The Intersection of Legacy Agriculture and Urbanization on Soil and Water Quality in Arequipa, Peru

Abstract:

Arequipa, Peru has a long history of intensive agriculture dating back thousands of years. Dramatic urbanization is causing shifts in land use and putting pressure on this already water-stressed city. The Chili River runs through the middle of Arequipa and is the main water source for many competing stakeholders, including hydroelectric operations, farmers, residents, and one of the largest copper mines in the world. Agriculture in the city is irrigated by Chili River water through a complex system of canals that has gradually expanded with the increased urbanization. Population growth has also led to the formation of informal migrant communities on the outskirts of town, agricultural expansion into previously uninhabited, arid portions of the city, and the city center expanding into traditional farming areas. Our study investigates the legacy effects of agriculture, mining, and urbanization on the city’s soil and water quality. We are studying the resilience of the traditional irrigation system in light of decreasing water availability due to growing demand, salinization of agricultural fields, and potential accumulation of heavy metals in soil and water from mining. Soil samples from selected agricultural fields covering the range of agricultural production ages in the city, as well as the corresponding irrigation water, were collected and analyzed for nutrients and heavy metals. Water samples were also collected along the length of the Chili River to determine the potential urban influence on water quality. A network model of the canal system was also created to determine water allocation under different scenarios including increased water deliverance to expanding urbanized areas, upstream withdrawals, and changing irrigation practices. Results from this research will support development of management strategies for the conservation and maintained productivity of agricultural lands in Arequipa.