Group 1 : Vegetation and water level

Date : 3.10.2023

Weather : cloudy and rainy

Atmosphere temperature : 8°C 

 Task 7    Vegetation Study

This task consist on observing and study the vegetation in the lake and around. 

Let see what we found : 

During the expedition, we found numbers 1, 2, 3 and 7 in the water. Cause of the automne season, most of the vegetation is already dead and the depth and a dark water color don't allow us to see the underwater plant except on the board. 

1 : grass / basic reeds 

2 : underwater water plants

3 : yellow water lily and floating plants

4 : algae

We learn that different water lillies can be recognized by the color of the flower and different species can be used as an indicator species. White flower meas white waterlily, which is an indicator for good water quality. Yellow waterlily is a more common as it is not as selective.

Around the lake their is many varieties of vegetation, and we can find basic plants in forest like mushroom, blueberries, trees, ... 

But a particularity on this lake is that the vegetation is growing. We can find many places with a beginning of swamp. And some of those ones became slowly a part of forest. You can be suprise in your walk, just go trough the vegetation and find your feet totally wet. 

A big part of this swamp is composed of moss, look like a vegetal carpet. 

 

 

Overview of vegetation

 

We learnt that vegetation is not a sign of pollution, otherwise that people can think. It's a sign of water quality and different vegetations indicate different quality. They are part of ecosystem and help in the conservation of a clear and good water. They produce nutrient for the wildlife too. 

But in some case they can be a problem. If there grow too much, cause of pollution, pesticide discharge, industries discharges, they can recover the water surface, blocking out the light and upsetting the ecosystem. 

 

To conclude, vegetation is a sign of water quality, you can swim, you can fish without worrying except if there is to much plants. 

 

 

Measuring water level (Task 6) 

The second task of the day was the measurement of the water level. The measurements were taken for the Pieni-Valkeinen and the Iso-Valkeinen Lake. The water level can be determined with a correctly adjusted levelling machine and already known pre-measured points. 

The two known pre-measured points are: 

Pieni-Valkeinen Lake      
Pre-measured point: Lid of the manhole cover

Height ($$h_{pmp1}$$): 99,064 m 
Measurement 1: D
ifference levelling machine and pre-measured point ($$h_1$$)= 1,4 m 
Measurement 2: Difference levelling machine and lake surface ($$h_2$$)= 3,185 m

Water Level Pieni-Valkeinen Lake      

Height of the levelling machine ($$h_{lm1}$$) = ($$h_{pmp1}$$) + ($$h_1$$) = 99,064 m + 1,400 m = 100,464 m 
Water level = ($$h_{lm1}$$) - ($$h_2$$) = 100.464 m – 3,185 m = 97,279 m 

The water level of the Piene-Valkeinen Lake is 97,279 meters.

Iso-Valkeinen Lake     
Pre-measured point: middle of a stump

Height ($$h_{pmp2}$$): 91,781 m     
Measurement 3: Difference levelling machine and pre-measured point ($$h_3$$)= 0,475 m 
Measurement 4: Difference levelling machine and lake surface ($$h_4$$)= 2,62 m 

Water Level Iso-Valkeinen Lake      

Height of the levelling machine ($$h_{lm2}$$) = ($$h_{pmp2}$$) + ($$h_3$$) = 91,781 m + 0,475 m = 92,256 m 
Water level = ($$h_{lm2}$$) - ($$h_4$$) = 92,256 m – 2,62 m = 89,636 m 

The water level of the Iso-Valkeinen Lake is 89,636 meters. 
As expected, it is below the water level of the Piene-Valkeinen Lake.

According to base maps of Maanmittauslaitos (MML, National land survey of Finland), water level at Pieni-Valkeinen is 96.3 m and in Iso-valkeinen 89.1 m. We can see that there are significant differences in our measurements. These errors can be caused by inexperienced measurers. It's also possible that MML has outdated information.