Vulnerability mapping of karst springs and its application for the delineation of protection zones (Mecsek Karst, Hungary)

Over the past decade or two, vulnerability mapping become a useful tool to determine the sensitivity of karst aquifers and allows the analysis of karstic aquifers affected by human activities. The Tettye Catchment, one of the eight catchments of the Mecsek Karst aquifer (SW Hungary), supplies drinking water for Pécs, the fifth most populous city in Hungary. However, due to its partly urbanized character and heterogeneous karstic features, this catchment is highly sensitive to anthropogenic impacts. In this study we aimed to generate resource vulnerability maps and risk maps to assess the role of physical and anthropogenic factors on groundwater vulnerability in the Mecsek Karst. Two formerly validated methods were used, the COP (Concentration, Overlaying layers and Precipitation) and SA (Slovene Approach) methods. The resource vulnerability maps, validated by former tracer tests, were combined with the hazard map obtained from the COST action 620 and EU Water Directive to generate risk maps. Tracer-based transit times were commonly less than 20 days in the majority of the areas of extreme vulnerability. During the current study, a new protocol has been elaborated for the delineation of the protection zones of karstic aquifers. Comparing the two methods, the SA performed better in terms of intrinsic vulnerability mapping, as it had a higher spatial resolution and was more detailed than the COP map and had a more sophisticated vulnerability indexing. In addition, high spatial correlation was revealed between the transit time maps and the SA map. Reassessed risk zonation, with appropriate legal consequences, likely minimizes undesired human activities within the zone of protection, hence maintaining water quality that complies with the protection acts

First Application of the Integrated Karst Aquifer Vulnerability (IKAV) method. Potential and Actual vulnerability in Yucatan, Mexico

Groundwater vulnerability maps are important decision support tools for water resources protection against pollution and helpful to minimize environmental damage. However, these tools carry a high subjectivity along the multiple steps taken for the development of such maps. Additionally, the theoretical models on which they are based do not consider important parameters such as pollutant concentration or pollutant residence time in a given section of the aquifer, solely focusing the analysis on a theoretical travel time from a release point towards a target. In this work, an integrated methodology for the evaluation of potential (intrinsic) and actual vulnerability is presented. This integrated method, named IKAV, was developed after the analysis of several study cases and the application of multiple intrinsic groundwater vulnerability methods in a selected study area. Also, a solute transport model served as the basis to define additional parameters for vulnerability analysis for areas severely affected by anthropogenic practices. A defined workflow and several criteria for parameters and attributes selection, rating and weighting assignment, and vulnerability classification are presented. The first application of the IKAV method was carried out in the Yucatan karst, demonstrating to be a reliable method for vulnerability estimation. Results demonstrated the scope of the IKAV method to highlight important regional conditions, minimizing the subjectivity, and expanding the analysis of vulnerability.

GIS Based Analysis of Niger-Benue River Flood Risk and Vulnerability of Communities in Kogi State, Nigeria

Flood remains one of the most common natural disasters. Its rate of occurrence and the associated destructive tendency are on a rising scale across the globe. Flood risk may increase due to human activities. It could also decrease by appropriate flood management and planning. However, this requires upgraded and newly generated reliable and up to date floodplain and flood vulnerability maps. Hence, this study analysed the Niger-Benue river flood risk and vulnerability of 256 communities in Kogi State. The aim is to generate reliable up to date flood vulnerability maps that categorises the communities into different vulnerability zones and identify likely locations for erecting flood shelter/refugee camps during flood events in the State. Shuttle Radar Topography Mission (STRM) Digital Elevation Datasets, the spatial location of 256 communities, shapefiles of Kogi State’s administrative boundaries and Niger-Benue river basin were among the datasets acquired for the study. The Digital Elevation Model (DEM) of the study area was created to depict topography and the heights of each component of the terrain. Also, a 3km buffer distance was created around the Niger-Benue river and four vulnerability zones were defined based on the terrain and proximity components of each community. Furthermore, choropleth maps were generated for each vulnerability zone based on the number of communities per Local Government Area (LGA). Findings of this study revealed that out of the 256 sampled communities, 161 representing 62.89% are exposed to varying degrees of vulnerability due to Niger-Benue flooding. Out of these, 33 (12.89%) are highly vulnerable, whereas each of the vulnerable (64) and marginally vulnerable (64) communities accounted for 25%. The rest 37.11% constituted the not vulnerable communities (95). Out of the highly vulnerable communities, 27.27% accounted for those located on river banks and 72.73% for those located within a 3km distance from the river. The majority of the riverbank communities were found in Kogi, Lokoja and Ajaokuta LGAs. Igalamela Odolu, Kogi, Ofu and Bassa were among the LGAs with a high number of vulnerable communities. The not vulnerable communities were mostly located around the Agbaja Plateau and Okoro-Agbo hills in Ijumu, Kabba/Bunu and Yaba East LGAs. It was concluded that the 9 communities (Ajaokuta, Eroko, Iche, Jamata, Numai, Okume, Agodo, Denbor and Gunji Twaki) located on river banks are exposed to the highest level of flood risk and invariably, the devastating impact of flood in Kogi State. Most communities in Ijumu, Kabba/Bunu and Yaba West LGAs are less likely to be affected by Niger-Benue River flooding. It is therefore recommended that communities within the highly vulnerable zones, beginning with the 9 located on river banks should be relocated to higher terrains. Also, future settlement development should be discouraged in the zone by the collaborative efforts of the State and LGA authorities. Further studies should be conducted around Ijumu LGA in view of identifying the most suitable locations for possible flood shelter/refugee camp development in the study area.

