دانلود رایگان مقاله انگلیسی ارزیابی نهایی ارقام مرجع برای مدیریت منابع آب با استفاده از اندازه گیری جریان لحظه ای - الزویر 2018

abstract

Reference stream gages are commonly used for a variety of hydrologic studies and water resources management purposes. Reference gage selection methods have been extensively investigated in literature. However, the posterior assessment of reference gages is a long-standing challenge faced by water resources managers. This study aims to evaluate the accuracy of using reference gages in estimating low flow conditions at ungaged sites. The proposed assessment method is comprised of three fundamental components including: (1) a field campaign to obtain instantaneous flow measurements at ungaged sites during baseflow conditions; (2) streamflow correlation and streamflow ratio analyses using field measured values at ungaged sites and concurrent reference gage data; and (3) map correlation analysis to identify alternative reference gages for ungaged sites with undesirable flow correlation and flow ratio values. The method was tested using 18 systematically selected reference gages used by the Susquehanna River Basin Commission for regulating water withdrawals and ensuring compliance with passby flow requirements. Streamflow monitoring during baseflow conditions over the course of four consecutive low flow seasons resulted in the collection of ten streamflow measurements for each ungaged site. The streamflow correlation coefficients between streamflow measurements at ungaged sites and concurrent reference gage streamflow data were found to be greater than 0.7 for 17 of the 18 sites. Map correlation analysis was conducted to identify alternative reference gages for three ungaged sites which exhibited high prediction errors or low streamflow correlation. The case study demonstrates that proposed posterior assessment method for evaluating reference gage performance is easy to use with reasonable cost.

4. Conclusions

Selection of appropriate reference gages for performing hydrologic analyses at ungaged sites is critical in water resources management practices. This study proposed an effective method to posteriorly examine the performance of selected reference gages, comprising a field campaign protocol, correlation analysis and streamflow ratio analysis, and map correlation. The method has been tested with 18 reference gages in the Susquehanna River Basin used for low flow protection purposes.

The field campaign protocol made it affordable and manageable to obtain effective onsite discharge measurements at ungaged sites. The subsequent streamflow correlation analysis and streamflow ratio analysis provide criteria to assess reference gages. The map correlation method generates alternative reference gages when the selected reference gage is undesirable. It should be noted that since it is difficult to find an appropriate reference gage for an ungaged site possessing an extremely small drainage area and unique hydrogeologic settings, an appropriate reference gage may not exist, and on-site monitoring may be warranted.

Unlike previous hydrologic studies used for hypothetical ungaged streams, the posterior assessment method was based on water management practices where no continuous streamflow records were available for validation. It provides a valuable tool for water resources managers and hydrologists to posteriorly assess reference gages with feasible cost and improved confidence in meeting regulatory objectives.