Thursday, October 1, 2015

Sunk in silt or: Some say seep, others say tsunami

It has rained for a couple of days now-perfect timing because we wanted to get to Rajarata at the end of the dry. Insects are suddenly rife and more important, you being to see rivulets and puddles of water as well as river heights rising dramatically. 

A look at every body of standing water shows you that the water is deeply colored with silt. Red puddles, brown puddles, grey puddles dot the countryside. But there is no clear water to be seen. Silt is a fact of nature that the ancient Sri Lankans coped with. 

Through neglect brought largely by centralized government control, cultivators in contemporary Sri Lanka are faced with diminishing water capacity and farming capabilities because of silt build-up. Silt covers the catchments, the forests, and the grasslands that lead to and during the wet season, become part of the tank. If the tank were a human body, neglected by lack of exercise we could picture it as hidden under slabs of fatty tissue. 

Two modes of action may help us deal with the silt. The first and most obvious is removal. But removing the silt must be seen as more than an odious chore. Rather, silt removal may be an opportunity to rebuild the tanks, redefining the contours that made the tanks self-sustaining valves that filtered and distributed water differentially. We may also seek commercial uses for the silt. High quality ceramic matrix? The next rage in skin care? The second mode of action is preventive. In Alisthana village near Thirappane they have replanted the tall reed beds that filter the water, as well as planting 8000 saplings to protect the water. These plantings come close to replicating ancient landscape patterns. They are so much more than "prettying up" the tanks. They are part and parcel of tank function. 

It may be semantics but there seems to be a difference of opinion among observers about how water flows into tanks. And this affects opinions on how to ameliorate that flow. Some posit that water seeps into the tanks. If it's a question of seepage alone then the short C-4 grasses we observed may suffice in holding onto some of that silt. Why then do the farmers complain about shrinking tanks? The other view, which was voiced by my guesthouse hosts in Anuradhapura, is that water may enter the tanks "like a tsunami," at least during periods of sustained heavy rainfall in December. If that is the case, then we need all the help from vegetation (the perehana and gasgommana) we can get. 

Height of flood in Anuradhapura, 2013

Either way, tank silt is an issue that we need to study more. During my day in the field with colleague Nimal Abeysingha and students from Rajarata University we began that quest.  

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