Rivers-Moore N A, Jewitt G P W
School of Bioresources Engineering and Environmental Hydrology, University of KwaZulu-Natal, P/Bag X01, Scottsville 3209, South Africa.
J Environ Manage. 2007 Jan;82(1):39-50. doi: 10.1016/j.jenvman.2005.12.004. Epub 2006 Mar 24.
Water temperatures, and in particular daily maximum water temperatures, are a critical water quality parameter. An understanding of associated resource management issues, including links between water temperature variability and aquatic diversity values, should be part of any management programme that considers river systems. Simple rule-based models have been shown to be appropriate tools within an adaptive management approach, both because of their heuristic value and in their application for scenario generation. Such a model was developed to simulate changes in the condition factor of Chiloglanis anoterus [Crass, R.S., 1960. Notes on the freshwater fishes of Natal with descriptions of 4 new species. Annals of the Natal Museum 14, 405-458] (Pisces: Mochokidae) in response to annual frequency of exceedance of a threshold temperature under three broad environmental scenarios for part of the Sabie River falling within South Africa's Kruger National Park. This model has potential for application within the adaptive management programme being implemented by the Kruger National Park. Results show that under broad scenarios of a 10% reduction in mean daily flow rates, or a 2 degrees C increase in mean daily air temperatures, system variability is likely to increase relative to reference conditions . It is suggested that so-called "thresholds of probable concern" (TPCs), which are based on current levels of "natural" system variability, are useful as management targets for achieving a "desired future state" for the river system. The model, recognised as a preliminary hypothesis, highlights a lack of knowledge regarding the nature of system variability, and the correspondingly wide confidence limits of the proposed TPC restricts its utility in a short-term management context. Thus, it is now recognised that its value lies more in its use as a long-term modelling tool to reflect water temperature responses to flow variability. This highlights the fact that research outcomes may not always be those intended at the beginning of a project and that opportunities to implement these may be lost as lags in understanding relative to project lifetimes often exist.
水温，尤其是每日最高水温，是一个关键的水质参数。对相关资源管理问题的理解，包括水温变化与水生生物多样性价值之间的联系，应该成为任何考虑河流系统的管理计划的一部分。基于简单规则的模型已被证明是适应性管理方法中的合适工具，这既是因为它们的启发式价值，也是因为它们在情景生成中的应用。开发了这样一个模型，以模拟南非克鲁格国家公园内萨比河部分区域在三种广泛环境情景下，奇洛兰尼斯鲶鱼（[克拉丝，R.S.，1960年。纳塔尔淡水鱼类的笔记及4个新物种的描述。纳塔尔博物馆年鉴14，405 - 458]，双鱼座：鲿科）的条件因子随超过阈值温度的年发生频率的变化。该模型在克鲁格国家公园正在实施的适应性管理计划中有应用潜力。结果表明，在平均日流量率降低10%或平均日气温升高2摄氏度的广泛情景下，相对于参考条件，系统变异性可能会增加。建议基于当前“自然”系统变异性水平的所谓“可能关注阈值”（TPCs），作为实现河流系统“期望未来状态”的管理目标是有用的。该模型被认为是一个初步假设，突出了对系统变异性本质缺乏了解，并且所提议的TPC的相应宽泛置信区间限制了其在短期管理背景下的效用。因此，现在认识到它的价值更多地在于作为一种长期建模工具，以反映水温对流量变化的响应。这突出了一个事实，即研究结果可能并不总是项目开始时预期的结果，而且由于相对于项目生命周期在理解上的滞后，实施这些结果的机会可能会丧失。