Vulnerability Assessment as a Basis for Sanitary Zone Delineation of Karst Groundwater Sources—Blederija Spring Case Study

The application of groundwater vulnerability methods has great importance for the sanitary protection zones delineation of karstic sources. Source vulnerability assessment of karst groundwater has mainly relied on the European approach (European Cooperation in Science and Technology—COST action 620), which includes analysis of the K factor, which refers to water flow through the saturated zone of the karst system. In the paper, two approaches to groundwater vulnerability assessment have been applied, COP + K and TDM (Time-Dependent Model) methods, to produce the most suitable source vulnerability map that can be transformed into sanitary protection zones maps. Both methods were tested on the case example of Blederija karst spring in Eastern Serbia. This spring represents a classical karst spring with allogenic and autogenic recharge. Dual aquifer recharge points out the necessity for the inclusion of the vulnerability assessment method created especially for the assessment of karst groundwater. Obtained vulnerability maps show similar results, particularly in the spring and the ponor areas, and these zones are most important for future protection. The COP + K method brings out three vulnerability classes that can be directly transformed into three sanitary protection zones. Contrary to the previous one, the TDM method uses water travel time as a vulnerability degree. The results show that the final map can be easily used to define sanitary zones considering different national legislation.

Vulnerability of urban floods in association with the sewage system and geographical features in the Giulești – Sârbi neighborhood, Bucharest, Romania

The study aims to analyze the vulnerability of floods and their impact in the Giulești-Sârbi area, the marginal northwestern neighborhood of Bucharest. The location of the accumulation lake has hydrological importance for the studied area. The anthropogenic dam is one of the susceptible sources of floods, but the most inefficiency of the sewage system is the actual principal cause, which frequently flows back when there are significant increases in rainfall. The motivation for choosing the study is represented by the vulnerability of the Giulești-Sârbi area and by the lack of a study on flood vulnerability and frequency in the area. A questionnaire was also applied locally, some of the results being presented in this paper. The main objectives of the study refer to the spatialization at the street level of the vulnerability of floods and their following impact. It also compares the vulnerability of floods after two key periods: before and after the construction of the dam, respectively 1980 and 2020 – for the comparison and evolution of terrain changes. The problem was also analyzed by the vulnerability related to the slope, land use and geological characteristics. The results show that the Giulești-Sârbi neighborhood is still susceptible to floods. The most affected streets are those from the southeastern part of the neighborhood and punctually to the NW. On the other hand, the application of the questionnaire shows that the southernmost street (Răsadniței Street) did not register problems as often as the current hazard maps from the rowater.ro source for which the highest vulnerability was expected to show. The areas indicating problems according to the questionnaires and Romanian Waters National Administration maps largely coincide with the results of the vulnerability maps resulting in this paper. The main solution that can reduce the effect of flood vulnerability is the modernization of the sewage system.

Integration of GIS and Hierarchical Multi-Criteria Analysis for Mapping Flood Vulnerability: The Case Study of M'sila, Algeria

This paper proposes the integration of GIS (Geographic Information System ) and HMA (Hierarchical Multi-criterion Analysis) offering a low-cost methodology to produce vulnerability maps. The quintessential role the rivers play in urban development has long been asserted and accepted. However, one of the subsequent consequences of these urban development activities is the increased frequency of floods. The case in point is the city of M’sila, Algeria. The subject city was settled along the banks of a river known as Oued El Ksob, which undoubtedly had a significant influence on its development. In the last 50 years, M’sila has experienced significant spatial growth, especially in its north and northwest sides. As such, the work presented in this article aims to assess the vulnerability of the city to the risks of flooding. The approach used is based on the combined use of the HMA method coupled with the GIS. The process allowed the graphical representation of the resulting analysis of complex data of the territory, i.e. the mapping of its vulnerability to flooding. The map has four vulnerability categories ranging from low to very strong. The proposed system serves as an essential decision-making tool for local government officials.

