Spatial distribution and contamination assessment of heavy metals in surface soils of Hassi Messaoud, Algeria

An increase in heavy metal pollution in the soils of Hassi Messaoud (Algeria) due to intense industrialization and urbanization has become a serious environmental problem. There are three large industrial complexes that have been established in the region of Hassi Messaoud for petroleum extraction field and refinery. The region hosts several industrial facilities which are the main sources for hazardous wastes. Surface soil samples from 58 sampling sites (systematically sampled; 1 × 1 km regular grid), including different functional areas in Hassi Messaoud, were collected and analyzed. The results showed that the average concentrations of Cu, Ni, Mn, Pb and Zn in soil of Hassi Messaoud were up to 13.17, 35.78, 121.21, 130.97 and 61.08 mg/kg, respectively. Ni concentrations were comparable to background values, while Cu, Mn, Pb and Zn concentrations were higher than their corresponding background values. Among the functional areas, the industrial regions displayed the highest metal concentrations, while the lowest concentrations occurred in rural soil. Principal component analysis coupled with cluster analysis showed that: (1) Pb and Zn had anthropogenic sources; and (2) Ni, Cu and Mn were associated with parent materials. Contaminations in soils were classified as geoaccumulation index and enrichment factor. Pollution index values of Cu, Ni, Mn, Pb and Zn varied in the range of 0.04–5.41, 0.46–2.49, 0.01–5.73, 0.62–152.9 and 0.09–53.01, with mean values of 1.32, 1.08, 1.26, 5.64 and 3.1, respectively. The integrated pollution index (IPI) of all the analyzed samples varied from 0.42 to 31.59, with a mean of 2.48, and more than 5.45 % of samples are extremely contaminated; 18.18 % are heavily contaminated; 60 % are moderately contaminated; and others are low contaminated. The spatial distribution of IPI showed that desert and rural areas displayed relatively lower heavy metal contamination in comparison with other areas.     

Urban form study: the sprawling city—review of methods of studying urban sprawl

There is a large body of research on urban forms. This review paper focuses on the urban sprawl using new and old approaches and new techniques from the subfield of urban Geography. There has been a debate among researchers about the definition of the sprawl, which makes it difficult to suggest a reliable model of the urban sprawl. This review is extremely selective. Numerous papers have focused on measuring the in terms of its physical cost or the environmental and transportation measures linked to this phenomenon. Several attempts have been made to improve the measurement of the sprawl using new approaches. Furthermore, this paper show that certain researchers did not attempt to explore new methods to investigate the urban sprawl in the past and present overlay layers for many years, researchers may use cartography techniques, for example, thereby collecting 20 years of data to match layers and show the differences in any metropolitan area. Several problems remain like differences in the understanding of the sprawl among planners and between other researchers interested in this issue. Also, it is problematic to find one measure, such as mixing different measures together to distinguish between car density and resident density. This study evaluated and reviewed old and recent studies to show that the most important issue in the urban sprawl relates to measurements. Incorporates inform and which measure is best. This article argues that urban spatial expansion reviews some of articles written on urban sprawl and showing the different approaches to studying.

     

Discussion of “Interfacing the geographic information system,remote sensing,and the soil conservation service-curve number method to estimate curve number and runoff volume in the ASIR region of Saudi Arabia” by Fawzi S. Mohammad,Jan Adamowski

The soil conservation service curve number (SCS-CN) method is one of the most commonly used methods to compute the direct runoff from a rainfall event. Since the method was established, numerous researches were undertaken to improve the method through accurate estimation of its parameter and especially the curve number (CN). However, the essence of the SCS method, as an event-based Hortonian mechanism method, remained unchanged. The main assumption of the method related to the rainfall input is that the rainfall is continuous in time and uniform over the watershed. Mohammad and Adamowski (2015) paper apparently used the SCS method to estimate the annual runoff using the annual rainfall as one cumulative rainfall input value, which is a violation of the event-based principle of the method and of the assumption of the continuity of the rainfall event.To re-estimate the average annual runoff more realistically for the Asir region, Saudi Arabia, daily rainfall data from 14 rainfall stations are used for calculating the resulting runoff depths, on a daily event-by-event rainfall basis, throughout the whole simulation period. The resulting runoff depths are added for each year, and the total cumulative annual runoff values for each year are averaged to get the average annual runoff. The runoff values based on the previously mentioned procedure are an upper limit of the actual average annual runoff as the underlying SCS equations discard evaporation and similar long-term losses. Nevertheless, the average runoff values obtained in the discussion paper are an order of magnitude (at least five to tenfold) lower than the ones of the original paper. An equation is proposed to obtain a more realistic estimate of the average annual runoff, to be used with the average annual rainfall as an input, if the annual value is the only available rainfall information.     

Assessment of models predicting anthropogenic interventions and climate variability on surface runoff of the Lower Zab River

Multi-regression, hydrologic sensitivity and hydrologic model simulations were applied to quantify the climate change and anthropogenic intervention impacts on the Lower Zab River basin (LZRB). The Pettitt, precipitation-runoff double cumulative curve (PR-DCC) and Mann–Kendall methods were used for the change points and significant trend analyses in the annual streamflow. The long-term runoff series from 1979 to 2013 was first divided into two main periods: a baseline (1979–1997) and an anthropogenic intervention period (1998–2013). The findings show that the mean annual streamflow changes were consistent using the three methods. In addition, climate variability was the main driver, which led to streamflow reduction with contributions of 66–97% during 2003–2013, whereas anthropogenic interventions caused reductions of 4–34%. Moreover, to enhance the multi-model combination concept and explore the simple average method (SAM), Hydrologiska Byrans Vattenbalansavdelning (HBV), Génie Rural a Daily 4 parameters (GR4J) and Medbasin models have been successfully applied.