A network of precipitation measurements can be converted to areal estimates using any of a number of techniques which include the following:ġ) Arithmetic Mean - This technique calculates areal precipitation using the arithmetic mean of all the point or areal measurements considered in the analysis.Ģ) Isohyetal Analysis - This is a graphical technique which involves drawing estimated lines of equal rainfall over an area based on point measurements. A dense network of point measurements and/or radar estimates can provide a better representation of the true volume over a given area. Runoff from excess precipitation in each zone is used to calculate streamflow which is then used to produce river stage forecasts.Ī single point precipitation measurement is quite often not representative of the volume of precipitation falling over a given catchment area. Large river basins are subdivided into these smaller catchments or runoff zones. This is because the models simulate the rainfall-runoff process on a drainage catchment area basis. The river forecasting models in use by the NWS require areal estimates of precipitation. Hydrologic Requirement for Areal Estimates of Precipitation The ABRFC produces NWS WSR-88D 1-hour radar precipitation estimates for our area of responsibility on an approximate 4 by 4 km square grid resolution. The Z reflectivity factor is then used in an equation referred to as a "Z-R relationship" to determine rainfall rate. This return power is used to calculate a reflectivity factor, Z. The actual measurement taken by the radar is of backscattered power of the echo returns. Another method of measuring precipitation is through the use of radar. All of the above gages measure precipitation at a point. For those items in the ending inventory, it is the same as the weighted-average method, where we need to calculate how much work has been done to them already.Liquid precipitation is traditionally measured using various types of rain gages such as the non-recording cylindrical container type or the recording weighing type, float type and tipping-bucket type. For those units that were in the beginning inventory, we need to figure out how much work was DONE on them in this period to get them to the point of being transferred to the next process. In this method, both the beginning and ending inventory is converted into equivalent units, so there is a bit more work to do. The units that were both started and finished in the current period.The units that were in beginning inventory and completed.In this method, the units that have been moved to the next process are divided into two parts: FIFOĮquivalent units can also be calculated using the FIFO method. Our equivalent units of production for the period is 1,200 units (700 + 500). (1000 × 50%) + 700 units that were transferred out. We would have 500 equivalent units in our WIP inventory. We also have 1000 partially completed units that are 50% complete. Those are considered 100% complete for the work done in that department, otherwise they wouldn’t be moving forward to the next process.ħ00 units were transferred from process 1 to process 2. One thing to keep in mind when using the weighted average method, we don’t need to compute the equivalent units for the ones transferred out. In this method we use the following equation: There are two ways we can calculate the equivalent units of production for a department or process: weighted-average or FIFO (first in, first out). Any units that have been moved into process 2, will be subtracted from the WIP inventory for process 1. We could then add these equivalent units to the ending WIP inventory for process 1. If we have 1000 units in the ending WIP inventory after process 1, this would equal 350, using the formula for equivalent units. Let’s assume we figure the ending WIP inventory to be 35% complete as to the process. We call this the equivalent units of production method of costing:Įquivalent units = number of partially completed units × Percentage completedĪt the end of process 1, our planners have their paper and ink ready to be printed.
How can we figure out the costs at each stage of production? The easiest way is to figure out what percentage of the planner is completed, as to the work in that department. Each department has an ending inventory of unfinished planners. In order to calculate a product unit cost, those costs need to be accumulated, as the planner isn’t finished. In each department raw materials, labor and overhead are being added to the planners. So the Ultimate Planner goes through three departments on its way to finished goods inventory. Calculate equivalent units of production and cost per equivalent unit using the weighted average and FIFO methods.
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