This research is intended to assess the regional pattern of hypsometric curves (HCs) and hypsometric integrals (HIs) for the watersheds draining into the Jordan Rift (River Jordan, the Dead Sea, and Wadi Araba watersh...This research is intended to assess the regional pattern of hypsometric curves (HCs) and hypsometric integrals (HIs) for the watersheds draining into the Jordan Rift (River Jordan, the Dead Sea, and Wadi Araba watersheds). Hypsometric analysis was performed on 22 drainage basins using ASTER DEM (30 m resolution) and GIS. The area-elevation ratio method was utilized to extract the hypsometric integral values within a GIS environment. A prominent variation exists in the HC shapes and HI values. The highest hypsometric values are found for the Dead Sea ( = 0.87) and River Jordan ( = 0.77) watersheds. Whereas the lowest values ( = 0.51) characterized Wadi Araba catchments, except Wadi Nukhaileh (lower Wadi Araba) which yields an HI value of 0.26. Seventeen HCs pertained to the River Jordan and the Dead Sea watersheds evince remarkably upward convex shapes indicating that such drainage basins are less eroded, and at the youth-stage of the geomorphic cycle of erosion. Catchments draining to Wadi Araba are of intermediate HI values (0.41 - 0.58) which are associated with a balance, or dynamic equilibrium between erosion and tectonic processes. Accordingly, they correspond to a late mature stage of geomorphic development. Additionally, Wadi Nukhaileh yields the lowest HI value (0.26) and is associated with highly eroded terrain of late mature geomorphic evolution, approaching an old stage therefore, with distorted concave upward curves. High HI values indicate that these watersheds have been subjected to tectonic uplift, down faulting of the Rift and intense rejuvenation. Differences in HI values can be attributed to disparity in tectonic uplift rate, base level heights, and mean heights of the River Jordan watersheds, the Dead Sea and Wadi Araba watersheds, and variation in lithology, which caused noticeable differences in rejuvenation processes, and channel incision. Regression analysis reveals that R<sup>2</sup> values which represent the degree of control of driving parameters on HI, are positive and generally low (ranging from 0.026 to 0.224) except for the height of base level (m) parameter which contributes 0.42 (significant at 0.1% level). Such results mean that the height of base level has a significant at 0.1% level. It is obvious that the most crucial driving morphometric factor influencing HI values of the Jordan Rift drainage basins, is the height of base level (m).展开更多
Hypsometric analysis is considered an effective tool for understanding the stages of geomorphic evolution and geological development of river catchment, and for the delineation of erosional proneness of watershed. In ...Hypsometric analysis is considered an effective tool for understanding the stages of geomorphic evolution and geological development of river catchment, and for the delineation of erosional proneness of watershed. In the present study, twenty eight fourth order sub-basins of W. Mujib-Wala (Southern Jordan) were selected, and hypsometric analysis was carried out using 30 m ASTER DEM. Elevation-relief ratio method was employed to calculate the hypsometric integral values within GIS environment. The hypsometric integral values range from 0.71 to 0.88, whereas, the hypsometric curves exhibit remarkably upward convex shapes which indicate that all sub-basins and the W. Mujib-Wala watershed are at the youth-age stage of geomorphic development. Thus, they are of high susceptibility to erosion, incised channel erosion and mass movement activity. Marginal differences exist in mass removal from the watershed and the 28 sub-basins are attributed to variation in tectonic effect, lithology and rejuvenation processes. The relation between basin area and hypsometric integral was examined using regression analysis. Results reveal that negative and weak relationships dominate, where r<sup>2</sup> ranges from 0.05 to 0.478 which confirm with other results reported elsewhere. Indirect assessment of erosion status based on hypsometric integral values was validated using estimated sediment yield information related to wadi Mujib and wadi Wala watersheds separately. The recorded sediment yields were in affirmation with high hypsometric integrals values, where higher values of hypsometric integrals and sediment yields occurred in the western part of the W. Mujib-Wala watershed. These findings would help in the construction of appropriate soil and water conservation measures across the watershed and its sub-basins to control soil erosion, to conserve water, and to reduce sediment discharge into the W. Mujib and W. Wala reservoirs.展开更多
