Development of water management strategies in southern Mesopotamia during the fourth and third millennium B.C.E.

The last two decades witnessed increasing scholarly interest in the history of water management in southern Mesopotamia. Thanks to many geoarchaeological research projects conducted throughout the central and southern Iraqi floodplains, a general understanding of the macrophases of anthropogenic manipulation of this vast hydraulic landscape has been achieved. However, current narratives mostly rely on studies at a regional scale and are based on excessively long chronological phases (often spanning a whole millennium). A finer-tuned analysis at a submillennial scale is needed to better appreciate the dynamics that led to the development of artificial canals and irrigation systems and the creation of harbours in cities and other navigation-related facilities. The Iraqi-Italian QADIS project is addressing this issue through a systematic geoarchaeological investigation in the south-eastern area of the Qadisiyah province. We aim to update the current narrative by analysing case studies involving specific periods of occupation. We performed 17 boreholes to propose a date on the functioning period of the hydraulic works in five selected archaeological sites of this region. This approach allowed us to understand changes in water management strategies in both the short and the medium term (i.e., on a scale of centuries). In this paper, we present the results for the fourth and third millennia B.C.E. This period witnessed a crucial passage from the basic exploitation of natural watercourses for irrigation and occasional navigation to the emergence of the first system of artificial canals and intraurban harbours.     

North Qorveh volcanic field,western Iran: eruption styles,petrology and geological setting

Mineralogy and Petrology - In the metamorphic Sanandaj-Sirjan Zone of western Iran, the “North Qorveh Volcanic Field” is constituted by Pleistocene scoria cones and associated deposits....     

Facies Analysis, Sequence Stratigraphy and Diagenetic Studies of the Jurassic Carbonates of the Kohat Basin, Northwest Pakistan: Reservoir Implications

The present study deals with the depositional facies, diagenetic processes and sequence stratigraphy of the shallow marine carbonates of the Samana Suk Formation, Kohat Basin, in order to elucidate its reservoir quality. The Samana Suk Formation consists of thin to thick-bedded, oolitic, bioclastic, dolomitic and fractured limestone. Based on the integration of outcrop, petrographic and biofacies analyses, the unit is thought to have been deposited on a gentle homoclinal ramp in peritidal, lagoonal and carbonate shoal settings. Frequent variations in microfacies based sea-level curve have revealed seven Transgressive Systems Tracts (TSTs) and six Regressive Systems Tracts (RSTs). The unit has undergone various stages of diagenetic processes, including mechanical and chemical compaction, cementation, micritization, dissolution and dolomitization. The petrographic analyses show the evolution of porosity in various depositional and diagenetic phases. The fenestral porosity was mainly developed in peritidal carbonates during deposition, while the burial dissolution and diagenetic dolomitization have greatly enhanced the reservoir potential of the rock unit, as is further confirmed by the plug porosity and permeability analyses. The porosities and permeabilities were higher in shoal facies deposited in TSTs, as compared to lagoonal and peritidal facies, except for the dolomite in mudstone, deposited during RSTs. Hence good, moderate and poor reservoir potential is suggested for shoal, lagoonal and peritidal facies, respectively.     

Recognition of the time and level of emplacement of the Sillai Patti carbonatite complex,Malakand Division,Northwest Pakistan: Constraints from fission-track dating

