1 00:00:00,506 --> 00:00:13,186 [ Music ] 2 00:00:13,686 --> 00:00:14,126 >> Welcome back. 3 00:00:14,726 --> 00:00:17,976 Thanks for joining me for the second segment covering unconfined 4 00:00:18,116 --> 00:00:20,636 and confined aquifers using a physical model. 5 00:00:22,346 --> 00:00:28,296 For our first demonstration, we'll look at an unconfined aquifer composed of gravel and sand. 6 00:00:28,916 --> 00:00:33,336 In the model, you can see the aquitard at the base of the unconfined aquifer 7 00:00:33,736 --> 00:00:35,556 and open to the surface at the top. 8 00:00:35,916 --> 00:00:39,926 We will use dye to show how water flows through the aquifer. 9 00:00:40,196 --> 00:00:43,836 On the right side of the tank, we have higher elevations. 10 00:00:44,026 --> 00:00:47,006 And to the left, we have a lake and a river. 11 00:00:47,786 --> 00:00:51,186 As we start to inject the dye, where you think it will go? 12 00:00:53,266 --> 00:00:54,206 Let's watch. 13 00:01:13,506 --> 00:01:14,956 Did you figure it out? 14 00:01:15,586 --> 00:01:17,986 The dye flows from high head to low head. 15 00:01:18,336 --> 00:01:21,156 Head essentially means the height of the water surface. 16 00:01:21,156 --> 00:01:24,776 There is more horizontal movement than vertical movement. 17 00:01:25,366 --> 00:01:30,016 You can also see that the low permeability aquitard is restricting the dye 18 00:01:30,016 --> 00:01:32,236 from flowing into deeper aquifers. 19 00:01:32,856 --> 00:01:38,066 Eventually, groundwater flow paths discharge the dye into the river. 20 00:01:38,516 --> 00:01:45,746 For that confined aquifer, you can see it is kept by an aquitard and an aquiclude, 21 00:01:45,746 --> 00:01:49,776 a type of aquitard that allows no water to flow through. 22 00:01:50,476 --> 00:01:52,466 Watch what happens when we inject the dye. 23 00:02:07,256 --> 00:02:11,156 The dye follows a similar path of the unconfined aquifer. 24 00:02:11,636 --> 00:02:15,556 There is little vertical movement yet lots of horizontal movement. 25 00:02:54,776 --> 00:03:01,456 As the dye reaches the artesian wells, the dye flows up and discharges onto the land surface. 26 00:03:02,226 --> 00:03:06,226 Again, this is because confined aquifers are under pressure. 27 00:03:22,636 --> 00:03:24,916 In a fractured bedrock aquifer, 28 00:03:25,176 --> 00:03:29,446 a type of confined aquifer commonly called a [inaudible] aquifer, 29 00:03:30,066 --> 00:03:33,656 the surrounding rock has very low, if any permeability. 30 00:03:34,486 --> 00:03:39,436 Thus, it is kept by an aquiclude, a layer of rock which will not transmit water. 31 00:03:39,926 --> 00:03:43,146 As we inject the dye, where do you think it will go? 32 00:03:43,916 --> 00:03:46,006 Think about the speed of the water too. 33 00:03:46,546 --> 00:03:50,266 Will it slow faster or slower than the other aquifers? 34 00:03:51,306 --> 00:03:52,176 Let's watch. 35 00:03:52,266 --> 00:03:54,376 Look at that. 36 00:03:55,196 --> 00:03:59,476 The dye flows only through the fractures, not through the rock matrix. 37 00:03:59,816 --> 00:04:03,606 And it flows much more quickly than the other aquifers. 38 00:04:09,866 --> 00:04:14,576 Again, once it reaches an artesian well, the dye discharges 39 00:04:14,686 --> 00:04:17,496 onto the land surface and flows into the river. 40 00:04:18,516 --> 00:05:00,860 [ Music ]