Artificial neural network models for forecasting monthly precipitation in Jordan

Forecasting precipitation in arid and semi-arid regions, in Jordan in the Middle East for example, has particular importance since precipitation is the unique source of water in such regions. In this study, 1-month ahead precipitation forecasts are made using artificial neural network (ANN) models. Feed forward back propagation (FFBP), radial basis function (RBF) and generalized regression type ANNs are used and compared with a simple multiple linear regression (MLR) model. The models are tested on monthly total precipitation recorded at three meteorological stations (Baqura, Amman and Safawi) from different climatological regions in Jordan. For the three stations, it is found that the best calibrated model is FFBP with respect to all performance criteria used in the study, including determination coefficient, mean square error, mean absolute error, the slope and the intercept in the best-fit linear line of the scatter diagram. In the validation stage, FFBP is again the best model in Baqura and Amman. However, in Safawi, the driest station, not only FFBP but also RBF and MLR perform equally well depending on the performance criterion under consideration.     

Experimental determination of three-dimensional dispersivities in homogeneous porous medium

Laboratory tracer experiments were conducted to investigate longitudinal dispersivity (α _x ) as well as the transversal (α _y ) and vertical (α _z ) dispersivities in homogeneous 3–5 mm sandy aquifer. The experiments were carried out in a channel 12-m long, 1.35-m wide and 0.60-m high which was built in the Hydraulics Laboratory of Civil Engineering Department in Dokuz Eylul University. NaCl was used as a tracer and conductivity values were measured at 220 measurement points. Mass Transport 3 Dimensional (Zheng and Wang in SERDP-99-1, US Army Engineer Research and Development Center, Vicksburg, MS, 1999; MT3DMS code) which is a three-dimensional solute transport simulation model incorporating finite differences solution option was used to solve the three-dimensional advective–dispersive transport equation. The estimated dispersivity values were modified until an acceptable compatibility between the observed and calculated concentrations at measurement points was reached. The best match was obtained for α _x  = 12 cm, α _y /α _x  = 0.2 and α _z /α _x  = 0.05. These values are compatible with those encountered in the literature.     

Hydrogeochemical factors effecting the scaling problem in Balçova geothermal field,İzmir, Turkey

Reservoir fluid compositions have been assessed from analytical data on water samples collected from thermal and cold waters in Balçova geothermal field. The results of mineral equilibrium modelling indicate that the waters, with some exceptions, are systematically supersaturated with respect to calcite, aragonite, dolomite, chalcedony and quartz, but undersaturated with respect to amorphous silica, celestite, anhydrite and gypsum and undersaturated or supersaturated with respect to barite, low-albite, K-feldspar, gibbsite and Fe(OH)₃(a). Calculation of mineral saturation states and geochemical analyses of scale and field observations show that carbonate minerals (calcite, aragonite and dolomite) are most likely to be precipitated as a scale type. Besides carbonates, scale formation risk of amorphous silica, Fe(OH)₃(a), anhydrite, barite and celestite minerals should be taken into account in some wells and surface equipment. Most of the waters, with some exceptions, have carbonate scaling risk at all temperatures, whereas the other scaling risks only exist over a limited temperature range. While silica, Fe(OH)₃(a) and barite show a scaling tendency at low temperatures, anhydrite and celestite scaling occurs at higher temperatures.     

Spatial and temporal characterization of standard duration-maximum precipitation over Black Sea Region in Turkey

Natural Hazards - This study characterises the spatial and temporal behaviours of maximum precipitation over the Black Sea Region in northern Turkey. Maximum precipitation data of 14 standard...     

A new approach to time-load-deformation-stress hypersurface of rocks to stability analysis of underground openings

The most important developments in rock engineering are about time-dependent deformation behavior of rocks under different loads. Many studies have been done for the purpose of identifying mathematically time-load-deformation (TLD) characteristics of the rocks. These studies have made an important contribution to the research on the stability of constructions built in rock masses, and rock material is the main part of the rock mass in which the engineering constructions. When considered from this point of view, the time-dependent deformation behavior of the rocks under different loads is important to determine unstable conditions of the rock constructions in the long term. Researches in rock masses use surfaces based on TLD data. On the other hand, the strength of the rock is also part of these analyzes. The new model developed in this study has four variables such as time, load, deformation, and strength. Therefore, TLD surfaces developed for time-load-deformation has been associated with another variable and three-component (TLD) surfaces eventually transformed into four-component (time-load-deformation-strength; TLDS) hypersurfaces. Hypersurfaces, which illustrate new TLDS behaviors of the rocks, developed in underground openings in different rock constructions in different areas. It is thought that the TLDS hypersurfaces will especially be contributed to the numerical modeling studies of rock construction analysis.     

Prediction of soil loss differences and sediment accumulation at the Nilufer creek watershed,Turkey, using multiyear satellite data in a GIS

This study integrates the RUSLE, remote sensing and GIS to assess soil loss and identify sensitive areas to soil erosion in the Nilufer creek watershed in Bursa province, Turkey. The annual average soil loss was generated separately for years 1984 and 2011, in order to expose possible soil loss differences occurred in 27 years. In addition, sediment accumulation and sediment yield of the studied watershed was also predicted and discussed. The results indicated that very severe erosion risk areas in 1984 was 13.4% of the area, but it was increased to 15.3% by the year 2011, which needs immediate attention from soil conservation point of view. Furthermore, the estimated annual sediment yield of the Nilufer creek watershed was increased from 903 to 979 Mg km^?2 y^?1 in 27 years period. The study also provides useful information for decision-makers and planners to take appropriate land management practices in the area.     

Pre‐treatment of Waste Foundry Sand Via Solidification/Stabilization

This study was performed to propose a suitable treatment for waste foundry sand (WFS) before persistent disposal. It was observed that solidification/stabilization (S/S), which is the common pre‐treatment method because of its comparatively easy and inexpensive applicability, can treat WFS including dissolved organic carbon (DOC) above hazardous landfilling limits. Regular sand was partially replaced with WFS with a ratio of 0–90 wt% in order to prepare three different kinds of mortar samples, where Portland limestone cement (PLC) alone, calcium lime (CL) alone, and PLC together with CL were contained as binders. Leaching behaviors of all S/S products were analyzed according to the TS EN 12457‐4 leaching test. The treatment efficiency was assessed to reduce the DOC content to the levels under the European landfill acceptance criteria. Furthermore, heavy metals (Ni, Zn, Cr), fluoride (F^?), total dissolved solids leachability, and total organic carbon content were analyzed in order to investigate the pre‐treatment ability and to determine whether S/S products can be disposed of in a landfill site with municipal wastes or in a separate landfill site. The results showed that S/S of WFS is an efficient pre‐treatment technique before its disposal in a landfill and provides economical advantages compared to hazardous waste landfilling.