Landscape Analysis Over 30 Years to Assess the Impact of River Damming On Natural Ecosystem

Abstract

Although there are considerable profits in dam projects, they contribute to significant environmental changes. Landscape patterns are influenced by human pressure and are altered continuously. This study investigated the changes in the landscape pattern of Jask’s coastal area in Iran due to the Jagin River dam’s construction. A proposed methodology employed satellite images from 1987 to 2018 and classified them by multiple approaches to make LULC maps. Eight information categories were evaluated after classification. The accuracy of the classification was determined using the error matrix and kappa index. FRAGSTATS software was applied to calculate several landscape metrics such as edge density (ED), largest patch index (LPI) and Shannon’s diversity index (SHDI). The study reported that water right especially in the recent years, because of excessive use of reserve water, decreased and downstream of Jagin River was dried. The landscapes were continuously characterized by anthropogenic pattern features (agriculture land, aquaculture land, built-up land and residential land) after the dam’s construction. Rangeland cover and riparian vegetation decreased, and agriculture land increased with in filling pattern. The sand dune area has been spread to the residential area and roots of mangrove forests, because of this reason some parts of mangrove forest dried and roads are covered by sand dune. Their temporal comparison allowed us to localize the change in landscape patterns under the study time. The results can help decision-makers to evaluate the net benefits acquired as a result of the dam projects.