Research question and Summary of possibilities

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)