在21世纪建立稳定的水利投资体系的几点探索

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。     

Assessment on soil fertility of Dongting Lake wetland area （China） based on GIS and fuzzy evaluation

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.     

降雨条件下坡地水分转化特征实验研究

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。     

流域侵蚀产沙过程随尺度变化规律研究

寻求不同尺度下侵蚀产沙过程的变化规律和普遍规律,是进行尺度转换的基础。本文以岔巴沟流域及其团山沟径流场实测水文数据为基础,探讨了不同尺度下流域径流过程、侵蚀产沙过程、水沙关系随尺度的变化规律。通过对峁坡、全坡面、毛沟、支沟、干沟的径流和泥沙分析表明,全坡面将流域径流过程、侵蚀产沙过程、水沙关系有机的区分开为坡面和沟道两种类型的变化过程,而全坡面又对毛沟的径流和泥沙起主导作用。     

中国的农业环境问题与农业发展战略

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。