Rainfall-runoff modelling approaches for investigating the role of human factors in influencing hydrological drought

One of the main driving forces - human factors - directly affects runoff processes by influencing the amount of water available and the development of hydrological droughts.The study investigated the role of human factors in the development of hydrological droughts in the Kamienna catchment and attempts to identify the main human factors that caused these changes through the analysis of remote sensing data. The hydro-climatic variables are divided into a baseline period and a disturbed period, using the method to detect changes in the runoff processes. We applied the rainfall-runoff model - SWAT - calibrated during the baseline period and used it to reconstruct the naturalized runoff during the disturbed period. The baseflow filtering algorithm was applied to separate baseflow from direct runoff. Drought indices: Streamflow Drought Index (SDI) and the Standardized Baseflow Index (SBFI) were used as indicators for hydrological drought analysis using observed and naturalized hydrological variables. The observation-based runoff indicators showed more successive hydrological droughts of longer duration and intensity in the catchment than the naturalization-based runoff indicators, especially in the 1980s, 1990s and 2000s. From 2010, shortly after the Wiory reservoir became operational, naturalized runoff matched observed runoff, indicating increased groundwater recharge and baseflow and⁄or systematic release of excess water from the reservoir during the dry season. This indicates the positive role of reservoirs on downstream runoff by mitigating hydrological drought events. Analyses of changes in land cover dynamics supported these changes caused by human factors in the watershed. This study contributes to our understanding of how human factors influence hydrological drought in the catchment, which is important for drought adaptation. 

Keywords: Rain-runoff model, hydrological drought, drought indices, land cover dynamics, human factors.