Conjunctive use operation policies play a vital role in the sustainability of water resources and their optimal allocation. To be realistic conditions of real water resource system should be considered in simulation and derivation of operating rules of real-world water resource system. In this research, the combined fuzzy logic and direct search optimization technique is used to account for the uncertainty associated with parameters affecting groundwater table level fluctuations. These parameters include specific yields and inflow recharge and outflow discharge from the aquifer, which are typically uncertain. A membership function is determined for each parameter using hydrogeologic and piezometric data. For each membership value (a level cut), the corresponding intervals are determined. These intervals are considered as constraints on the membership value of the groundwater table level fluctuations in the optimization model. The process is repeated for other a level cuts to obtain the fuzzy number. For the uncertainty influencing the water demands, a Conjunctive use model with water resources constraints is developed. Using this model, the priorities for the different zones and their optimal allocations are determined. The results show that the better the real conditions are reflected in the Conjunctive use model, the better will the system be reliably capable of handling the water demands. The results of the proposed model also indicate that it present reliable allocations compared to the static conventional models and that it performs more desirably and practically in allocating supplies to water demands as it duly includes the opinions of the decision-makers involved.

In the recent decades, continuous droughts in Iran caused a growing withdrawal trend from groundwater resources and reduce in surface water resources, especially storage volume of dams. Therefore, operation of water resources requires reviewing based on hydrologic conditions and especially, drought. On the other side, for the definition and characterization of drought by indices, a comprehensive survey of data existence, index applicability and goals in water resources operation is needed. In this article and towards an applicable standardized index in the Conjunctive use of water resources, nonparametric functions used to achieve integration and applicability. The status of water resources is calculated via integration of climatic water balance and available hydrologic water by multivariate nonparametric function to obtain integrated drought index (IDI). In this study, the Zayandehrud River Basin is selected as the case study due to Conjunctive use of surface and groundwater and occurrence of recent droughts in it. Zayandehrud Dam has a key role in streamflow regulation for downstream demands in the basin. With the index tool to determine the condition of the subbasins, dam resource reoperation is followed by the purpose of the minimum drought intensity. This way of operation resulted in demands supply reliability of more than 90%, Lenjanat aquifer balance, storage increase of Isfahan-Borkhar and Kuhpaye-Segzi aquifers by 400 million cubic meters, supply of Gavkhooni wetland water right with reliability of 96% and mean increase of 2.7 million cubic meters per month in streamflow entering the wetland in comparison with the past. The results underline the importance of the drought conditions consideration in the Conjunctive use of water resources at the basin.

In the most of arid and semi-arid countries, the quality and quantity of available water resources play a significantly limiting role in development. In these regions, the Conjunctive management is a suitable alternative that can lead to the optimal operation of available water resources. In this study, a Conjunctive use model is developed in order to maximize water supply demands in 30-year period historical records. Discharge from resources, consumption priority in sectors and zones, inter-basin water conveyance plans and water demands are considered as the optimization model’s constraints. The ultimate goal of the study is to present short-term, medium-term and long-term operating policy. The sequential genetic algorithm is used to speed up the convergence to near global solution. The operating rules of surface and groundwater resources are separately developed for agriculture as well as domestic demands in the annual and monthly manner, respectively in the three above-mentioned periods. Finally, these rules are verified based on previously unused historical records.The results showed that the proposed model can effectively improve water resources potential, sustainable groundwater resources and undesirable use in agriculture sector.

Conjunctive use of surface and ground water resources is one of the aspects of integrated water resources management. In this paper, Conjunctive use of water resources has been studied for arid regions in which the only source of surface water is the water transferred into the region. For this purpose, first, the region’s groundwater has been simulated using the Modflow-Pmwin model. The results have then been used to develop an optimization model with a genetic algorithm and different alternatives have been investigated toward optimal use of water resources. Obtaining monthly patterns for water withdrawal based on controlling an aquifer’s level is the main objective of the optimization model. Yazd’s aquifer in central Iran has been selected as the case study. The results of the optimization model showed that supplying all the demands considering the present condition for the imported surface water (max 50 MCM annually), will cause a 2 meter fall in the aquifer’s level in 5 years. An annual increase of 40 percent in the amount of imported surface water should be reached in order to meet all the demands with negligible drop in the aquifer’s level.

Conjunctive use of surface and ground-water resources, compared to disjunctive operation of these systems, increases system reliability and decreases water deficits and operational costs. In this study, the two alternatives of groundwater (GWOpt model) operation and Conjunctive use of surface and groundwater resources (CONJ model) are considered for Abhar river basin in Iran. In both models, the objective function is minimization of mean groundwater drawdown. The vast amount of calculations needed for distributed parameter optimization models is a major limitation in real systems. However, the above two models are linear and the unit response matrix approach is utilized. The first step in this approach is to calculate the unit response matrices (as the behavior of the groundwater system) using a simulation model, such as MODFLOW. The next step involves incorporating these matrices into the optimization model. The results obtained from the solution of the optimization model indicate that the mean drawdown in the CONJ model is less than that in the GWOpt model. In addition, a decrease of only 6% decrease was observed in the mean drawdown when compared to the simulation model. A decision support system has also been developed that enables the model to be used in real situations.

