河流健康评价的时空特征与参照基线探讨

DISCUSSION OF RIVER HEALTH ASSESSMENT ON SPATIAL AND TEMPORAL SCALE AND BASELINE

随着河流退化成为世界各国面临的主要水环境问题,旨在从水质、生物、生态等众多角度综合评估河流系统状况、改进河流管理的河流健康概念得以提出并受到关注。时空特征与参照基线的确定是河流健康评价的两个重要环节,前者将不同时空尺度相联系,为评价指标的选取提供参考,后者将河流理想目标与人类管理需求相结合,为评价标准的确定提供依据。结合河流等级理论、河流连续体概念和四维模型,分析河流系统的主要特点及时空特征,并从点(断面、点位)、线(河流、河段)、面(流域、水系)等级剖析河流健康评价的空间尺度,从短、中、长层次识别河流健康评价的时间尺度,从而剖析不同时空尺度河流健康评价的维度特征和评价重点;从河流健康评价的标准出发,定义了最小干扰状态(MDC)、历史参考状态(HC)、最低干扰状态(LDC)、最佳可达状态(BAC)等4种河流健康评价的参照基线,探讨了参照点位法、专家判断法、历史数据法、模型推算法等参照基线计算方法的确定程序和适用范围,最后从时空特征与参照基线等方面提出了我国河流健康评价的开展建议。

As river degradation becoming the primary problem faced by the river ecosystem of countries all over the world,more attention has been paid to river health assessment.Determination of reference condition and identification of spatial and temporal features are described as the critical components of river health.The spatial and temporal features aids to the selection of indicator of river health assessment,while establishment of reference condition contributes to the determination of criterion.Considering river hierarchy theory,river continuum concept and a four-dimensional matrix,main characteristics of river system and features of its spatial and temporal scale were analyzed.The paper profiled spatial scale of river health assessment from dot（section and site）,line（stream and reach）,and surface（river basin and river system） grades,and demonstrated temporal scale from short（temporal dot）,middle（temporal segment） and long（temporal section） hierarchies.Reference baselines of river health assessment,including minimally disturbed conditions（MDC）,historical condition（HC）,least disturbed condition（LDC） and best attainable condition（BAC） were defined.Determination procedure and application scope of reference baseline calculating methods using reference site,historical data,expert opinion or simulation models were discussed.Finally,some suggestions to improve the effectiveness of river health assessment were presented.