Brief introduction of experiments,laboratories and stations in geomorphology.The achievements in experimental fluvial geomorphology gained in the last 30 years in China include channel pattern modelling,studies on inf...Brief introduction of experiments,laboratories and stations in geomorphology.The achievements in experimental fluvial geomorphology gained in the last 30 years in China include channel pattern modelling,studies on influence of boundary conditions,applications of fluvial geomorphology,its experimental theories and techniques,etc.Problems in fluvial geomorphic experiments are indicated,tendencies in the development of this branch of geomorphology are predicted,and suggestions are made.展开更多
The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara d...The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara domes, which are a part of the laterally extensive belt of flexures bounded by the Kachchh Mainland Fault(KMF) to their north and called as Northern Hill Range(NHR). Parameters such as longitudinal profile, Hack profile, stream length gradient index(SL), hypsometric curve, hypsometric integral(HI), valley floor width to height ratio(Vf), elongation ratio(Re) and escarpment sinuosity(ES) were analysed. Hack profiles of the major rivers draining through the area show similar convex up nature suggesting primary influence of the tectonics in controlling and shaping the landscape of the region. Elongation ratio <6 and undergone higher degree of fluvial erosion indicated by the low values of hypsometric integral suggest the tendency of river systems to increase the basin area longitudinally rather than laterally. The study suggests that higher net uplift in the eastern half(Jumara dome) caused the rivers to overcome the structural control and to carve out generally straight north oriented channels. The rivers of western part(Jara dome) show more prominent structural control of cuesta girdles formed in compact lithologies and attributed to the domal structure. The ~10 km long Jaramara scarp believed to the remnant of older KMF scarp, is a product of headward erosion of the fluvial channels through different hard and soft litho-units of the area. The similar orientation of Jaramara scarp and morphology of the Ukra intrusive body suggests that the Ukra intrusive played a significant role in controlling the formation and morphology of the Jaramara scarp.展开更多
The Navasota River Basin,itself a tributary of the Brazos River in Texas,is a dynamic watershed undergoing many natural and anthropogenic changes.Local stakeholder involvement in this watershed is quite high,and many ...The Navasota River Basin,itself a tributary of the Brazos River in Texas,is a dynamic watershed undergoing many natural and anthropogenic changes.Local stakeholder involvement in this watershed is quite high,and many landowners in the southern portion of the watershed have concerns regarding the increasing frequency and duration of flooding on private property adjacent to the river,often attributing these impacts to the construction of the Lake Limestone dam.In this study,we examine historical flow data,channel morphology,land use/land cover,and precipitation.Our findings indicate that while there appears to be increasing flow in the northern portion of the watershed,temporal data gaps near the watershed outfall prevent the indication of such a trend in the southern portion of the watershed.Nevertheless,other natural and anthropogenic factors are evident in the watershed that may have a significant influence on downstream flooding.Overall river sinuosity(meandering)declined over the study period,with some river segments encountering significant straightening.Total river length declined by 4.3 km from 1972 to 2020.The number and length of offtake channels also decreased substantially during this period.Land use/land cover use shifted dramatically,with a 39.2%increase in impervious cover and a 12.5%decrease in herbaceous cover since 1972.Finally,yearly precipitation increased,with the change point occurring in 1972.Our findings suggest that the shortening and straightening of the river has reduced its volumetric capacity over time.Coupled with increasing impervious surface cover and precipitation,more water is being delivered downstream at a rate exceeding the watershed's ability to discharge it,thereby contributing to flooding issues expressed by stakeholders.We recommend that bathymetric data and supplemental flow monitoring and modeling within the watershed is needed to fully understand how anthropogenic and natural forces may further affect streamflow in the future.展开更多
文摘Brief introduction of experiments,laboratories and stations in geomorphology.The achievements in experimental fluvial geomorphology gained in the last 30 years in China include channel pattern modelling,studies on influence of boundary conditions,applications of fluvial geomorphology,its experimental theories and techniques,etc.Problems in fluvial geomorphic experiments are indicated,tendencies in the development of this branch of geomorphology are predicted,and suggestions are made.
基金The present study was funded by the Ministry of Earth Sciences(MoES),Government of India in the form of research project(Project 474 No.Mo ES/P.O.(Seismo)/1(170)/2013)MoES/P.O.(Seismo)/1(120)/AFM/2015 to DMM and LSC。
文摘The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara domes, which are a part of the laterally extensive belt of flexures bounded by the Kachchh Mainland Fault(KMF) to their north and called as Northern Hill Range(NHR). Parameters such as longitudinal profile, Hack profile, stream length gradient index(SL), hypsometric curve, hypsometric integral(HI), valley floor width to height ratio(Vf), elongation ratio(Re) and escarpment sinuosity(ES) were analysed. Hack profiles of the major rivers draining through the area show similar convex up nature suggesting primary influence of the tectonics in controlling and shaping the landscape of the region. Elongation ratio <6 and undergone higher degree of fluvial erosion indicated by the low values of hypsometric integral suggest the tendency of river systems to increase the basin area longitudinally rather than laterally. The study suggests that higher net uplift in the eastern half(Jumara dome) caused the rivers to overcome the structural control and to carve out generally straight north oriented channels. The rivers of western part(Jara dome) show more prominent structural control of cuesta girdles formed in compact lithologies and attributed to the domal structure. The ~10 km long Jaramara scarp believed to the remnant of older KMF scarp, is a product of headward erosion of the fluvial channels through different hard and soft litho-units of the area. The similar orientation of Jaramara scarp and morphology of the Ukra intrusive body suggests that the Ukra intrusive played a significant role in controlling the formation and morphology of the Jaramara scarp.
文摘The Navasota River Basin,itself a tributary of the Brazos River in Texas,is a dynamic watershed undergoing many natural and anthropogenic changes.Local stakeholder involvement in this watershed is quite high,and many landowners in the southern portion of the watershed have concerns regarding the increasing frequency and duration of flooding on private property adjacent to the river,often attributing these impacts to the construction of the Lake Limestone dam.In this study,we examine historical flow data,channel morphology,land use/land cover,and precipitation.Our findings indicate that while there appears to be increasing flow in the northern portion of the watershed,temporal data gaps near the watershed outfall prevent the indication of such a trend in the southern portion of the watershed.Nevertheless,other natural and anthropogenic factors are evident in the watershed that may have a significant influence on downstream flooding.Overall river sinuosity(meandering)declined over the study period,with some river segments encountering significant straightening.Total river length declined by 4.3 km from 1972 to 2020.The number and length of offtake channels also decreased substantially during this period.Land use/land cover use shifted dramatically,with a 39.2%increase in impervious cover and a 12.5%decrease in herbaceous cover since 1972.Finally,yearly precipitation increased,with the change point occurring in 1972.Our findings suggest that the shortening and straightening of the river has reduced its volumetric capacity over time.Coupled with increasing impervious surface cover and precipitation,more water is being delivered downstream at a rate exceeding the watershed's ability to discharge it,thereby contributing to flooding issues expressed by stakeholders.We recommend that bathymetric data and supplemental flow monitoring and modeling within the watershed is needed to fully understand how anthropogenic and natural forces may further affect streamflow in the future.
