Evaluation of the impact of urban expansion and hyperconcentrated flow generation in a dry creek (#1880)

Authors

Escobar Alama, Angel Gabriel

Castro Camacho, Nicolas Josias

Rau Lavado, Pedro Christopher

Abstract

Hyperconcentrated flows are complex phenomena frequently linked to disasters in urban settlements. To comprehend the entirety of disaster hazards, it is crucial to adopt a broad perspective that encompasses environmental variables delineating the impact of imperviousness in stream areas, a common occurrence in urban expansion. The study was carried out in the 8.4 km2 California dry creek in Chosica, Lima, Peru, and had the following objectives: 1) identify the most appropriate remote sensing products for mapping urban sprawl and imperviousness and their relationship to watershed hydrologic properties; 2) analyze hyperconcentrated storm flow hydrographs and their direction over the California watershed with a meteorological approach for the theoretical, 2013 and 2022 scenarios; and 3) estimate the rate of sediment generation in the watershed through the MUSLE method for the theoretical, 2013 and 2022 scenarios. The Normalized Difference Building Index (NDBI) was used to detect built-up areas between 2013 and 2022; and the Normalized Difference Vegetation Index (NDVI) and the Bare Soil Index (BSI) were proposed for a more accurate representation of area conditions. Peak flows were also evaluated using variations of the rational method, adapted to the study area. Soils were characterized, and critical erosion zones were identified using the MUSLE method and based on field reconnaissance. The results revealed the relative impact of imperviousness on the increase of hyperconcentrated flow peaks, both in magnitude and time of occurrence. It is highlighted that the widely used Normalized Difference Building Index (NDBI) does not adequately represent urban growth, confirming its limitations for desertic areas. These findings emphasize the importance of addressing imperviousness as a component of urban development, its negative effects on land-use planning, and the opportunity to adopt complementary nature-based solutions.