scholarly journals Issues and Application of Linearized Models in Geomorphic Properties of the Ikpa Watershed, Nigeria

2019 ◽  
pp. 1-10
Author(s):  
Umo, Ikpong Sunday ◽  
M. C. Ike ◽  
Ojinma, C. Chux
Keyword(s):  
Overland Flow ◽  
Predictive Ability ◽  
Infiltration Rate ◽  
Shuttle Radar Topography Mission ◽  
Rainfall Amount ◽  
Research Directions ◽  
Rainfall Events ◽  
Topographic Attributes ◽  
The Relationship ◽  
Dry And Rainy Seasons

Though more geomorphological researches are being conducted and previous ideas are being reviewed among geographers and earth scientists, only limited attempts are focused on coupling the relationships among geomorphic attributes on the watersheds in the Humid Tropics. These invariably induced new trends and research directions at diverging scales. This paper is guided by three specific objectives: (1) to employ the Shuttle Radar Topography Mission (SRTM) in deriving the morphologic attributes of the Ikpa Watershed (11) to assess the association and effect of discharge on basin texture, infiltration rate, length of overland flow, and rainfall amount in the Ikpa Watershed, Akwa Ibom State. (111) To describe the relationship between discharge, rainfall amount, and morphologic attributes of the Ikpa Watershed. The watershed was stratified into six sub-basins and data (rainfall and discharge) systematically generated for three months each during the dry and rainy seasons; while the topographic attributes were generated indirectly using SRTM, backup with the four topographic maps. The analysis using multiple linear regression yielded a coefficient of 0.986. Also, the R square value of 0.859 implied that 85.9 percent of the proportion of variation in discharge amount of the Ikpa watershed is accounted for by the four independent variables. A comparison of the computed ANOVA result of 8.469 with the Table value of 7.7086 implied that variation in mean discharge is attributed to the significant effect of basin texture, infiltration rate, length overland flow, and rainfall amount in the Ikpa watershed. The results of the curve estimate for linear, logarithmic, and quadratic equations suggested normal predictive ability and each significant at 0.05 confidence level. This study concluded that the dominances of gully erosion at the upstream and peak-flood discharge at the middle and downstream areas of the watershed are directly influenced by the rainfall events and morphology of the landform.   

Assessment of »True« Variability of Small Rainfall Events in a Small Mountainous Watershed in the Summer

1982 ◽  
Vol 13 (4) ◽  
pp. 205-212 ◽  
Author(s):  
Lawrence C. Nkemdirim ◽  
Brian D. Meller
Keyword(s):  
Spatial Distribution ◽  
Standard Error ◽  
Rain Gauge ◽  
Rainfall Amount ◽  
Rainfall Events ◽  
Mountainous Watershed ◽  
Rainfall Volume ◽  
Areal Rainfall ◽  
The Relationship ◽  
Rain Gauge Network

The standard error of mean areal rainfall was calculated for various densities of rain gauge network in a small mountainous watershed in the summer of 1978. It is shown that a) the optimum gauge density required to assess mean rainfall is about 3 gauges/km2; b) the »true« variability in the spatial distribution of rainfall decreases with increasing rainfall amount; and c) the relationship between »true« variability and rainfall volume is linear in that watershed.

scholarly journals INFLUÊNCIA DAS CARACTERÍSTICAS AMBIENTAIS E DOS INFLUÊNCIA DAS CARACTERÍSTICAS AMBIENTAIS E DOS ATRIBUTOS DO SOLO NA INFILTRAÇÃO DA ÁGUA EM ÁREA URBANAATRIBUTOS DO SOLO NA INFILTRAÇÃO DA ÁGUA EM ÁREA URBANA

2020 ◽  
Vol 38 (4) ◽  
pp. 1029-1038
Author(s):  
Jéssyca Stanieski de SOUZA ◽  
Isabel Kaufmann de ALMEIDA ◽  
Glauber Altrão CARVALHO ◽  
Teodorico ALVES SOBRINHO ◽  
Cláudia Gonçalves Vianna BACCHI
Keyword(s):  
Physical Properties ◽  
Overland Flow ◽  
Infiltration Rate ◽  
Soil Physical Properties ◽  
Capital City ◽  
Soil Infiltration ◽  
Environmental Characteristics ◽  
Mato Grosso ◽  
Flow Simulator ◽  
The Relationship

