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该文通过对我省“九五”水利投入的分析,提出新世纪建立稳定的水利投资体系的原则和基本内容。 相似文献
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Assessment on soil fertility of Dongting Lake wetland area (China) based on GIS and fuzzy evaluation 总被引:1,自引:0,他引:1
Using soil data of the Second National Field Survey, the soil fertility of wetland ecosystem of Dongting Lake was evaluated
by using the technology of GIS and method of fuzzy evaluation. Integrated with the wetland actuality of Dongting Lake and
particularity of paddy, seven factors (including soil organic matter, total nitrogen, total phosphorus, total potassium, available
phosphorus, available potassium, and pH value), closely related with soil fertility, were chosen to establish the index system
of synthetical evaluation. Based on the effect degree of each selected index on soil fertility, a judgment matrix was built,
and the weight coefficient was determined by the method of correlation coefficient. Finally, under the support of the spatial
analysis module of GIS (Geographic Information System), the spatial distribution properties of soil fertility in wetland ecosystem
of Dongting Lake were studied. The results show that the soil fertility of Dongting Lake wetland ecosystem is not very good,
and the area of type III and type IV achieves 69.8%. As a result, many countermeasures should be taken to improve the soil
fertility. As for the spatial properties, the soil fertility level of central and west Dongting Lake is much higher than that
of north and south part. The soil fertility of paddy field surpasses that of red soil, and the contents of soil organic matter
and total nitrogen in paddy field are large. 相似文献
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降雨条件下坡地水分转化特征实验研究 总被引:25,自引:2,他引:23
坡地水分转化规律研究对于探讨坡地水土流失以及坡地养分迁移规律具有重要意义。本文以黄绵土为试验材料,通过模拟降雨试验,研究了不同雨强条件下坡面入渗过程与产流特征。结果表明:(1)在地表坡度15°、土壤容重1.28~1.30g/cm3的条件下,坡面平均入渗率(ia)与降雨强度(iR)具有极显著的抛物线函数关系,当iR=1.35mm/min 时,ia具有最大值(1.01mm/min);初始产流时间(tp)随iR的增大而减小,二者呈幂函数关系。(2)坡面产流以后,入渗率(i)随降雨历时(t)呈幂函数形式降低,坡面产流强度(VR)随t的延长呈对数函数形式增加。(3)随着雨强的增大降雨的入渗量略有增加,但降雨向土壤水分的转化率则显著降低。 相似文献
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通过分析我国农业环境的气候、资源.环境和生态平衡等方面存在的问题之后,提出了我国农业的发展战略,完善农村政策体系.实行多种形式的土地经营体制,资源管理法制化,遏制恶化态势;贯彻“科教兴国”方针,提高人口素质:改善生态环境.实现农业可持续发展。 相似文献
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