EROS in Action - Landscapes of West Africa with Gray Tappan

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Gray Tappan and Francis Dwomoh discuss Landsat's contribution to the studies they have conducted regarding landscape changes in West Africa.
 

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Length: 00:05:53

Location Taken: US

Transcript

Gray Tappan, I’m a geographer with the US Geological Survey, EROS Center. Most of that time focused on West Africa. Now, Africa really stands out because there’s a lot of US Foreign Aid going to Africa, and a lot of need for the remote sensing and so there were, there were a lot of interest in bringing these technologies to Africa. There have been other Atlases and they very effectively showcased satellite imagery, particularly Landsat, as a way of looking at natural resources and problems with those resources. Degradation, or conservation problems, or, and particularly changes. No one had really tackled multi-date mapping, and the trends that you get from that. So that’s really the contribution of our work in these seventeen countries and for the whole region. I am Francis Dwomoh, from Ghana. My research is basically using various kinds of remote sensing data sets to look at climate, land use, land cover, wildfires. How they are changing in space and time and how they interact to effect forest loss. I basically look at a West African sub-region along the Atlantic coast. Mainly from Ghana all the way to Guinea. There were challenges at several levels. One is the sheer magnitude, the sheer size of West Africa. The vast area of West Africa. The complexity of the landscapes. The diversity. And then there were methodology challenges of how do you map land cover through time and get it right. And, we decided early on in this project to go with just the good old fashioned visual analysis, visually mapping, manual mapping of Landsat imagery. Visual interpretation. In our landscape, the changes are quite heterogeneous and they occur at very, very fine scale. You know people or families on the order of acres, one acre, one hectacres, that kind of thing. So to be able to resolve that kind of detail, you need a sensor like Landsat’s, and that has been very valuable in this kind of investigation. The whole mapping effort and monitoring effort with Landsat and the tools that we developed here. The idea was to do the mapping with them as partners. Never to do the mapping for them, but with them. We were sort of there as facilitators, providing the imagery, some of the GIS experience, the tools. But the mapping was done, a lot of it was done by them. And then, if there were problems in, you know, it’s challenging. Again the challenges of interpreting, correctly interpreting mapping with Landsat, there are problems. But, so some of the challenges they had, we would review their results and bring everything up to a high level of accuracy. With these data sets I able to see those changes. But when I bring in other data sets, like climate, population growth, and other socioeconomic data, then it’s able to give me a better understanding of not only why the changes are occurring as the map shows, but what is driving those kind of changes. It’s gratifying to know that Gray’s data captures some of this change, from 1973 all the way to the 2000’s. It is something that is critically important and I think even for the local people. The local communities who see drained rainforests in their livelihood, all these resources disappearing over time. They come, able to sit down with their resource managers and be able to see where the data changes are occurring, where, and when. And that’s as valuable to them to plan ahead. Just to get those trends and put a visual behind them is really important, and that’s getting the attention at the national…You know, there are a lot of Presidents and Prime Ministers now who have seen our work and have been talking about it, and calling for more monitoring. So, it does flag some of the major problems that the region is experiencing. Environmental problems, problems with limited land, limited resources in a fast growing population. But the case studies, particularly the case studies, that we did also show lots of successes in land management that lead to viable ecosystem services, stability, improvements in some cases. So, there are vast areas of Niger, which is a very dry country, that have far more tree cover today, than 20, 30, 40 years ago, and our work directly shows that. And it was, in fact, thanks to time series images, that proved, that yeah, there’s much more tree cover in southern Niger, parts of Mali, parts of Burkina, than 30, 40 years ago, despite the growing population. So, it’s not intuitive. There were some huge success stories that have caught the attention of the world really.