This study aimed to explore groundwater potential zones in the EGMB of Alluri Seetharama Raju district, Andhra Pradesh, India, for drinking and agriculture purposes. To achieve this goal, 72 Vertical Electrical Soundi...This study aimed to explore groundwater potential zones in the EGMB of Alluri Seetharama Raju district, Andhra Pradesh, India, for drinking and agriculture purposes. To achieve this goal, 72 Vertical Electrical Soundings(VES) were conducted using the Schlumberger electrode configuration. The resistivity sounding data were analyzed to determine the aquifer thickness, basement depth, Dar-Zarrouk parameters,and aquifer transmissivity. Spatial distribution maps were generated for these parameters to understand the subsurface formation. The analysis revealed a linear groundwater potential zone(8.46 km~2) in the eastern part of the study area, extending in the NNE-SSW direction for 9.6 km. Six VES locations(P24, P27, P29,P30, P33, and P38) in this zone exhibit good potential(>30 m aquifer thickness), while the three VES locations(OP19, P5, and P46) in the central region are recommended for drilling bore wells. Additionally,moderate aquifer thickness(20–30 m) are identified in other VES locations(OP14, OP20, P4, P10, P12,P13, P15, P17, P18, P31, P46, and P50) along streams in the western and central part of the area, which can yield reasonable quantities of water. This information is useful for groundwater exploration and watershed management to meet the demands of tribal population in the study area.展开更多
To study the influence of rainfall on pavement skid-resistance performance and driving safety,the water film thickness(WFT)concept considering the longitudinal and transverse slopes of the pavement was utilized based ...To study the influence of rainfall on pavement skid-resistance performance and driving safety,the water film thickness(WFT)concept considering the longitudinal and transverse slopes of the pavement was utilized based on the total discharge formulation and turbulence theory of slope flow.Using experimental data measured using the British pendulum test under varying WFT levels,a model for calculating the skid resistance,namely the British pendulum number(BPN),was formulated and used to quantitatively evaluate the effects of rainfall intensity,transverse,and longitudinal slopes on the computed BPN.The study results reveal that skid resistance is linearly proportional to the pavement transverse slope and inversely proportional to the rainfall intensity and the pavement longitudinal slope.In particular,rainfall intensity,along with pavement texture depth,exhibited a significant impact on the tire-pavement friction and skid-resistance performance.The results further indicate that driving safety under wet weather is predominantly governed by skid resistance and visibility.The BPN and sideway force coefficient(SFC60)values for new asphalt pavements under different rainfall intensities are provided along with some modification to the stopping sight distance(SSD)criteria.Safe driving speed limits are also determined using a safe-driving model to develop the appropriate speed limit strategies.The overall study results provide some insights,methodology approach,and reference data for the evaluation of pavement skid-resistance performance and driving safety conditions under different pavement slopes and rainfall intensities.展开更多
Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as ...Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as pumping tests, permeameter measurements and grain size analysis are invasive and relatively expensive. A geoelectric investigation involving vertical electrical sounding was carried in parts of Enugu town, Enugu state, Nigeria. The survey was aimed at extrapolating the result of pumping tests over an area. Using the Dar Zarrouk parameter, a β constant of 0.32 was found to translate resistivity to transmissivity with clay content as the primary factor controlling the hydraulic conductivity. Results of the study show a strong correlation between aquifer transmissivity and longitudinal conductance (R2 = 0.82). Estimation of aquifer transmissivity values based on the results of the resistivity measurements also made it possible to demarcate area with good groundwater potential in parts of Enugu town, Nigeria.展开更多
Twenty five vertical electrical sounding using the Schlumberger configuration with current electrode spacing of AB/2 = 100 m were carried out in Hussara, north-eastern, Nigeria. The field data were smoothened and inte...Twenty five vertical electrical sounding using the Schlumberger configuration with current electrode spacing of AB/2 = 100 m were carried out in Hussara, north-eastern, Nigeria. The field data were smoothened and interpreted using IX1D inversion [1] computer software. Secondary resistivity and secondary resistivity derived parameters were used to determine the potential aquifer horizon. Longitudinal conductance map of the third geoelectric layer indicates a higher conducting zone along the eastern part which may indicate possible concentration of weathered materials. Intermediate conductance striking from the north to the southeast may constitute a horizon with increased aquifer materials, while the lower conductivity values may indicate areas of fractured bedrock where the degree of decomposition of the rock fragments is minimal. The transverse resistance map of the same horizon revealed the contour values increasing from the west towards the east perhaps due to the increasing presence of fresh bedrock close to the surface.展开更多
