Assessing the impacts of rainfall intensity and urbanization on storm runoff in an arid catchment

In the past few decades, rapid urbanization has occurred in many regions of the Kingdom of Saudi Arabia due to increasing population and urban development. Additionally, the effects of global warming on rainfall characteristics have been observed. This rapid change in urbanization and climate change has cause significant changes in the nature of land surfaces and rainfall patterns, which affect the runoff process and the amount of surface runoff during floods. This study investigated the effect of urbanization and rainfall intensity for Hafr Al-Batin watershed located in Saudi Arabia. For this purpose, a hydrologic model, HEC-HMS, was adopted to simulate the flow of different rainfall intesities and urbanization levels. Simulated results showed that for a 100-year storm, a 24-h duration, and an urbanization level of 80%, the peak flow was 213% higher than the estimated current peak and the runoff volume was 112% higher than the current runoff volume. These results show a strong linear correlation between the level of urbanization and both peak discharge and runoff volume. Furthermore, the results indicate that for short return periods, the peak flow is more sensitive to the level of urbanization compared to long periods.     

Influence of Geo-environmental and Chemical Factors on Thermotolerant Coliforms and <Emphasis Type="Italic">E.coli</Emphasis> in the Groundwater of Central Kerala

Geo-environmental studies in parts of Ernakulam district (Kerala, India) were carried out. The study area comprises of sedimentary (Limestone, sandstone, Clay and Lignite) and crystalline (Charnockite and gneisses) rocks. The sedimentary terrain is characterized by confined and unconfined aquifers. In hard crystalline formations groundwater occurs under phreatic conditions in the shallow weathered portions and under semi confined to confined conditions in the deep-seated fractures. The study area is demarcated into five areas based on soil types. Climate is hot humid to hot summer with heavily raining monsoon. Two major rivers Periyar and Muvattupuzha drain through the area. Agricultural and industrial activities are prevalent in Ernakulam district. The major cause of pollution in the study area is due to the presence of coliforms. Detailed investigations carried out to identify the coliforms indicated spatial and seasonal changes in the distribution pattern. Monsoon and post monsoon showed significantly high total coliforms compared to pre-monsoon. Thermo-tolerant coliforms is high during monsoon season. This seasonal change could be due to the effect of rainfall, overland flow, nutrient load and temperature change. Wide variations in the coliform counts are observed in wells situated near rivers, canals, paddy fields and in water bodies lying close to pilgrimage center, fertilizer industry, and public places. It is noticed that the chemical characteristics of the groundwater influence the coliform survival. pH, nitrite, bicarbonate, hardness, and alkalinity play a significant role in controlling coliform count. At the outset, the study highlighted the impact of anthropogenic activities on ground water in a coastal district of Kerala state.     

Development of Earthquake Event Detection Technique Based on STA/LTA Algorithm for Seismic Alert System

The drainage basin of the Kalyani river, a tributary of Gomati river has been mapped and delineated using Survey of India toposheets (1:50,000 scale) and remote sensing satellite data. The digitization, slope map preparation and statistical calculations have been carried out with the help of geographical information system (Arc GIS 10). Kalyani a fifth order river exhibits meandering behavior having 2.45 sinuosity index (SI). The Kalyani river basin has about 1235 km²area with NW-SE sloping trend. The total number of first, second, third, and fourth order streams are 373, 71, 12 and 2 respectively, showing dominance of first order streams in the basin. The mean bifurcation ratio (Rb) of the entire basin is 4.8, which indicates that the drainage is not much influenced by geological structures and exhibits dendritic drainage pattern. Relief ratio (Rr) indicates low to medium surface run-off, and low stream power for erosion. The analysis of river bank height ‘r’ (escarpment) and longitudinal profile of the river closely reveals neotectonic activity at some locations in the basin. To prepare a comprehensive watershed development and management plan, it is important to understand the topography and drainage characteristics of the region.     

