Laserfiche WebLink
Prior to calculating the river gains and river point flows, however, the segment of river which is of <br />interest must be properly defined (i.e., Kersey to Julesburg). The only stipulation on the defined <br />river segment is that the river channel flow entering the segment and exiting the segment are <br />known apriori. Such boundaries are generally defined by river gauges, however, locations where <br />the flow in the river becomes negligible (Q z 0; referred to throughout as 'Dry River Points') will <br />also suffice as adequate boundary conditions. An unlimited number of river structures (gauges, <br />diversion points, and/or inflow points) can be contained within the river segment of interest. It is <br />important to note that several river reaches (as defined above and illustrated in Figure 1) may <br />exist within the defined river segment. The procedure to calculate subreach gains is performed on <br />a daily basis and is listed below. <br />GAIN COMPUTATIONS <br />1. If appropriate, partition the overall river segment of interest into the maximum number <br />of reaches. The number of reaches will equal the total number of gauging stations and <br />diversions points drying the river less one. Because diversions which dry the river are <br />utilized as reach boundaries the number of reaches within a given river segment can <br />vary from day to day. The following water balance, or volume conservation equation, <br />is used to compute the gains for the reach: <br />Gains = - (I Inflows - Outflows) <br />Inflows include measured values of tributary stream inflows, reservoir releases to the <br />river, and boundary inflows at the up river reach boundary. Alternatively, outflows <br />include measured diversions (canal or ditch) and boundary outflows at the down river <br />reach boundary. Positive river gain values (Y_Outflows > YInflows) denote a gaining <br />river. Negative river gain values (EInflows > YOutflows) denote a losing river. The <br />value of the computed gains from the above equation exhibits the units of cubic feet <br />per second (cfs) and represents the gain for the entire reach. <br />2. The calculated reach gains are then distributed in a pro rata fashion over the entire <br />length of each corresponding reach. This is performed by dividing the calculated reach <br />gain by the total length of the reach (river miles) resulting in gain per unit river mile. <br />Each subreach within the reach is then denoted as having this same gain value, in cfs <br />per river mile. To calculate the total gain occurring within any given subreach the gain <br />(cfs/ river mile) must be multiplied by the subreach length. <br />3. The concluding subreach gain values, in cfs per river mile, for all subreaches are then <br />archived to a table or database by subreach name and historical date. <br />Embedded within the gain computations are two notable assumptions that deserve further <br />discussion. The first assumption entails neglecting the storage component within the water <br />0 <br />pt lgmd wpd <br />