Development of groundwater needs the capabilities to distinguish the different aquifer layers found in a region, and thereafter the parameters which can be used expressly to define the aquifer type. The past studies i...Development of groundwater needs the capabilities to distinguish the different aquifer layers found in a region, and thereafter the parameters which can be used expressly to define the aquifer type. The past studies in the Olbanita sub-basin have accorded the area as having one aquifer, which has resulted into generalization of the aquifer parameters. The objective in this study is to map the main aquifer layer and determine its parameters. The use of modeled geoelectric layers from Vertical Electrical Sounding (VES) data has been used in the study area to distinguish the major aquifer from the minor ones. There is noted an excellent correlation between the geoelectric layers and the lithologies as outlined by the driller’s log clearly delineating four aquifer stratums. The main aquifer is identified to be geoelectric layer 11 and 12, defined by a thickness of 30.18 m mainly of tuffs, and 17.39 m mainly of weathered phonolites. Hydraulic conductivity of the main aquifer averages value of 17.16389314 m/day, in consideration of the ranges 0.248690465 m/day to 74.62681942 m/day for the 31 VES points. For the aquifer breadth of 30.18 m, the Transmissivity values vary from a minimum of 57.32119 Ωm<sup>2</sup> to 53365.49 Ωm<sup>2</sup> and for 47.57 m breadth, the range is between 11.83021 Ωm<sup>2</sup> and 1390.921 Ωm<sup>2</sup>. The variance of longitudinal unit conductance shows that 63.15 percent of the aquifer represented by one lithology is having lowest values of S (<sup>-1</sup>), an indication that the resistivity values of these points are relatively high when compared to their corresponding breadths. Notably, where the geoelectric layer is represented by more than one lithologic layer, the longitudinal unit conductance has high values of S (~1.1 - 5.3 Ω<sup>-1</sup>) at about 83.33 percent of the aquifer, thus giving a manifestation that a change in lithology has an implication in the aquifer characteristics. The transverse resistance values have a direct proportionality to both the aquifer layer thickness and the geoelectric layer resistivities. Evidently, using the close range of resistivities record indicates that indeed transverse resistance increases with increase in aquifer thickness. For example, for resistivities 52.677 Ω, 54.78 Ω, 54.297 Ω, 57.819 Ω, and 51.85 Ω, for 30.18 m, 47.57 m, 136.35 m, 190.84 m, 277.93 m thicknesses respectively, have their correlated transverse resistances values notably rising incrementally, from 1589.7919 Ωm<sup>2</sup>, 2605.8846 Ωm<sup>2</sup>, 7403.396 Ωm<sup>2</sup>, and 11034.178 Ωm<sup>2</sup> correspondingly. There is confirmation that the modeled VES data can help map aquifers despite the limited resources of borehole logs that can used as control points.展开更多
文摘This study aimed to explore groundwater potential zones in the EGMB of Alluri Seetharama Raju district, Andhra Pradesh, India, for drinking and agriculture purposes. To achieve this goal, 72 Vertical Electrical Soundings(VES) were conducted using the Schlumberger electrode configuration. The resistivity sounding data were analyzed to determine the aquifer thickness, basement depth, Dar-Zarrouk parameters,and aquifer transmissivity. Spatial distribution maps were generated for these parameters to understand the subsurface formation. The analysis revealed a linear groundwater potential zone(8.46 km~2) in the eastern part of the study area, extending in the NNE-SSW direction for 9.6 km. Six VES locations(P24, P27, P29,P30, P33, and P38) in this zone exhibit good potential(>30 m aquifer thickness), while the three VES locations(OP19, P5, and P46) in the central region are recommended for drilling bore wells. Additionally,moderate aquifer thickness(20–30 m) are identified in other VES locations(OP14, OP20, P4, P10, P12,P13, P15, P17, P18, P31, P46, and P50) along streams in the western and central part of the area, which can yield reasonable quantities of water. This information is useful for groundwater exploration and watershed management to meet the demands of tribal population in the study area.
基金The National Natural Science Foundation of China(No.51478114)
文摘To study the influence of rainfall on pavement skid-resistance performance and driving safety,the water film thickness(WFT)concept considering the longitudinal and transverse slopes of the pavement was utilized based on the total discharge formulation and turbulence theory of slope flow.Using experimental data measured using the British pendulum test under varying WFT levels,a model for calculating the skid resistance,namely the British pendulum number(BPN),was formulated and used to quantitatively evaluate the effects of rainfall intensity,transverse,and longitudinal slopes on the computed BPN.The study results reveal that skid resistance is linearly proportional to the pavement transverse slope and inversely proportional to the rainfall intensity and the pavement longitudinal slope.In particular,rainfall intensity,along with pavement texture depth,exhibited a significant impact on the tire-pavement friction and skid-resistance performance.The results further indicate that driving safety under wet weather is predominantly governed by skid resistance and visibility.The BPN and sideway force coefficient(SFC60)values for new asphalt pavements under different rainfall intensities are provided along with some modification to the stopping sight distance(SSD)criteria.Safe driving speed limits are also determined using a safe-driving model to develop the appropriate speed limit strategies.The overall study results provide some insights,methodology approach,and reference data for the evaluation of pavement skid-resistance performance and driving safety conditions under different pavement slopes and rainfall intensities.
