In crosswell observation of electromagnetic tomography, now there is no feasible way to calibrate the in situ radiation constant, while the effect of induced wave field always exists in observational data. Therefor...In crosswell observation of electromagnetic tomography, now there is no feasible way to calibrate the in situ radiation constant, while the effect of induced wave field always exists in observational data. Therefore the absorption coefficient obtained by a common used image reconstruction method is only a relative value. The consistency of tomograms in linked profiles inevitably is affected seriously. An improved equation involving the effect of induced wave field and an alternative tracing method to calculate the in situ radiation constant is proposed in the present paper. Based on the results from a series of parameter calibration performed in water and the experiments with rock samples, the standard meter readings of borehole electromagnetic systems, types EW—1 and JWQ—3, are accurately defined here. Additionally, frequency reduction and boundary smoothing of linked profiles are discussed. In research on groundwater prospecting in Tanggongta, Inner Mongolia, we used the above mentioned method and obtained the tomograms of linked profiles with good consistency. The absorption coefficient in the tomogram are not only reasonable and reliable, but also coincided with the result from rock parameter measurement. The depth, extension direction and water bearing structure of two aquifers were well detected. This result correctly guides hydrologic drilling there.展开更多
Influence of structural and lithological controls of various drainage patterns and their stream orientations（for 2nd, 3rd and 4th order steams） were identified to evaluate the direction and controlling factors of dr...Influence of structural and lithological controls of various drainage patterns and their stream orientations（for 2nd, 3rd and 4th order steams） were identified to evaluate the direction and controlling factors of drainage network. To investigate the prospect of groundwater, hydrogeomorphological features of river basin viz. Mulki-Pavanje were identified and mapped. To evaluate the characteristics of the basin, different morphometric parameters（linear, areal and relief） were computed in sub-basin wise（SB-I to-VII）. The linear parameters suggest drainage network is controlled by geomorphology. The form factor（Ff）, elongation ratio（Re） and circularity ratio（Rc） suggest that the basin is in an elongated shape. The drainage density（Dd） indicates resistant/permeable strata under medium-dense vegetation with moderate relief. The areal parameters of the sub-basins（except SBI and Ⅲ） indicates moderate ground-slopes associated with moderately permeable rocks, which promote moderate run-off and infiltration. Drainage texture（T） of the whole basin indicates coarse texture while the SB-I, and Ⅲ showing an intermediate texture. The relief parameters namely ruggedness number（Rn） infers low basin relief and poor drainage density. To identify the most deficit/surplus zones of groundwater suitable weightages were assigned to the hydrogeomorphological units and morphometric parameters. The study reveal that the basin manifest that SB-Ⅲ shall be most deficit zone of groundwater, whereas SB-VII, VI and V are found to show increase in groundwater potentiality. Groundwater prospect area in this basin is estimated to be 7% area under poor, 44% area under moderate and 49% area under good to excellent. This paper demonstrated the potential application of geographical information system（GIS） techniques to evaluate the groundwater prospect in absence of traditional groundwater monitoring data.展开更多
文摘In crosswell observation of electromagnetic tomography, now there is no feasible way to calibrate the in situ radiation constant, while the effect of induced wave field always exists in observational data. Therefore the absorption coefficient obtained by a common used image reconstruction method is only a relative value. The consistency of tomograms in linked profiles inevitably is affected seriously. An improved equation involving the effect of induced wave field and an alternative tracing method to calculate the in situ radiation constant is proposed in the present paper. Based on the results from a series of parameter calibration performed in water and the experiments with rock samples, the standard meter readings of borehole electromagnetic systems, types EW—1 and JWQ—3, are accurately defined here. Additionally, frequency reduction and boundary smoothing of linked profiles are discussed. In research on groundwater prospecting in Tanggongta, Inner Mongolia, we used the above mentioned method and obtained the tomograms of linked profiles with good consistency. The absorption coefficient in the tomogram are not only reasonable and reliable, but also coincided with the result from rock parameter measurement. The depth, extension direction and water bearing structure of two aquifers were well detected. This result correctly guides hydrologic drilling there.
文摘Influence of structural and lithological controls of various drainage patterns and their stream orientations（for 2nd, 3rd and 4th order steams） were identified to evaluate the direction and controlling factors of drainage network. To investigate the prospect of groundwater, hydrogeomorphological features of river basin viz. Mulki-Pavanje were identified and mapped. To evaluate the characteristics of the basin, different morphometric parameters（linear, areal and relief） were computed in sub-basin wise（SB-I to-VII）. The linear parameters suggest drainage network is controlled by geomorphology. The form factor（Ff）, elongation ratio（Re） and circularity ratio（Rc） suggest that the basin is in an elongated shape. The drainage density（Dd） indicates resistant/permeable strata under medium-dense vegetation with moderate relief. The areal parameters of the sub-basins（except SBI and Ⅲ） indicates moderate ground-slopes associated with moderately permeable rocks, which promote moderate run-off and infiltration. Drainage texture（T） of the whole basin indicates coarse texture while the SB-I, and Ⅲ showing an intermediate texture. The relief parameters namely ruggedness number（Rn） infers low basin relief and poor drainage density. To identify the most deficit/surplus zones of groundwater suitable weightages were assigned to the hydrogeomorphological units and morphometric parameters. The study reveal that the basin manifest that SB-Ⅲ shall be most deficit zone of groundwater, whereas SB-VII, VI and V are found to show increase in groundwater potentiality. Groundwater prospect area in this basin is estimated to be 7% area under poor, 44% area under moderate and 49% area under good to excellent. This paper demonstrated the potential application of geographical information system（GIS） techniques to evaluate the groundwater prospect in absence of traditional groundwater monitoring data.