This study investigated the influence of the environmental characteristics and soil properties on the soil infiltration rate in urban permeable area. The experiments were conducted at nine sampling points located in the urban perimeter of Campo Grande, capital city of Mato Grosso do Sul State, in the Brazilian Midwest. The infiltration rates were determined using a portable integrated rainfall and overland flow simulator. Each experiment was repeated three times, and a total of twenty-seven plots were collected. At the same time, environmental characteristics and soil physical properties, that may affect infiltration rate, were also evaluated. The relationship between the infiltration rate, the environmental plot characteristics and the soil physical properties was verified using a linear correlation matrix.

scholarly journals The dominant runoff processes on grassland versus bare soil hillslopes in a temperate environment - An experimental study

2019 ◽  
Vol 67 (4) ◽  
pp. 297-304 ◽  
Author(s):  
Gabriel Minea ◽  
Gabriela Ioana-Toroimac ◽  
Gabriela Moroşanu
Keyword(s):  
Overland Flow ◽  
Bare Soil ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Rainfall Events ◽  
Natural Rainfall ◽  
Antecedent Precipitation ◽  
Temperate Environment ◽  
The Relationship

Abstract This paper aimed to investigate the dominant runoff processes (DRP’s) at plot-scale in the Curvature Subcarpathians under natural rainfall conditions characteristic for Romania’s temperate environment. The study was based on 32 selected rainfall-runoff events produced during the interval April–September (2014–2017). By comparing water balance on the analyzed Luvisol plots for two types of land use (grassland vs. bare soil), we showed that DRP’s are mostly formed by Hortonian Overland Flow (HOF), 47% vs. 59% respectively. On grassland, HOF is followed by Deep Percolation (DP, 31%) and Fast Subsurface Flow (SSF, 22%), whereas, on bare soil, DP shows a higher percentage (38%) and SSF a lower one (3%), which suggests that the soil-root interface controls the runoff generation. Concerning the relationship between antecedent precipitation and runoff, the study indicated the nonlinearity of the two processes, more obvious on grassland and in drought conditions than on bare soil and in wet conditions (as demonstrated by the higher runoff coefficients). Moreover, the HOF appeared to respond differently to rainfall events on the two plots - slightly longer lag-time, lower discharge and lower volume on grassland - which suggests the hydrologic key role of vegetation in runoff generation processes.

INNOVATION CAPABILITY, ABSORPTIVE CAPACITY AND SMES PERFORMANCE IN PAKISTAN: THE MODERATING EFFECT OF BUSINESS STRATEGY

2018 ◽  
Vol 13 (Number 2) ◽  
pp. 1-11
Author(s):  
Muhammad Zulqarnain Arshad ◽  
Darwina Arshad
Keyword(s):  
Economic Growth ◽  
Absorptive Capacity ◽  
Business Strategy ◽  
Innovation Capability ◽  
Research Directions ◽  
Conceptual Paper ◽  
And Performance ◽  
New Research ◽  
The Relationship ◽  
Crucial Part

The small and medium-sized enterprises (SMEs) play a crucial part in county’s economic growth and a key contributor in country’s GDP. In Pakistan SMEs hold about 90 percent of the total businesses. The performance of SMEs depends upon many factors. The main aim for the research is to examine the relationship between Innovation Capability, Absorptive Capacity and Performance of SMEs in Pakistan. This conceptual paper also extends to the vague revelation on Business Strategy in which act as a moderator between Innovation Capability, Absorptive Capacity and SMEs Performance. Conclusively, this study proposes a new research directions and hypotheses development to examine the relationship among the variables in Pakistan’s SMEs context.

scholarly journals Reduction in mobility and COVID-19 transmission

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pierre Nouvellet ◽  
Sangeeta Bhatia ◽  
Anne Cori ◽  
Kylie E. C. Ainslie ◽  
Marc Baguelin ◽  
...  
Keyword(s):  
Predictive Ability ◽  
Control Measures ◽  
Social Distancing ◽  
Beneficial Effects ◽  
Mobility Data ◽  
Strict Control ◽  
Before And After ◽  
Proxy Measure ◽  
Lower Transmission ◽  
The Relationship

