فهرست مطالب a. faridhosseini

Drought has always been one of the major hazards in semi-arid and arid regions of the world. Drought caused a series of effects on many sectors of economics , especially natural resources. During two last decades, Iran has suffered from several severe to extreme agricultural droughts which caused significant decreases in agriculture yields. In this paper, it’s tried to estimate drought and evaluation performance of the NDVI based Temperature Vegetation Dryness Index (TVDINDVI) and the LAI based Temperature Vegetation Dryness Index (TVDILAI) using vegetation and temperature MODIS products in Northern Khorasan during three years 2003 , 2008 and 2013 (as wet, Dry and normal years respectively). The results showed that TVDILAI index has performed better than TVDINDVI index. The result of linear correlation analyzed between indices and the cumulative precipitation of the currently 16 days ,early 16 days and early 1 month, 2 month, 3 month, 5 month and 7 month showed the indices, specially TVDILAI, had a close relationship with early 2 month precipitation than the others. This is due to the delayed responses of vegetation to precipitation.

Evaporation from bodies of water, like lakes and reservoirs among other natural evaporating surfaces like canopies and wet soils, constitutes a signi cant source of water loss aecting global water balance and energy exchange between land and atmosphere. Hence, formulating lake evaporation rates has been of great interest for many years and is de nitely a challenge due to its complicated nature. Evaporation from lakes and reservoirs in Iran is commonly estimated using pan evaporation, which is well known to have signi cant uncertainty both in magnitude and timing. Reservoir operation and development of a new storage and water accounting strategies require more accurate evaporation estimates, especially for drinking water in arid conditions. In this study, an attempt has been made to estimate evaporation from a body of water using a new approach based on an energy balance model. For this purpose, a new energy balance method for two surfaces was established using water (evaporating surface) and bare soil (non-evaporating surface) as references. Considering similar conditions for two surfaces, an identical aerodynamic resistance ratio was assumed for both. With this assumption, a new form of energy balance was obtained which only depends on net radiation and temperature. The derived reference and water surface energy balance (RWEB) model were applied to estimate evaporation from the Doosti dam reservoir and was compared with other conventional methods. To evaluate the performance of the RWEB model, it was compared with the BREB and the pan methods. According to the evaluations, the RWEB results obtained for evaporation from 2011 to 2012 were satisfactory. The RMSD values for the RWEB and pan methods were obtained as 1.02 and 1.7, respectively. Therefore, the results indicate the good performance of the RWEB method. The RWEB sensitivity analysis showed that the model has the highest sensitivity to air and reference surface temperature and the least sensitivity to net radiation. Thus, evaporation from the body of water can be estimated accurately by precise measurements of air temperature and relatively reasonable estimations of the other parameters (reference and water temperature and net radiation).

Planning and management of water resource and river basins needs use of conceptual hydrologic models which play a significant role in predicting basins response to different climatic and meteorological processes. Evaluating watershed response through mathematical hydrologic models requires finding a set of parameter values of the model which provides thebest fit between observed and estimated hydrographs in a procedure called calibration. Asmanual calibration is tedious, time consuming and requires personal experience, automaticcalibration methods make application of more significant CRR models which are based onusing a systematic search procedure to find good parameter sets in terms of at least oneobjective function.

