hydrological variabilities in the basin.

scholarly journals Variación temporal y espacial en la estructura de la comunidad de pequeños mamíferos en un bosque tropical seco

2011 ◽  
Vol 1 (1) ◽  
pp. 19
Author(s):  
Yolanda Domínguez-Castellanos ◽  
Gerardo J. Ceballos González
Keyword(s):  
Tropical Forest ◽  
Small Mammals ◽  
Dry Forest ◽  
La Selva ◽  
Temporal And Spatial Variability ◽  
Palabras Clave ◽  
Spatial Changes ◽  
Temporal And Spatial ◽  
Precipitation Records

Resumen: La estructura de una comunidad biológica está conformada por atributos como la composición, la riqueza y la abundancia de las especies, e influenciada por los cambios temporales y espaciales, que a su vez, se refleja en la composición y abundancia de especies de dicha comunidad. El objetivo fue evaluar la variabilidad temporal y espacial de la comunidad de pequeños mamíferos en la selva seca de Chamela, Jalisco, considerando los dos tipos de vegetación predominantes (selva baja y selva mediana). El muestreo abarcó 18 años y la información generada se compiló en una base de datos, en la que se incluyen los registros de precipitación de los mismos periodos. Con los datos obtenidos se concluye que la abundancia anual de especies varió año con año, registrándose 13 especies de pequeños mamíferos en el área (Tlacuatzin canescens,Megasorex gigas, Spilogale pygmaea, Liomys pictus, Oryzomys melanotis, O. couesi,Nyctomys sumichrasti, Reithrodontomys fulvescens, Osgoodomys banderanus, Peromyscus perfulvus, Baiomys musculus, Sigmodon mascotensis y Xenomys nelsoni). A pesar de que la estructura y cambios temporales de la vegetación modificaron de forma distinta a cada tipo de selva, la composición fue igual para ambas, no obstante la selva mediana es más rica y diversa en especies que la selva baja. Esta estructura de la comunidad de pequeños mamíferos mostró una variación a largo plazo tanto en composición como en riqueza. Por lo que las características de la región de Chamela, permiten la coexistencia de las especies haciendo un uso diferencial del hábitat. Palabras clave: Pequeños mamíferos, comunidad, selvas secas, Jalisco, México. Abstract: The structure of a biological community consists of attributes such as composition, richness and abundance of species, and influenced by the temporal and spatial changes, which in turn is reflected in the composition and abundance of species of that community. The objective was to evaluate the temporal and spatial variability of the community of small mammals in the dry forest of Chamela, Jalisco, considering the two predominant types of vegetation (lowland and tropical forest). The sample comprised 18 and the information generated is compiled in a database, which includes the precipitation records the same periods. The data obtained showed that the annual abundance of species varied from year to year, recorded 13 species of small mammals in the area (Tlacuatzin canescens, Megasorex gigas, Spilogale pygmaea, Liomys pictus, Oryzomys melanotis, O. couesi, Nyctomys sumichrasti, Reithrodontomys fulvescens, Osgoodomys banderanus,Peromyscus perfulvus, Baiomys musculus, Xenomys nelsoni and Sigmodon mascotensis). Although the structure and temporal changes of vegetation changed differently for each type of forest, the composition was the same for both, despite the tropical forest is richer and more diverse in the lowland species. The community structure of small mammals showed a long-term variation in composition and in wealth. So that the characteristics of the region of Chamela allow coexistence of species making a differential use habitat. Key words: small mammals, community, dry forest, Jalisco, Mexico.

Estimation of temporal and spatial changes in micronutrients in the soil using geostatistical analysis

2017 ◽  
Vol 4 (2) ◽  
Author(s):  
GARIMA SHUKLA ◽  
G. C. MISHRA ◽  
S. K. SINGH
Keyword(s):  
Spatial Distribution ◽  
Dynamic System ◽  
Spatial Variation ◽  
Uttar Pradesh ◽  
Geostatistical Analysis ◽  
Statistical Analyses ◽  
Distribution Maps ◽  
Spatial Changes ◽  
Temporal And Spatial ◽  
Using Data

Investigation of temporal and spatial changes is essential in soil because of its heterogeneous, diverse and dynamic system. In present paper, content of some important major micronutrients namely zinc, boron and iron were estimated at different unsampled locations in Sevapuri block of Varanasi district, Uttar Pradesh by using some Geostatistical analysis. After normalizing the data, geo-statistical analyses were used to illustrate spatial variation and then spatial distribution maps of micronutrients were prepared. On the basis of these maps amount of micronutrients at unsampled location were estimated by using data of sampled locations.

The Giving Up of Weekly Rest-Days by Migrant Domestic Workers in Singapore: When Submission Is Both Resistance and Victimhood

Social Forces ◽  
2019 ◽  
Vol 98 (4) ◽  
pp. 1695-1718
Author(s):  
Margaret Fenerty Schumann ◽  
Anju Mary Paul
Keyword(s):  
Work Experience ◽  
Home Country ◽  
Domestic Workers ◽  
Sociology Of Law ◽  
Signaling Mechanism ◽  
Contract Renewal ◽  
Temporal And Spatial ◽  
Using Data ◽  
Do So ◽  
Migrant Domestic Workers

AbstractWhy do so few live-in migrant domestic workers (MDWs) in Singapore utilize their weekly rest-day entitlement? Using data drawn from 3,886 online profiles of prospective MDWs and 40 interview sessions with MDWs, employers, and manpower agencies, we demonstrate how the industry encourages a “logic of submission” around rest-days. Through processual analysis, we unearth multiple, repeated moments of capitulation at key moments in a MDW’s work-life: (1) their interactions with a recruitment agency while still in their home country; (2) their matching with an overseas employer; (3) the duration of their two-year contract; and (4) the time of contract renewal. Submission to less frequent rest-days can secure their employability and financial mobility but also further individuates the MDW within the employer’s household and may lead to the engraining of a habitus of submissiveness towards their employers that can open the door to workers’ exploitation. We demonstrate how nationality and work experience further inflect this logic of submission to motivate non-Filipina and inexperienced MDWs to request even fewer rest-days than their counterparts. By combining feminist migration scholarship on Asian MDWs, with a sociology of law analysis, we offer up an example of how the same act of submission can simultaneously embody both resistance and victimhood depending upon the temporal and spatial scale used, and varying interpretations of the rest-day benefit as a much-needed respite, a monetizable benefit, or a signaling mechanism.

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