The changing pattern of the Lower Yellow River （LYR） obtained from the traditional studies, which mainly did literal analysis based on historical documents related to the LYR are too macroscopic and absent of intuit...The changing pattern of the Lower Yellow River （LYR） obtained from the traditional studies, which mainly did literal analysis based on historical documents related to the LYR are too macroscopic and absent of intuitiveness. This paper integrates all the records in historical documents related to course shift, flood and overflow of the last 3000 years and stores them in a GIS database. Then, all the data will be visualized in the form of map, which is helpful to show and understand the rules those events conform more intuitively and accurately. Taking these data as foundation, this study summarizes characteristics of the LYR＇s courses and influence scope, and classifies them both into three types; divides the flow directions of the LYR＇s courses into two periods, and proposes its changing pattern; concludes the character- istic of diversion points of courses shift events; calculates the velocity of courses shifts, gra- dient and sinuosity, and analyzes their changing patterns. Finally, this study classifies factors that may influence the occurrence of a course shift into two types： the internal factors, such as sediment rate, gradient and sinuosity of the river, and the external factors, such as precipita- tion and human activities.展开更多
The lower reaches of the Yellow River is in the danger of changing course, as has been indicated by the annually increasing prolong and advance of its drain season and the annually increasing extension of its drain se...The lower reaches of the Yellow River is in the danger of changing course, as has been indicated by the annually increasing prolong and advance of its drain season and the annually increasing extension of its drain section. The impacts of this tendency have been partially shown by the tremendous economic loss and serious damage to the ecological balance. This paper makes an analysis of the causes of the drain of the Yellow River, its harmful impacts, and our inadequacy of knowledge. It also proposes some solutions to this problem for discussion.展开更多
土壤养分是土壤肥力的基础,掌握其含量与分布特征可为改善立地条件、建设高效农田防护林体系提供科学依据。以盐城市阜宁县和淮安市涟水县黄河故道土壤为研究对象,采用层次分析法(AHP)与物元分析模型相结合的方式,分别对研究区内有林地...土壤养分是土壤肥力的基础,掌握其含量与分布特征可为改善立地条件、建设高效农田防护林体系提供科学依据。以盐城市阜宁县和淮安市涟水县黄河故道土壤为研究对象,采用层次分析法(AHP)与物元分析模型相结合的方式,分别对研究区内有林地和无林地土壤有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾7个指标的变化特征进行了分析评价。结果表明:①随着远离河堤,土壤有机质、全氮、碱解氮、全钾、速效钾含量呈增加趋势;全磷含量呈减少趋势;有效磷在有林地呈减少趋势,在无林地呈增加趋势。②有林地土壤有机质(2~3级)、全氮(1~2级)含量显著高于无林地,而其余指标与无林地基本一致。③在距黄河故道<0.5、0.5~1.0和1.0~1.5 km 3个区域内,有林地土壤养分等级分别为较丰富Ⅱ、丰富Ⅰ、丰富Ⅰ,无林地土壤养分等级分别为贫乏Ⅳ、适量Ⅲ、适量Ⅲ。可见,开展农田防护林建设能有效促进土壤有机质、氮素的积累,提升土壤养分等级,若在此基础上合理追施磷肥,能进一步提高土壤肥力及其生态、经济效益。展开更多
基金Project supported by the Ministry of Science and Technology of China, No.2009BAH50B01No.2008BAK50B05
文摘The changing pattern of the Lower Yellow River （LYR） obtained from the traditional studies, which mainly did literal analysis based on historical documents related to the LYR are too macroscopic and absent of intuitiveness. This paper integrates all the records in historical documents related to course shift, flood and overflow of the last 3000 years and stores them in a GIS database. Then, all the data will be visualized in the form of map, which is helpful to show and understand the rules those events conform more intuitively and accurately. Taking these data as foundation, this study summarizes characteristics of the LYR＇s courses and influence scope, and classifies them both into three types; divides the flow directions of the LYR＇s courses into two periods, and proposes its changing pattern; concludes the character- istic of diversion points of courses shift events; calculates the velocity of courses shifts, gra- dient and sinuosity, and analyzes their changing patterns. Finally, this study classifies factors that may influence the occurrence of a course shift into two types： the internal factors, such as sediment rate, gradient and sinuosity of the river, and the external factors, such as precipita- tion and human activities.
文摘The lower reaches of the Yellow River is in the danger of changing course, as has been indicated by the annually increasing prolong and advance of its drain season and the annually increasing extension of its drain section. The impacts of this tendency have been partially shown by the tremendous economic loss and serious damage to the ecological balance. This paper makes an analysis of the causes of the drain of the Yellow River, its harmful impacts, and our inadequacy of knowledge. It also proposes some solutions to this problem for discussion.
文摘土壤养分是土壤肥力的基础,掌握其含量与分布特征可为改善立地条件、建设高效农田防护林体系提供科学依据。以盐城市阜宁县和淮安市涟水县黄河故道土壤为研究对象,采用层次分析法(AHP)与物元分析模型相结合的方式,分别对研究区内有林地和无林地土壤有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾7个指标的变化特征进行了分析评价。结果表明:①随着远离河堤,土壤有机质、全氮、碱解氮、全钾、速效钾含量呈增加趋势;全磷含量呈减少趋势;有效磷在有林地呈减少趋势,在无林地呈增加趋势。②有林地土壤有机质(2~3级)、全氮(1~2级)含量显著高于无林地,而其余指标与无林地基本一致。③在距黄河故道<0.5、0.5~1.0和1.0~1.5 km 3个区域内,有林地土壤养分等级分别为较丰富Ⅱ、丰富Ⅰ、丰富Ⅰ,无林地土壤养分等级分别为贫乏Ⅳ、适量Ⅲ、适量Ⅲ。可见,开展农田防护林建设能有效促进土壤有机质、氮素的积累,提升土壤养分等级,若在此基础上合理追施磷肥,能进一步提高土壤肥力及其生态、经济效益。
