In the post-flood scenario, floodplains and riverbanks should ideally be earmarked for agriculture rather than housing, the State Soil Survey and Soil Conservation Department has recommended. The department has also called for a ban on cultivation on very steep slopes in landslide-prone regions.
The recommendations are part of a 313-page report, Soil Health Status of Kerala in the Post-Flood Scenario, prepared by the department after a detailed study in 13 districts (except Kasaragod) affected by the devastating 2018 flood.
The report was released at the recent VAIGA expo organised by the Agriculture Department in Thrissur. The flood had affected the physical and chemical properties of the soil, the report said. Topsoil erosion and sediment deposits have changed soil characteristics in both upland and lowland regions.
In fact, the flood washed away a significant volume of nutrient-rich topsoil through sheet erosion. “With the changing climate and changing patterns of rainfall, the behaviour of rivers also changes and they may deviate from the normal watercourse and flow through inhabited areas as it happened during the recent flood. Our land-use policy has to be reformed in such a way to accommodate these changes,” the report warned.
“Floodplains and riverbanks should be exclusively demarcated for agricultural crops rather than housing. The very steep slopes of environmentally fragile areas have to be kept under thick vegetation and cultivation in these areas — which provoke phenomena like a landslide, landslip, land subsidence and so on — has to be strictly prohibited.”
In Idukki, cultivation should be avoided in areas with a slope of more than 33%, the department said. “If cultivation in such areas is unavoidable, proper soil conservation measures with provision to drain excess water have to be adopted,” it said.
In Wayanad, unscientific land excavations in areas with more than 25% slope should be avoided at all costs, the report said. Construction activities in the district should also avoid fragile zones. Heavy metal studies in Thrissur and Ernakulam districts revealed the occurrence of cadmium above permissible limits in some locations.
Soil acidity was a major problem in the post-flood scenario, the report said. Widespread deficiency of nitrogen, potassium, calcium, magnesium and boron also was noticed.