Published: July 28, 2022

People collecting water in AfricaDenis Muthike is the lead author of a new paper that validates and compares satellite-based rainfall tools over a variety of conditions to better understand their reliability and validity.

Denis Muthike, an environmental studies PhD candidate, is the lead author of a paper in the Journal of Hydrometeorology that validates and compares satellite-based rainfall tools over Africa. 

We asked him about the research, his time at CU Boulder and where the work goes from here.

Question: How did you get to CU Boulder? What drew you to the university?
Answer: My first encounter with CU Boulder was through a three-month project that professor Evan Thomas did with the Regional Centre for Mapping of Resources for Development on remote sensing data analysis to support his borehole sensor monitoring research in Kenya. 

I then started working with Evan's team to write a grant proposal that was eventually funded by NASA to expand that work to improve drought management through improved water services. In 2019 Evan invited me to visit his research lab where I saw the innovative work being done there – continuing the great work the Mortenson Center has done for years. 

The diversity of his students and the reputation of the center prompted me to discuss an opportunity to pursue my PhD with him at CU Boulder. I am glad I was able to visit his lab because that was when I also met my co-advisor Professor Jason Neff who – upon listening to my background and work with NASA SERVIR and RCMRD – was eager to bring me in as an environmental studies student.

Q: Why is this research into rainfall tools important?
A: Increasingly, satellite-derived rainfall data is used for climate research and action in Africa. In this study, we use six years of rain gauge data from 596 stations to validate three gauge-calibrated satellite rainfall products – we wanted to see how well they perform and how accurate they are in different conditions.

Eventually information from these kinds of remote sensors will be used to help agencies identify areas that are likely to experience drought crises and then begin to implement early interventions to address them. Being able to predict, react and understand the conditions at play is all based on getting good readings from these sensors into the right hands. This paper shows that we still have some work to do to reduce errors introduced from satellite data.

It is all part of the Drought Resilience Impact Platform (DRIP) – an integrated systems-based approach to reducing drought impacts and improving water quality and soil health that is being researched and explored on campus right now. 

Q: What are the potential high-level applications of this kind of research? Why do we want to study these questions?
A: Drought crises in East Africa have catastrophic impacts on millions of vulnerable people in mostly underdeveloped regions. These crises cause humanitarian challenges that, for the most part, have been managed through reactive approaches. Our research questions enable us to apply new approaches by providing predictions of rangeland health and groundwater use in support of early warning and pro-active actions that can be implemented before crises occur. Understanding biases in climate data helps us account for those errors in our drought models, and in most cases, it helps highlight limitations for decision makers using our research outputs. This is critical especially during the implementation of early actions to mitigate drought impacts.

Q: What was is it like working with Associate Professor Evan Thomas and others in the Mortenson Center?
A: Professor Thomas is really an incredible person. His broad depth in knowledge of global challenges and his experience applying unconventional methods to solve multi-disciplinary problems means it is always a great opportunity to get to work with him and his research group. So far, we have provided a novel product to agencies in Kenya. This product has been possible because of the strength and high-quality work that the center (with the leadership of Professor Thomas) carries out in developing economies.