The Influence of El Niño on Settlement Patterns in Lomas de Lachay, Central Coast, Peru

The Lomas de Lachay region is located about 100 kilometres north of Lima, between Río Chancay and Río Huaura valleys. It is situated approximately 10 km from the coastline, where advection fogs meet the first ridges of the Andes allowing for the development of a peculiar ecosystem of fog oases known as lomas. Three distinct geosystems have been distinguished there: coastal desert, lomas and mountain desert. While during El Niño with episodes of ENSO the mountain desert and valleys of perennial rivers are devastated by catastrophic floods caused by torrential rains, in lomas El Niño less abundant precipitation comes about which permits the development of vegetation and also the presence of active springs during the dry season. Due to the increased availability of water in periods of frequent El Niño episodes human groups in the past were able to establish permanent settlements in the Lomas de Lachay area. When El Niño events became rare, however, only seasonal exploitation of lomas w...