Research Items (5)
- Jan 2019
- Spatial Modeling in GIS and R for Earth and Environmental Sciences
Construction of sub-surface dams is a suitable technique for collecting and storing the sub-surface flows in arid areas. This area has a high potential of sediment yield and evapotranspiration. Thus, the present research aimed to suggest and propose suitable areas for construction of sub-surface dams using SWAT and Boolean algorithms in the GIS environment and priority of them according to MCDM models. At first, Boolean algorithm was applied by different factors such as; distance to faults, slope percent, geology, and land use and 10 suitable sites are recognized of 32 potential areas. Subsequently, sites data, maps, and related information were prepared using SWAT model (water quantity and quality) and field study investigations. Eventually, the ten sites identified ranked and compared using TOPSIS and AHP MCDM techniques based on ten conditioning factors (Water quantity, Water quality, Length of Axis, Depth of Axis, Reservoir storage coefficient, Reservoir volume, Lithology of embankment, Reservoir slope, Water demand and Accessibility) in R software environment. The result of AHP models showed that 30% of sites located in first priority, 50% in secondary, and 20% in third priority. In contrast, in TOPSIS model, first priority was 30% of sites, 40% in secondary, and 30% in third priority. The results showed that TOPSIS model has been better ranking ratio of AHP model in this study. In general, MCDM models are a suitable method for ranking the underground dam sites. Keywords: Sub-surface dam, Boolean algorithm, SWAT, TOPSIS, AHP
Abstract Underground dams are structures built in underground and are capable of saving and making the underground water available. In this research, by using the SWOT analysis model, suitable locations were investigated for the development of an underground dam in the Keriyan area of Hormozgan province. At first, the necessary data and information were provided by visiting the region and presenting a questionnaire to the residents of the area and experts to investigate the strengths, weaknesses, opportunities and threats in the region for the underground dams. In the final step, by using the SWOT model and QSPM matrix, a comprehensive and appropriate strategy for underground dams was determined. The results showed that among the internal factors, not decreasing the volume of the reservoir due to deposits and reducing the evaporation from the reservoir with a final value of 0.85 and 0.66, and among the external factors, the willingness and cooperation of the relevant organizations and the disruption of downstream water rights with a final value of 0.68 and 0.66 had the greatest impact on selecting the strategy. Based on the results related to the internal and external factors, the strategy was placed in the maximum-maximum quadrant; in line with the strategy, by using the strengths and opportunities, the weaknesses should be overcome and the threats should be tackled. Some strategies were presented. In order to prioritize these strategies, the quantitative matrix QSPM was used. Finally, the hydrological, economic, social and environmental evaluating strategies of underground dams, before and after the construction, with a final score of 19.3 were prioritized.
The most part of Iran County is located in an arid and semi-arid region, thus in most parts of a region; groundwater is the only water resource. This research presents a method based on a spatial multi-criteria evaluation (SMCE) due to design possible sites for an underground dam, and ranks them according to their suitability. The mentioned method was tested for the sitting of an underground dam in the Alborz Province, Iran. At first, screening algorithm was done using exclusionary criteria, and thirty one potential areas were recognized in the study area. In the next step, the suitable gorge or valley was recognized using the combination of basic maps and extensive field surveys (long axis of tank level) in each potential area. Subsequently, it was used of the analytical hierarchy process (AHP) as a powerful tool for decision making in spatial multi-criteria evaluation in order to evaluate different criteria for underground dam sites. SMCE techniques were then applied to combine the criteria, and obtain a suitability map in the study area. These sites were then compared and ranked according to their main criteria such as water, storage, axis, and socio-economic. All these criteria were assessed through GIS modeling. This method shows passable results and could use for site selection underground dam in other regions of Iran County.
Drought is known as one of the main natural hazards especially in arid and semi-arid regions where there are considerable issues in regard to water resources management. Also, climate changes has been introduced as a global concern and therefore, under conditions of climate change and global warming, the investigation of drought severity trend in regions such as Iran which is mainly covered by arid and semi-arid climate conditions is in the primary of importance. Therefore, in this study, based on the application of Reconnaissance Drought Index (RDI) for assessment drought severities, and also the implementation of non-parametric Mann- Kendall statistics and Sen’s slope estimator, the trends in different time series of RDI (3, 6, 9, 12, 18 and 24 monthly time series) were investigated. Results indicated the frequent decreasing trends in RDI time series particularly for long term time series (12, 18 and 24 monthly time series) than short term ones. Decreasing trend in RDI time series means the increasing trend in drought severities. Since the water resources especially ground water in most cases are affected by long term droughts, therefore, increasing trend in drought intensities in long term ones can be a threat for water resources management in surveyed areas.