中文摘要：

准确了解区域洪水灾害风险演变状况及规律，对于洪水灾害预警与管理具有重要意义。本文利用1990年和2000年洪水灾害风险等级数据和风险指数数据，分析了10年来区域洪水灾害风险演变规律。研究表明：（1）1990～2000年10年之间，研究区的洪水灾害风险在空间分布格局及时间演变过程上都发生了显著变化。（2）高风险区与较高风险区的面积在增加，较低风险区、中等风险区的面积在逐渐减少，这是区域洪水灾害风险等级结构变化最突出的特征。（3）区域洪水灾害风险等级之间的不对等转化是各种风险等级结构特征发生实质性变化的主要原因。（4）2000年区域洪水灾害风险较1990年高，整个区域洪水灾害风险在增加，但局部地区洪水灾害风险变化不一。（5）区域洪水灾害风险演变的本质就是风险等级类型结构和功能的自组织，对于揭示洪水灾害演变的普遍现象和机制具有重要意义。

英文摘要：

Flood disasters are among the world＇s most frequent and damaging types of disaster. Flood hazard, flood risk and disasters are the products of an interaction between environmental and social processes. Accurate comprehension of the condition and rule of flood disaster risk change is of critical importance for early warning and flood disaster administering. The study area, situated in the northeast of Kelantan Delta in Malaysia, is the main flood disaster area. In the other papers, the maps and data of flood disaster risk zones and flood risk index have been calculated using the Fuzzy Comprehensive Assessment （FCA） method. In this paper, the condition and rule of risk change in the past decade are analyzed based on risk zone data and risk index data of flood disasters in 1990 and 2000. The risk data of the two phases are overlaid and areas of risk zone changes are summarized. Risk dynamic degree, transition matrix of risk zone change, risk index change, and the mean of change are calculated. Some conclusions are drawn as follows. （1） The variation of risk zones is significant in the spatial pattern and time change from 1990 to 2000. （2） Highest risk zone and higher risk zone are increasing. Moderate risk zone and lower risk zone are decreasing. （3） Conversion among risk zones is lopsided. It is the main reason for the variation taking place in the spatial pattern of risk zones. （4） Mean risk index of 2000 is higher than that of 1990 in the whole area. Risk change is different in the local zones. （5） The change process of flood disaster risk is self-organized and complex. The self-organized character of flood disaster system is significant to reveal the internal universal phenomenon and mechanism.