Threshold is a limit and marginal point when a qualitative change takes place. Since threshold principle was firstly used in landform research by S.A.Schumm in the 1970s, the quantitative research on watershed landfor...Threshold is a limit and marginal point when a qualitative change takes place. Since threshold principle was firstly used in landform research by S.A.Schumm in the 1970s, the quantitative research on watershed landform development stage has come true. Davis proposed a three-stage model on landform evolution: young, mature and old stages. Thereafter Strahler quantified this model by hypsometric analysis method. The authors thought that the material movement stage cannot be expressed by hypsometric method in watershed landform at development stage, because of the uncertainty on stage delimitation. To meet this shortcoming, this paper presents an integral erosion value method. A clear delimitation on landform development stage in the Loess Plateau region has been tested by this method. The result shows that gullied loessial hilly area is at the mature stage, and gullied loessial tableland area is at the young stage. It is estimated that from the point of erosion related sediment yield, natural erosion accounts for 70% of the total erosion amount, and artificial accelerating erosion is 30%. Therefore soil and water conservation is very crucial for the Loess Plateau.展开更多
Geomorphological study of a basin is important for understanding theoverall basin characteristics which are helpful for the management of waterresources, construction along the river bank and natural hazard mitigation...Geomorphological study of a basin is important for understanding theoverall basin characteristics which are helpful for the management of waterresources, construction along the river bank and natural hazard mitigationwithin the area. The study was carried out in the Karra Khola Basin, oneof the prominent basins in the Eastern extreme of the Hetauda Dun Valley,Central Nepal, to investigate geomorphic characteristics of the mainstream of the basin, categorize them into various stream types and studybasin development through drainage basin’s morphometric parameters.Geographical Information System (GIS) and Remote sensing techniquesusing satellite images were used as a tool to make the morphometricanalysis of the basin along with its major 13 sub-basin and delineate streamclassification following the Rosgen’s Level I hierarchical inventory. Themain stream of the Karra Khola is characterized as A-, B- and C-typeand the tributaries segments as B- and F-type. The basin is structurallyunaffected and has the permeable surface area and elongated shape. Thehypsometric analysis indicates that the basin is mostly at the old stage ofgeomorphic development while four out of 13 sub-basin being at maturestage. The Karra Khola sub-basin have higher risk to flash flooding(Lg=0.1-0.16km). Drainage density value reveals that the basin is highlysusceptible to flooding, gully erosion, etc. Similarly, dissection index valueimplies that the north eastern region of the basin is highly vulnerable toerosion as it at the younger stage of geomorphic development. Since thestudy area is highly sensitive to future natural hazards, further study andappropriate measures should be followed for safeguarding against thefuture risk along the Karra Khola basin and its tributaries.展开更多
文摘This research is intended to assess the regional pattern of hypsometric curves (HCs) and hypsometric integrals (HIs) for the watersheds draining into the Jordan Rift (River Jordan, the Dead Sea, and Wadi Araba watersheds). Hypsometric analysis was performed on 22 drainage basins using ASTER DEM (30 m resolution) and GIS. The area-elevation ratio method was utilized to extract the hypsometric integral values within a GIS environment. A prominent variation exists in the HC shapes and HI values. The highest hypsometric values are found for the Dead Sea ( = 0.87) and River Jordan ( = 0.77) watersheds. Whereas the lowest values ( = 0.51) characterized Wadi Araba catchments, except Wadi Nukhaileh (lower Wadi Araba) which yields an HI value of 0.26. Seventeen HCs pertained to the River Jordan and the Dead Sea watersheds evince remarkably upward convex shapes indicating that such drainage basins are less eroded, and at the youth-stage of the geomorphic cycle of erosion. Catchments draining to Wadi Araba are of intermediate HI values (0.41 - 0.58) which are associated with a balance, or dynamic equilibrium between erosion and tectonic processes. Accordingly, they correspond to a late mature stage of geomorphic development. Additionally, Wadi Nukhaileh yields the lowest HI value (0.26) and is associated with highly eroded terrain of late mature geomorphic evolution, approaching an old stage therefore, with distorted concave upward curves. High HI values indicate that these watersheds have been subjected to tectonic uplift, down faulting of the Rift and intense rejuvenation. Differences in HI values can be attributed to disparity in tectonic uplift rate, base level heights, and mean heights of the River Jordan watersheds, the Dead Sea and Wadi Araba watersheds, and variation in lithology, which caused noticeable differences in rejuvenation processes, and channel incision. Regression analysis reveals that R<sup>2</sup> values which represent the degree of control of driving parameters on HI, are positive and generally low (ranging from 0.026 to 0.224) except for the height of base level (m) parameter which contributes 0.42 (significant at 0.1% level). Such results mean that the height of base level has a significant at 0.1% level. It is obvious that the most crucial driving morphometric factor influencing HI values of the Jordan Rift drainage basins, is the height of base level (m).
