Without a doubt, one of the main development foundation in different countries is providing water and it has the important role in improving the quantity and quality of life. Water resources management with the goal of maximizing economic and social development is not possible without having a logical view on Environmental Requirement. In past designing the structures focuses on providing the domestic, agriculture and industry requirements, So in most cases environmental water rights have been ignored. The Bakhtegan basin also has the same problem. The fundamental problem in this basin is the inappropriate planning of the water resources in which cause the decrease in discharge of the rivers of this basin, reducing the area under cultivation and the drought of the Bakhtegan lake. The main objective of this study was to determine the water balance of Bakhtegan basin and multi-objective optimization of operation of the basin’s reservoirs-Doroodzan, Mollasadra and Sivand dams- with Bakhtegan lake revival.
In this regard the data of the basic demand -agriculture- of the basin in five node introduced to the WEAP. 1- The cultivation area in up of Mollasadra dam 2- Kamfirooz plain (between Mollasadra dam to Doroodzan dam) 3- Areas in up of Sivand dam 4- between Doroodzan and Sivand dam to hydrometery station, Hasanabad 5- hydrometery station- Hasanabad- to Bakhtegan lake, domestic demand of two cities, Shiraz and Marvdasht, the water supply resources data such as three dams Doroodzan, Mollasadra and Sivand, hydrometery data, groundwater data (we consider groundwater like a reservoir). The basin model has been simulated for 15 years from 1999 to 2013. For the reference scenario that starts from 2016 and end in 2035 the average of the demand sites data has been considered the deterministic situation was considered in hydrometery stations data. Plus the reference scenario the 3 other scenarios were considered in the model. 1- changing the efficiency as much as 10 percent and 20 percent scenario 2- Optimize scenario 3- Optimize plus changing 10 percent in efficiency scenario. The results of these scenarios show that the agriculture area node 3 has the lowest value of reliability among the five agriculture areas. According to considering the first priority for domestic demand the reliability values were obtained 100 percent in all scenarios. According to the results in all scenarios the best results for reliability and coverage values were obtained in optimized and combined scenarios (combined scenario is made up of the optimized scenario and 10 percent changing in efficiency scenario). In reference scenario, the tenant method was used to calculate the environmental requirement that it doesn’t seem this method could give the appropriate values, so year was divided into three periods. For example September, October, November and December are one period. With considering 60 variables in optimization (NSGA II) model to provide environmental requirement, the optimized values for this requirement were obtained.

 Due to the lack of surface water resources in Bakhtgan- Maharloo basin, the amount of water withdrawn from groundwater resources has been more than the allowed limit. This amount has significantly affected surface water resources which led to some phenomena such as drying up of the Kor river, creating subsidence in 70% of basin plains, economic damages caused by reduction in the area under cultivation in downstream of kor river and drying up of Bakhtegan lake. In order to obtain a general view of this basin and optimal management of its groundwater resources, the situation of groundwater resources has been considered. In this regard, the unit hydrograph of Bakhtgan- Maharloo basin plains and annual variations of the groundwater levels were studied. For preventing from further decline in the groundwater level some scenarios such as reducing the area under cultivation, changing cropping patterns, changing irrigation system and combination of these scenarios were presented. 19 out of 28 case studies which had 14 years (2002-2016) of groundwater level data were considered. The results illustrated that among 19 studied plains, all plains except Kherameh and Shiraz have the annual decline of more than 25 cm, also 68% of the plains have the annual decline of more than 50 cm, 47% of the plains have the annual decline of more than 75 cm and 26% of the plains have the annual decline are more than one meter. In this research, the plains more than 1 meter‘s annual decline including Arsanjan, Kavar- Maharloo, Sa'adat abad, Sydan- Faroogh and Marvdasht with decline values of 2.43, 1.75, 1.44, 1.09, 1.02 meter respectively, were regarded as critical plains. At the next step, by taking into account the cultivation information, crop patterns, irrigation systems, and the volume of water-supply into the farm in pumping wells, four scenarios were performed and the annual decline under new conditions were calculated and compared with the prior annual decline. From the results, it can be expressed that only the use of modern irrigation systems instead of traditional systems in all or part of the dominant crops of the area under cultivation is not alone sufficient to reduce the available decline and will not compensate the major part of aquifer ‘s annual decline of these fields. Therefore, it is necessary to change the major crop pattern into products with low water needs to be considered. The investigations showed that the second scenario (changing irrigation method for the available crop pattern) is operationally more appropriate among other scenarios but the third scenario (case b) (changing irrigation method and crop pattern Simultaneously) has a highest impact on compensating aquifer‘s decline among all scenarios. In conclusion, according to the critical conditions of this basin the third scenario is suggested.

