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