The purpose of this study was to investigate the possibility of the limestone as an adsorbed media and low-cost adsorbent. Batch adsorption studies were conducted to examine the effects of the parameters such as initial metal ion concentration C₀, particle size of limestone D_L, adsorbent dosage and equilibrium concentration of heavy metal C_e on the removal of the heavy metal (Cu) from synthetic water solution by limestone. The removal efficiency is increased with the increase in the volume of limestone (influenced by the media specific area). It has been noted that the limestone with diameter of 3.75 is the most effective size for removal of copper from synthetic solution. The adsorption data were analyzed by the Langmuir and Freundlich isotherm model. The average values of the empirical constant and adsorption constant (saturation coefficient) for the Langmuir equation were a = 0.022 mg/g and b = 1.46 l/mg, respectively. The average values of the Freundlich adsorption constant and empirical coefficient were K_f = 0.010 mg/g and n = 1.58 l/mg, respectively. It was observed that the Freundlich isotherm model described the adsorption process with high coefficient of determination R², better than the Langmuir isotherm model and for low initial concentration of heavy metal. Also, when the values of amount of heavy metal removal from solution are predicted by the Freundlich isotherm model, it showed best fits the batch study. It is clear from the results that heavy metal (Cu) removal with the limestone adsorbent appears to be technically feasible and with high efficiency.

In this study, the catchment area’s runoff of Hemren dam reservoir within middle River Diyala reach beyond Derbendi-Khan dam at the northeast of Iraq is simulated using the Soil Water Assessment Tool (ArcSWAT-2012) model integrated with remote sensing and geographical information systems. The model was calibrated in monthly time step for the period extended from 1981 to 2000 with 2 years of warm-up period and validated with observed stream flow for years between 2001 and 2008. The model calibration and parameters sensitivity analysis were conducted using automatic calibration method within the SWAT-CUP program. The model performance for the studied catchment area was evaluated with many statistical criteria. In general, the performance of the model was good. Results of sensitivity analysis showed that there are seven parameters that mostly effect on the hydrological processes in the studied catchment; these were ALPHA_BF, CH_K2, CN2, CH_N2, SOL_AWC, REVAPMN, and GW_REVAP. Results showed that an effective runoff happens at wet seasons, and there is not continuous effective base flow from the studied catchment, and the average annual inflow volume to Hemren dam reservoir during the simulation period was 0.871 BCM, i.e., 17.42% of the overall inflow volume to Hemren dam reservoir. Furthermore, it was founded that the use of climate forecast system reanalysis of global weather station data is possible in the studied catchment area. Finally, a simple direct regression formula is determined by correlating the monthly runoff volume with monthly rainfall depth.

This study provides a simulation of groundwater flow and advective-dispersive migration of radioactive Co-60 through an aquifer with three layers, which release or leak to groundwater from the Active Metallurgy Testing Laboratory (LAMA) Nuclear Facility-Iraq due to the nuclear accident scenario. Processing Modflow for windows (PMWIN) and Modular Three-Dimensional Multispecies Transport (MT3DMS) Models were used for this purpose. The study area and the contaminated area were 12.7 km² and 0.005625 km², respectively. Water levels of the groundwater have been measured in six monitoring wells. The simulation time was assumed to have started in 2016. The PMWIN model simulated the flow for two scenarios of water level in Tigris River (average and minimum water levels). The MT3DMS model simulated 10 years of plume travel, beginning in 2016. The simulated Co-60 concentrations after five years of travel were 32.34 and 34.44 μg/m³ for the two scenarios. The maximum predicted Co-60 concentrations at the end of Year 10 were 34.86 and 37.31 μg/m³, respectively. The sensitivity analysis showed that the simulated hydraulic heads in the observation wells and the simulated plume of Co-60 were highly sensitive to changes in the effective porosity but less sensitive to changes in other parameters of the dispersion and chemical reaction processes. The time necessary to reach steady state condition was predicted to be approximately 16 years. The contaminated area was isolated by using remedial process which is represented by three fully penetrating pumping wells with a suitable flow rate (0.045 m³/s) for controlling the movement of Co-60 pollutant.