文摘Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as pumping tests, permeameter measurements and grain size analysis are invasive and relatively expensive. A geoelectric investigation involving vertical electrical sounding was carried in parts of Enugu town, Enugu state, Nigeria. The survey was aimed at extrapolating the result of pumping tests over an area. Using the Dar Zarrouk parameter, a β constant of 0.32 was found to translate resistivity to transmissivity with clay content as the primary factor controlling the hydraulic conductivity. Results of the study show a strong correlation between aquifer transmissivity and longitudinal conductance (R2 = 0.82). Estimation of aquifer transmissivity values based on the results of the resistivity measurements also made it possible to demarcate area with good groundwater potential in parts of Enugu town, Nigeria.
文摘Twenty five vertical electrical sounding using the Schlumberger configuration with current electrode spacing of AB/2 = 100 m were carried out in Hussara, north-eastern, Nigeria. The field data were smoothened and interpreted using IX1D inversion [1] computer software. Secondary resistivity and secondary resistivity derived parameters were used to determine the potential aquifer horizon. Longitudinal conductance map of the third geoelectric layer indicates a higher conducting zone along the eastern part which may indicate possible concentration of weathered materials. Intermediate conductance striking from the north to the southeast may constitute a horizon with increased aquifer materials, while the lower conductivity values may indicate areas of fractured bedrock where the degree of decomposition of the rock fragments is minimal. The transverse resistance map of the same horizon revealed the contour values increasing from the west towards the east perhaps due to the increasing presence of fresh bedrock close to the surface.
文摘Development of groundwater needs the capabilities to distinguish the different aquifer layers found in a region, and thereafter the parameters which can be used expressly to define the aquifer type. The past studies in the Olbanita sub-basin have accorded the area as having one aquifer, which has resulted into generalization of the aquifer parameters. The objective in this study is to map the main aquifer layer and determine its parameters. The use of modeled geoelectric layers from Vertical Electrical Sounding (VES) data has been used in the study area to distinguish the major aquifer from the minor ones. There is noted an excellent correlation between the geoelectric layers and the lithologies as outlined by the driller’s log clearly delineating four aquifer stratums. The main aquifer is identified to be geoelectric layer 11 and 12, defined by a thickness of 30.18 m mainly of tuffs, and 17.39 m mainly of weathered phonolites. Hydraulic conductivity of the main aquifer averages value of 17.16389314 m/day, in consideration of the ranges 0.248690465 m/day to 74.62681942 m/day for the 31 VES points. For the aquifer breadth of 30.18 m, the Transmissivity values vary from a minimum of 57.32119 Ωm<sup>2</sup> to 53365.49 Ωm<sup>2</sup> and for 47.57 m breadth, the range is between 11.83021 Ωm<sup>2</sup> and 1390.921 Ωm<sup>2</sup>. The variance of longitudinal unit conductance shows that 63.15 percent of the aquifer represented by one lithology is having lowest values of S (<sup>-1</sup>), an indication that the resistivity values of these points are relatively high when compared to their corresponding breadths. Notably, where the geoelectric layer is represented by more than one lithologic layer, the longitudinal unit conductance has high values of S (~1.1 - 5.3 Ω<sup>-1</sup>) at about 83.33 percent of the aquifer, thus giving a manifestation that a change in lithology has an implication in the aquifer characteristics. The transverse resistance values have a direct proportionality to both the aquifer layer thickness and the geoelectric layer resistivities. Evidently, using the close range of resistivities record indicates that indeed transverse resistance increases with increase in aquifer thickness. For example, for resistivities 52.677 Ω, 54.78 Ω, 54.297 Ω, 57.819 Ω, and 51.85 Ω, for 30.18 m, 47.57 m, 136.35 m, 190.84 m, 277.93 m thicknesses respectively, have their correlated transverse resistances values notably rising incrementally, from 1589.7919 Ωm<sup>2</sup>, 2605.8846 Ωm<sup>2</sup>, 7403.396 Ωm<sup>2</sup>, and 11034.178 Ωm<sup>2</sup> correspondingly. There is confirmation that the modeled VES data can help map aquifers despite the limited resources of borehole logs that can used as control points.
