Showing 33 results for Groundwater
Kh. Bargahi, S. A. A. Moosavi,
Volume 10, Issue 3 (10-2006)
Abstract
Limitation of suitable water resources is the most important problem of agriculture in Iran. Considering the condition of shallow and saline groundwater in many parts of Iran, and relative resistance of safflower to salinity, it is necessary to study the contribution of groundwater to water consumption of safflower. In this research, the effects of different water table depths and salinity of groundwater on contribution of groundwater to evapotranspiration of safflower were studied. The treatments were four levels of water table depth (50, 70, 90, and 120 cm), two levels of groundwater salinity (EC of 0.6, and 10 dSm-1 ), and two irrigation regimes (irrigation with a depth of water equal to 75 percent of evaporation from water surface and frequency of 5 days, and no irrigation). The experiment was performed in a randomized complete block design with treatment combinations arranged in factorial manner and three replications. For fixing the water table in the pots (PVC pipe 200 mm in diameter and 120 cm high), a special equipment was built on the principle of Marriot bottle that was able to measure the contribution of groundwater to evapotranspiration of the plants. Results showed that salinity of groundwater, irrigation regime, and their interactions have significant effects on evapotranspiration of safflower. In addition, effects of water table depth, salinity of groundwater, irrigation regime, interaction of salinity and water table depth, interaction of water table depth and irrigation regime, and interaction of water table depth, salinity, and irrigation regime on evaporation from soil surface were significant. The ratio of contribution of groundwater to plant water consumption and evapotranspiration was in the range of 52.5 and 54.9% for saline groundwater and 81.7 to 82.7% for fresh groundwater. The ratio of evaporation from soil surface and evapotranspiration was in the range of 4.5 to 53.6% for different treatments. In all treatments of groundwater depths, irrigation treatment significantly decreased evapotranspiration, but no significant change in evapotranspiration was observed in irrigated and no irrigated treatments. Maximum amount of evapotranspiration (251 cm) occurred in the 50 cm depth of groundwater with salinity of 0.6 dS/m under irrigated condition, and minimum amount (43.9 cm) occurred in the 90 cm depth to groundwater with salinity of 10 dS/m under no irrigation condition. Generally, salinity of groundwater caused significant decrease in evapotranspiration, evaporation from soil surface, transpiration, and contribution of groundwater to evapotranspiration.
M. Sabohi, Gh. Soltani, M. Zibaie,
Volume 11, Issue 1 (4-2007)
Abstract
The objective of this study was to evaluate the strategies for groundwater resources management, including competition groundwater pumping, optimal control in groundwater pumping, groundwater use and tax policy, water users' participation in groundwater pumping control, and cooperation among government and water user associations in Narimany plain located in Khorasan Province. Irrigation water demand of sugar beet growers was estimated for empirical assessment of the strategies. The results indicated that among the strategies, groundwater use and tax policy may lead growers to sustainable use of groundwater resources. Furthermore, the results showed a desirable strategy is affected by cultural, social, and economic characteristics of growers and general prevalent conditions of society. Moreover, each strategy calls for its obligations, for instance, it is necessary to have an efficient taxation system for the proposed strategy. Hence, by internalizing the external cost of groundwater overdraft (that is taxing water users) government can force them to consider the adverse effects of their decisions on other producers.
E Marouf Pour, H Moazed, H.a Kashkouli, H Moahamad Vali Samani,
Volume 12, Issue 46 (1-2009)
Abstract
Tracer experiments are very important in the studies related to aquifer contamination for determination of dispersion coefficient. In this study, the effect of sampling method on the dispersion coefficients of two simulated sandy aquifers was examined. The physical model was made from Plexiglas material with inner length, width and height of 72, 10 and 120 cm, respectively. A solution containing 9 g/l sodium chloride (Ec = 14 ds/m) was used as the non - reactive (conservative) contaminant. Homogeneous sands with coarse and medium particle sizes were used as media for the simulated aquifers. The experiments were carried out in the aquifers with various thicknesses from 20 to 100 cm with 10 cm thickness increment. Point and mixed samples were taken through all experiments. The results of the study showed that (1) for both simulated aquifers, the dispersion coefficient values obtained by point sampling method were close to the values obtained by other researchers from laboratory experiments (2) In all the experiments, the dispersion coefficient values obtained by mixed sampling method were higher than those obtained by the point sampling method (3) with increasing the aquifer thickness, the dispersion coefficient values obtained from the mixed samples varied but did not have a uniform trend which could be due to the unavoidable experimental errors and (4) there was no difference between the breakthrough and pore volume curves of various aquifer thicknesses obtained from point and mixed samples. Overall, based on the results obtained from this research, in studies related to aquifer contamination, it is recommended to take point samples instead of mixed samples to obtain more precise results.