Increasing water demand is one of the most challenging issues for water resource planners and managers. Solution to water shortage problems are not solved only through development of new water resource projects, more importantly they can be solved by efficient water management within the existing projects. In this context, Conjunctive use management is one of the alternatives for the optimum utilization of available water resources and can improve water use productivity. In the present study, a mathematical model is presented to evaluate different scenarios of Conjunctive use of surface and groundwater with various hydrological and management constraints to arrive at optimal cropping patterns for optimal use of water resources for maximizing gross margin. The results indicated that by using surface and groundwater Conjunctively, reliability of the irrigation water could be improved. It caused to reduce the losses due to water uncertainty and therefore, acted as a risk management system against the uncertainty in water. Also the results showed that the net benefit from the proposed Conjunctive use system is almost double from 189 to 372 milliard Rials and water productivity increaseed by 13 percent.

The Conjunctive use of surface and groundwater in irrigation networks influences the performance of canals. One condition of Conjunctive use is to add the groundwater to the surface water via a canal to satisfy demand. Management and operation of the canal is a complex task that must consider demand variation and groundwater entering the canal. The variety of decision variables in Conjunctive use requires the use of optimization techniques to determine optimal operation. Simulation models should be combined with optimization models for this purpose. In this research, an irrigation conveyance system simulation (ICSS) hydrodynamic model was used to simulate the flow in an irrigation canal. A combined optimization technique was used that considered the complex and implicit relations between the objective function and decision variables. A model based on the shuffled complex evolution (SCE) optimization technique, a heuristic intelligent search technique, was used to develop an ICSS-SCE model. The proposed model was applied to the L8 canal of the Qazvin irrigation network, consisting of five Conjunctive wells. Two options (25 and 40%) for demand increase provided by groundwater was considered. For each option, regular and optimum operations (four options in total) were taken into account. Optimal control settings (for water flow) were determined and canal performance for each option was calculated using the ICSS-SCE model. The results showed that setting controls according to optimal recommendations influenced by Conjunctive use led to considerable performance improvement of the canal and intakes. The objective function of the canal was improved in two cases by 40-48%. In general, it was concluded that the proposed model was capable of determining optimal operation of the irrigation canals under Conjunctive surface and groundwater use.

Sistan region located in Southeast, Iran is one of the many places that are badly in need of special policies for water resource management. Conjunctive use of surface plus groundwater is a common way of an integrated water resources management. The aim followed in this study is to evaluate the strategy of conjunction of saline subsurface water with fresh surface water (Hirmand River) in Sistan region. To achieve this, an experiment was performed within a randomized complete block design of five treatments and three replications on sorghum on the experiment al field of Zabol University located in Sistan dam area within spring of 2013. The fresh and saline water samples required for the experiment were provided from Hirmand river (EC= 1.2 dS/m) and a well existing on the field (EC= 15 dS/m), respectively. Treatments consisted of; control, irrigated with one-half of salty water, alternation in time, mixed vs completely salty water. The studied traits were comprised of the biological attributes of sorghum as well as salinity changes within the soil profile. The analysis of variance showed that there are significant differences (p<0.01) in dry weight of stem, leaf and aerial organs of the plant, plant height and leaf area index for all the treatments. Following, control the one-half salty treatment, with an increase of 75.8 % in leaf dry weight and 55.3 % in weight of aerial organs (in comparison with the completely salty treatment) presented the most appropriate performance. Also, a comparison of soil profile salinity prior to, and after the experiment showed that all the foresaid treatments caused an increase of salinity in all the soil profile layers (except for 80-100 cm layer for which, the salinity was affected by the water table). The results of yield components and soil profile salinity showed that for the crop sorghum an alternate use of saline and fresh water (alternate time treatment) is more appropriate than a mixing of them. Therefore in such regions as Sistan plain with scarce fresh water, the methods of one-half and alternate time could be employed for irrigation.

In order to study the effect of irrigation with saline water under different methods on yield quantitative and qualitative characteristics of Sorgum. An experiment conducted in experimental farm of Islamic Azad University Shahr-e-Qods Branch. Experimental design Included four treatments included T1: Saline and fresh water treatment, T2: Alternative saline and fresh water treatment, T3: Mixed saline and fresh water treatment, T4: Control treatment. Result had shown best water use efficiency in T1 treatment than control treatment. T1; 19%, T2; 35% and T3; 50% decrease observed than control treatment.