High-frequency samples have been collected at Jiangjia Spring, the outlet of Qingmuguan underground river system (QURS) in Chongqing in late April, 2008. The variations of hydrogeochemical compositions are found respo...High-frequency samples have been collected at Jiangjia Spring, the outlet of Qingmuguan underground river system (QURS) in Chongqing in late April, 2008. The variations of hydrogeochemical compositions are found responding rapidly to storm events. Principal component analysis (PCA) of the 20 variables is employed to interpret the relationships with specific processes that control the groundwater hydrogeochemical formations. Through PCA, 84.961% of the total amount information is extracted to indicate the formations of groundwater hydrogeochemical features in QURS during storm events. The first component separates the soil erosion (i.e., increases in turbidity and concentrations of Al3+, TFe, TMn, Ba2+ and NO2?), and dilution effect (i.e., decreases in specific conductance and concentrations of HCO3?, Ca2+ and Sr2+), accounting for 41.495% of the variability in the data. The second component indicates residual fertilizers and duck’s waste from farmlands (i.e., increases in specific conductance and concentrations of Na+, NO3-, PO43-,K+and Cl-), contributing to 37.449%. The dissolution of dolomite and dolomitic limestone makes up 6.017%. During the first rainfall event, the groundwater quality is mainly affected by residual fertilizers and duck’s waste from farmlands, whereas in the second rainfall event, it is mainly affected by increased turbidity and ionic concentrations caused by soil erosion.展开更多
Anambra State of Nigeria is ravaged by ecological hazards of gully erosion and landslides. Over 450 active gully and landslide sites with depths ranging from 5 m to over 120 m are concentrated on both sides of the Awk...Anambra State of Nigeria is ravaged by ecological hazards of gully erosion and landslides. Over 450 active gully and landslide sites with depths ranging from 5 m to over 120 m are concentrated on both sides of the Awka-Nanka-Umuchu-Orlu cuesta. The Idemili River and Odo River form the major drainage basins of the area. The geomorphic characteristic of the cuesta/escarpment is a major controlling factor in groundwater recharge and discharge within the drainage basins. Rise in aquifer levels result in hydrogeotechnical implications of gully development and landslides. The calculated values of hydraulic properties of conductivity and transmissivity range from 1.20×10^-1 to 5.93×10^-1 cm/s and 1.15×10^5-13.05×10.3 m^2/s respectively. The values of groundwater velocity and groundwater discharge were 82 m.yearl and 2.96×10^6 m^3.yearl The plasticity index of the soil in the gully prone areas is relatively low ranging from 12.50-36.57%. The unique features of the geologic formations together with obtained aquifer characteristics favour gully/landslide hazards in the area.展开更多
基金supported by the National Key Technologies R & D Program of China (Grant Nos.2006BAC01A09 and 2006BAC01A16)National Natural Science Foundation of China (Grant No. 40672165)+2 种基金Natural Science Foundation of Chongqing (Grant Nos. CSTC2007BC7001 and CSTC2009BA0002)Open Foundation of Chongqing Key Laboratory of The Three Gorges Storehouse District Forest Ecology Protects and Restores (Grant No.CKL200802)Fund for Graduate Student of Technologic Innovation in Southwest University (Grant Nos. ky2008001 and kb2009004)
文摘High-frequency samples have been collected at Jiangjia Spring, the outlet of Qingmuguan underground river system (QURS) in Chongqing in late April, 2008. The variations of hydrogeochemical compositions are found responding rapidly to storm events. Principal component analysis (PCA) of the 20 variables is employed to interpret the relationships with specific processes that control the groundwater hydrogeochemical formations. Through PCA, 84.961% of the total amount information is extracted to indicate the formations of groundwater hydrogeochemical features in QURS during storm events. The first component separates the soil erosion (i.e., increases in turbidity and concentrations of Al3+, TFe, TMn, Ba2+ and NO2?), and dilution effect (i.e., decreases in specific conductance and concentrations of HCO3?, Ca2+ and Sr2+), accounting for 41.495% of the variability in the data. The second component indicates residual fertilizers and duck’s waste from farmlands (i.e., increases in specific conductance and concentrations of Na+, NO3-, PO43-,K+and Cl-), contributing to 37.449%. The dissolution of dolomite and dolomitic limestone makes up 6.017%. During the first rainfall event, the groundwater quality is mainly affected by residual fertilizers and duck’s waste from farmlands, whereas in the second rainfall event, it is mainly affected by increased turbidity and ionic concentrations caused by soil erosion.
文摘Anambra State of Nigeria is ravaged by ecological hazards of gully erosion and landslides. Over 450 active gully and landslide sites with depths ranging from 5 m to over 120 m are concentrated on both sides of the Awka-Nanka-Umuchu-Orlu cuesta. The Idemili River and Odo River form the major drainage basins of the area. The geomorphic characteristic of the cuesta/escarpment is a major controlling factor in groundwater recharge and discharge within the drainage basins. Rise in aquifer levels result in hydrogeotechnical implications of gully development and landslides. The calculated values of hydraulic properties of conductivity and transmissivity range from 1.20×10^-1 to 5.93×10^-1 cm/s and 1.15×10^5-13.05×10.3 m^2/s respectively. The values of groundwater velocity and groundwater discharge were 82 m.yearl and 2.96×10^6 m^3.yearl The plasticity index of the soil in the gully prone areas is relatively low ranging from 12.50-36.57%. The unique features of the geologic formations together with obtained aquifer characteristics favour gully/landslide hazards in the area.
