The application of groundwater modelling to simulate the behaviour of groundwater resources in the Ramhormooz Aquifer, Iran.

In this study, groundwater modelling was proposed as management tool in Ramhormooz Plain, south western Iran. After definition of a conceptual model, the necessary data were defined into various packages of MODFLOW. Subsequently, the model was calibrated by trial and error estimation and the results were finally optimised by PMWIN through PEST code. After verification process, the model was used as a management tool for evaluating four management alternatives, including prediction of groundwater levels according to average historical recharge and discharge conditions, development of aquifer, prediction of aquifer response to installation of drainage and response against conjunctive use of surface water and groundwater in critical areas

Evaluating the Potential of Groundwater Pollution in Kherran and Zoweircherry Plains through GIS-based DRASTIC Model

Zoweircherry and Kherran plains are located in the northeast ofAhwazin Khuzestan province. The water supply of these plains is a crucial issue and the quality of groundwater is also under the threat as a result of an increase in the use of agrochemicals. For this reason, assessing the vulnerability is an important factor in any policy-making decision for these plains. Focusing on this issue, this paper attempts to produce a groundwater vulnerability map for Zoweircherry and Kherran plains. The map is designed to show areas of highest potential for groundwater pollution on the basis of hydro-geological conditions and human impacts. Seven major hydro-geological factors (depth to water table, net recharge, aquifer media, soil media, topography, impact of vadose zone and hydraulic conductivity) were incorporated into DRASTIC model and Geographical Information System (GIS) was used to create a groundwater vulnerability map by overlaying the available hydro-geological data. The results of model exhibit that the west and southwest of the aquifer are dominated by medium vulnerability while small areas on northwest and east of the study area have no risk of pollution. Other parts of aquifer have low vulnerability. The nitrate analysis of groundwater samples shows that the existing nitrate on the west and southwest parts of aquifer is more than the existing nitrate on its other parts which, therefore, confirms the results of the vulnerability assessment

Land Use Management by Assessing Aquifer Vulnerability in Khovayes Plain Using the DRASTIC and SINTACS Models

Land use change is a gradual process that entails dire consequences for groundwater quality and quantity. Quantitative changes in groundwater can be usually monitored by controlling the annual groundwater balance. Monitoring qualitative changes in groundwater, however, is both time-consuming and expensive. DRASTIC and SINTACS models exploit aquifer properties to predict its vulnerability. In this study, aquifer vulnerability assessment was performed by the DRASTIC & SINTACS models for future land use management in Khovayes, southwest Iran. The DRASTIC Model is based on hydrological and hydrogeological parameters involved in contaminant transport. SINTACS parameters are the same as those of the DRASTIC model, except that weighting and ranking the parameters are more flexible. Once vulnerability maps of the study region had been prepared, they were verified against the nitrate map. A correlation coefficient of 0.4 was obtained between the DRASTIC map and the nitrate one while the correlation between the SINTACS and the nitrate maps was found to be 0.8. Map removal and single-parameter sensitivity analyses were carried out, which showed the southwestern stretches of the study area as the region with the highest risk of vulnerability

Application of Time Series Analysis in Determination of Lag Time in Jahanbin Basin

شماره 51- سال 1383                                                                                                                        آب و فاضلاب     One of the important issues that have significant role in study of hydrology of basin is determination of lag time. Lag time has significant role in hydrological studies. Quantity of rainfall related lag time depends on several factors, such as permeability, vegetation cover, catchments slope, rainfall intensity, storm duration and type of rain. Determination of lag time is important parameter in many projects such as dam design and also water resource studies. Lag time of basin could be calculated using various methods. One of these methods is time series analysis of spectral density. The analysis is based on fouries series. The time series is approximated with Sinuous and Cosines functions. In this method harmonically significant quantities with individual frequencies are presented. Spectral density under multiple time series could be used to obtain basin lag time for annual runoff and short-term rainfall fluctuation. A long lag time could be due to snowmelt as well as melting ice due to rainfalls in freezing days. In this research the lag time of Jahanbin basin has been determined using spectral density method. The catchments is subjected to both rainfall and snowfall. For short term rainfall fluctuation with a return period  2, 3, 4 months, the lag times were found 0.18, 0.5 and 0.083 month, respectively

Zonation of groundwater quality in terms of drinkability, using Fuzzy Logic and Schoeller deterministic method for Northern Dezful - Andimeshk Plain, Iran

Abstract In the Northern Dezful-Andimeshk Plain, the primary source of drinking water is groundwater, which has low quality in some places. Thus, groundwater quality in this area needs an accurate evaluation. In this research, the fuzzy and Schoeller deterministic method assessed the Northern Dezful-Andimeshk Plain drinking water, and the results of both methods were used to zone and compare the drinking quality of the plain groundwater in the Arc GIS environment. The deterministic method classifies drinking water quality from good to bad. According to this method, 56.81% of the total area of the plain has good quality, 20.83% of the total area is acceptable, 18.77% of the total area has inappropriate quality, and 3.57% of the total area has bad quality. However, in the fuzzy method, groundwater in 21.6% of the total area of the plain with a confidence percentage of 70% to 81% is desirable, in 75.23% of the total area of the plain with a confidence percentage of 32% to 70% is acceptable, and 3.69% of the total area of the plain with drinking confidence of 20% to 22% is nonacceptable. The results showed that the fuzzy method is better than the Schoeller deterministic method because it reduces uncertainties, increases accuracy in the evaluation, increases flexibility in the threshold limits of water quality parameters, and provides a quantitative and qualitative assessment of drinking water. Also the zoning map obtained from this method is more compatible with environmental and pollution realities. Graphical Abstrac

Initial assessment of recharge areas for large karst springs: a case study from the central Zagros Mountains, Iran

Sousan Spring emerges from the Keyno Anticline, Zagros Mountains (Iran), and the mean annual discharge is ~24 m3 /s. Geological and hydrochemical evaluations suggest that the spring recharge is from the limestone Ilam-Sarvak Formation (Cretaceous) but the Mafaroon Fault, a major thrust feature, influences the regional groundwater flow path by juxtaposing other strata. Geological, geochemical, stable isotope and water balance studies were employed to interpret this behavior. Using the isotope data, the sources and elevations of the recharge area were found. Temporal variations of the isotopic data were compared with variations of electrical conductivity (EC). Unexpectedly, high EC was associated with a relative increase of discharge and depletion of δ18O. Several hypotheses were investigated and approximate water balance studies employed for validation. It was found that an elongated catchment on the Keyno Anticline plus a lesser catchment on a pair of parallel anticlines recharge the aquifer. While the long groundwater flow path along the Keyno Anticline plus guidance by Mafaroon Fault and the adjacent Garou shaly strata lead to increased EC in the Sousan Spring at the end of the dry season, a flow pulse from two adjoining anticlines (Mahalbakh and Shirgoon) arrives at the same time to increase the discharge and deplete the δ18O signal. Apparently the spring did not experience true base flow conditions during the recorded hydrological year. Although the spring response to specific precipitation events was similar to typical karst aquifers, standard interpretation of recession curves and related coefficients will not be practical at Sousan