M Valipour, M Karimian Eghbal, M.j Malakouti, A Khosh Goftamanesh,
Volume 12, Issue 46 (1-2009)
Abstract
Salinization and alkalization are considered spatiotemporal dynamic soil degradation processes. In order to investigate the effects of agricultural activities on land degradation and soil salinity, Shamsabad area in Qom province was selected. Aerial photos (1955) and satellite images (1990-2002) were used to examine the changes in land use. Soil samples were collected from 25 locations in the study area from 0-50 cm and 51-100 cm depth at each location. For comparative purposes, sampling locations in this study were similar to locations used for salinity study in 1983. For each sample, pH, electrical conductivity (ECe), base saturation percentage, exchangeable sodium, lime and texture were measured. Land use and salinity maps were created by using geographic information system (GIS) softwares. Results revealed an increase of 9.5 times in cultivated lands in 47 years. Increase in agricultural activities in the study area has also intensified the pressure on water resource in the area, lowering ground water tables and degrading water quality. In the 0-50 cm soil depth, the average soil ECe was 6.5 dS/m in 1983, which increased to 10.7 dS/m in 2005. If soil salinity trend and pressure on water resources continue, large part of Shamsabad area is expected to change to desert in near future years.
S. M. Mousavi, A. Hoshmand, S. Bromandnasab, M. Yazdani,
Volume 16, Issue 60 (7-2012)
Abstract
The common method of irrigating rice in paddy fields of Iran, like most countries, is flooded irrigation. The water required in this method is too much. However, because of water shortage in recent years, and malfunctioning of irrigation systems, it is needed to use water in a reasonable way and increase water use efficiency. Therefore, it is necessary to know water loss amounts at the paddy fields. The deep percolation (DP) was measured by closed- and open-bottom rings in 4 locations, and 7 sites at each location, of paddy fields in Somae-Sara city, Guilan province. These locations were selected on the base of different physiographic units. The average DP of these locations was also monitored during plant growth season. The measurements were performed twice a week. Results showed that the rate of DP varied during the season, and could take a positive or negative value. The most important factors of these variations were the lateral seepage (from surrounding rice fields) and the high perched groundwater table in paddy fields.
E. Sahebjalal, F. Dehghany, M. S. Tabatabaeezade,
Volume 17, Issue 65 (12-2013)
Abstract
Groundwater is the most important source of water supply for agricultural purposes in arid and semi-arid areas. In many areas, excessive use of high quality water resources leads to reducing the available water resources and turning to the use of low quality water resources. Thus, knowing the temporal and spatial variation of groundwater quality is a necessary factor for implementation of sound water resource management and establishment of the suitability between water quality and its usage. In order to investigate water quality changes, this study was divided into two phases. In the first phase, for evaluation of the quality of groundwater for irrigation 76 wells were sampled in Bahadoran plain, in the year 2006. The SAR, EC, ions B3+ and Cl- were analyzed as the evaluation indexes. Then, using geostatistical methods the maps of each parameter were prepared. Finally, considering FAO criteria, these maps were overlaid and separate water quality maps were derived. The EC map indicated that in 48 and 52 percent of the groundwater lies in severe and slight to moderate restriction class for irrigation purposes. Moreover, the thematic map of infiltration restrictions indicates that the groundwater has no restriction in 66 percent of the area while 11% of groundwater causes low to moderate and 23 percent causes severe limitation. In the next phase, to examine changes in groundwater salinity during a 5-year period, 38 wells were sampled and the groundwater salinity map for the year 2011 was prepared. Finally, using subtraction of the salinity maps of given years, the salinity changes map was derived. The results of thematic map showed that groundwater salinity increased in 26.47 percent of the study area. In contrast, there was a decrease of about 31.14 percent in groundwater salinity over the 5-year period while 42.39 percent of the region’s groundwater remained unchanged. Since the study area is under cultivation of pistachios and salt threshold of this tree is 8 ds/m so the area of about 8 percent of the area was added to the previous limited areas. Therefore, irrigation management and planting development plan in Eastern and Southeastern areas should be revised.
