Evaluation of Cretaceous–Paleogene boundary based on calcareous nannofossils in section of Pol Dokhtar, Lorestan, southwestern Iran

The Pol Dokhtar section of southern Lorestan, faulted Zagros range of southwestern Iran, contains one of the most complete Early Campanian to Danian sequences. The lack of a good fundamental paleontological study is a strong motivation for investigating calcareous nannofossils in southwestern Iran. The majority of the section is made of shale, marl, and partly of marly limestone and clay limestone, respectively. As a result of this study, 24 genera and 45 species of nannofossils have been identified and presented for the first time. This confirms the existence of biozone CC18 of zonation scheme of Sissingh (Geologie en Minjbouw 56:37–65, 1977) to NP1 of zonation of Martini, which suggests the age of Early Campanian to Danian. All Early Campanian to Danian calcareous nannofossil biozones from CC18 (equivalent to the Aspidolithus parcus zone) to NP1 (equivalent to the Markalius inversus zone) are discussed. Also, the zonal subdivision of this section based on calcareous nannofossils has shown continuity in Cretaceous/Paleocene boundary in south part of Lorestan Province. We can also learn about the predominant conditions of the studied sedimentary basin that was in fact part of the Neotethys basin with the existence of indexed species calcareous nannofossils that indicate warm climate and high water depths of the basin in low latitudes.     

Flood-hazard assessment and risk-based zoning of a tropical flood plain: case study of the Yom River,Thailand

Abstract

This study contributes to the comprehensive assessment of flood hazard and risk for the Phrae flood plain of the Yom River basin in northern Thailand. The study was carried out using a hydrologic–hydrodynamic model in conjunction with a geographic information system (GIS). The model was calibrated and verified using the observed rainfall and river flood data during flood seasons in 1994 and 2001, respectively. Flooding scenarios were evaluated in terms of flooding depth for events of 25-, 50-, 100- and 200-year return periods. An impact-based hazard estimation technique was applied to assess the degree of hazard across the flood plain. The results showed that 78% of the Phrae flood-plain area of 476 km² in the upper Yom River basin lies in the hazard zone of the 100-year return-period flood. Risk analyses were performed by incorporating flood hazard and the vulnerability of elements at risk. Based on relative magnitude of risk, flood-prone areas were divided into low-, moderate-, high- and severe-risk zones. For the 100-year return-period flood, the risk-free area was found to be 22% of the total flood plain, while areas under low, medium, high and severe risk were 33, 11, 28 and 6%, respectively. The outcomes are consistent with overall property damage recorded in the past. The study identifies risk areas for priority-based flood management, which is crucial when there is a limited budget to protect the entire risk zone simultaneously.

Citation Tingsanchali, T. & Karim, F. (2010) Flood-hazard assessment and risk-based zoning of a tropical flood plain: case study of the Yom River, Thailand. Hydrol. Sci. J. 55(2), 145–161.     

The relationship between lineaments and borehole yield in North West Province, South Africa: results from geophysical studies

Airborne magnetic data and Landsat imagery, as well as time-domain electromagnetic soundings, were used to assess groundwater potential of the region around the town of Mafikeng in North West Province, South Africa. Lineaments were extracted based on on-screen digital data derived from magnetic and Landsat 7 imagery. The relationship between lineament-intersection density and borehole yield was assessed using statistical analysis. The results were discussed with respect to factors that determine the groundwater potential of the area. Correlation between lineament-intersection frequency and borehole yield is 60?C65% in the south and southeastern parts, and 45?C50% within 5?C30?km radius of Mafikeng. The eastern and western parts of the study area are characterized by weak or no correlation. Areas that correspond to high correlation between lineament-intersection frequency and borehole yield suggest the significance of cross-cutting structures in controlling groundwater potential zones, while results that suggest low or no correlation represent the influence of other factors. The overall results demonstrate that the combined analysis of airborne magnetic data, satellite imagery, borehole yield and ground-based time-domain electromagnetic soundings provide the best approach for groundwater assessment within the hard rock and carbonate terrains of the study area.     

