Reflections and standing waves on the Tianlai cylinder array

In 21 cm intensity mapping,the spectral smoothness of the foreground is exploited to separate it from the much weaker 21 cm signal.However,the non-smooth frequency response of the instrument complicates this process.Reflections and standing waves generate modulations on the frequency response.Here we report the analysis of the standing waves in the bandpass of the signal channels of the Tianlai Cylinder Array.By Fourier transforming the bandpass into the delay time domain,we find various standing waves generated on the telescope.A standing wave with time delay at~142 ns is most clearly identified which is produced in the 15-meter feed cable.We also identify a strong peak at a shorter delay ofτ<50 ns,which may be a mix of the standing wave between the reflector and feed,and the standing wave on the 4 m intermediate frequency(IF)cable.We also show that a smoother frequency response could be partially recovered by removing the reflection-inducted modulations.However,the standing wave on the antenna is direction-dependent,which poses a more difficult challenge for high precision calibration.     

Earthquake source characteristics along the arcuate Himalayan belt: Geodynamic implications

The occurrences of moderate to large magnitude earthquakes and associated subsurface geological processes were critically examined in the backdrop of Indian plate obliquity, stress obliquity, topography, and the late Tertiary regional tectonics for understanding the evolving dynamics and kinematics in the central part of the Himalayas. The higher topographic areas are likely associated with the zones of depressions, and the lower topographic areas are found around the ridges located in the frontal part of the orogen. A positive correlation between plate and stress obliquities is established for this diffuse plate boundary. We propose that the zone of sharp bending of the descending Indian lithosphere is the nodal area of major stress accumulation which is released occasionally in form of earthquakes. The lateral geometry of the Himalayas shows clusters of seismicity at an angle of ～20^° from the centre part of the arc. Such spatial distribution is interpreted in terms of compression across the arc and extension parallel to the arc. This biaxial deformation results in the development of dilational shear fractures, observed along the orogenic belt, at an angle of ～20^° from the principal compressive stress axis.     

Determination of water balance equation components in irrigated agricultural watersheds using SWAT and MODFLOW models : A case study of Samalqan plain in Iran

Increasing water demands,especially in arid and semi-arid regions,continuously exacerbate groundwater as the only reliable water resources in these regions.Samalqan watershed,Iran,is a groundwater-based irrigation watershed,so that increased aquifer extraction,has caused serious groundwater depletion.So that the catchment consists of surface water,the management of these resources is essential in order to increase the groundwater recharge.Due to the existence of rivers,the low thickness of the alluvial sediments,groundwater level fluctuations and high uncertainty in the calculation of hydrodynamic coefficients in the watershed,the SWAT and MODFLOW models were used to assess the impact of irrigation return flow on groundwater recharge and the hydrological components of the basin.For this purpose,the irrigation operation tool in the SWAT model was utilized to determine the fixed amounts and time of irrigation for each HRU(Hydrological Response Unit)on the specified day.Since the study area has pressing challenges related to water deficit and sparsely gauged,therefore,this investigation looks actual for regional scale analysis.Model evaluation criteria,RMSE and NRMSE for the simulated groundwater level were 1.8 m and 1.1%respectively.Also,the simulation of surface water flow at the basin outlet,provided satisfactory prediction(R²=0.92,NSE=0.85).Results showed that,the irrigation has affected the surface and groundwater interactions in the watershed,where agriculture heavily depends on irrigation.Annually 11.64 Mm3 water entered to the aquifer by surface recharge(precipitation,irrigation),transmission loss from river and recharge wells 5.8 Mm3 and ground water boundary flow(annually 20.5 Mm³).Water output in the watershed included ground water extraction and groundwater return flow(annually 46.4 Mm³)and ground water boundary flow(annually 0.68 Mm³).Overally,the groundwater storage has decreased by 9.14 Mm3 annually in Samalqan aquifer.This method can be applied to simulate the effects of surface water fluxes to groundwater recharge and river-aquifer interaction for areas with stressed aquifers where interaction between surface and groundwater cannot be easily assessed.     

