Journal of Spatial Analysis

The runoff simulation have  particular importance in Civil works, river training, design and planning of ground water resources, flood control and prevention of environmental hazards and reduction of erosion and sedimentation in the watershed. The runoff in each region varies according to climatic conditions, hydrological, soil and vegetation in the basin. Simulate these processes need to provide the necessary information on the spatial variation of these factors.  In this context, given the diversity of hydrological models, to achieve the most appropriate simulation of hydrologic models and choose the appropriate model requires the evaluation of their performance in each area is commensurate with hydrological conditions. So hydrologicl models, need to recognize the capabilities and limitations of basins.  In this study, the performance of the two models of rainfall – runoff including IHACRES and SWAT models was compared and evaluated in runoff simulation for two watersheds Yalfan and Sulan in Hamedan province in West of Iran .  

     The SWAT model uses various information, including;  hydrometry, climate , soil , topography, vegetation and land use . SWAT (Soil & Water Assessment Tool) is a river basin scale model developed to quantify the impact of land management practices in large and complex watersheds. SWAT model is a hydrology model with the following components: weather, surface runoff, return flow, percolation, evapotranspiration, transmission losses, pond and reservoir storage, crop growth and irrigation, groundwater flow, reach routing, nutrient and pesticide loading. SWAT model uses a two-level disaggregation scheme; a preliminary sub-basin identification is carried out based on topographic criteria, followed by further discretization using land use and soil type considerations. Areas with the same soil type and land use form a Hydrologic Response Unit (HRU), a basic computational unit assumed to be homogeneous in hydrologic response to land cover change.

     IHACRES model is a catchment-scale rainfall – stream flow modeling methodology whose purpose is to characterize the dynamic relationship between rainfall and stream flow, using rainfall and temperature (or potential evaporation) data, and to predict stream flow. The model can be applied over a range of spatial and temporal scales - from small experimental catchments to basins; using minute, daily or monthly time steps. It can be used to fill gaps in data, extend stream flow records, as well as explore the impact of climate change and identify effects of land use changes.

    Data used in this study includes temperature, precipitation and runoff in the period of 2010-1983. Rainfall and temperature data were used from weather stations and runoff gauging stations from basin Sulan  and Yalfan hydrometry stations. In this study we select two periods, first period from 1983 to1999 for calibration and the second period from 1999 to 2009 for validation. Some of the required basic information such as soil, vegetation, topography and land-use maps were used to carry out the research were received from the Research Center of Agriculture and Natural Resources of Hamedan province.      Accordingly, after collecting basic data and analysis of the sensitivity parameters, then calibrate and validate the models. To determine the ability of models Nash Sutcliffe (NS) and determination coefficient ( R2) were evaluated .

    The results showed that both models are acceptable in simulating runoff in both basins. According to the results obtained in the simulation by SWAT model in both basins, Nash Sutcliffe on a monthly scale in the Yalfan basin for calibration period is 0.68 and verification period is 0. 74 and for Sulan basin calibration period is 0.69 and verification period 0.76.

    The flow rate during validation periods have high accuracy. In the Yalfan basin observed daily flow 1.17 cubic meters per second and simulated flow is 1.10 cubic meters per second. As well as an overview of the values of the coefficient of determination can be seen in both basins, amount represents the high precision simulation in monthly and daily scales. Based on the results obtained in the two basins, IHACRES model has been good performance on a monthly scale, so that the Nash Sutcliffe in the Yalfan basin for calibration period 0.68 and for verification periodic 0.72 in the Sulan basin for calibration period 0.64 and for verification periodic 0. 65. In general, both models can be seen by comparing the SWAT model was calibrated and validated with the highest Nash Sutcliffe on the monthly and daily scales. Generally it can be concluded that to simulate the daily and monthly runoff, the SWAT model is recommended for evaluation hydrology process in the Yalfan and Sulan basins. It is essential in most similar studies to determine of rainfall-runoff models with respect to variability of rainfall-runoff models in different climate periods of dry and wet years.

Dust particles are important atmospheric aerosol compounds. The particles are resulting performance of strong winds at the soil surface desert areas. Sources of dust are 2 types: 1- Natural Resources 2- Human Resources. Iran is located in the desert belt which this problem cause increased the frequency of dust storms, especially in South East (Sistan) and South West. China Meteorological Administration Center classifies storms based on particles type, visibility and speed storms to 4 kind: Floating Dust, Blowing Dust, Sand/Dust Storm and Sever Sand/Dust Storm. In general, the effects of dust storms in 7 of Environment (particles into remote areas, the effect of dust particles on the material, climate, oceans and deserts), public health and health (increase of respiratory diseases , cardiovascular problems, digestive, eye, skin, reduced hearing, infections, reduced life expectancy and premature death, etc.), economic (unemployment, road accidents, damage to communication lines, air, land, sea, increase water turbidity in water utilities, creating uncertainty for all economic activities, etc.), Agriculture and Livestock (negative effect on the growth of plants and animals, reduced productivity and diversification, intensification of plant and animal pests and diseases, rising costs maintenance of livestock, etc.), socio-cultural (poverty and the loss of local jobs, destruction of subcultures, rural migration to the cities, closure of educational premises, industrial units, services, etc.) and military-security (disabling weapons, food and beverage contamination, the threat of sensitive electronics and power transmission systems, and reduce the useful life sitting on warehouse equipment, logistics cargo weight gain, etc.) can be evaluated. One way to identify, evaluate and forecast dust storm modeling. Dust cycle consists of 3 parts, dust emissions, dust and subsidence transfer dust that can be simulated by models.

In this study using the WRF_Chem model with FNL^[1] input data and GOCART schema, sever dust storm in Sistan region was simulated to date 14 & 15 July 2011. Satellite images of the event was received by the MODIS sensor. Dust concentration data was received from the Department of Environment. The dust storm code, minimum visibility data and maximum wind speed data was received from the, Meteorological Organization.

The results of the simulation for dust concentration which peak amount of dust was for 21Z14July2011 and 03Z15 July 2011. Model output showed maximum wind speed 20 m/s with North to South direction in the study area. The model predicts maximum dust concentration for the latitude 31 degree North and longitude 54 degree East to 66 degree East (Within the study area). MODIS sensor images showed clearly the sever dust storm. Simulated time series in Figure 3-1 Changes in dust concentration during the event show in the Sistan region. As can be seen from the peak of the concentration of dust in 21 hours on 14 July (350 micrograms per cubic meter) and 03 hours on 15 July (425 micrograms per cubic meter) 2011 was created. Model simulation and satellite images indicated which the Sistan region, especially dry bed of Hamoun wetland in East of Iran was main source of sand and dust storm. Also, based on the model output blowing wind direction from North to South on Iran which converging these currents in East Iran caused by strong winds in the lower levels (According to the meteorological data), arise dust, increasing the dust concentration (According to Department of Environment data), increasing the dust and being transferred to the Southern regions, especially  Oman sea. To identify the source of the sand and dust storm, the path of the particle and anticipated this event cant actions and warned to stop and reduce effects its. . Simulation of dust particles in the resolution of 10 and 30 kilometers, the plains of Sistan in Iran's East region as the main source screen. The findings suggest that compliance with the maximum concentration limits on known sources of particles (especially Sistan plain dry bed of plain wetlands) is. Check drawings wear rate showed that the source of dust in the Sistan region, particularly the high potential of our wetlands dry bed of soil erosion in wind activity 120 days during the hot and dry conditions, and silt and clay up to thousands of kilometers away from their source transfers. Vector lines on maps wear rate, indicative of converging flow north-south and severe dust storms in history is this. It is better than models forecast dust events and rapid alert