I. Vayskarami, K. Payamani, A. Shahkarami, A. Sepahvand,
Volume 17, Issue 65 (12-2013)
Abstract
The main aim of flood water spreading in Iran is to recharge groundwater. Understanding the effect and efficiency of such projects is one of the most important activities in managing and implementing water spreading. The purpose of this study was to investigate the effects of water spreading on groundwater resources in Kohdasht plain. Data and information required including precipitation rate, groundwater level and groundwater exploitation were collected and analyzed for a ten year period. First of all, in order to assess the three variables test of normality was performed and then all the data was normalized. The results showed that before implementing the water spreading project, fluctuations of groundwater were proportional to utilization of groundwater resources, showing a declining rate. After implementing the project, a turning point on groundwater level was observed. Also, another turning point was recognizable in hydrological year 1377-1378. In addition to overexploitation, drought affected the aquifer so dramatically that standard index in hydrological year 1371-1372 decreased from 0.3 to -1.5 in hydrological year 1377-1378.
R. Jafari, L. Bakhshandehmehr,
Volume 18, Issue 68 (9-2014)
Abstract
Continuous decline of groundwater quality for agricultural purposes has become a major concern in extensive arid and semi-arid regions. Therefore, mapping the quality of groundwater on a broad scale is an essential step in land management. This study aimed to map spatial distribution of two important groundwater quality indices including EC and SAR in Isfahan province, Iran, using geostatistical techniques. Different techniques such as Kriging, IDW and
RBF were applied to water quality data of 540 groundwater wells to map continuous variations of the EC and SAR indices in Arc GIS 9.3 environment. Among the interpolation methods, the Kriging by circular variogram model performed best and had the lowest RMSe error. Therefore, the produced maps from this technique were classified based on Wilcox method. Results showed that EC varies across the province from 392.2 in the west to about 17917.6 µmmhos/ cm in the northwest and eastern parts of the study area. The highest and lowest SAR values were estimated in the towns of Khour va Biabanak and Semirom, ranging from 38.9 to 0.13, respectively. According to the map of irrigation water quality based on Wilcox method, about 12.13 % of the region was classified as good, 16% as moderate, 17.5% as unsuitable and 54.35% as unusable category. In general, the quality of groundwater in Isfahan province decreases from west to east and also from south to north, especially in playas (non-agricultural lands) where the unusable class is dominant.
M. R. Yazdani, M. Parsinejad, A. R. Sepaskhah, N. Davatgar, S. Araghinejad,
Volume 18, Issue 69 (12-2014)
Abstract
Intermittent irrigation of paddy fields with long intervals can cause cracks in heavy soils, facilitate loss of water and finally damage the crop. This study was carried out in order to investigate the cracking trend and some other factors affecting soil cracking in four different physiographical areas of paddy field. The study areas were Rasht, Shanderman, Astaneh and Khomam in Guilan province. The experiment was carried out in paddy fields with transplanted rice by determining the physical properties relevant to cracking behavior after irrigation withdrawal in the reproductive stage. Soil analysis showed that despite similarity in type of dominant minerals, the linear expansion coefficients of Rasht and Khomam soils were higher than those of two other areas. In addition, there was a significant relationship between crack dimensions and volumetric soil water content and clay content. Furthermore, the temporal variation in study of crack development (depth, width and density) showed that they varied in different areas and were affected by volumetric soil water content and the groundwater depth. In addition, the depth of cracks in all soils did not reach the hard pan. All the investigated soils showed a definite threshold for width and depth of cracks for 20-25 days after irrigation withdrawal. After this period, specific values for width (about 3.0, 2.0, 2.5, and 5.0 cm) and depth of cracks (20, 25, 17, and 27 cm) were registered for Astaneh, Khomam, Shanderman and Rasht, respectively
S. A. Banimahd, D. Khalili, A. A. Kamgar-Haghighi, Sh. Zand-Parsa,
Volume 18, Issue 70 (3-2015)
Abstract
In the present research, the performances of six empirical models, i.e., simple threshold exceedance, fixed proportion exceedance, quadratic function of storage, power function of storage, cubic function of storage, and exponential function of storage were investigated for estimation of groundwater potential recharge in a semi-arid region. First, the FAO Dual Crop procedure was used to calibrate evaporation from bare soil during the occurrence of potential recharge period. Then, the empirical models were calibrated utilizing soil moisture and potential recharge data. For validation of empirical models, soil moisture and potential recharge were simultaneously estimated for an independent event. Results indicated that 5 of the six models (except for the simple threshold exceedance model) were able to estimate potential recharge with a reasonable accuracy, showing the maximum computed value of NRMSE (Normalized Root Mean Square Errors) of 24.4 percent. According to validation results, exponential, cubic, and power function models provided better estimation of potential recharge in comparison with the linear models. Also, all of the applied empirical models were able to simulate soil moisture during the recharge period with an acceptable accuracy. Finally, the exponential model with minimum NRMSE value for soil water simulation and also acceptable performance of potential recharge estimation was recommended for estimation of potential recharge in the study area.
