Volume XXI |

Morphometry and Topographic Wetness Index Analysis for flood inundation mapping in Mata Allo watershed (South Sulawesi, Indonesia)

Abstract: Along with climate change, natural disasters will occur more frequently such as floods. Floods that occur in watersheds which include various human activities, such as Mata Allo (Indonesia) will especially cause a large enough impact. The elongated shape of the watershed has a slow response to peak discharge and time lag. The Mata Allo watershed is dominated by slopes above 25%→45% (65%) and agricultural land use which accounts for 53% of the area, which has an obvious impact on the amount of runoff and erosion that occurs. The eroded soil will be carried away by surface runoff and deposited in the plains between mountains and river floodplains. Based on the results of the study, the Topographic Wetness Index (TWI) map indicates that the part between the mountains and the floodplain around the Mata Allo river had a high TWI value. A high TWI value indicates a high vulnerability to anticipate flooding in the event of overflowing from the Mata Allo River. River morphometry, land use, and hydrological behavior in a watershed are closely related to the TWI value in the Mata Allo watershed.

Volume XXI |

Correlation between precipitation and orography – key element of the Spatial Decision Support System for Prevention and Management of Floods in the Firiza Basin (Northwest Romanian Carpathians)

Abstract: Research on the influence of relief on precipitation has been identified in many studies conducted locally, regionally or globally. However, the research on the area analyzed in the present paper is comparatively lacking. The surrounding mountain area we refer to is represented by the Someș and the Tisa watersheds. The present study focuses on analyzing the influence of the relief, i.e. of the altitude, slope orientation relative to the position of the Sun and the movement of air mass as a factor on precipitation and rainfall gradient. For that, datasets of daily precipitation recorded at 62 rainfall stations were used, as follows: 36 rainfall stations in Maramureş County, 19 rainfall stations in Satu Mare County, and 7 rainfall stations in Bistrița-Năsăud County. Precipitation data from rainfall stations located in the neighborhood of the study area were used in order to determine the influence of relief on frontal precipitation. The second purpose of the research was to determine if there is a correlation between precipitation and altitude. To this end, ArcGIS and Microsoft Office software were used. The results seem to confirm the major influence of the relief over the dynamic convection imposed to the air masses on ascending slopes, various average vertical precipitation gradients and differentiated distribution of rainfall. The present analysis and its results will highly contribute as an input element in a Spatial Decision Support System for Prevention and Management of Floods in Firiza Basin (North-Western Carpathians).

Volume XX |

Analysis of the Relationships Between the Phreatic Aquifer and Natura 2000 Habitats from ROSCI0224 Scroviștea

Abstract: The analysis of the relationships between groundwater and terrestrial ecosystems contributes to the conservation of biodiversity and the quantitative and qualitative status of the aquifer.
The main goal of the paper is to analyze the relationships between the phreatic aquifer of ROIL16 (Vlăsia Plain) and the six Natura 2000 habitats from the Site of Community Importance (SCI) ROSCI0224 Scroviștea.
This work is based on hydrogeological, geological data, mathematical modeling of the phreatic aquifer (October 17-19, 2017), and the methodology used for study the relationship between groundwater bodies and terrestrial ecosystems, developed by the R.A.H. (2015).
The evaluation of the dependence (high – A, medium – B, nule – C) relations, between the phreatic aquifer and the habitats, is made mainly by correlating the depth of the hydrostatic level with the depth of the root system of plant and tree species.
The main findings based on the hydrogeological, ecological criteria, and analysis algorithms highlight the fact that most habitats and later the Scroviștea site are dependent on groundwater. The six Natura 2000 habitats (3150, 3160, 91M0, 91F0, 91E0 și 92A0) are analyzed individually concerning the depth of the groundwater level. In the evaluation of the degrees of dependence of the habitats, two other criteria are applied, maximum and arithmetic mean about their extension surface. Thus, four habitats (91M0, 91F0, 91E0, and 92A0) are identified with high dependence on groundwater, and two habitats (3150 and 3160) with nule dependence. Considering only this stage of analysis, it was considered that the SCI Scroviștea has a high dependence on the phreatic aquifer.
For a correct assessment of the dependence relations between groundwater and habitats, analyzes related to the hydrodynamic and hydrochemical regime of the groundwater aquifer and the correlation of this information with analyzes from specialized studies performed for plant and tree species are required.

Volume XIX |

Flood Mapping and Estimation of Flood Water-Level Using Fuzzy Method and Remote Sensing Imagery (Case Study: Golestan Province, Iran)

Abstract: Recently, the heavy precipitation occurred across the north of Iran caused an unprecedented flood. Due to the topographic conditions of the study area, not paying attention to the regular dredging of the river has caused a lot of problems for the local people. On the other hand, due to the frequent rainfall, the occurrence of flooding for a long time was another major problem. The combination of Remote Sensing and GIS can make a substantial contribution to flood assessment and management. In the present study, a fuzzy method is developed to show the hidden potential of Landsat satellite images for flood mapping. This paper presents the process of rapid access to water level information, which can provide valuable data for decision makers. The overall accuracy obtained for the flooded and damaged area is 87.23% and 46% respectively, and Root Mean Square Error (RMSE) of 27.68 cm is obtained for water-level based in the proposed algorithm.

Volume XIX |

The Buzău river alluvial fan – a groundwater modeling approach to sustainable exploitation

Abstract: Knowledge of groundwater resources is a key challenge for hydrogeologists, especially due to a continuous increase in demand for drinking water. This paper aims to investigate the consequences of overexploitation of the phreatic aquifer from the Buzău River alluvial fan and to assess alternatives operating programs related to achieving a sustainable groundwater exploitation. The study was achieved using data (groundwater level and general information from 97 hydrogeological boreholes) from the National Institute of Hydrology and Water Management, Romania, and collected in the field between July 18-19, 2017 (river stages for Buzău and Călmățui). The aquifer data was statistically analyzed and the obtained results allowed the design of a conceptual model for the hydrostructure and a mathematical model for the groundwater flow, using the FREEWAT software. Continuous exploitation of the phreatic aquifer through the catchment fronts that supply the city of Buzău (Crâng, Zahăr I, and Sud fronts) was simulated using the hydrodynamic model, in a transient regime. The maximum allowable flows were defined for each hydrogeological borehole that exploits the phreatic aquifer, using the mathematical model (values between 4.0 and 19.0 l/s). The exploitation of these flows was performed for 10 years, with time steps that allowed an analysis of the depression cone extension and drawdown value after 90 days, 180 days, one year, and five years of continuous pumping. After ten years, the resulting depression cone reached a diameter of 9.8 km and the groundwater level decreased with a maximum of 8.26 m, in a hydrogeological borehole. For stationary simulation (which is not influenced by the time parameter), it was observed that pumping with the maximum allowable flows resulted in a drawdown that exceeds one-third of the water column, which indicates overexploitation.