Abstract
Abstract: In this study, the runoff curve number map for Navrud watershed in north of Iran was determined based on the soil hydrological group, land-use and land-cover using remote sensing and geographical information system. For this objective, land-cover and Land-use situation maps were prepared using NDVI index and Landsat satellite data, respectively. Runoff curve number maps were determined using the overlay prepared maps in GIS and SCS table. For evaluating the accuracy of estimated curve numbers, runoff maximum discharge was calculated using HEC-HMS model and compared to the observed values. Furthermore, the climate change trend and probabilistic distribution functions were considered to predict the flood risk. The effects of climate change were defined by atmospheric general circulation models for A1B, A2 and B1 scenarios. Error analysis between calculated and observed discharge showed that watershed curve number was determined with acceptable accuracy.
Highlights
Necessity of accurate estimation of hydrological parameters for the optimal design of hydraulic structures is the main reason for various studies and different methods
With preparation of land-use, landcover and soil hydrological group maps, by SCS table that has written as Visual Basic program in Excel software, curve number can be determined for any number of the pixel of watershed
Navrud watershed by about 60% of high density forest and relatively high density forest and 32% of B hydrological groups and 80% of excellent and good vegetation coverage conditions led to lower curve number such as 55 and 61 allocated about 30% of watershed area and weight average curve numbers of the watershed is lower than the average watershed curve numbers
Summary
Necessity of accurate estimation of hydrological parameters for the optimal design of hydraulic structures is the main reason for various studies and different methods. One of the most important issues regarding decisions relevant to water resources is the estimation of peak discharge and runoff volume in zones with low or less data as like as most watershed of Iran. With attention to lack or deficit statistics and accurate data, application of experimental formulas could be considered as one of the sensible and useful ways for achieving of mentioned goals (Asadi et al, 2017, Melesse and Shih, 2002). Field measurements in the watershed scale may be time consuming and decision-making in this condition could be impossible. Development of remote sensing techniques and application of measuring devices in various fields could be prepared for large amounts of data in water engineering. Geographical information system (GIS) is one of the most important tools for water resources data analysis in the previous studies (Schumann et al, 2000)
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