M. Goodarzi, J. Abedi Koupai, M. Heidarpour, H. R. Safavi,
Volume 19, Issue 73 (11-2015)
Abstract
Due to the time and space changes of hydrological events in the arid and semi-arid regions, recharge measurement in these areas is very difficult. Hence, groundwater recharge is a complicated phenomenon for which there is not a fixed method to determine. The aim of this research was to develop a method for estimation of groundwater recharge based on a hybrid method. In this study, a hybrid method for calculating recharge was presented by combining empirical methods with a mathematical model, MODFLOW, and AHP analysis. The results showed that the most important parameters affecting groundwater recharge are soil properties, unsaturated thickness, land cover, land slope, irrigation and precipitation, from which the soil properties and precipitation are most important. The results showed that the overall impact of small changes in precipitation and temperature significantly affect the groundwater recharge, and heavy soils are much more sensitive to these changes than light soils. By changing 10% precipitation, the recharge rate is changed between 16% and 77% and by changing 1ºC temperature, the recharge rate is changed between 6% and 42%. Also, results showed that precipitation and evapotranspiration changes in four months including December, January, February and March had significant effects on annual recharge rate. Using the results of this research, the vulnerable areas of the plain, appropriate places and time for artificial recharge could be identified. Overall, the results of this study can be useful in various aspects of groundwater management.
A. Taheri Tizro, H. Nozari, H. Alikhani,
Volume 20, Issue 76 (8-2016)
Abstract
To procure the status of groundwater level fluctuations in arid and semi-arid areas, it is necessary to obtain accurate forecast of fluctuations data. Time series as a linear model have been utilized to generate synthetic data and predict future groundwater level. Minitab17 software and monthly depth of groundwater level data of 20 years (1991-2011) for 25 piezometric wells of plain were used. Time series models of each well were selected and 5 years temporal forecasting was accomplished. The predicted depth of groundwater level data was converted to Groundwater level data using ARCGIS10 and GS+5.1.1 software. Ordinary kriging with a spherical variogram was selected for interpolation of groundwater level. Five years spatial forecasting was done and spatial forecasting and groundwater level drop forecasting maps were prepared. Forecasting results of groundwater level show that over the next 5 years, the area covered by two intervals of groundwater level, 1100-1140 m and 1140-1180 m, will increase and the area covered by three ranges of 1180 -1220 m, 1220-1260 m, and 1260-1300 m, will decline. Also, according to the 5-year groundwater level drop forecasting map of the plain, the highest level of groundwater level drop, more than 16 meters for Qasemabad bozorg areas, located in North East and central of the plain, and the lowest level of the groundwater level drop, about 0.5 m for Mohammad Abad Afkham Aldoleh Lands, located in outlet area of the plain, have been predicted.
M. Aghapour Sabbaghi,
Volume 22, Issue 4 (3-2019)
Abstract
With regard to the crisis of water resources in the country, overdraft of groundwater resources has caused undesirable situation for most of the plains. On the one hand it is necessary for the stability of the resources are constantly using these resources, future generations need to be considered. In this regard, in this study make a cropping pattern with aims to develop a sustainable supply of groundwater resources in the Baghmalek plain has been considered. In this study, time series variables technique are used for predicting future values of variables. Also, the dynamic programming model, is used to determine the cultural pattern. Information needed for this research in two ways questionnaire and the use of statistics resource of agri-jahad and Khuzestan province`s water and power organization in 2013, has been collected. The results show that water input is considering as a limited production factor in the agricultural sector of the region. In addition, using of above pattern, will make fundamental changes in the region`s cropping pattern. The use of modern irrigation methods can increase the agricultural production capacity to double size. The main proposed of study is choosing the patterns that consider intergenerational sustainability about scares inputs such as water.
