Understanding changes and trends in projected hydroclimatic indices in selected Norwegian and Polish catchments

Abstract

The aim of the study is to investigate trends in selected hydroclimatic indices using novel and conventional tools, for future climate projections in the twentyfirst century. Selected quasi-natural Norwegian and Polish catchments are used as a case study. The projected flows are provided by GR4J rainfall-runoff conceptual model, coupled with an ensemble of climate model projections from EURO-CORDEX initiative. The trends are analysed using conventional Mann-Kendall and modified MannKendall statistical approaches, a time-frequency approach based on discrete wavelet transform (DWT) and the dynamic harmonic regression (DHR) method. Of all methods applied the DHR gives the most conservative trend estimates. Trends depend on the specific hydroclimatic character and flow regime of the catchment. The results confirmed that in catchments with a rainfall-driven flood regime, an increase in the amount of precipitation is followed by increased flows, with strong seasonal changes, whereas, in catchments with a snow-driven flood regime, despite an increase of mean annual flow, decrease in annual maximum flow is observed. Generally, positive trend is the most dominant in all catchments studied and the methods were consistent in detection of trend except in seasonal trend test.

Seasons' Shifts in Some Depressions of the Eastern Carpathians, Based on Daily Temperature Analysis

“…These changes are present worldwide (Meresa et. Al, 2017) also in Carpathians (Melo et al, 2013) and in Romania (Micu et al, 2014;Croitoru and Piticar, 2013).…”

River flow characteristics and changes under the influence of varying climate conditions

“…Climate change and variability have contributed to water resource problems, such as flooding, drought, water shortage, excess water, water quality, and waterlogging to different extent (Meresa & Gatachew, ; Meresa, Osuch, & Romanowicz, ; Middleton & Souter, ; Osuch, Lawrence, Meresa, Napiorkowski, & Romanowicz, ; Romanowicz et al, ). Based on the recent research efforts on climate change, Poland will be one of the countries exposed to the risk of extreme natural disasters due to climate change, such as heavy precipitation, drought, and flood (Meresa et al, ; Meresa, Romanowicz, & Napiorkowski, ; Middleton & Souter, ; Osuch et al, ; Piniewski et al, ; Romanowicz et al, ). However, the effects of hydrological extremes due to varying climate conditions are not fully addressed to understand and represent the existing extreme water‐related problems.…”

“…The projections of future hydrological drought and floods characteristics in Europe under a +2°C global warming concept was reported by Roudier et al (), the result shows there will be a prolonged drought due to high evapotransparation in most part of Europe. Similarly, the issues of uncertainty in hydrological modeling and hydrological projections in the near and far future due to climate change are not new; there is a plethora of research work published on this subject in local and regional scale (Addor et al, ; Meresa et al, ). Particularly, Meresa and Romanowicz () assessed the critical role of uncertainty that is comes from climate change, hydrological parameters and flood frequencies (the error in fitting distribution models for annual extreme flow series) in the BialaTarnowska mountainous catchment in Poland.…”

“…In most studies, characteristics of floods, annual maximum flow, mean maximum flow, and univariate flow quantile indices (Meresa et al, ; Meresa Hadush, ; Osuch et al, ) are frequently used because of there are very direct and simple to understand. The evaluation and projection using such indices have been actively conducted in Poland (Meresa & Gatachew, ; Meresa et al, ; Middleton & Souter, ; Osuch et al, ; Piniewski et al, ; Romanowicz et al, ); and this information has not always been sufficient to fully describe the flood dynamics of a given river. Therefore, analysing flood characteristics that are corresponding to various durations (D), flood intensity (I), flood magnitude (M), flood volume (V), and a number of events (NF) and their change in the future atmospheric dynamics change also very important.…”

The impacts of changes in climate and land use on hydrological processes

“…That problem is discussed in more detail by Meresa et al (2017) who present a comparison of projections of high flow trends based on varying time horizon. The GR4J conceptual, lumped precipitation-flow model (Perrin et al 2003) was used to derive flood estimates for ten Polish and eight Norwegian catchments in the 21st century.…”