Observations on the ichnospecies <Emphasis Type="Italic">Monomorphichnus multilineatus</Emphasis> from the Nagaur Sandstone (Cambrian Series 2-Stage 4), Marwar Supergroup,India

The Ediacaran–Cambrian Marwar Supergroup exposed in the western Rajasthan, India yielded abundant sigmoidal scratches assigned to ichnospecies Monomorphichnus multilineatus from the Nagaur Sandstone belonging to the Cambrian (Series 2-Stage 4). Nagaur M. multilineatus are recorded from the intertidal regime. It is an addition to already known depositional environments for this ichnospecies, which are known from shallow marine, wave-dominated, to non-marine or brackish water and storm-dominated sequences. Classical systematics of M. multilineatus is enriched with additional information in the paper. Its significance has been discussed regarding the palaeoecology of trace producers. Comprehensive statistical analyses help reveal its behaviour and feeding pattern of the causative organism of M. multilineatus. Hierarchical Cluster Analysis (HCA), average linkage and Pearson Correlation were performed to establish the natural grouping and behaviour of the specimens. HCA indicates that the studied Nagaur specimens belong to ichnogenera Monomorphicnus and ichnospecies, i.e., multilineatus. Pearson correlation, involving thickness and length of individual specimen, was positive. It indicates that the amount of food required by individual adult specimen was more and thereby requiring more grazing to provide enough food for survival. All the known occurrences of M. multilineatus are reviewed in the present study for their mode of preservation, depositional environment, palaeoecology and taphonomy.     

Near-source strong motion database catalog for Iran

This paper discusses a newly developed high-quality integrated dataset of shallow earthquake ground motions that occurred in Iran, from 1976 to 2013. A total of 860 three-component strong motion records are processed from 183 earthquake events, moment magnitudes 5.0?≤?M _w ?≤?7.4, and rupture distances of R _RUP  ≤ 120 km. Strong motion data from Iran having special tectonic features and shallow earthquakes with depths less than 35 km are included. This paper presents a thorough procedure used to collect and to generate a database following the Next-Generation Attenuation-West research projects. This database can be used in the development and ranking of ground motion models and for seismological and engineering hazard and risk analyses. Unprocessed strong motion records are obtained from the Iranian Strong Motion Network (ISMN). The time series collected were thoroughly examined through several rounds of quality reviews. The newly generated database includes the peak ground acceleration, peak ground velocity, and pseudo-spectral acceleration for the 5% damped with periods ranging from 0.01 to 10 s. The database also includes ground motion information and source characterization and parameters. This study is the near-source compiled ground motion database that can be used for Iran, and it is consistent with standard worldwide databases.     

Nonlinear analysis of seasonality and stochasticity of the Indus River

Abstract

One of the world's largest irrigation networks, based on the Indus River system in Pakistan, faces serious scarcity of water in one season and disastrous floods in another. The system is dominated both by monsoon and by snow and glacier dynamics, which confer strong seasonal and inter-annual variability. In this paper two different forecasting methods are utilized to analyse the long-term seasonal behaviour of the Indus River. The study also assesses whether the strong seasonal behaviour is dominated by the presence of low-dimensional nonlinear dynamics, or whether the periodic behaviour is simply immersed in random fluctuations. Forecasts obtained by nonlinear prediction (NLP) and the seasonal autoregressive integrated moving average (SARIMA) methods show that the performance of NLP is relatively better than the SARIMA method. This, along with the low values of the correlation dimension, is indicative of low-dimensional nonlinear behaviour of the hydrological dynamics. A relatively better performance of NLP, using an inverse technique, may also be indicative of the low-dimensional behaviour. Moreover, the embedding dimension of the best NLP forecasts is in good agreement with the estimated correlation dimension. This provides evidence that the nonlinearity inherent in the monthly river flow due to the snowmelt and the monsoon variations dominate over the high-dimensional components and might be exploited for prediction and modelling of the complex hydrological system.