There are different elements in water. That are effective on the physical and chemical quality of water, so that these elements change incertain conditions such as increase and decrease in water discharge. One of these conditions is drought. Drought is one of the biggest natural disasters that its impact on human societies is more than other disaster. In this research for examine the drought effect in Tuyserkan Plain, we used the monthly, seasonal and annually rain data in Tuyserkan city in a 22 years statistics period (1372-1393). For this purpose we used standard precipitation indicates (SPI). For examine the change of water table a 22 years statistics period of it was used in the same time with a statistics period of rain. In study of change of quality parameters of plain, an 11 years statistics period was used. Examine of changes was done according to the non-parameteric man-kendall test. The results in spite of they show lake of significant trend in quality parameters of watershed, but is shows decreasing significant trend in water table of this plain, in 53 cm decreasing annual average amount. The results of rain analysis show in this period, rain in whole of plain decreased 81.95 mm, that it is 3.75 mm yearly decreasing. Totally according to the standard precipitation indicates the area situation is near to normal. In terms of the changes of quality parameters, shows significant relation between data of wet and dry periods according to T-test in significant level at 5 %.

 Drawdown of Groundwater level causes increases in effective stress and create permanent compaction in the sediments and therefore land subsidence. The most important damage is the irreversible loss all or part of the groundwater reservoir. Detection and control of these areas is the most important approaches that should be considered. In this study, at first land subsidence potentially map and its possible values in Sirjan plain from october 1998 to march 2014 in effect 12-meter drop in water level during this period was prepared by using the basic raster model. Then it is done simulation groundwater resources in Sirjan plain by using GMS. With this attitude which calibration model for october 2010 in steady and for october 2010 to september 2013 in unsteady. Also it is done model validation for period of one year from october 2013 to September 2014. After verifying the accuracy of the model using validated, It was predicted changes in groundwater levels in this plan, in both stance: maintaining the current situation or Implementation of wastewater collection project and out of the plain for 4 years later (october 2014 to september 2018). After determining the level of groundwater and the drop, the effects on land subsidence was assessed using the basic raster model. The results showed, It is predicted the subsidence to amount 3.34m in north west plain in Period of 15 years from October 1998 to march 2014 and will occur maximum subsidence to 10cm per meter drop groundwater level. The results also showed, with implementation of wastewater collection project in the urban area will occur maximum drop to 10 m during 4 years.the decline in groundwater levels increase the area affected by land subsidence from 330 square kilometers (13%) is in normal mode to 440 square kilometers(17.3%).

Drought in the North West of the city Behbahan last decade led to a withdrawal of groundwater unprincipled that this decline in groundwater levels in the area have followed; Hence artificial recharge as a method of low-cost and high reliability in water resources management could be one way to compensate for the drop in groundwater level. The aim of this study was to determine appropriate locations for artificial recharge of aquifers using GIS and multivariate techniques MCDM decision to strengthen the groundwater in the area. Effective criteria in location that was considered in this study include: geology, slope, transmissivity of aquifer, surface permeability, the thickness of unsaturated zones, groundwater quality, land use, distance from water resources, distance from wells, springs and Distance from road. After weighting criteria based on the Analytic Hierarchy Process (AHP) and paired comparisons method effective criteria map was prepared in GIS. The final map of the integration of Maps with overlay of the five classes is: very suitable, suitable, moderate suitability, unsuitable and very unsuitable, results from a combination of criteria was developed that showed 15.6% of the region is very suitable for artificial recharge, 10.7% suitable, 18.8% moderate, 12.6% are unsuitable and 42.2% very unsuitable to artificial recharge. Finally, with regard to very suitable and suitable areas within the study of check Dam and infiltration basins were selected as the best method of artificial recharge.

Wetlands are considered as the most vital ecosystems due to their numerous habitat functions and values. Recently however, a continuous loss of these valuable ecosystems is being observed as the result of inappropriate management of water resources, droughts and inattention to the environmental right of water of the wetlands, which could cause serious environmental consequences. Bakhtegan Lake is one of most critical wetlands in Iran, with diverse international and regional impact and habitat values, which has been totally dried out due to lack of supply water from Kur River. A potential solution for recovering and protecting this lake is estimation of Environmental Water Requirements, and then supplying this amount of water. In this research, firstly, the methods and case studies of determination EWRs of wetlands were investigated, and an ecological approach was then selected as an appropriate method. According to the proposed approach, important functions of the lake were considered and Greater Flamingo specie was selected as the main index of estimation EWRs of Bakhtegan Lake. Consequently, EWRs of the Lake was estimated at the minimum and maximum levels, i.e. 680 and 1870 MCMs respectively with the aim of maintaining the mentioned index in the lake. According to the fact that Bakategan Lake is located in an arid area and has experienced temporary dryness in the past, especially in the summers, it is expected that the lake could be recovered by supplying this amount of water

 