Geochemical Characterization and Controlling Factors of Chemical Composition of Spring Water in a Part of Eastern Himalaya

This paper focuses on the suitability of spring water for drinking and irrigation purposes in a part of eastern Himalaya, south Sikkim. There are many anthropogenic and geogenic factors contributing as a source of major cations and anions in the spring water. The spring water chemistry show a variation in EC, pH, TDS, Temperature, Na⁺, K⁺, Mg²⁺, Ca²⁺, Fe²⁺, Pb, Mn, Cu, HCO₃^-, Cl^-, PO₄^3-, NO₃^-, F^- and SO₄^2-. Mainly two types of water quality indexing has been used, one for suitability of spring water for drinking purposes and the other for irrigation purposes. For drinking purposes, Piper diagram used for determination of water type, water quality index (WQI) for quality monitoring and saturation index for mineral dissolution in water. % Na, RSC (Residual Sodium Carbon) and SAR (sodium absorption ratio) have been used for irrigation suitability. Piper diagram shows that CaHCO₃ type of water was dominant in the study area. The WQI depicted excellent category and SAR, percent sodium and RSC (Residual Sodium Carbon) depict excellent, good and permissible category for irrigation purposes. Principle component analysis (PCA) was used to determine the major influencing factor responsible for the variability in the parameters analysed of spring water.     

Transport behavior of nZnO in geosynthetic clay liner used in municipal solid waste landfills under temperature effect

The transport process of nZnO in geosynthetic clay liner (GCL), an anti-seepage material used in municipal solid waste (MSW) landfills, under different seepage temperature conditions was conducted. The transport behavior of nZnO in GCL was analyzed. Results showed that the retardation performance of current GCL used in MSW landfills anti-seepage system against nZnO pollutants was poor. nZnO successfully permeated the GCL and entered external soil–groundwater environment, posing health threats to the life of organisms. Although seepage temperature exerted a small effect on nZnO suspension leakage volume, change in seepage temperature affects the mass of transported nZnO in GCL by redispersion of nZnO in suspension. As the seepage temperature increases, the mass of nZnO that permeated the GCL increases, reaching a maximum at 50 °C, and then decreases.     

A study of the factors influencing the occurrence of landslides in the Wushan area

Due to the complex natural geological conditions, many slope-related geological hazards occur in the Three Gorges Reservoir area in China. This study focuses on the characteristics of landslide development and their underlying mechanisms in this area. A statistical analysis is conducted to determine the characteristics of landslide development in the Wushan area, including the landslide distribution as a function of the elevation, slope, landslide material composition, scale, lithology, boundary conditions, instability mechanism, stratigraphic age, attitude, and sliding direction. The mechanisms of slope instability and the effect on the occurrence of landslides are analyzed. This study provides important reference material for landslide research in the Three Gorges Reservoir area and similar stratigraphic areas.     

Study on the quantitative relationship between soil in situ strength and drilling parameters

The rational use of drilling parameters is a hot issue in the field of geotechnical engineering and geological engineering. A new method, for evaluating the bearing capacity of soils using drilling parameters was proposed. First, through the mechanical analysis of the drill bit, the preconditions and theoretical formulas for calculating the bearing capacity of soils using the bit’s torque are clearly defined. Next, drilling tests and dynamic cone penetration tests were performed on miscellaneous fill, silty clay, sandy clay, medium coarse sand and gravel sand, and the empirical formula for calculating the bearing capacity of these soils were given. Then, using the new method and the empirical formula, the bearing capacity of the soil under the roadbed was examined. The test results show that the bit’s torque is a good parameter for the evaluation of the bearing capacity of the soil. Finally, the application scope of the new method and the empirical formula is discussed, and the subsequent research directions are pointed out.     

Characterization,modeling, and remediation of karst in a changing environment

This introductory editorial paper provides a review and prospective outlook of the achievements and challenges in karst research under a changing environment. A brief discussion of the past and future karst research has been focused on: (1) data and new technologies; (2) modeling of karst flow and reactive transport; (3) responses of karst hydrosystems to climate variability and changes across scales.