My professional work right now mostly revolves around remote sensing of the dynamism of the wetlands in the Okavango Delta, a vast inland river delta in northwestern Botswana. It's a unique system, because most river deltas pour into oceans, seas, or lakes... but this one just ends. The water evaporates into the Kalahari desert air or percolates deep into its sands or gets sucked up by the trees of the area enduring the arid climate.
photo from wikimedia
The Delta also has a distinct hydrology. The rainy season here is approximately December-March, during which the entire landscape gets rain and the landscape gets green. Simultaneously, the Angolan Highlands, a plateau northwest of the Okavango Delta, collects a ton of water, which moves slowly through its forested landscape and spongy peatlands. This water then flows into the Okavango 3-5 months later, allowing the Delta and its wetlands another pulse of blue and green, in the peak of the hot summer. A recent paper called this service the "water tower" of the Okavango Delta, providing water when it is scarcest and turning the landscape into a vast oasis.
The magic of wetlands is their in-betweenness. They aren't totally wet—that's lakes and oceans. But they aren't very dry, either—that would make them a terrestrial ecosystem like shrubland or something. The Okavango is a huge area (~20,000 square kilometers) that's sometimes covered in a meter of water, sometimes completely dry, and everywhere in-between in both water depths and duration inundated. It's complex! Hence the need to study these dynamics!
As a scientist, I love these complexities because it forces me to be crafty in my definitions and methodology. Consider this: I want to know where all the wetlands are across the Okavango. OK, then... how wet? for how long? What is enough to define the wetland?
Our team started by getting to know the vegetation of the Delta, to see if certain plants are clearly wetland species (like papyrus and other sedges), and then we can look for those to define the wetlands. Using remote sensing data, a very common process is "water masking" wherein the wet regions of a satellite image are identified, typically before focusing on either only the wet areas or only the dry. We found these methods rarely worked in the Okavango, which has such a murky delineation between wet and dry, one that changes dramatically with the seasons. Instead, we've leaned on an algorithm (called "DSWE") trained across a wide variety of wetland types that designates a few gradations of wet-ness, and we think this works pretty well. By a combination of optical properties (i.e. "is it green?"), output from this algorithm, and vegetation characteristics, we're getting quite good performance at identifying the various flavors of wetlands here.
Whenever we categorize things, we risk simplifying them, crushing the assemblage of forces that make an entity itself into a reduction. I wrote a little post many years ago about how false the distinction can be between land and water in the marshy muds. The liminality of wetlands is part of their definition, with many slightly different flavors of not-quite-wet-and-not-quite-dry. But by all accounts, this murkiness challenges to those seeking to clearly define, delineate, and instrumentalize these landscapes.
from Salish Magazine.
The dynamic amphibiousness of wetlands and their subtypes—swamps, mires, bogs, marshes, mudflats, etc—is ripe with counter-cultural possibility. They are also distinct in their accumulative nature, building up layers and layers of history as sediments deposit and lay down stratigraphies which may ultimately be modified or twisted under outside forces. Shoals have been theorized as shifting encounters of blackness and nativeness (in the USA) by Tiffany Lethabo King / sedimentary layers positioned as sequences of class warfare and industrial production in East Anglia / wetland development or conservation as sites of performed moral and political ecology in state-building / and marshes that challenge technical "earth mastery" modes of knowledge.
I'm still learning about the Okavango Delta and its interconnections with people, economy, chemistry, animal migration, and more. But I see possibility here to pick up these threads of counternarrative, as a region subject to powerful pressures of leisure travel, colonial tensions, water abstractions, and extractive industries. The murky difficulties of the wetlands pose problems to domineering modes of thinking.
Plenty else going on in life but gosh it's hard to keep track of! I'll sign off by asking, if you can spare $10, please consider donating to City Surf Project, a San Francisco-based nonprofit I've loved for years. They support getting kinds from under-resourced backgrounds into the ocean for personal growth, leadership training, and (duh) learning how to surf. It's a magical group! I am fundraising here towards international surfing day (tomorrow!).
Half wet / half dry,
Lukas