Arabian Journal of Geosciences

Consolidation settlement tests are costly and time-consuming, whereas tests for determining soil physical properties can be performed very rapidly and at lower costs. Therefore, it will be very helpful if the soil compression index (CC) can be determined using soil physical parameters. This study investigated correlations between the CC and the physical properties of undisturbed and remolded Tehran clay by performing 125 consolidation tests and through determining the physical properties. Based on the results, the correlations between the CC and dry density (γd), between the CC and initial void ratio (eo), and between the CC and wet density (γw) are valid and have correlation coefficient (R2) of 0.87, 0.87, and 0.89, respectively, for undisturbed Tehran clay. These correlations have been proposed for engineering applications in this area. Furthermore, available empirical correlations were compared with those presented in this study and the results suggested that the low accuracy of some of the available correlations for estimating the CC of Tehran clay soil required accurate evaluations before using them in engineering applications. Moreover, using artificial neural network showed high potential in predicting the CC and have coefficient (R) close to 1.

Understanding spatial runoff conditions in flood-prone ungauged catchments is crucial for effective watershed management to reduce flood risks in the lower catchment. Our study aimed to estimate spatial runoff under different land uses and rainfall frequencies in a flood-prone Dechatu River Catchment (DRC), Dire Dawa, Ethiopia. A goodness-of-fit test was carried out before the rainfall frequency analysis—Generalized Extreme Value, Log Pearson Type 3, and Gumbel max—via Kolmogorov Smirnov and Anderson Darling test. Then, the rainfall extremes for different return periods (RPs) are integrated with the Soil Conservation Service Curve Number model to estimate the spatial surface runoff. The highest annual daily maximum rainfall estimated 53–79 mm and 83–89 mm for 2 to 25-years and 50 to 200-years RPs, respectively. The northwestern part of DRC noted the highest surface runoff impacts compared to the eastern catchment. The highest runoff volumes are predominantly from bare land, open shrubs, and cultivated land in descending order ranging from 1.45 million m3 (in 2 years RP) to 2.5 million m3 (in 200 years RP); however, a relatively low runoff below 0.75 million m3 is depicted in the upper catchment. The spatial runoff estimates of short (2 to 10 years) and long (25 to 200 years) RPs can be used for implementing moisture conservation measures and constructing water storage structures to reduce the flash flooding impacts in Dire Dawa city, which claims human lives and property damages when intense rainfall from hilly mountains of eastern Ethiopia is observed.

Present active tectonics is affecting central Alborz and created various dynamic landforms in Buin Zahra-Avaj area, northern Iran. The area, located between the southern central Alborz and the edge of northwestern central Iran, is the result of both the Arabian–Eurasian convergence and clockwise rotation of the south Caspian Basin with respect to Eurasia in which most of the steep fault planes have a left lateral strike-slip component and most of the dip-slip faults are reverse, dipping SW. Since this region consists of several residential and industrial areas and includes several fault zones, the assessment of the structures of the present activity is vital. Six significant morphometric indices have been applied for this evaluation including stream length–gradient (SL), drainage basin asymmetry factor (Af), hypsometric integral (Hi), ratio of valley floor width to valley height (Vf), drainage basin shape (Bs), and mountain front sinuosity (Smf). The combined analyzed indices, represented through the relative tectonic activity (Iat), were used. The study area was divided into four regions according to the values of Iat. These classes include class 1 (very high activity,18%), class 2 (high, 20%), class 3 (moderate, 44%), and class 4 (low, 18%). The results of these indices are consistent with field observations on landforms and the deformation of Quaternary deposits.

The purpose of this study is to develop an overall methodology for assessing soil erosion hazard. Two models are implemented in Haffouz watershed (central Tunisia), which is generally prone to erosion processes. The first is a multi-parametric approach based on expert’s knowledge and Analytic Hierarchy Process (AHP), while the second is a statistical technique based on logistic regression (LR). Six parameters (slope gradient, annual precipitation, lithofacies, vegetation index, drainage density, and land use) are used for both methodologies. A thematic layer map is generated for each parameter using geographic information system (GIS) and remote sensing, while the weighting coefficients of each methodology are used for the compilation of AHP and LR final maps. Both models give similar results depicting that, in general, a moderate hazard condition of soil erosion was found in the study area. The proposed approaches also resulted in the identification of the highly eroded areas, requiring immediate action.

Themed by the compensation mechanism of the environmental influences of coal resource development, this thesis puts forward a basic framework of a standard environmental compensation system for coal resource development. Based on the consideration of the correlation between environmental costs and environmental capacities, this thesis constructs an evaluation index system of environmental costs and capacities for coal resource development from the three aspects of the natural, ecological, and social environments. For calculating the environmental capacities and costs, relative quantities are introduced and an improved fuzzy mathematical evaluation model is constructed. The evaluation index system of the environmental costs is divided into two types; the first consists of an index that can be directly measured by losses in value and of compensation values that can directly adopt the present values of the index, and the other consists of an index that cannot be directly represented by losses in value and of compensation values that must be measured by the recovery costs, which are the costs of recovering from the present to the normal values. By collecting all compensation values, we can design the standard compensation system for the environmental influences of coal resource development.

The Mugling–Narayanghat road section falls within the Lesser Himalaya and Siwalik zones of Central Nepal Himalaya and is highly deformed by the presence of numerous faults and folds. Over the years, this road section and its surrounding area have experienced repeated landslide activities. For that reason, landslide susceptibility zonation is essential for roadside slope disaster management and for planning further development activities. The main goal of this study was to investigate the application of the frequency ratio (FR), statistical index (SI), and weights-of-evidence (WoE) approaches for landslide susceptibility mapping of this road section and its surrounding area. For this purpose, the input layers of the landslide conditioning factors were prepared in the first stage. A landslide inventory map was prepared using earlier reports, aerial photographs interpretation, and multiple field surveys. A total of 438 landslide locations were detected. Out these, 295 (67 %) landslides were randomly selected as training data for the modeling using FR, SI, and WoE models and the remaining 143 (33 %) were used for the validation purposes. The landslide conditioning factors considered for the study area are slope gradient, slope aspect, plan curvature, altitude, stream power index, topographic wetness index, lithology, land use, distance from faults, distance from rivers, and distance from highway. The results were validated using area under the curve (AUC) analysis. From the analysis, it is seen that the FR model with a success rate of 76.8 % and predictive accuracy of 75.4 % performs better than WoE (success rate, 75.6 %; predictive accuracy, 74.9 %) and SI (success rate, 75.5 %; predictive accuracy, 74.6 %) models. Overall, all the models showed almost similar results. The resultant susceptibility maps can be useful for general land use planning.