Abstract :
Land use and land cover change naturally or by humans can have a significant impact on the hydrological cycle region. these impacts will appear in the form of increase peak flow and volume of surface runoff, increase potential flood risk and decrease water quality. Therefore, a better understanding and assessment of land use change impacts on watershed hydrologic process is of great importance for predicting flood potential and the mitigation of hazard, and has become a crucial issue for planning management, and sustainable development of the watershed. The aim of the present study is evaluate effects of land use changes on hydrologic response at Abolabbas basin in during the nineteen years period (1990-2009). In this paper, the techniques of Remote sensing, Geographic Information System and HEC-HMS hydrologic model was used to achieve the purpose intended. After performing needed preprocesses on satellite images and evaluate the accuracy of different classification algorithms, images were classified using a three-layer perceptron artificial network with fine accuracy in eight class of land use. Land use maps were entered as a data layer in GIS, and the area was calculated for each class of land use. Then these land use maps with the hydrologic soil map were integrated using GIS tools and HEC-Geo-HMS extension to produce CN maps of 1990 and 2009. The HEC-HMS rainfall-runoff model using of the SCS-CN method for estimating runoff in Abolabbas basin was calibrated and validated for 4 storm events in the study area. Results of the simulation showed that changes in land use at study area that occurred in the direction the reduction in the level of forest and increased level of rangelands and residential areas has caused peak flow and flood volume during the study period increased 5.5 and 5.1 percent, respectively. On the other hand the results showed, this land use change not effect on the time of peak in flood hydrograph. On the whole the results showed that trend of land use changes in during the study period was cause to increase the flood volume and especially, peak flow hydrograph.

River is the main source of water supply for human needs such as drinking, agriculture and industry. The base flow of the river considered as part of the river flow, arising from groundwater. So understand the contribution of the base flow is important for water usage, water allocation, pollution impact assessment, low flow hydrology and flood hydrology. Base flow generally estimated by graphical methods, filtering methods, tracking methods and conceptual models. The filtering methods are most applicable for easy handling and effective results. The aim of this study is to check the base flow of the river due to the discharge of groundwater in Abolabas river basin located in southwest of Iran. In this regard the filtered smoothed minima base flow separation method, recursive digital filter method (Lyne & Holick Algorithm) and filtered smoothed minima method are used. Base flow separated by daily discharge data of the river during the statistical period. The results showed that due to karstic basin of the basin, the proportion of base flow is more than runoff for all methods. Also results showed that filtered smoothed minima method is not compatible with base flow logic because the creation of peaks and sharp points in some places. Finally filtered smoothed minima method which is the combination of the two prior methods present reliable result among them 

Drought is transient phenomenon , slow , repetitive and integral part of the climate of each region. Drought begins with a substantial reduction in precipitation over the long-term average rainfall and over time, reduced soil moisture and surface and ground water resources will continue to decrease. This phenomenon is the most important in Bakhtegan basin because of its importance in strategic areas, agricultural lands and associated Tashk and Bakhtegan lakes is more. Increasing greenhouse gases in recent decades and the resulting temperature rise due to the balance of the Earth 's climate and climate change in most regions of the global. Studies suggest that this phenomenon may have a negative impact on various sectors including water resources , agriculture , natural resources and environment, health , industry and economy. Thus, that will decrease in precipitation , relative humidity and increase temperature and due to the drought crisis severe losses to agriculture and the economy. To study the effects of climate change on meteorological droughts in future periods (2074-2045 , 2044-2015) were used the output of general circulation models HADCM3, GFDLCM2.1 and CSIROMK3.5 published under the two scenarios A2 and B1. LARS – WG model was used for statistical downscaling output of the three models. The model of rainfall - runoff IHACRES was used to simulate daily flows in future periods. Drought indices used in this study is the Standardized Precipitation Index (SPI) and standard Discharge index (SDI). Result shown that catchment area of study has been involved from 2007 to 2010 years with extensive meteorological drought. The highest very severe drought in all the time scales occurs at stations located in the South West Catchmen. The highest very severe hydrological drought in all the time scales occurs at Shoor- shirin basin and Roodsefid basin has been involved from 2008 to 2010 years. In the future period, 2015- 44, 2045 -74under the three models and two emission scenarios , the overall maximum temperature rise caused them to March, April , May and minimum temperature occurs in January and October. Rainfall increases during the months of September to January and deacrease in the months of February to June. The highest minimum flow in future periods (2045-2074 , 2015-2044) for Jamlbeig station ( Shuor Kharestan ) in April and Jamlbeig station ( Shirin ) in February , March and April ,also Dehkadeye Sefid in March and April. The results shown that scenario A2 have Meteorological and hydrological drought frequencies higher than the B1 scenario. The results shown that risk analysis of meteorological and hydrological drought characteristics , the probability of duration and magnitude specified time period in future is equal to or less than the current time.