Journal of Range and Watershed Managment

Abstract Hydrological drought is used to show the reduction of surface flows and the drop in the level of underground water reservoirs, lakes, and rivers. The present research was carried out to determine the basic flow index values and to check its efficiency in determining the type of flow regime and regional analysis of hydrological drought in the Halil-Rood watershed. For this purpose, three homogeneous hydrological drought zones were determined based on the threshold level and cluster analysis, and then the base flow index was calculated on a daily scale using the daily discharge data in 10 hydrometric stations in the homogeneous zones. The results showed that the regional average of the annual base flow index is 0.38 with a standard deviation of 0.193 in the long-term statistical period and the range of the base flow index is 0.12-0.29. Based on the 70th, 80th, and 90th percentiles, the river flow regime was divided into four classes, and it was found that 100% of the watershed sub-basins of the study area had an unstable regime. Also, the results of drought zoning showed that hydrological drought occurred at the threshold level of 70 in the southeast of the region in the area of the Dehroud hydrometric station and in the levels of 80 and 90 in the northwest of the region in the area of Baft and Cheshme-Arus stations. The results of the present research can be used in the assessment of underground water supply, water supply systems, irrigation management, hydrological drought monitoring, and regional models in the estimation of water resource reserves in areas without statistics.

Abstract The desert environment is aeolian, being dominated by the wind. The dynamics of wind erosion are driven by both natural processes, including climate and its fluctuations, and human activity. Separating the climatic and anthropogenic causes of wind erosion can improve the understanding of its driving mechanisms. The aim of current research is to evaluate the spatio-temporal dynamics of the aeolian process based on the sand dunes morphology and the analysis of the spatial correlation between wind erosion dynamics and climate fluctuations. Based on meteorological, remote sensing and field observations data, the impacts of climate fluctuations on the temporal and spatial changes of the aeolian process were evaluated according to the indicator of the creation and expansion of sand dunes .MODIS remote sensing data was used to study the sand dunes morphology. The temperature, precipitation, wind speed and other meteorological data used in this study were all derived from two synoptic stations of Qom and Kashan. The analysis of the elongation and form of the sand dunes as the wind direction indicator showed that the studied area is affected by the winds region of the Qom (northwest and west). The results of climate studies showed that over the last 27 years, the region has a rising temperature trend, while the average precipitation in the region has decreased in the same period. The relationship between drought conditions and aeolian process showed that the region experienced severe drought conditions more than normal or abnormally dry conditions during 1369 to 1395.

Abstract The complexity of the urban environment makes it difficult to consider all the vulnerable components of the urban. Hence, decision-making in urban environments is one of the most important issues in modern management. As a result, the purpose of this study is to investigate the urban vulnerability of Azimiyeh in Karaj to flood based on multi-criteria decision-making method. The statistical population includes specialists who had sufficient knowledge and experience in the field of vulnerability management in urban areas. To this research, first, comprehensive knowledge of the factors affecting the urban vulnerability to floods was obtained using library studies, and then, the results of the Delphi technique, , was shown that among the primary indices, a total of 11 effective indicators were selected and a map of each of them was prepared using ArcGIS software. Then, the urban vulnerability to floods was calculated using the TOPSIS method. The study area was divided into 13 sub-areas based on runoff directional pattern and field observations, and then the decision matrix was made according to 13 sub-areas and 11 indicators. The results showed the vulnerability of this region to floods, which among the studied sub-areas, in sub-areas No. 1 and 2 observed the highest of flood vulnerability and the lowest of it observed in sub-area No. 13. Causes of flood vulnerability in the region include a direct connection to the upstream catchment that has lithology impermeable and geologically impermeable, high-density of building and population, and lack of proportionate open spaces.

Abstract The development and implementation of practical natural resources and catchment management
policies require a comprehensive knowledge of the system processes (biological, physical, and
socio-economic), their complicated interactions, and how they react to different changes. The
current research assessed the ecological, physical, and socio-economic consequences of
biologically-based management scenarios targeting runoff and soil erosion problems in the
Darenari catchment. The Darenari catchment with an approximate area of 554 ha is located in Fars
province, Iran. Three biological activities and 8 management scenarios were considered. Ecological
consequences were studied using the weighted land cover area index (WLCAI). Physical effects
were investigated applying the runoff curve number (SCS-CN) hydrologic model. Economic and
social effects were assessed applying the cost/benefit analysis as well as examining the outcomes of
a social survey. Then, a fuzzy AHP approach was applied to weigh the criteria and ultimately, the
best management option was chosen using FTOPSIS model. The results showed that social criteria
with the highest weight and scenario No 8 was the best scenario and had first priority. The results
idicated that the multi-criteria decision making techniques included capability of expressing
different aspects of the problem and are the perfect tool for watershed resources management.

Abstract Consecutive droughts in Sistan and Baloochestan province cause water resources restriction and this is
a very significant problem for this region. In this study, in order to forecast the drought cycle in 9
climatological stations in the province, we used Artificial Neural Networks. The input data were
average of annual rainfall data in all stations and also deciles precipitation index, which the first 30
years from 1971 to 2000 used for training the network and the last 8 years from 2001 to 2008 for
simulating it. The network consists of Multilayer Perceptron (MLP) and Back Propagation Algorithm
(BP) and also sigmoid transfer function. Number of Neurons in hidden layer was 10 with 1-10-1
structure and was calculated based on the lowest RMSE. Then drought prediction was done in neural
network with the trained algorithm and without using actual and observed data in 2009 to 2012.
Results showed that, the network was able to simulate and forecast DPI index with 97% regression
and average RMSE error less than 5%. According to drought indices, results showed that the drought
will have an increasing trend in all stations in this region in 2009 to 2011. Therefore, by using this
method, drought can be predicted in later years without any need to have actual meteorological data
and also can be used in water resources management, drought management and climate changes.