Will Restoration of Ecological Functions of Tank Cascade System Contribute to Reduce CKDu in Sri Lanka? A review

Abstract

People in the dry zone of Sri Lanka where hydraulic civilization once thrived, suffer from occurrence of a chronic kidney disease of unknown etiology (CKDu). The etiology for CKDu is now shown to be multi factorials and but related to water. Ancient people in the dry zone used surface water of tank cascades system and this system was interlinked with the ecosystem and social system of the area. It is hypothesized that the adverse changes that took place to the ecosystem of the tank cascade system and new commercial practices of agriculture in the CKDu prevalent area have also become reasons for the spreading of CKDu. This review assesses the effect of different components of the tank cascade systems in improving the water quality. A number of studies have reported positive effects of improving the surface water quality of the tank by the Wew Ismaththa (closer catchment), Thaulla (upper peripheral gentle sloping land), Kattakaduwa (Interceptor) Iswetiya or Potawetiya (upstream soil ridges), Godawala (small silt trapping pond). The review also identified functions of Thaulla area approximately similar to a constructed wetland. This review highlights the issues and gaps in our understanding the ecological functioning of Globally Important Agricultural Heritage System. It is suggested that reconstruction of ecofriendly structural components of tanks and reestablishment of tank cascade system in the area would help to combat the spreading of CKDu in dry and intermediate zone of the country.

Phytoextraction of Nutrients and Heavy Metals by two Monocot Plants in Thaulla Area of Small Reservoir in Anuradhapura, Sri Lanka

“…Wetland plants have special physiological processes such as cluster roots to accumulate essential nutrients such as N and P (Zedler, 2010). Thaulla in small tanks can be considered approximately as a wetland (Abeysingha et al, 2018). Lower concentration of N reported in the present study also supports the hypothesis that the Thaulla can act partially as a wetland.…”

“…As this system is adapted agricultural system managed with time tested indigenous techniques, FAO (2018) recognized this system as a Globally Important Agricultural Heritage System. In this system, water discharged from the upper tank to the command area, flood water of the upper tank and water draining from the paddy fields in the upstream command area are captured by the tank at downstream which flow through thaulla area (Abeysingha et al, 2018). This micro-land region of the tank is partially covered with water but only completely flooded mostly during the rainy season particularly, during the North East monsoon season.…”

Glyphosate’s Synergistic Toxicity in Combination with Other Factors as a Cause of Chronic Kidney Disease of Unknown Origin

“…Most paddy lands in the CKDu-affected area are irrigated by an ancient cascade system of tanks. Abeysingha and colleagues provide a detailed account of how the design of the cascade irrigation system and the adverse changes that took place to the ecosystem with the introduction of new commercial practices of agriculture (mostly the use of agrochemicals) in the CKDu endemic area have contributed to its rapid spread [34].…”

Variation of Water Quality of Four Micro Watersheds Outlets in Upstream of Mahaweli River during Maha Cropping Season

“…The incidence of cognitive impairments, especially in children, and cancers of all sorts are links to toxicants such as Hg, Pb, As, and Cd (Obiri et al, 2010). In addition, various studies shows that As, Cd are causes for the chronic kidney disease of unknown etiology that prevailed mainly in dry zone area of Sri Lanka (Abeysingha et al, 2018a). However, tested mean concentration of As, Cd and Pb were within the permissible levels of all four micro watersheds waters during Maha cropping season 2018/19.…”