Insights into catchment behaviour for water harvesting assessment in the East India Plateau

As part of an Australian Centre for International Agricultural Research (ACIAR) funded project investigating water harvesting techniques in tribal villages in West Bengal, India, a network of monitoring sites has been set up in the ~2 km2 Headwater subcatchment of the Chapai Nula (referred to as the Pogro sub-catchment after one of the villages located in the sub-catchment), with a smaller 0.5 km2 sub-catchment operating as a control. During the wet season, there is a significant excess of rainfall (~300 mm in 2006), a significant fraction of which remains in the catchment. Consequently, there is potential for planting of dry season crops in low-land parts of the catchment. Due to the high rainfall intensity (up to 240 mm/hr), low infiltration rates (andlt;40 mm/hr) and low vegetation density in the upland areas, a significant fraction of the rainfall runs off to the lower areas of the catchment. The monitoring has also shown that the ponds in the Pogro study site are porous, and act as a source of recharge the groundwater system (typically 5-10 mm/day) as well as being a surface storage.