Posted on June 26, 2013 by James Douglas
Today I spent another day at the barn because I felt like I could accomplish more here than out in the field. I started out the day trying to identify all the ways in which my model was faulty so that I could then go through the process of trying to fix it. The first thing that I realized was that my solar radiation calculations- done using spatial analyst- could be calibrated to the region in which my water balance was being calculated (or so I thought). The basic idea was that diffuse solar radiation and solar transmissivity varies depending on your location relative to the sun, and this difference can have a pronounced effect on the overall PET of the system. In order to perform this correction, a calibration had to be performed using the established values of a solar radiation collection station near the study area. I went through the process outlined by the creator of the model, however ArcMap kept crashing when I had to run the batch edit that compared all possible permutations of the pertinent variable. This meant that all of the work I had done for the past three hours was useless. I threw up my hands and surrendered to the frustrations of data analysis.
This setback was especially problematic because calibrated solar radiation rasters were essential to the process of creating PET adjustment coefficients for the model run on watersheds outside of the NE US. This left me with relatively little to do for the rest of the day. However, I remembered that Dr. Wechsler had said the an updated 5m DEM was going to be available soon and so I created a set of models that would produce updated outputs from the water balance toolset if this new data was made available before the project deadline. This took up the rest of my work day. In the evening, I talked to Dr. Becker, who reminded me that I should get at least one discharge reading that I could compare with the water balance toolset. Embarrassed that I had forgotten about this, I agreed, and we decided to accomplish this task on the last field day (!) tomorrow. He also sent me a link to a paper that had been published on surface groundwater contributions to Kahana bay, which is a bay on Oahu that we drive by everyday on the way to the Ka’a’awa, and one that is controlled by many of the same hyrdrogeological processes as the environment that we are studying. It was a very interesting read, and one that opened my eyes to both what can be accomplished in terms of hydrological study in an environment as complex as this, as well as the inadequacies of this REU environment for legitimate scientific progress.
This accomplished, I set my sights on another day in Oahu- partly comprised of data collection and partly comprised of data analysis.