Z. Abbasi, H. Azimzadeh, A. Talebi, A. Sotoudeh,
Volume 22, Issue 4 (3-2019)
Abstract
Groundwater quality evaluation is very necessary to provide drinking water. Groundwater excessive consumption can cause subsidence and penetration of saline groundwater into freshwater aquifers in Ajabshir Plain, on the Urmia lake margin. The main goal of the current project was to evaluate the groundwater quality by employing the qualitative indices of groundwater and GIS. Ten parameters of 15 wells including EC, TDS, total hardness as well as the concentration of Ca++, Na+, Mg++, K+, SO4--, HCO3- and Cl- were analyzed. At first, the maps of parameters concentration were prepared by the kiriging method. Then based on WHO drinking water standards, the maps were standardized and ranked for drawing the maps of quality indices. The results showed that quality index changes were in the range of moderate (61) to acceptable (81). Removing the single map method of sensitivity analysis detected the quality index was more sensitive to the K+ parameter. Finally, the quality index from the eastern north to the western south of Ajabshir Plain and the other areas was ranked in the acceptable and moderate classes, respectively.
F. Negahban Khajeh, Y. Dinpashoh,
Volume 23, Issue 2 (9-2019)
Abstract
Studying the trends of water table in any region especially in arid and semi-arid regions is an important issue. This study focuses on assessing groundwater table changes in Tabriz plain. For this purpose, non-parametric Mann-Kendall test is used. In studing groundwater level the information of 14 pizometric wells in the period of 1991-2013 was used. Significant levels of 1, 5 and 10% were used for the trend test. Slope of trend lines is estimated using the sen's estimator method. The homogeneity of trends were tested using the Van Belle and Hughes method. The results showed that groundwater level in the most of pizometric wells have decreasing trend, That was significante in 1% sifnificance level. According to the research, trend of groundwater level was negative in all of the stations in April and maximum negative trend was belong to Dizaj Leily Khany station (Z= -6/47) that was significante in 1% sifnificance level. Also the minimum negative trend was belong to Ana Khaton station (Z= -0/322). The minimum groundwater level was -1.45 in Said-Abad station.
M. Moradizadeh, K. Shirani,
Volume 23, Issue 4 (2-2020)
Abstract
Water resources management depends on the precise assessment of water storage and access in each region, as well as environmental interactions of these resources. The man objective of this study was to delineate the potential zones of groundwater storage using FAHP. Mapping and assessment of it required maps of geomorphology, drainage, density, lineament density, slope and vegetation, which were initially prepared as the input layers in FAHP; the appropriate weights were attributed to them based on FAHP. Potential zones of ground water were classified into five classes of poor, average, good, very good and excellent. The number and density of available wells and springs in the study area dealt with the potential of the region for groundwater storage. So, ROC was used to assess the validation of results, considering spring points as signs of water resources. According to the results, classes of very good, good, average, weak, and very weak were ranked as the first to the last in terms of privilege order with an area of 37.7, 55, 40, 107, and 98.4 square kilometers, respectively.
F. Yosevfand, S. Shabanlou,
Volume 23, Issue 4 (2-2020)
Abstract
In this study, the groundwater level (GWL) of the Sarab Qanbar region located in the south of Kermanshah, Iran, was estimated using the Wavelet- Self- Adaptive Extreme Learning Machine (WA- SAELM) model. An artificial intelligence method called “Self- Adaptive Extreme Learning Machine” and the “Wavelet transform” method were implemented for developing the numerical model. First, by using the autocorrelation function (ACF), the partial autocorrelation function (PACF) and the effective lags in estimating GWL, eight distinctive SAELM and WA- SAELM models were developed. Later, the values of the observational well were normalized for estimating GWL. Next, the most optimized mother wavelet was chosen for the modeling. By evaluating the results of SAELM and WA- SAELM, it was concluded that the WA- SAELM models could estimate the values of the objective function with higher accuracy. Then, the superior model was introduced, showing that it could be very accurate in forecasting the GWL. In the test mode, for example, the values of R (correlation coefficient), Main absolute error (MAE) and the NSC- Sutcliffe efficiency coefficient (NSC) for the superior model were calculated to be 0.995, 0.988 and 0.990, respectively. Furthermore, an uncertainty analysis was conducted for the numerical models, proving that the superior model had an underestimated performance.
