Wireless sensor networks (WSNs) are widely used in many different number of applications, like border surveillance, under water sensor networks etc. In a large WSN, there is significant reduction in the amount of communication overhead and energy consumption when in network data aggregation is performed. Various methods available for data aggregation are: hierarchy aggregation, averaging. Different algorithms which performs secured data aggregation considered are ESPDA (Energy efficient and secure pattern based data aggregation), SRDA (Secure reference based data aggregation). However in all these approaches the algorithms do not allow intermediate nodes to perform data aggregation thus limits the benefit of data aggregation. In this paper the new approach i.e. built in self test (BIST) is considered which will perform secured data aggregation.

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Identification of groundwater recharge zone is an important factor for water resource management in any area. The present study investigates the potential water recharge zones in the Sikkim state, a mountain region of the Eastern Himalayas. To identify potential watershed recharge zone in the region, a combination of geographic information system (GIS)-based weighted overlay index (WOI) tools and analytic hierarchy process (AHP) pairwise matrix techniques was applied. The delineated watershed recharge sites were classified into five different potential zones. The results show that the majority of the study area (54.22%) was under moderate recharge potential zone. Some of the suitable recharge potential sites are forest-covered regions; therefore, the construction of surface check dams could be a suitable recharge method; it will escalate the discharge in springs and also help to make them perineal. This study provides first-hand information on the groundwater recharge potential of East Sikkim, where the populace depends largely on spring water discharge. Also, it is useful in selecting areas for digging staggered contour trenches, pits, and other structures to recharge the spring water and improve the watershed management system.