Small reservoirs for a sustainable water resources management

Abstract

Small reservoirs are widely used for storing water, especially for irrigation purposes. During the last decades, in Italy many of these reservoirs have been dismissed, becoming an untapped resource. As a matter of fact, maintenance problems connected to these structures together with their natural tendency to silt have favored the use of other water supply resources such as withdrawal from wells. The increase of drought periods and the high water volume demand for agricultural purposes suggest to evaluate a full and rational use of all water resources, leading to a rediscovery and enhancement of untapped resources. Specifically, this research focuses on small reservoirs and on their potential contribution to a sustainable water management in agriculture. Unfortunately, there are no reliable data on their number, spatial distribution and potential storage volume. The aim of this work is to define reservoir spatial distribution and evaluate potential available water volumes. The upper Tiber river basin has been selected as a case study for the methodology proposed. The work starts from the acquisition and re-elaboration of the old census of small reservoirs, evaluating, through GIS and regression techniques, the distribution over the territory and the available volumes. Then the reservoir census and the derived database were updated for the period from 2015 up to 2019 introducing combined computational procedures of remote sensing techniques and GIS, based on satellite images and water index calculation. The results of the semi automatic procedure used show good performance in lake identification, making it a promising tool for a fast and reliable water body identification and evaluation in wide areas.