Volume XVII |

Playing with water – An introduction to experimental hydrology

Abstract: Water is the most important resource for the humankind, thus understanding hydrological processes could be con-sidered a vital task. Therefore, the main aims of this papers are to assess: (i) the current status of hydrologic field ex-periments; (ii) the techniques and the stages of the field hydrologic experiments at the microscale/plot-scale. Microscale hydrological studies are important both socially and economically as they emphasize the role of key factors (e.g. slope) in the utilization of water resources, the identification of critical hydrological thresholds for mobilizing, the propagation of soil particles in water flows and also the time it takes for pesticides, nutrients, and heavy metals to be mobilized. The key to conducting a successful hydrological microscale experiment lies in performing repeated attempts in the field. From an economic point of view, expedition (temporary) hydrologic field experiments are beneficial, as they shorten the working period and reduce the financial costs of the data acquisition process. One of the challenges of experimental hydrology is the manipulation of “upscaling” or the statistical approach taken towards gathering and processing data.

Volume XV |

A Special Issue: Hydrological Behaviour in Small Basins Under Changing Conditions

Abstract: The present paper aim to overview on the Euromediterranean Network of Experimental and Representative Basins conference – ERB 2016. The 16th Biennial Conference ERB was held 5–8 September 2016 in Bucharest, Romania, and was hosted by National Institute of Hydrology and Water Management. The conference program focused on the theme “Hydrological behaviour in small basins under changing conditions”. The conference was followed by a field work on microscale hydrologic monitoring of water balance elements in Voinești Experimental Basin.This special issues of Forum geografic/Geographical Phorum – Geographical studies and environment protection research (indexing in international databases) includes selected works – contained a variety of hydrology subjects – presented at the Euromediterranean Network of Experimental and Representative Basins conference. All published papers are assigned to Digital Object Identifier (DOI).

Volume XV |

Temporal rainfall properties at events scale in the Curvature Subcarpathians (Romania)

Abstract: Characteristics of rainfall events (RE) play a determinant role in the hydrologic process in a small catchment (e.g., runoff formation, flood elements), water balance and water resource management. The goal was to investigate temporal rainfall properties at events scale. The study was based on long-term properties of rainfall events (e.g., depths, intensities), recorded in the warm semester (the period between 1 April and 30 September; 1980-2010) at Voinești Experimental Basin (VEB), Romania. Rainfall events values were recorded by a pluviograph, production of the former USSR. The rain gauge is situated at the central place of the VEB (altitude 500 m a.s.l.), in Curvature Subcarpathians. A valuable database with 1852 rainfall events characteristics was created. The depths (mm) and durations (min) of each RE were recorded and rainfall maximum and average intensities (mm/min) were calculated. Rainfall events were characterized by small depth (up to 15.7 mm; up to 90th percentile) ~ 93% and they were concentrated (34.4%) in May. Almost half of RE (48.2%), had short duration (up to one hour) and the smallest depth (95% confidence interval, 3.85–4.56 mm), while those with durations longer than 5 hours (10.5%) were specific the September (22.5%). Regarding maximum intensities of rainfall events, just 16 events exceeding 1 mm/min (0.86%), which denote insignificant occurrence – encountered phenomenon in all months, especially in August – and mild torrential character. Insignificant rainfall events correlations between rainfall parameters were observed. Just “time – depth” correlation has been notable (Pearson’s r: 0.631). Absolute frequency of rainfall events parameters in most cases shows a strong density of smallest interval. These results may have important implications for next runoff plot study.

Volume XIII |

Research of water balance at hydrological micro-scale in the Aldeni experimental basin (Romania)

Abstract: The paper presents a number of aspects regarding the Aldeni Experimental Basin (Romania). In order to experimentally investigate micro-scale (plot scale) hydrological impact of soil erosion, the National Institute of Hydrology and Water Management founded, in 1984, the Aldeni Experimental Basin (AEB). AEB is located in the Curvature Subcarpathians, a region characterized by a sharp erosion of soil. Experimental investigations at a micro-scale are aimed towards: determining the parameters of the water balance equation, during natural and simulated rainfall; researching of runoff genetic and soil erosion processes on runoff plots; extrapolating relations involving runoff coefficients from a micro-scale to meso-scale. Runoff plots have A = 80 sq m (20 x 4m), WNV-ESE aspect and an average slope of 5.6%; one runoff plot is maintained with grass, and the other is devoid of grass by digging (processing) and the structure of the first horizon with a depth of 20 cm has been changed, which resulted in a greater development of infiltration than in the first runoff plot. Complex measurements and sampling observations of the necessary elements for the quantitative estimation of the water balance equation are achieved with the help of specific equipment on standard climatologic and hydrological time (hourly and pentads) at hydrometric stations and meteorological platform, while at runoff plots scale per rainfall event. Nowadays, the latest evolutions in data acquisition and transmission equipment are represented by sensors (such as sensors to measure the soil moisture). Exploitation and dissemination of hydrologic data is accomplished by: research themes/projects, yearbooks of basic data (Experimental Basins Yearbook) and scientific papers.

Volume XIII |

Statistical assessing of hydrological alteration of Buzău River induced by Siriu Dam (Romania)

Abstract: In this paper we evaluate the hydrological impact produced on the river mean daily discharge (water) of Buzău River by Siriu Dam. The study data was the daily mean discharge registered from the 1st of January 1955 to the 31st of December 2010, at the Nehoiu hydrometric station on the Buzău River. The flow of this river is controlled in its upper reach by Siriu Dam, from 1984. The main method used for the evaluation of the hydrologic alteration at temporal scale was based on the tests provided by the Indicators of Hydrologic Alteration (IHA) software. The statistical analysis proved that the built of Siriu Dam had a moderate influence on the mean daily discharge regime of Buzău River at large time intervals, significant changes appearing at small time scales.