AbstractIn response to the COVID-19 pandemic, countries have sought to control SARS-CoV-2 transmission by restricting population movement through social distancing interventions, thus reducing the number of contacts. Mobility data represent an important proxy measure of social distancing, and here, we characterise the relationship between transmission and mobility for 52 countries around the world. Transmission significantly decreased with the initial reduction in mobility in 73% of the countries analysed, but we found evidence of decoupling of transmission and mobility following the relaxation of strict control measures for 80% of countries. For the majority of countries, mobility explained a substantial proportion of the variation in transmissibility (median adjusted R-squared: 48%, interquartile range - IQR - across countries [27–77%]). Where a change in the relationship occurred, predictive ability decreased after the relaxation; from a median adjusted R-squared of 74% (IQR across countries [49–91%]) pre-relaxation, to a median adjusted R-squared of 30% (IQR across countries [12–48%]) post-relaxation. In countries with a clear relationship between mobility and transmission both before and after strict control measures were relaxed, mobility was associated with lower transmission rates after control measures were relaxed indicating that the beneficial effects of ongoing social distancing behaviours were substantial.

scholarly journals Assessment of Rainfall-Induced Landslide Distribution Based on Land Disturbance in Southern Taiwan

2021 ◽  
Vol 10 (4) ◽  
pp. 209
Author(s):  
Chih-Ming Tseng ◽  
Yie-Ruey Chen ◽  
Chwen-Ming Chang ◽  
Yung-Sheng Chue ◽  
Shun-Chieh Hsieh
Keyword(s):  
Satellite Image ◽  
Extreme Rainfall ◽  
Land Area ◽  
Rainfall Events ◽  
Land Disturbance ◽  
Bare Land ◽  
Southern Taiwan ◽  
The Impact ◽  
Landslide Distribution ◽  
The Relationship

This study explores the impact of rainfall on the followed-up landslides after a severe typhoon and the relationship between various rainfall events and the occurrence, scale, and regional characteristics of the landslides, including second landslides. Moreover, the influence of land disturbance was evaluated. The genetic adaptive neural network was used in combination with the texture analysis of the geographic information system for satellite image classification and interpretation to analyze land-use change and retrieve disaster records and surface information after five rainfall events from Typhoon Morakot (2009) to Typhoon Nanmadol (2011). The results revealed that except for extreme Morakot rains, the greater the degree of slope disturbance after rain, the larger the exposed slope. Extreme rainfall similar to Morakot strikes may have a greater impact on the bare land area than on slope disturbance. Moreover, the relationship between the bare land area and the index of land disturbance condition (ILDC) is positive, and the ratio of the bare land area to the quantity of bare land after each rainfall increases with the ILDC. With higher effective accumulative rainfall on the slope in the study area or greater slope disturbance, the landslide area at the second landslide point tended to increase.

Diagnostic grammar and assessment: translating criteria into questions

1989 ◽  
Vol 19 (1) ◽  
pp. 57-68 ◽  
Author(s):  
Lee N. Robins
Keyword(s):  
Diagnostic Criteria ◽  
Catchment Area ◽  
Predictive Ability ◽  
Diagnostic Interview ◽  
Good Prediction ◽  
Interview Schedule ◽  
Validity Data ◽  
Validity Assessment ◽  
Standardized Interview ◽  
The Relationship

SynopsisThere has been concern about whether standardized psychiatric interviews make valid diagnoses. Agreements between the Diagnostic Interview Schedule (DIS), as an example of a standardized interview, with independent assessments by a clinician are reasonably high in most studies, but the clinical assessment is itself of uncertain validity. Using predictive ability is an alternative way of judging validity. Data are presented to show that the DIS is almost as good at prediction as a clinician's assessment, but here too there are problems. Because prediction is probabilistic (i.e. the same disorder can have multiple outcomes, and different disorders can share outcomes), it is not possible to say how good prediction has to be to demonstrate perfect validity.Across varied methods of validity assessment, some disorders are regularly found more validly diagnosed than others, suggesting that part of the source of invalidity lies in the diagnostic grammar of the systems whose criteria standardized interviews evaluate. Sources of invalidity inherent in the content and structure of a variety of diagnoses in DSM-III and its heir, DSM-III-R, are reviewed and illustrated, in part with results from the Epidemiological Catchment Area study.The relationship between diagnostic criteria and standardized interviews is symbiotic. While attempts to adhere closely to existing diagnostic criteria contribute to the diagnostic accuracy of standardized interviews, the exercise of translating official diagnostic criteria into standardized questions highlights problems in the system's diagnostic grammar, enabling standardized interviews to contribute to improvements in diagnostic nosology.