Weirs are one of the world wide water resources management structures, which are beside their activity in rising water surface to become important source for electricity by using low head hydropower turbines, it improve the hydraulic and the environment of the river reach.140,000m long of Tigris River reach between Al-Fatha and Samraa cities at Salahaldeen province in Iraq was selected to evaluate the usefulness of constructing system of weirs series by calculating the range of improvements in the hydraulic properties, in the environment and estimating the hydroelectric power potential of the study reach. GIS, Global Mapper (Ver.11) and DEM (digital elevation model) combined with surveyed cross-sections of the river bed were used for the delineation and knowing the number of cross – sections and its area. 30 cross sections were used for river reach in this study. One dimensional and steady flow HEC-RAS model was used .It was calibrated to estimate water surface profiles through a group of equations and to calculate the suitable hydraulic conditions along the study reach. The optimum value of manning coefficient was 0.027. The study area was evaluated and the system of five weirs with heights of (3.7 – 6.0 m) was proposed along the river reach. Their locations depend on trial and error process, geometric of the cross – sections and the ratio of the height of the weirs to the design head. The simulated results by using HEC-RAS model were tested to know the reach behavior against three different discharge values (200, 1242, 8616 m3/s), with return period of 1, 1.15 and 42.50 years respectively, and to compare the hydraulic changes in the study reach before and after installing the weirs and to know the net heads for running the low head hydropower turbines. The results illustrate improvement in the reach hydraulic properties of the river reach. According to the criteria of hydro – power system classifications, the type of hydro – power in this case study was small and the suitable turbine was Kaplan turbine with flow rate of 30m3/sec and with ranges of net heads of (3.29 – 6.08 m). 7 and 41 turbines were chooses for the flow rates of 200 and 1242 m3/sec respectively. The Kaplan turbine is running with very high efficiency below the design flow and with suitable runner diameter. The total estimated capacity of one turbine was (5.38 –7.60 MW) and for seven units, it was (37.66 - 53.20 MW) at one weir. These capacities will cover some of the growth in demand to the electricity in Iraq. It covers about (300, 000) capita of population in the study area. It was found that the maximum cost of the electromechanical equipment for hydro project was 42.91 million US$ .

Soil Water Assessment Tool (ArcSWAT2009) model is applied on the Greater-ZabRiver catchment at north of Iraq. The model was calibrated from 1993-2002 and validated from 2003-2013.The calibrated model for hydrological conditions was used to assess the water quantity (monthly stream flows).The study identified optimum parameters and with widest ranges of variation for better rates simulation. The water balance components were correctly estimated. The results showed that the average simulated stream flow for the study period (1993-2013) was 363 m3/sec which is less than the average value of stream flow (417 m3/sec) for the period (1930-1992) .The watershortage problem effects on the management of water resources. Based on statistical indicators, the evaluation indicates that the model had a good performance for both calibration and validation periods in Greater-Zab River watershed. The model can be used efficiently in semi-arid regions to support water management policies in Iraq. The model performance evaluation showed a good correlation between the observed and simulated monthly average stream flow for calibration and validation periods with R2 (0.99,0.87),EN.S(0.99,0.86) and D ( 2.76,1.22) respectively. A sensitivity analysis was carried out on the major input parameters and the results showed that there are ( 11 ) out of (41) parameters sensitive. The most sensitive is the (CN2). Results of hydrologic budget show that the ratios of the annual base flow and the flow of the hydrograph shape to the total flow are 20 % (base flow index) and 42 % respectively. The lateral flow,computed as a percentage of average annual rainfall varies greatly from 4.8% to 38% and the actual evapotranspiration is much lower than potential evapotranspiration. The ratio between the average yearly precipitation and potential evapotranspiration was 45 %. In a future study, it is recommended to use land cover and climate change scenarios, their projected impacts and adaptation. The study results are helpful for the management and planner of water resources in Iraq which relate to the sustainability and water quantity.