Mikrozonasi di Daerah Plampang, Nusa Tenggara Barat

ABSTRAK Provinsi Nusa Tenggara Barat (NTB) merupakan daerah dengan aktivitas kegempaan yang tinggi. Fenomena ini disebabkan oleh adanya aktivitas tektonik sebagai akibat pertemuan Lempeng Eurasia-Australia (zona subduksi) di bagian selatan dan Sesar Flores di bagian utara serta adanya keberadaan sesar-sesar lokal. Terkait dengan rencana pengembangan kawasan Samota di Pulau Sumbawa, NTB, perlu dilakukan suatu kajian kegempaan. Tujuan penelitian ini adalah memetakan indeks kerentanan seismik (Kg) melalui pengukuran mikrotremor dengan analisis menggunakan metode Horizontal to Vertical Spectral Ratio (HVSR). Hasil penelitian berupa peta kerentanan seismik daerah Plampang yang menunjukkan bahwa sisi utara lokasi penelitian memiliki indeks kerentanan seismik rendah yang ditandai dengan nilai amplifikasi kurang dari tiga jika dibandingkan daerah lainnya. Geologi sisi utara lokasi penelitian tersusun oleh batuan gunung api dengan karakteristik batuan keras, ketebalan sedimen sangat tipis, dan tersusun atas batuan Tersier atau lebih tua. Peta kerentanan seismik berguna sebagai acuan dalam mitigasi gempa bumi untuk mengurangi risiko yang ditimbulkan. ABSTRACT Nusa Tenggara Barat (NTB) Province is an area with intense seismic activity. This phenomenon is caused by tectonic activity as the result of the convergency of the Eurasia-Australia Plates (subduction zone) in the south and the Flores Fault in the north as well as the presence of local faults. Regarding the plan to develop the Samota area in Sumbawa Island, NTB, a study concerning earthquakes should be done. The purpose of this study is to map the seismic vulnerability index (Kg) through microtremor measurement by using the Horizontal to Vertical Spectral Ratio (HVSR) analysis method. The result of the study is a seismic vulnerability map of the Plampang area which its northern part has a low seismic vulnerability index indicated by the amplification factor value of less than three compared to other areas. The geology of the northern part of the Plampang area consists of volcanic rocks which has hard rock characteristic, very thin sediment thickness, and composed of Tertiary or older rocks. Seismic vulnerability maps can be useful as a reference for earthquake mitigation to reduce its risks.

DRASTICAI, a New Index for Groundwater Vulnerability Assessment—A Portuguese Case Study

Groundwater vulnerability assessment has become a useful tool for groundwater pollution prevention. Groundwater vulnerability maps provide useful data for protecting groundwater resources. Identification of agricultural patterns is an important issue for optimized land management. The watershed of the Tagus River is the backbone of this study. Naturtejo UNESCO Global Geopark, in the central interior of Portugal, corresponds to a rural area. Intensive agricultural practices showed an increasing trend in the last decades. The method that is most used internationally to assess vulnerability is the DRASTIC index. In this study, the DRASTICAI index is introduced. A new attribute—anthropogenic influence—is added here. Five levels of increasing vulnerability, from low to high, can be recognized here. The municipality of Idanha-a-Nova is most affected by intensive agricultural activities, showing spatial patterns of DRASTICAI with a clear influence of anthropogenic activities, with high needs for groundwater abstraction. A robust assessment of groundwater quality has a key role. Climate change scenarios and water scarcity are important issues in the coming years, and particularly in the studied area. Therefore, optimized groundwater management is essential to consider in policy-making strategies.

Evaluation of groundwater vulnerability to pollution using DRASTIC, composite DRASTIC, and nitrate vulnerability models

Background: Groundwater protection against pollution is a very important issue. Groundwater vulnerability maps are useful tools for protecting aquifers and assessing the potential for contamination. Therefore, the purpose of this study was to prepare vulnerability maps and perform sensitivity analysis to identify the most influential factors in the vulnerability of the studied aquifer. Methods: In this study, groundwater vulnerability to pollution was evaluated using DRASTIC, composite DRASTIC, and nitrate vulnerability (NV) models. Drastic is an index for the systematic assessment of potential groundwater pollution. In this method, the drastic index was calculated from the total weight and rank of the factors. For this purpose, first the factors affecting the pollution transfer, were weighted, ranked, and merged using GIS software. Then, using the overlapping techniques and after applying the necessary weight coefficients on each layer, a map of the vulnerability area of the study aquifer was prepared. Results: It was revealed that there is a significant linear relationship between all three models with the distribution of nitrate concentration. Accordingly, it was the most efficient NV model, followed by the composite DRASTIC (CD) and DRASTIC models, respectively. Also, in the studied aquifer, the DRASTIC index was between 147 and 136, the combined DRASTIC index was between 70 and 190, and the nitrate index was between 13 and 132. Conclusion: Vulnerability assessment of the studied aquifer using DRASTIC, and combined DRASTIC, and NV indices shows that, according to the DRASTIC index, 69.7% of the studied aquifer was in the medium vulnerability class. Also, according to the combined DRASTIC index, the largest area (53.62%) has low vulnerability and 31.56% has moderate vulnerability. But according to the nitrate index, 77.16% of the aquifers had very low vulnerability.