Dynamics of communal land degradation and its implications in the arid mountains of pakistan: A study of District Karak,Khyber Pakhtunkuwa

Similar to other areas of Pakistan, land resources in Khyber Pakhtunkhwa （KP） is kept under various ownership regimes for socio-economic and ecological benefits. For the last three to four decades, communal lands and resources are subjected to high rate of degradation and deterioration, which is leading to multifarious socio-economical and ecological implications. This paper intends to look into factors that are responsible for the degradation of communal land and the adaptability of the management mechanisms developed by the local inhabitants to conserve these resources. Moreover, this study also explores the sustainability of these adopted strategies in present circumstances. Data regarding socio-economic parameters of the inhabitants and their interactions with communal lands were collected through questionnaire cum interview method. As long-term climatic data for the area do not exist therefore focus group discussions were conducted to document the changing trend in rainfall regimes and temperature variations for the last about four decades. Results indicate that communal lands are highly vulnerable to degradation due to biophysical and anthropogenic factors. Local inhabitants have developed suitable measures to control the situation, however, accelerated socio-economic transformations in the area have weakened the role of local institutions and that led to further degradation of these resources. Nevertheless, a number of locally formulated rules have been revived and implemented and it is hoped that these threatened resources would be conserved.     

Preliminary studies on the primary production of north-west Persian Gulf during post-monsoon period

Primary productivity, chlorophyll-a and the euphotic zone depth were determined averagely as 161 mg C (m³ day)^–1, 3.48 mg m^–3 and 6.2 m, respectively, in the north-west Persian Gulf during the post monsoon period in 1975 and 1976.     

A nonlinear polar coordinate shallow water model for tsunami computation along North Sumatra and Penang Island

A nonlinear shallow water model in cylindrical polar coordinate system is developed, using an explicit finite difference scheme with a very fine resolution, to compute different aspects of tsunami at North Sumatra and the adjacent island Simeulue in Indonesia, and the Penang Island in Peninsular Malaysia. The pole of the frame is placed on the mainland of Penang (100.5°E) and the model area extends up to the west of Sumatra (87.5°E). The model is applied to simulate the propagation of tsunami wave towards North Sumatra, Simeulue and Penang Islands associated with Indonesian tsunami of 26 December 2004. The model is also applied to compute water levels along the coastal belts of those islands. Computed and observed water level data are found to be in good agreement and North Sumatra is found to be vulnerable for very high surges. The computed and observed arrival times of high surges are also in reasonable agreement everywhere. Further studies are carried out to investigate the effect of convective terms and it is found that their effects are insignificant in tsunami propagation and weakly significant for wave amplitude very near to the coast.     

Assessing the potential underestimation of sediment and nutrient loads to the Great Barrier Reef lagoon during floods

Much of the sediment and nutrient load to the Great Barrier Reef (GBR) lagoon happens during over bank floods, when discharge can be significantly underestimated by standard river gauges. This paper assesses the potential need for a flood load correction for 28 coastal rivers that discharge into the GBR lagoon. For each river, daily discharge was divided into flows above and below a 'flood' threshold to calculate the mean annual percentage flow above this threshold. Most GBR rivers potentially need a flood load correction as over 15% of their mean annual flow occurs above the minor flood level; only seven rivers need little/no correction as their flood flows were less than 5% of the mean annual flow. Improved assessment of the true load of materials to the GBR lagoon would be an important contribution to the monitoring and reporting of progress towards Reef Plan and associated marine load targets.     

Neutron stars:a relativistic study

We study the inner structure of a neutron star from a theoretical point of view and the outcome results are compared with observed data. We propose a stiff equation of state relating pressure with matter density. From our study we calculate mass(M),compactness(u) and surface redshift(Zs) for two binary millisecond pulsars,namely PSR J1614–2230 and PSR J1903+327,and four X-ray binaries,namely Cen X-3,SMC X-1,Vela X-1 and Her X-1,and compare them with recent observational data.Finally,we examine the stability for such a type of theoretical structure.