Wednesday, October 14, 2015

Tank Cascade or Village Tank Morphology? Function or theory?

The question of unwrapping, unraveling, elucidating, or "uncovering" the landscape carries its own complexity beyond the complexity of topic, landscape itself, we are studying during this Fulbright. Part of the complexity is political or quasi-political. Its roots, like the roots of landscape, are embedded among histories that are at once dissonant and parallel. 

It seems to me this is especially apparent in a Sri Lankan context. Late the other afternoon we traveled by train from Vavuniya south to Colombo. Up in the Vanni, the region of which Vavuniya is the capital, and later as we transitioned into the Anuradhapura region while it was still light enough to see, we observed that over every stream, whether ephemeral or active, a bridge, however insignificant, carried the train safely above. How many streams in this part of the world? How many jungle rivulets? How many lost corners? 

How much engineering had the British employed to find these places, adjust them, and cover them with their network of transport, commerce, and conquest? 

To say that the British "tamed" these places is wholly wrong. But to note that these places are impregnated with British and later Western technology is perhaps not inaccurate. Railroads reach to the remotest corners of this island, as do roads and other infrastructure. Many of these, though not all, were introduced by the British. They exist in a huge, intricate network over terrains varied and heterogenous. The variation is so great, the obstacles so rife, and the remoteness so profound, it amounts to a modern miracle that this infrastructure is maintained as well as it is at the national level. So when topo maps of Sri Lanka were undertaken it's no wonder that rail lines, roads, and similar landscape features were depicted with pride. They are embedded in this landscape like raisins in a scone. Or should I say, like chiles in a sambol. 

But these features are not the only infrastructure in this landscape. An even more intricate human-built fabric, one that holds the hand of nature rather than strapping it to straitjacket, characterized this place. The genius of Brohier, who first and fully described the "hydraulic civilization" of ancient Sri Lanka followed on the findings of Parker and other astute British observers. These landscape explorers had found themselves in an extensive human-built matrix of land and water unlike what existed in any other part of the world. Like the colonial infrastructure that was to come later, this matrix effectively covered every square kilometer of the Dry Zone of Sri Lanka. Through neglect, willful destruction, and natural forces the tank systems had declined and in many places disappeared. But like a moldering skeleton the hardscape of the tanks persisted widely here and there. We saw one such tank the other day, all but abandoned, but distinctly present. Unlike a skeleton, disembodied from living tissue, the tank system was able to be revivified. It was available for human repair and re-use. 

Brohier revealed much about the tanks but to my knowledge he didn't articulate the cascade system. This was left to later scholars, notably CMM Madduma Bandara and CR Penanokke. They unearthed, as it were, the indigenous, vernacular landscape of Sri Lanka. The physical and social undertaking they documented, the construction and maintenance of tens of thousands of village tanks over hundreds of years was, as Brohier noted, truly "prodigious" in scope. It shaped the cultural landscape ecology that was and still is synonymous with much of Sri Lanka. 

Articulating the tank cascade system was in a sense a national and nationalist statement, similar to the massive archeological endeavors of 20th century Mexico or Israel. But in contradistinction to these efforts, which were largely but certainly not exclusively focused on physical structures centered around worship, the tank systems were and are a banausic artifact of everyday life and sustenance in Dry Zone Sri Lanka. They are still in use and they are deeply and closely woven into the fabric of the countryside. The village tank is still the village tank, however neglected or silted over. Cultivators still use it for irrigation. It is still used for bathing, washing clothing, harvesting fish, lotus, and foods. The tank still functions as a wildlife refuge and its banks are still the site of shrines, offerings, and other periodic religious functions. 

So the cascade system is kind of insoluble unit of the landscape, bounded neither by political nor social constructs but embodied watershed by watershed. Whether ancient villages of a given series of tanks (cascade) communicated about the flow of water from one to the next is not known. Professor Bandara in personal communication with me explained that such a communications structure is presently unknown. Nor are all the methods the ancients or their descendants, returning cultivators of the 19th century, used to build and maintain these structures. But they were maintained and curated over the hundreds (sometimes thousands) of years they were in use. The cascade system by whatever name or account remains the indivisible unit by which the Dry Zone of Sri Lanka may be characterized. 

At the same time as the "cascade system" remains indivisible there is the reality of the anatomy and morphology of the individual village tank. These terms, which we normally reserve for living organisms, were introduced to me by my friend and colleague MUA Tennakoon, just as I was conceptualizing tanks in this fashion. The tanks are alive in that their biotic features are components of tank function. Plants, animals, and microorganisms all play some role in tank function. And rather than just holding water, tanks appropriate its behaviors in order to filter and distribute water and water-borne chemicals differentially. I consider the tank to be a sort of valve, harnessing, controlling, and behaving as a conduit for water. Perhaps the Sinhala word for tank, wewa, is somehow through Sanskrit related to the Latin word for valve, valva

The ability of tanks to perform complex functions is hindered by neglect. As naturally-borne silt builds in tanks their ability to hold water is decreased. As surrounding forests and reed-beds are degraded or destroyed, their tangible or intangible functions are lost. Introduced species of plants and animals alter the tanks. For example the tunneling activity of lotus tubers plays some role in the the interaction between the tank surface and water that comes into contact with it. As lotuses are out-competed by invasive plants this role is lost.  Tank morphology changes as well, perhaps imperceptibly when the tanks are full and lush with wildlife, so that the functions of filtering, for example alkaline solutions, are altered. The silt may sequester certain elements like phosphorous and nitrogen, slowing the eutrophication process. But to what extent and how effectively still needs to be seen. My colleague Nimal Abeysingha and I, accompanied by students from Rajarata University collected over 50 soil samples from a dry tank bed a couple of weeks ago, just before the rains. As these samples are analyzed we will come to better understand the role of silt in tanks. But we need to collect more. And we need to assay them for heavy metals such as cadmium and arsenic that directly impact human health in Dry Zine Sri Lanka. 

Now that we understand to a great extent the morphology of the tank cascade system I would propose that we shift our energy slightly, to pay greater attention to tank morphology, anatomy, and function. I'm not the first person to propose this. It's been part of the work of Madduma Bandara and especially MUA Tennakoon as well, in addition to other voices in the IWMI (International Water Management Institute). But while the elucidation of the cascade system was arguably a post-colonial response to an otherwise imposed geography, it is tank function at the village level that reflects the performance, agricultural, social, and societal, of the Dry Zone countryside. Without functional tanks, agriculture, already on the wane in the countryside, will wither. No matter how well we understand the cascade system, and we should continue to study that as well, the individual tank is the heart of agricultural function in this country. We should move our efforts to understand it better.

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