scholarly journals Overland Flow Resistance Law under Sparse Stem Vegetation Coverage

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1657
Author(s):  
Jingzhou Zhang ◽  
Shengtang Zhang ◽  
Si Chen ◽  
Ming Liu ◽  
Xuefeng Xu ◽  
...  
Keyword(s):  
Flow Resistance ◽  
Overland Flow ◽  
Vegetation Coverage ◽  
Dominant Factor ◽  
Roughness Coefficient ◽  
Hydraulic Parameters ◽  
Slope Condition ◽  
Manning Roughness ◽  
The Relationship ◽  
Manning Roughness Coefficient

To explore the characteristics of overland flow resistance under the condition of sparse vegetative stem coverage and improve the basic theoretical research of overland flow, the resistance characteristics of overland flow were systematically investigated under four slope gradients (S), seven flow discharges (Q), and six degrees of vegetation coverage (Cr). The results show that the Manning roughness coefficient (n) changes with the ratio of water depth to vegetation height (h/hv) while the Reynolds number (Re), Froude number (Fr), and slope (S) are closely related to vegetation coverage. Meanwhile, h/hv, Re, and Cr have strong positive correlations with n, while Fr and S have strong negative correlations with n. Through data regression analysis, a power function relationship between n and hydraulic parameters was observed and sensitivity analysis was performed. It was concluded that the relationship between n and h/hv, Re, Cr, Q, and S shows the same law; in particular, for sparse stem vegetation coverage, Cr is the dominant factor affecting overland flow resistance under zero slope condition, while Cr is no longer the first dominant factor affecting overland flow resistance under non-zero slope condition. In the relationship between n and Fr, Cr has the least effect on overland flow resistance. This indicates that when Manning roughness coefficient is correlated with different hydraulic parameters, the same vegetation coverage has different effects on overland flow resistance. Therefore, it is necessary to study overland flow resistance under the condition of sparse stalk vegetation coverage.

Geo-informatics based Morphometric Analysis of a Reservoir Catchment in Shivalik Foothills of North-West India

2021 ◽  
Vol 58 (03) ◽  
pp. 286-299
Author(s):  
Mahesh Chand Singh ◽  
Rohit Singh ◽  
Abrar Yousuf ◽  
Vishnu Prasad
Keyword(s):  
Form Factor ◽  
Soil Erosion ◽  
Morphometric Analysis ◽  
Overland Flow ◽  
Infiltration Rate ◽  
Elongation Ratio ◽  
Alos Palsar ◽  
Bifurcation Ratio ◽  
Runoff Potential ◽  
Drainage Texture

The present study examined 35 morphometric parameters related to stream/drainage network, catchment geometry, and relief aspects for hydrological characterization of the Thana Dam catchment using geospatial tools and techniques. The dam catchment was delineated using the high-resolution Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) Digital Elevation Model (DEM) data in ArcGIS 10.4.1 software using the Arc Hydro tools. The catchment is comprised of 4th order stream, obtained using a stream threshold value of 100 m length. The lower values of elongation ratio (0.61), circularity ratio (0.22), and form factor (0.29) indicated higher soil erosion potential, mainly due to their inverse relationship with land erodibility. Moreover, the higher values of stream frequency (15.7), drainage density (>5.0), drainage texture (7.48 km-1), and mean bifurcation ratio (4.08-6.33) indicated higher runoff potential, which would intensify the soil erosion, mainly due to their direct relationship with erodibility. Bifurcation ratio, elongation ratio, circulatory ratio, form factor, altogether indicated an elongated shape of the catchment with a fine drainage texture. The higher values of bifurcation ratio and texture ratio of the catchment also indicated severe overland flow (low infiltration rate) with a limited scope for groundwater recharge in the area, which in turn might significantly encourage the soil erosion. Overall, it was concluded that the catchment has a huge runoff potential resulting in high soil erosion due to its fine texture, impermeable subsurface material, steep slope, low infiltration rate, limited vegetation, longer duration of overland flow, and higher surface runoff. The morphometric analysis was found to be suitable for identifying catchment shape and the factors affecting hydrologic conditions and erodibility of the catchment. Thus, Geo-informatics based morphometric analysis of a reservoir catchment can be useful to study the erosion potential in relation to hydrologic (rainfall-runoff relationship) and other related land characteristics (e.g., relief, slope, infiltration rate, etc.).

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