文摘Hypsometric analysis is considered an effective tool for understanding the stages of geomorphic evolution and geological development of river catchment, and for the delineation of erosional proneness of watershed. In the present study, twenty eight fourth order sub-basins of W. Mujib-Wala (Southern Jordan) were selected, and hypsometric analysis was carried out using 30 m ASTER DEM. Elevation-relief ratio method was employed to calculate the hypsometric integral values within GIS environment. The hypsometric integral values range from 0.71 to 0.88, whereas, the hypsometric curves exhibit remarkably upward convex shapes which indicate that all sub-basins and the W. Mujib-Wala watershed are at the youth-age stage of geomorphic development. Thus, they are of high susceptibility to erosion, incised channel erosion and mass movement activity. Marginal differences exist in mass removal from the watershed and the 28 sub-basins are attributed to variation in tectonic effect, lithology and rejuvenation processes. The relation between basin area and hypsometric integral was examined using regression analysis. Results reveal that negative and weak relationships dominate, where r<sup>2</sup> ranges from 0.05 to 0.478 which confirm with other results reported elsewhere. Indirect assessment of erosion status based on hypsometric integral values was validated using estimated sediment yield information related to wadi Mujib and wadi Wala watersheds separately. The recorded sediment yields were in affirmation with high hypsometric integrals values, where higher values of hypsometric integrals and sediment yields occurred in the western part of the W. Mujib-Wala watershed. These findings would help in the construction of appropriate soil and water conservation measures across the watershed and its sub-basins to control soil erosion, to conserve water, and to reduce sediment discharge into the W. Mujib and W. Wala reservoirs.
文摘Threshold is a limit and marginal point when a qualitative change takes place. Since threshold principle was firstly used in landform research by S.A.Schumm in the 1970s, the quantitative research on watershed landform development stage has come true. Davis proposed a three-stage model on landform evolution: young, mature and old stages. Thereafter Strahler quantified this model by hypsometric analysis method. The authors thought that the material movement stage cannot be expressed by hypsometric method in watershed landform at development stage, because of the uncertainty on stage delimitation. To meet this shortcoming, this paper presents an integral erosion value method. A clear delimitation on landform development stage in the Loess Plateau region has been tested by this method. The result shows that gullied loessial hilly area is at the mature stage, and gullied loessial tableland area is at the young stage. It is estimated that from the point of erosion related sediment yield, natural erosion accounts for 70% of the total erosion amount, and artificial accelerating erosion is 30%. Therefore soil and water conservation is very crucial for the Loess Plateau.
文摘Geomorphological study of a basin is important for understanding theoverall basin characteristics which are helpful for the management of waterresources, construction along the river bank and natural hazard mitigationwithin the area. The study was carried out in the Karra Khola Basin, oneof the prominent basins in the Eastern extreme of the Hetauda Dun Valley,Central Nepal, to investigate geomorphic characteristics of the mainstream of the basin, categorize them into various stream types and studybasin development through drainage basin’s morphometric parameters.Geographical Information System (GIS) and Remote sensing techniquesusing satellite images were used as a tool to make the morphometricanalysis of the basin along with its major 13 sub-basin and delineate streamclassification following the Rosgen’s Level I hierarchical inventory. Themain stream of the Karra Khola is characterized as A-, B- and C-typeand the tributaries segments as B- and F-type. The basin is structurallyunaffected and has the permeable surface area and elongated shape. Thehypsometric analysis indicates that the basin is mostly at the old stage ofgeomorphic development while four out of 13 sub-basin being at maturestage. The Karra Khola sub-basin have higher risk to flash flooding(Lg=0.1-0.16km). Drainage density value reveals that the basin is highlysusceptible to flooding, gully erosion, etc. Similarly, dissection index valueimplies that the north eastern region of the basin is highly vulnerable toerosion as it at the younger stage of geomorphic development. Since thestudy area is highly sensitive to future natural hazards, further study andappropriate measures should be followed for safeguarding against thefuture risk along the Karra Khola basin and its tributaries.
