Water Erosion and Sediment Yield Experiment

Manawatu Flood of 2004

Exercise 1. Water ErosionWater erosion can results in the loss of soil from the land. Depending on the erosion type, this can result in a considerable amount soil being removed. An example of the severity of water erosion is the Manawatu Flood of 2004. Watch the Manawatu Flood video and answer the following questions.1.How much rain was recorded during the storm event in a 24 hour period?2.How many tonnes of sediment per second passed under the Fitzherbert Bridge?

1-23.How many tonnes of soil was lost down the Manawatu River?4.How many tonnes of soil was lost across the Manawatu Region?5.What was the economic damage to the region?Experiment 1. One way of measuring water erosion is to measure sediment yield from a known catchment area. In this experiment the erosion loss from a small ‘plot’ of soil will be measured under standard conditions. The apparatus is set up for you and you should follow the instructions below.Instructions1. Make general notes on the condition of each soil sample and the pattern and amount of erosion occurring in each tray.2. All pottles from each of the two treatments will be combined as 2 samples, microwaved until dry and weighed. The results will be provided.3. Determine the structural stability of each treatment by:(a)Collecting 3 aggregates of each sample. Half fill each petri-dish with water. (c)Gently lower the aggregates into their corresponding petri-dish. DO NOT disturb for the next ½ hour.(d)Record your observations on the result sheet; (i) after ½ hour, and (ii) after agitatio