Compare erosion measurements without inventing a reservoir budget
Two fictional experimental plots have the same area, soil type and slope. Repeated measurements under the study conditions give annual soil loss rates of 22 tonnes per hectare for a bare treatment and 4 tonnes per hectare for a covered treatment. The exercise asks students to consider applying each measured rate over a hypothetical 45 hectares, solely as an arithmetic scenario. It supplies no sediment delivery ratio, rainfall distribution for future years, reservoir capacity, crop yield or cost data. A team nevertheless claims that every tonne of lost soil must enter a downstream reservoir and that a particular subsidy must therefore save a stated amount of money. Another team rejects the comparison because only one of the rates is a whole number larger than ten. The task is to calculate the difference, explain what the observations support, and identify which proposed extensions are not established by the supplied evidence.
1. Compute the rate reduction and hypothetical total losses.
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The difference is 18 tonnes per hectare, a reduction of 18/22 times 100, approximately 81.8 percent. Across 45 hectares the respective arithmetic totals are 990 and 180 tonnes per year, a difference of 810 tonnes under the prescribed scenario.
2. What conclusions require additional evidence?
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The measurements support a comparison under the study conditions, not a universal future outcome. Delivery to a reservoir requires transport and deposition information; monetary benefits need actual costs and valuations. The whole-number size of either rate is irrelevant to whether the comparison can be calculated.