Citizen science flow – an assessment of simple streamflow measurement methods

Abstract

Abstract. Wise management of water resources requires data. Nevertheless, the amount of\nstreamflow data being collected globally continues to decline. Generating\nhydrologic data together with citizen scientists can help fill this growing\nhydrological data gap. Our aim herein was to (1)\xa0perform an initial\nevaluation of three simple streamflow measurement methods (i.e., float, salt\ndilution, and Bernoulli run-up), (2)\xa0evaluate the same three methods with\ncitizen scientists, and (3)\xa0apply the preferred method at more sites with\nmore people. For computing errors, we used midsection measurements from an\nacoustic Doppler velocimeter as reference flows. First, we (authors) performed 20 evaluation\nmeasurements in headwater catchments of the Kathmandu Valley, Nepal.\nReference flows ranged from 6.4 to 240\u2009L\u2009s −1 . Absolute errors averaged\n23\u2009%, 15\u2009%, and 37\u2009% with average biases of 8\u2009%, 6\u2009%, and\n26\u2009% for float, salt dilution, and Bernoulli methods, respectively.\nSecond, we evaluated the same three methods at 15 sites in two watersheds\nwithin the Kathmandu Valley with 10 groups of citizen\nscientists (three to four members\neach) and one “expert” group (authors). At each site, each group performed three simple\nmethods; experts also performed SonTek FlowTracker midsection reference\nmeasurements (ranging from 4.2 to 896\u2009L\u2009s −1 ). For float, salt\ndilution, and Bernoulli methods, absolute errors averaged 41\u2009%, 21\u2009%,\nand 43\u2009% for experts and 63\u2009%, 28\u2009%, and 131\u2009% for citizen\nscientists, while biases averaged 41\u2009%, 19\u2009%, and 40\u2009% for\nexperts and 52\u2009%, 7\u2009%, and 127\u2009% for citizen scientists,\nrespectively. Based on these results, we selected salt dilution as the\npreferred method. Finally, we performed larger-scale pilot testing in\nweek-long pre- and post-monsoon Citizen Science Flow campaigns involving 25\nand 37 citizen scientists, respectively. Observed flows ( n=131 \npre-monsoon; n=133 post-monsoon) were distributed among the 10 headwater\ncatchments of the Kathmandu Valley and ranged from 0.4 to 425\u2009L\u2009s −1 \nand from 1.1 to 1804\u2009L\u2009s −1 in pre- and post-monsoon, respectively.\nFuture work should further evaluate uncertainties of citizen science salt\ndilution measurements, the feasibility of their application to larger\nregions, and the information content of additional streamflow data.