Estimation of Annual Maximum and Minimum Flow Trends in a Data-Scarce Basin. Case Study of the Allipén River Watershed, Chile

Abstract

Data on historical extreme events provides information not only for water resources planning and management but also for the design of disaster-prevention measures. However, most basins around the globe lack long-term hydro-meteorological information to derive the trend of hydrological extremes. This study aims to investigate a method to estimate maximum and minimum flow trends in basins with limited streamflow records. To carry out this study, data from the Allipén River watershed (Chile), the Hydrologiska Byråns Vattenbalansavdelning (HBV) hydrological model at a daily time step, and an uncertainty analysis were used. Through a calibration using only five years of records, 21-year mean daily flow series were generated and the extreme values derived. To analyze the effect of the length of data availability, 2, 5, and 10 years of flows were eliminated from the analyses. The results show that in the case of 11 years of simulated flows, the annual maximum and minimum flow trends present greater uncertainty than in the cases of 16 and 19 years of simulated flows. Simulating 16 years, however, proved to properly simulate the observed long-term trends. Therefore, in data-scarce areas, the use of a hydrological model to simulate extreme mean daily flows and estimate long-term trends with at least 16 years of meteorological data could be a valid option.

Community structure of benthic invertebrates in the Allipén River basin, North Patagonia, Araucania region (38º S, Chile)

“…The Allipén River rises in the Andes Mountains, in the southern part of Chile, specifically in the La Araucanía region (Medina and Muñoz, 2020;Vargas et al, 2010), afterwards receives the waters of Trufultruful River and Zahuelhue River, it has a 108 km length and a 2,325 km 2 basin area (Figure 1). The river drains to the northern part of the Toltén basin and ends its route 15 km east of Pitrufquén, leading to the Toltén river (38º51'S and 71º45'W) (DGA, 2004).…”

Hydroclimatic Variability in the Bilate Watershed, Ethiopia

“…This insignificant trend in most seasons before and after the changing point indicates a decrease in the statistical significance of hydroclimatic variable trends as the data years are limited or below ten years, which the World Meteorological Organization (WMO) recommends for data-scarce regions [95]. Correspondingly, a study in Chile estimating annual maximum and minimum flow trends [96] revealed higher uncertainty and less significance of trend results for the limited data length than longer years.…”