Blog2:
Hi again
This
blog-post serves to keep you up do date concerning our project in Schinznach-Dorf.
As the local tree-nursery is interested in getting an idea of the water flux,
our team is exerted to answer this challenging but rather interesting economic question.
By putting up a sound sampling design in these blogs, we’ll be able to collect
significant dates until the end of May.
As a first
step, we need a clear idea of what we are planning to find out. As Ruth Cohn
once said: “If we have little time, let us use a lot of it at the beginning”.
So it’s of considerable value for the success of a project not to rush in this
phase.
After
taking this advice into account, a possible research question could be:
-
Concerning weather conditions: Is
the difference between the irrigated water in the tree-nursery and the backflow
into the pond including evapotranspiration of the plants higher than 10 %?
This
question targets the loss of water in the irrigation system. The benefit of the
10 % threshold has to be proven, but it’s in my opinion of utmost importance to
quantify the difference. This leads to a statement about the functionality of the
artificial water flux, and additionally, to a quantification of its loss.
The hypothesis
could be:
H0: The water cycle is closed. All water that
is used for irrigation runs back, excluding the amount of evapotranspiration.
H1: The water cycle isn’t closed. There is a
loss of water in the system.
To collect
all the necessary data to finally answer the question shown above, our research
team splits up into 1 large- and 1 small-scale sub group. Several possible
research methods (measurements + computations) from the large-scale group (remote
sensing) are listed up in the table below where the applicability is indicated
as well.
Tabel: Index and Applicability for project Schinznach
Application
/ Index
|
+/-
|
Use
|
Notes
|
Applicability
|
NDVI
(ρNIR-ρRed)
/(ρNIR+ρRed)
|
Differs between
vegetation and not veg.
|
Vegetation
ground cover
|
Differs
in plant types (Cherry laurel, Thuja)
|
++
|
NDWI
[p(0.86um
)- p(1.24um)]/
[p(0.86 um)+ p(1.24um)]
|
To specialised
for the short period of the project
|
Water
content in plant canopy
|
Plant
Coverage should be nearly 100% -> highly influenced by soil
background
|
+
|
GNDVI
(NIR-Green) / (NIR+Green)
|
More specialised
than NDVI (photosynthesis activity)
|
Comparable
to NDVI
|
Necessary
for upscaling water flux measurements
|
+++
|
DSM
|
For land
cover classification (+ GNDVI)
|
Different
heights
|
Estimate
biomass (tree, shrub, perennial)
|
+++
|
To compute
these indexes, spectral and morphological information is required. Establishing
a sound flight plan for the UAV as well as a good strategy to record the corresponding
ground truth is therefore of high importance. We will then bring together this
scale by using GIS.
References:
- - NDWI A Normalized Difference Water Index for Remote Sensing of Vegetation
Liquid Water From Space (Bo-Cai Gao, 1996)
- Relationship Between
Remotely-sensed Vegetation Indices, Canopy Attributes and Plant Physiological Processes: What
Vegetation Indices Can and Cannot Tell Us
About the Landscape (Edward P. Glenn, et.al.,2008)