The Sillai Patti carbonatite complex represents the second largest carbonatite body of the Peshawar Plain Alkaline Igneous Province of northern Pakistan. It is situated about 20 km west of Malakand, near Sillai Patti village. Here, the carbonatite occurs along a fault in the form of a sheet striking in the NNE–SSW direction and dipping towards south. The carbonatite body is about 12 km long and 2–20 m thick, predominantly intruded along the faulted contact of metasediments and granite gneiss but locally, within the metasediments.A fission-track age of 29.40 ± 1.47 Ma was obtained for the Sillai Patti carbonatite complex. Close resemblance of fission-track apatite age of this study with the fission-track as well as other high temperature radiometric ages from the same and the neighboring carbonatite complexes of the alkaline belt of northern Pakistan suggests emplacement of the Sillai Patti carbonatite complex at higher crustal level and subsequent extremely fast cooling to near ambient temperatures (<60 °C) required for the complete retention of fission tracks in apatite. The age data also point out that the fission-track age of 29.40 ± 1.47 Ma of this study is the age of intrusion of the carbonatitic magma of Sillai Patti carbonatite complex to shallow, near-surface level.Comparison of the uplift induced denudation rates of the region with the world data clearly reflects the presence of a post collisonal extensional environment in the region south of Main Mantle Thrust during Oligocene time. This strongly negates the idea of the earlier workers of emplacement of the carbonatite complexes of the Loe-Shilman and Sillai Patti areas along thrust faults during Oligocene.     

Unstable modes of non-axisymmetric gaseous discs

We present a perturbation theory for studying the instabilities of non-axisymmetric gaseous discs. We perturb the dynamical equations of self-gravitating fluids in the vicinity of a non-axisymmetric equilibrium, and expand the perturbed physical quantities in terms of a complete basis set and a small non-axisymmetry parameter ε. We then derive a linear eigenvalue problem in matrix form, and determine the pattern speed, growth rate and mode shapes of the first three unstable modes. In non-axisymmetric discs, the amplitude and the phase angle of travelling waves are functions of both the radius R and the azimuthal angle φ. This is due to the interaction of different wave components in the response spectrum. We demonstrate that wave interaction in unstable discs, with small initial asymmetries, can develop dense clumps during the phase of exponential growth. Local clumps, which occur on the major spiral arms, can constitute seeds of gas giant planets in accretion discs.     

Risk assessment of agricultural water requirement based on a multi-model ensemble framework,southwest of Iran

Water shortage and climate change are the most important issues of sustainable agricultural and water resources development. Given the importance of water availability in crop production, the present study focused on risk assessment of climate change impact on agricultural water requirement in southwest of Iran, under two emission scenarios (A2 and B1) for the future period (2025–2054). A multi-model ensemble framework based on mean observed temperature-precipitation (MOTP) method and a combined probabilistic approach Long Ashton Research Station-Weather Generator (LARS-WG) and change factor (CF) have been used for downscaling to manage the uncertainty of outputs of 14 general circulation models (GCMs). The results showed an increasing temperature in all months and irregular changes of precipitation (either increasing or decreasing) in the future period. In addition, the results of the calculated annual net water requirement for all crops affected by climate change indicated an increase between 4 and 10 %. Furthermore, an increasing process is also expected regarding to the required water demand volume. The most and the least expected increase in the water demand volume is about 13 and 5 % for A2 and B1 scenarios, respectively. Considering the results and the limited water resources in the study area, it is crucial to provide water resources planning in order to reduce the negative effects of climate change. Therefore, the adaptation scenarios with the climate change related to crop pattern and water consumption should be taken into account.

     

Analysis of recharge conceptualization in inverse groundwater modelling

ABSTRACT

This study presents a systematic illustration quantifying how misleading the calibration results of a groundwater simulation model can be when recharge rates are considered as the model parameters to be estimated by inverse modelling. Three approaches to recharge estimation are compared: autocalibration (Model 1), the empirical return coefficient method (Model 2), and distributed hydrological modelling using the Soil and Water Assessment Tool, SWAT (Model 3). The methodology was applied in the Dehloran Plain, western Iran, using the MODFLOW modular flow simulator and the PEST method for autocalibration. The results indicate that, although Model 1 performed the best in simulating water levels at observation wells in the calibration stage, it did not perform satisfactorily in real future scenarios. Model 3, with SWAT-based recharge rates, performed better than the other models in the validation stage. By not evaluating the model performance solely on calibration results, we demonstrate the relative significance of using more accurate recharge estimates when calibrating groundwater simulation models.

EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR M. Besbes