RIVERS!

Hello guys!I am really sorry for putting up this post late-.-||. Anyway, thank God, Guzheng SYF is finished!Hooray!XD
OK,let's do some revision. Do you still remember what we learnt on 17th of April?

1. River---Man and civilisation
River is so essential for human development. And learning about the essential living conditions for humans is also important for us. We find out that great civilizations have always flourished alongside rivers. For example, the Yellow River Valley, is always thought to be the cradle of The Chinese civilization. And the Nile River valley in Egypt was the site of the world's first great civilization. Our pretty teacher Ms. Tang also showed us a picture of Nile Delta (which is screenshoted from her favourate Google Earth), and we saw that there is a very high population density along the river but few people live elsewhere in that region.

The explanation is as simple as this:
River-->water necessary for farming & drinking--> better living conditions--> more people live and multiply along rivers.



2. Model-making Time
The second half of the lesson was used for model making activities. We were supposed to make models of deltas, waterfalls, floodplain and levees, meanders,rapids and ox-box lake with plasticine and put them in order according to how a river flows. I feel that this kind of hands on acitivities really helps in understanding. I can have a clear picture of how different parts of a river look like and why they are located at where they are.
Yeah this is the whole model done by Loulou,Jenny,Binghui and YIXUAN!



Before making a model like ours, you must understands what the different parts of the river are.:)By the way, Ms Tang showed us the photos of the waterfalls she took in U.S.,and those photos are cool!:)

OK, lastly, let me ask you a question that we have already discussed in class:
Is the speed of the water in the upper cause always the fastest?Why?


Done by:

GEO-PRESENTATION by YINGZHENG.-

Today’s lesson was a short lesson, but we did learn many important things. Firstly, we learnt in previous lessons about the equation regarding the hydrological cycle. The individual factors that can change are precipitation, evapotranspiration, total streamflow, and also change in soil water storage. These things alone, when changed, will affect our water cycle. We also looked into things like storm hydrographs and rainfall. Different groups took turns to present on the different factors which affected rainfall and such. This was different from an ordinary lesson as it was actually our classmates teaching us. It was very interactive as we asked many questions and clarified many doubts. We were also able to visualize better as there were drawings to aid us.
What we learnt today was mainly about the various factors that affect the hydrological cycle, and why they do. This was then referenced to the smaller factors that defined the water cycle. One factor that affected the activity of the hydrological cycle was afforestation and deforestation. Using the equation we learnt previously, during afforestation, runoff decreases, evapotranspiration increases, and soil water storage decreases. This is because there are more trees, there is an increase in interception, thus there will be less runoff. More tress would then also lead to higher evapotranspiration rates, and their roots, taking up space in the soil, will decrease the soils water storage capacity.
Another change in surrounding was deforestation. Deforestation is actually the exact opposite of afforestation. During deforestation, the number of trees decreases thus resulting in less interception, and more runoff. Similarly, less trees would result in less evapotranspiration, and the lower amount of roots in the soil would then increase its water storage capacity.
Next, there’s agriculture. Agriculture is the growth of vegetation. And as such, infiltration decreases, stemflow and root absorption increases and blocked surface area also increases, thus, throughflow and baseflow would decrease.
The last point presented was grazing. Grazing reduces the amount of vegetation, thus increasing infiltration. This would then result in an exact opposite of agriculture, therefore increasing total throughflow and baseflow.



---YINGZHENG

As we advance in our learning, I realized that we go more and more indebt into things. For Geography, I always thought that the water cycle was simply just the evaporation of water, formation of clouds, then rain. Although this still holds true, there are now many factors that we know that have to be taken into consideration before this “simple” process can take place. I also did not know that equations and graphs are actually constructed just to study the rain and its effects. Also, it did not occur to me that so many factors could cause a change in the storm hydrograph. Factors including: drainage density, shape of basin, steepness of slope, amount of rain, presence of vegetation and rock permeability. The range of these factors is so great that it is hard to imagine that the difference of something as minute as rock permeability as compared to something as large as drainage density can both have an effect on the hydrograph. Moreover, a simple tweak in only one factor such as the presence of vegetation can actually change the hydrograph by quite a lot. I cannot imagine how much thought has to be put in just to construct a graph that has majority of its factors different from the original graph. Through the learning of these factors, I found out that some things could be inferred from as long as you knew the definition of the term and some background knowledge. For example, the steepness of a slope. From basic knowledge we know that the steeper a slope is, the faster things can roll down. Thus, we then infer that the faster the rain droplets flow down the hill, the shorter is the basin lag time as the river would peak faster. There are some things that we can easily infer when we are studying, we just need to dig out the necessary background information and would be able to arrive at the conclusion.

Janell