Conceptual hydrologic models play a significant role inpredicting a basin’s response to different climatic and meteorological processes within natural systems. However, these models require a number of estimated parameters. Model calibration is the procedure of adjusting the parametervalues until the model predictions match the observed data. Manual calibration of high-fidelity hydrologic (simulation) models is tedious, time consuming and sometimesimpractical, especially when the number of parameters islarge. Moreover, the high degrees of nonlinearity involved in different hydrologic processes and non-uniqueness ofinverse-type calibration problems make it difficult to find asingle set of parameter values. In this research, the conceptual HEC-HMS model is integrated with the Particle Swarm Optimization (PSO) algorithm.The HEC-HMS model was developed as areplacement for HEC-1, which has long been considered as astandard model for hydrologic simulation. Most of thehydrologic models employed in HEC-HMS are event-basedmodels simulating a single storm requiring the specificationof all conditions at the beginning of the simulation. The soil moistureaccounting model in the HEC-HMS is the onlycontinuous model that simulates both wet and dry weatherbehavior.Programming of HEC –HMS has been done by MATLAB and techniques such as elite mutation and creating confusion have been used in order to strengthen the algorithm and improve the results. The event-based HEC-HMS model simulatesthe precipitation-runoff process for each set of parameter values generated by PSO. Turbulentand elitism with mutation are also employed to deal with PSO premature convergence. The integrated PSO-HMS model is tested on the Kardeh dam basin located in the Khorasan Razavi province.

Input parameters of hydrologic models are seldomknown with certainty. Therefore, they are not capable ofdescribing the exact hydrologic processes. Input data andstructural uncertainties related to scale and approximationsin system processes are different sources of uncertainty thatmake it difficult to model exact hydrologic phenomena.In automatic calibration, the parameter values dependon the objective function of the search or optimization algorithm.In characterizing a runoff hydrograph, threecharacteristics of time-to-peak, peak of discharge and totalrunoff volume are of the most importance. It is thereforeimportant that we simulate and observe hydrographs matchas much as possible in terms of those characteristics. Calibration was carried out in single objective cases. Model calibration in single-objective approach with regard to the objective function in the event of NASH and RMSE were conducted separately.The results indicated that the capability of the model was calibrated to an acceptable level of events. Continuing calibration results were evaluated by four different criteria.Finally, to validate the model parameters with those obtained from the calibration, tests perfomed indicated poor results. Although, based on the calibration and verification of individual events one event remains, suggesting set is a possible parameter.

All events were evaluated by validations and the results show that the performance model is not desirable. The results emphasized the impossibility of obtaining unique parameters for a basin. This method of solution, because of non-single solutions of calibration, could be helpful as an inverse problem that could limit the number of candidates. The above analysis revealed the existence of differentparameter sets that can altogether simulate verificationevents quite well, which shows the non-uniqueness featureof the calibration problem under study. However, the methodologyhas benefited from that feature by finding newparameter intervals that should be fine-tuned further inorder to decrease input and model prediction uncertainties.The proposed methodology performed well in the automatedcalibration of an event-based hydrologic model;however, the authors are aware of a drawback of the presentedanalysis – this undertakingwas not a completely fair validationprocedure. It is because validation events represent possiblefuture scenarios and thus are not available at the time ofmodel calibration. Hence, an event being selected as a validationevent should not be used to receive any morefeedback for adjusting parameter values and ranges.However,this remark was not fully taken into consideration, mostlybecause of being seriously short of enough observed eventsin this calibration study. Therefore, the proposed methodology,although sound and useful, should be validated inother case studies with more observed flood events.

Evapotranspiration (ET0) is a basic parameter for determination irrigation program which has to be estimated using interpolation methods due to its spatial variation. A factor which can affect interpolation results is interpolation stages sequence. Current study was conducted to compare two ways for preparation of spatial distribution maps of ET0. In the first way، ET0 was calculated using climatic data and Hargreaves-Samani method in weather stations positions and then were interpolated. In the second way، the Hargreaves-Samani equation components are firstly interpolated and then ET0 maps were produced by proper commands in GIS. So، 10-year climatic data (2001-2010) of 46 stations for preparation the maps and 5 stations as validation stations in Mazandaran province were gathered. The data were interpolated using Ordinary Kriging method and the interpolation error was compared using Root Mean Squared Standardized Error (RMSSE). The results showed that the temperature data has better spatial correlation and lower interpolation error. But for estimation verification، ET0 amounts derived from the two ways were compared to the computed ET0 in validation stations positions and showed that the two ways difference was not significant. So، these two ways have not differences for producing ET0 maps.