The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of th...The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of the Koshi system, Aandhikhola, Arungkhola, East Rapti, Karrakhola, Seti and main channel Narayani of the Gandaki system, and two independent systems within Nepal, Bagmati and Tinau. Among the morphologies, river bed or the substratum was taken as the main variable for the analysis which was categorized into 7 types as rocks, boulders, cobbles, pebbles, gravels, sand and silt. There were 23 sampling sites each with 2 stretches of around 100m in those rivers. The data were taken as a percentage, and to avoid biases it was observed visually by the same person for a complete year in every season. With 23 sites each with 2 stretches and 4 replicates corresponding to 4 seasons, there are altogether 184 observations, each termed as a case, that constitute this work. Canonical Discrimination Analysis (CDA) which is most suitable when the data pool is huge was applied to see if the rivers studied distinguish themselves in terms of its morphology. The result was remarkably successful and was close to the established regional classification of the rivers. This kind of river classification has great application in the utilization, conservation and restoration of the most important natural re-source of the country.展开更多
It is a key premise of ＇ecosystem approaches＇ to natural resources management that we must have an appropriate understanding of biodiversity values, and controls upon them, if we wish to manage them effectively. The...It is a key premise of ＇ecosystem approaches＇ to natural resources management that we must have an appropriate understanding of biodiversity values, and controls upon them, if we wish to manage them effectively. These biodiversity values, and associated ecosystem functionality, vary with space and time and are tied directly to landscape-scale relationships and evolutionary traits. In riverine systems, nested hierarchical principles provide a useful platform to assess relationships between landscape components across a range of scales. These understandings are most instructively synthesized through catchment-scale analyses. This paper outlines a rationale for systematic catchment-wide appraisals of river geodiversity. An initial application of these principles is presented for the Yellow River source zone in Qinghai Province, western China. Geo-ecological relationships are outlined for five broad sections of the trunk stream, highlighting implications for the management of these individual landscape compartments and for the system as a whole.展开更多
文摘The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of the Koshi system, Aandhikhola, Arungkhola, East Rapti, Karrakhola, Seti and main channel Narayani of the Gandaki system, and two independent systems within Nepal, Bagmati and Tinau. Among the morphologies, river bed or the substratum was taken as the main variable for the analysis which was categorized into 7 types as rocks, boulders, cobbles, pebbles, gravels, sand and silt. There were 23 sampling sites each with 2 stretches of around 100m in those rivers. The data were taken as a percentage, and to avoid biases it was observed visually by the same person for a complete year in every season. With 23 sites each with 2 stretches and 4 replicates corresponding to 4 seasons, there are altogether 184 observations, each termed as a case, that constitute this work. Canonical Discrimination Analysis (CDA) which is most suitable when the data pool is huge was applied to see if the rivers studied distinguish themselves in terms of its morphology. The result was remarkably successful and was close to the established regional classification of the rivers. This kind of river classification has great application in the utilization, conservation and restoration of the most important natural re-source of the country.
基金National Natural Science Foundation of China, No.41001008 International Science ＆ Technology Cooperation Program of China, No.2011DFG93160 No.2011DFA20820
文摘It is a key premise of ＇ecosystem approaches＇ to natural resources management that we must have an appropriate understanding of biodiversity values, and controls upon them, if we wish to manage them effectively. These biodiversity values, and associated ecosystem functionality, vary with space and time and are tied directly to landscape-scale relationships and evolutionary traits. In riverine systems, nested hierarchical principles provide a useful platform to assess relationships between landscape components across a range of scales. These understandings are most instructively synthesized through catchment-scale analyses. This paper outlines a rationale for systematic catchment-wide appraisals of river geodiversity. An initial application of these principles is presented for the Yellow River source zone in Qinghai Province, western China. Geo-ecological relationships are outlined for five broad sections of the trunk stream, highlighting implications for the management of these individual landscape compartments and for the system as a whole.