Y. Sabzevari, A Nasrollahi,
Volume 23, Issue 4 (2-2020)
Abstract
One of the ways to increase water productivity in agriculture is the use of new irrigation systems; for the precise design of these systems, water quality assessment is needed. The purpose of this study was to study the groundwater quality of Khorramabad plain for the implementation of drip irrigation systems. The qualitative indices of EC, SAR, TDS, TH, Na and pH were related to the statistical years 2006-2012. In this research, the data were normalized first and it was determined that the data were abnormal; so, the logarithmic method was used for normalization. To evaluate the groundwater quality of the area, land use methods were used. Among different methods, the ordinary kriging interpolation method with the least root mean square error for all parameters was used. Quality zoning maps showed that in the north and southwest, EC and SAR concentrations were in poor condition in terms of qualitative classification. TDS had a concentration of more than 4000 milligramrels, and Na had a concentration of more than 15 milligrams / ltr. In these areas, TH with the concentration of more than 730 mg / l had the highest contamination; in the central area of the plain, there was a higher risk of carbonate sediments. LSI rates in the western regions were more than one, which included about 12% of the plain; there were restrictions on the implementation of droplet systems in these areas. The best quality for implementing these systems was located in the south-east of the plain, covering 19% of the plain. Finally, the integrated map of qualitative characteristics showed that the maximum concentration of qualitative characteristics was located in the northern, central and southern regions, which included 62.29% of the plain area.
M. Noshadi, A. Ahadi,
Volume 23, Issue 4 (2-2020)
Abstract
Groundwater supplies a major portion of two basic human needs: drinking and agricultural water. Forecasting, monitoring, evaluating the performance and planning of this vital resource require modelling. The lag time of the groundwater level fluctuations against the rainfall is one of the essential data of the models. The purpose of the present study was to evaluate the piezometers behaviour by using the Pearson cross-correlation method between SPI and GRI indices in the Shiraz alluvial plain in order to determine the mentioned lag time. The results showed a similar behaviour for 86.2% of the piezometers. In 79.3% of the piezometers, groundwater level was declined one month after the rainfall event. The best correlation coefficient between the aforementioned indices was observed along the southwestern to the northeastern axis of the plain. The northern alluvial plain has a better correlation, as compared to the southern section because of the northern-southern slope of the plain. The central area of the plain had the highest correlation coefficient. The maximum correlation coefficients occurred at a time scale of 48 months. Also, since 2004, due to the decline in the atmospheric precipitation in the Shiraz plain, the SPI index has surpassed the drought level, although the trend has not been significant. However, the GRI does not follow this trend, showing a significant hydrological drought. The reason can be the disproportionate water extraction to recharge ratio in the alluvial aquifer of the plain.
H. Torabipoudeh, H. Yonesi, A. Arshia,
Volume 24, Issue 2 (7-2020)
Abstract
Understanding the quality of groundwater resources, which are the largest available freshwater reservoir, is one of the needs in planning and developing water resources. The purpose of this research was to study the quality changes of groundwater resources in the upstream aquifers of Zayandehrood Dam (1995-2016) and to evaluate water quality in terms of drinking and agricultural consumption and evaluation of IRWQIGC. For this purpose, EC, TDS, SAR, PH, TH, Cl, CO3, Ca, Mg, Na, K, HCO3 and NO3 parameters and heavy elements including zinc, copper, lead, cadmium and arsenic were investigated from laboratory samples. In the upstream aquifers of the Zayandehrood Dam, the water classification was mainly agricultural in the C2-S1 range, and it was generally acceptable in the drinking classes. The amount of heavy elements was allowed. The average amount of nitrate in the Chehelkhaneh, Damanehdaran, Boein-Miandasht and Chadegan aquifers was calculated to be 43.77, 48.08, 35.53 and 26.36 mg / l, respectively, and the maximum nitrate levels in these areas, however, were often exceeded. Nitrate zoning and IRWQIGC were performed by the kriging method. The lowest index values, which fell into relatively poor classes, were in the south and southwestern parts of Boein-Miandasht and south and south-west of the Chehelkhaneh, and in the central parts of Damanehdaran, and the south of Chadegan.
