应用生态工程治理台湾屏东县高树乡浊口溪之探讨

台湾特殊地理条件,于具有灾害潜在的河段,常须整治野溪、水土保持及水利工程设施,却忽略栖息于当地的原生物种;所幸近十几年来,生态工程在台湾日益盛行,许多水利建设也逐渐开始考量对环境生态的影响;然而,由于对河川欠缺完整性的规划管理概念,常导致部分施工成效仍待验证。本研究初步建立一规划设计的方法论,从利用简易的粒径量测方法及以HEC—RAS模拟河川水位开始,至如何应用生态工程的理论基础进行河溪整治,作一详尽说明,期能为日后工程界进行规划设计时之依据。     

Estimation of peak runoff and frequency in an ungauged stream of a forested watershed for flood hazard mapping

Kaynasli District in the western Black Sea region of Turkey has long been vulnerable to frequent flood damage due to the establishment of settlements within and around stream channels without regard to fluctuating peakstreamflow frequencies. The aim of this research was to determine the measures needed to protect the towns and villages from this type of damage. Daily total precipitation data for 1975–2010 were analysed, and rainfall-runoff models developed to estimate the potential yearly maximum discharge from each stream of sub-watersheds dominated by forests and/or agriculture. This was then calculated for different frequencies of the yearly maximum discharge. Flood analysis and mapping was modified via the one-dimensional Hydrologic Engineering CentersRiver Analysis System software to produce potential maximum discharge and geometric data for Kaynasli Creek. As the main creek of the sub-watershed, its crosssection was shown to be insufficient and incapable of containing the maximum discharge at the 100-year frequency presumed for the watershed, and subsequently was seen as having a high level of casualty risk. It was concluded that the one dimensional model could be useful, but 2D models were more suitable for these types of watersheds.     

Performance assessment of Doroodzan irrigation network by steady state hydraulic modeling

There is a need for improvement in the operation and management of many irrigation and drainage systems worldwide. Computer models are used widely for better management. One of such models is HEC-RAS that was applied to Ordibehesht Canal at the Doroodzan irrigation network, northwest of Fars province in the southern Iran. The model was calibrated and validated for two irrigation seasons during 2001 and 2002. The present gate opening rules used to control the offtakes were simulated by the model and the discharge reductions were evaluated. Discharge reduction of offtakes due to discharge reductions at system source were evaluated by the model. Results show that the present rule is not appropriate for the present system. Fluctuations of discharge at the beginning of canal show considerable and nonuniform changes in discharge of offtakes along the Ordibehesht Canal. The head offtakes show more reductions in the water delivered than middle and tail offtakes. A new sensitivity indicator was defined and used to show the response of offtakes due to discharge changes at system source. The study also shows that HEC-RAS model can be used successfully for a large and complex irrigation system for evaluation of its performance in the absence of observed flow data and improvement of irrigation management plans.     

HEC-RAS模型在汉江上游洪水演进和流量重建中的应用

【目的】研究HEC-RAS模型在汉江上游洪水演进和流量重建中的应用效果。【方法】通过对汉江上游安康至白河段的实地考察,基于数字流域平台及HEC-RAS模型对2010年"7·18"、2011年"9·19"2场洪水进行了演进模拟,并结合ArcGIS重现了2场洪水的淹没范围和水深。运用HEC-RAS模型对考察发现的5次洪痕进行洪峰流量的重建,与利用比降面积法的重建结果进行比对,并利用实测数据对重建结果进行了验证。【结果】模型的率定、2场洪水水位与流量等指标的模拟系列和实测系列的纳什效率系数(NSE)及确定性系数(R2)均大于0.91;此外,基于HEC-RAS模型重现的淹没区域与实地调查所得结果吻合度较好,且根据洪痕重建的洪峰流量误差为0.12%~2.88%,重建精度较高,优于比降面积法。【结论】HEC-RAS模型可用于汉江上游洪水的演进模拟和洪峰流量的重建,可视化的淹没范围、水深等成果可为安康市洪灾风险评价提供基础数据。