Citation Hassan, S. A. & Ansari, M. R. K. (2010) Nonlinear analysis of seasonality and stochasticity of the Indus River. Hydrol. Sci. J. 55(2), 250–265.     

Effects of long-term wastewater irrigation on soil physical properties and performance of selected infiltration models in a semi-arid region

ABSTRACT

In many arid and semi-arid countries, wastewater irrigation is becoming a common practice in agriculture. In this study, the effect of long-term (40 years) wastewater irrigation on selected physical and hydraulic properties of soil in different parts of a landscape was investigated. The performance of some infiltration models, including Philip (Ph), Kostiakov (Kos), Kostiakov-Lewis (Kos-L), Horton (Ho), Huggins and Monke (Hug-M), and linear and nonlinear Smith-Parlange (S-P(L) and S-P(NL)), was compared. This study was performed in the Urmia region, Iran, where flooding wastewater irrigation has been practised for at least 40 years. Five paired sites, each of which contained a measurement location at the wastewater-irrigated (WWI) and adjacent control area were studied. Accuracy of the infiltration models was evaluated using several statistical criteria, including root mean square error (RMSE) and Akaike information criterion (AIC). The models were classified into groups using cluster analysis based on level of similarity in their performance. The cumulative water infiltration into soils after 1 h (I_1h) was calculated using the selected most accurate models and introduced so as to use only one term to compare the infiltration behaviour of soils. Based on RMSE and AIC, the performance of the Ph, Ho, Kos and Kos-L models was considerably better than that of Hug-M, S-P(L) and S-P(NL). The ranking of the models in terms of their AIC values was: Kos-L > Ho > Kos > Ph > S-P(L) > Hug-M > S-P(NL). The models were classified into two distinct groups. The similarity among Ph, Ho, Kos and Kos-L models was more than 80% and for Hug-M, S-P(L), and S-P(NL) models, it was more than 79%. However, the similarity between these two groups of models was less than 58%.

Editor M.C. Acreman; Associate editor not assigned     

Screening Indian Mustard Genotypes for Phytoremediating Arsenic‐Contaminated Soils

Ten Indian mustard (Brassica juncea L.) genotypes were screened for their phytoremediation potential for arsenic (As) contaminated water under laboratory‐controlled conditions. The genotypes were grown in a hydroponic chamber for 20 days in 250‐mL beakers containing As‐contaminated water. During plant development, changes in plant growth, biomass, and total As were evaluated. Of the 10 genotypes (Pusa Agrani, BTO, Pusa Kranti, Pusa Bahar, Pusa Bold, Pusa Basant, Pusa Jai Kisan, Arka Vardhan, Varuna, and Vaibhav) Pusa Jai Kisan was the most effective in phytoremediating As‐contaminated water under hydroponic conditions. This will provide new information for Indian mustard genotypes for phytoremediating As‐contaminated soils.     

Integrated approach of geospatial visualization and modeling for groundwater management in hard rock terrains in Nagpur Urban Area,India

Groundwater management requires complete visualization of aquifer characteristics to understand scientific aspects and hence remains a challenge, especially in hard rock terrains. In the present research paper, a comprehensive approach using 3D stratigraphic model, fence diagrams and numerical modeling has been proposed to understand the groundwater status for effective recharge. The stratigraphy, groundwater flow, and groundwater fluctuations for the period 1999–2010 were analyzed. The total volume of formations, volume of voids, storage capacity, and quantities of recharge of unconfined aquifer system in the Nagpur urban area were estimated. The steady state groundwater flow model of Basalt formation was calibrated to evaluate the subsurface system using Processing Modflow (PMWIN 5.3.2). The calibrated hydraulic head is compared with field observed head. The comparative spatial analysis presents a simple integrated approach in identifying zones with falling groundwater trends suitable for groundwater recharge in hard rock terrain in Nagpur urban area.