Concentration of time (Tc) is a frequently used parameter in the evaluation of the hydrological response of different sizes hydrographic basin in case of rainfall events. The present study is innovative, because it has created an index that identifies the small-sized hydrographic basins that are exposed to the risk of flooding. The Moldavian Plain is an area located in the northeast of Romania where the local population is frequently affected by floods and flash floods caused by heavy rainfall events. The main purpose of the current study is to identify the settlements located in the small-sized hydrographic basins, which are associated with low concentration times and powerful surface runoff. The empirical method was applied in order to calculate the Tc for rainfall water, for each drainage basin, for a time class less than 6 hr. Calculations of the runoff water were also done for a theoretical extreme precipitation event, corresponding to the 1% occurrence probability. A total number of 312 basins were identified that are smaller than 30 km 2 , out of which 112 have Tc of less than 6 hr. These basins, in particular, pose flood risk for 12.4% of the villages and towns in the study area.

The evolution of groundwater levels is difficult to predict over medium and long term in the context of global climate change. Innovative trend analysis method (ITA) was used to identify these trends, and ITA index was calculated to measure their magnitude. The data used are sourced from 71 hydrogeological wells that were dug between 1983 and 2018 and cover an area of over 8000 km2 developed in the temperate continental climate in the north-eastern part of Romania. The results obtained by applying the ITA show a general positive trend for groundwater level over 50% of wells for winter and spring seasons and annual values. The negative trends were observed for more than 43% of wells for the autumn season followed by the summer season (less than 40%). The magnitude of trends across the region shows a significant increase for spring season (0.742) followed by winter season (0.353). Important changes in the trends slopes and magnitudes have been identified for groundwater level depth between 0 and 4 m (for winter and spring seasons) and between 4 and 6 m (for summer and autumn seasons). The results can be implemented in groundwater resources management projects at local and regional level.

Regional water resource management plans include various scenarios related to the anomalies and trends of hydro-climatic parameters. Two methods are used for the identification of the anomalies and trends associated with high flow (annual and seasonal) of the rivers in Eastern Romania, namely the quantile perturbation method (QPM) and the partial trend method (PMT). These methods were selected due to the fact that they are suitable for data sets which do not rely on restrictive statistical assumption as common parametric and nonparametric trend tests do. For six of the nine stations analyzed, the decreasing trend in high extremes for annual high flow based on the PTM is the same as the annual trend obtained with the QPM. Using the PI index (associated with PTM) for the estimation of trend intensity, values between −2.280 and −9.015 m3/s were calculated for the decreasing trend of the annual high flow and between +1,633 m3/s (in autumn) and −9.940 m3/s (in summer) for the seasonal high flow. The results obtained on the anomalies and trends of high river flow may represent a starting point in the analysis of the evolution of water resources and their effective management.

Shelter and evacuation-route planning represents the core of safe and efficient flood management. The methodology detailed in the present study includes an analysis of the suitability of areas for evacuation points, as well as an assessment of the degree of accessibility of those points during evacuation scenarios in small mountainous drainage basins. The analysis is based on water distribution and water-flow increase during the historic 2010 flooding of the Sucevița basin, when the discharge increased in merely 40 min. The proposed model considers the viability of pedestrian evacuation of the local population, as well as the degree of accessibility of nearby evacuation points. Thus, according to the results obtained for the mountain-based locality, 91.68% of the vulnerable population can be evacuated in 30 min, while 8.32% of the inhabitants require up to 54 min to reach an evacuation point. In the case of Marginea, located in a plateau area, the population under analysis can reach one of the evacuation points in approximately 36 min. The present study can support the implementation of non-structural flood management measures and decrease casualties through evacuation optimization.

In the context in which the distribution of the phreatic level represents one of the main components regarding the water supply of the population, it was necessary to approach a method aimed at highlighting the areas where the underground recharging capacity is favorable or unfavorable. In the present study, this technique called AHP (Analytical Hierarchy Process) was used to highlight the distribution of groundwater recharge areas in the Moldavian Plain area by assigning weight factors to each thematic layer. In the realization of the study were used thematic layers such as drainage density, slope, land use, precipitation distribution, groundwater level, soils, lithology. For the final map, we used the weighted overlay toolbox from the ArcGis software, giving the weight factor for each thematic layer. The new thematic layer was divided into 5 classes to highlight their distribution within the study area.