A multi‐century meteo‐hydrological analysis for the Adda river basin (Central Alps). Part I: Gridded monthly precipitation (1800–2016) records

Abstract

The 1800-2016 monthly precipitation record for the upper Adda river basin is presented. It is computed by applying the anomaly method to a qualitychecked and homogenized observation database. The reconstruction accuracy and its evolution over the study period is evaluated at both station and grid-cell levels. The anomaly-based interpolation provides rather robust estimates even for the early years of sparse station coverage with basin precipitation reconstruction errors around 10%. The Theil-Sen trend analysis on the basin precipitation series shows significant (Mann-Kendall p value <.05) long-term

A multi‐century meteo‐hydrological analysis for the Adda river basin (Central Alps). Part II: Daily runoff (1845–2016) at different scales

“…Its Theil-Sen slope turns out to be −136 mmÁcentury −1 , corresponding to a reduction of 11.8 ± 3.2% century −1 , which causes a runoff decrease of 233 ± 63 mm over the entire investigated period considering standard error estimates. As discussed more in detail by Crespi et al (2020), also the yearly record of average catchment precipitation has negative slope. The catchment precipitation decrease is however much lower (see Figure 6), and it is not statistically significant.…”

“…It can be compared with annual water losses estimated as the difference of corrected precipitation and runoff, thus neglecting the effect of water storage in artificial reservoirs, lakes, groundwater, snow and glaciers. The corrected precipitation record we use here (see Crespi et al, 2020) takes into account the underestimation of solid precipitation which is known to be relevant in mountain areas (Sevruk et al, 2009) and specifically in the investigated area (Eccel et al, 2012;Grossi et al, 2017). The assumption that water storage is not relevant for this estimation is reasonable as the change of these storage volumes at annual scale can be neglected with the exception of glaciers which experienced a significant retreat that in the last three decades accelerated with a volume loss of 12 mmÁyear −1 , as already discussed in Crespi et al (2020), providing an additional contribution to runoff.…”

“…The catchment precipitation time series was reconstructed at monthly resolution as described by Crespi et al . (2020) for the period 1845–2016. That paper presents also an annual catchment precipitation time series, corrected in order to take into account the systematic underestimation of solid precipitation of rain gauges.…”

“…Studies dating back to the mid‐nineteenth century are however rare and, therefore, a contribution on a new high‐quality 172‐year‐long daily runoff series, objective of the present work, is of important scientific value, especially because the analyses are run in parallel with those on the monthly catchment precipitation record, presented in the companion paper by Crespi et al . (2020).…”

“…This is the longest time series of daily runoff for Italian Alps. In addition, this series has been compared with monthly precipitation averaged at the catchment scale (Crespi et al ., 2020).…”