ارزيابي كارايي مدل HSPF در شبيه‌‌سازي متوسط ماهانه دبي جريان و توليد رسوب در حوضه‌ي آبريز اَبرو واقع در استان همدان

Evaluation of the Efficiency of HSPF Model to Simulate Mean-monthly Flow and Sediment Yield in Abaru Watershed, Located in Hamedan Province (Iran)

امروزه استفاده از مدل‌هاي هيدرولوژيكي به منظور درك بهتر فرايندهاي هيدرولوژيكي در حوضه‌هاي آبريز بسيار گسترش يافته و تحقيقات بسياري در اين خصوص گزارش شده است. مدل هيدرولوژيكيHSPF با پارامترهاي يكپارچه، قطعي و بر پايه‌ي فيزيكي براي شبيه‌سازي پيوسته‌ي فرايندهاي هيدرولوژيكي در حوضه‌هاي آبريز و شبكه‌ي رودخانه‌ها طراحي شده است. اين مدل كه به اطلاعات هواشناسي با گام زماني ساعتي نياز دارد، تا‌كنون در بسياري از نقاط جهان استفاده شده است. اين تحقيق به منظور ارزيابي مدل HSPF به‌عنوان مدلي با مبناي فيزيكي و پارامترهاي يكپارچه و قطعي، در شبيه‌سازي دبي جريان و توليد رسوب در حوضه‌ي آبريز اَبرو، با مساحتي حدود 4142 هكتار در استان همدان، انجام شده است. از داده‌هاي رواناب و رسوب اندازه‌گيري شده در ايستگاه هيدرومتري واقع در خروجي اين حوضه در سال‌هاي 1996-1997 براي كاليبراسيون مدل و از داده‌هاي سال‌هاي 1998-1999 براي اعتبار‌سنجي آن استفاده شده است. نتايج اين تحقيق نشان داد كه در حوضه‌ي آبريز اَبرو، مدل HSPF بر خلاف شبيه‌سازي توليد رسوب، دبي جريان را با دقت بالاتري شبيه‌سازي مي كند.

Hydrological models for simulating hydrological processes in watershed scales have been highly applied in recent years and a lot of research has been reported on this topic. The HSPF Model, Hydrologic Simulation Program Fortran, is for simulation of watershed hydrology and water quality for both conventional and toxic organic pollutants. This model is a lumped parameter, deterministic and physically based model.The HSPF model uses input data such as the time history of rainfall, temperature and solar radiation; land surface characteristics (such as land use patterns; and land management practices) to simulate the processes that occur in a watershed. The model outputs are flow discharge, sediment load, and nutrient and pesticide concentrations.The HSPF model includes an internal database management system to process the large amounts of simulation input and output. This research aims to evaluate the HSPF model performance for simulating mean-monthly flow discharge and sediment yield in Abaru watershed, located in Hamedan province (Iran). The watershed area is 4142 ha and its elevation ranges from 1957 to 3580 m above the mean sea level. The study area lies between 48° 28ʹ and 48° 42ʹ E longitude and 34° 34ʹ and 34° 45ʹ N latitude. The average annual precipitation of this study area is about 313 mm. The most part of the study area has been covered by the soils classified in the C and D hydrologic soil groups. The nearest measuring stations to this study area are Ekbatan Dam evaporation monitoring station and Hamedan airport synoptic station, respectively. The HSPF model was calibrated using field-measured data separately using flow discharge and sediment data, which are measured at Abaru hydrometric station where is located at the outlet of the study area.The calibration period was from 1996 to 1997 and 1998 -1999 was selected in validation period. Statistical measures to evaluate model efficiency were the correlation coefficient (R), Mean Error (ME), Nash-Sutcliff efficiency (NSE) and Root Mean Square Error (RMSE). The HSPF model simulated mean-monthly flow discharge nearly well having correlation coefficients of 0.89 and o.87, mean errors of 0.06 and 0.01 m3/s, Nash-Sutcliff efficiency of 0.48 and 0.79, and root mean square errors of 0.19 and 0.08 m3/s in calibration and validation periods, respectively. Unlike mean-monthly flow discharge simulation, the performance of the model for simulation of mean monthly sediment yield was not so good with correlation coefficients of 0.85 and o.67, mean errors of 53.89 and 10.46 ton/month, Nash-Sutcliff efficiency of 0.81 and 0.54, and root mean square errors of 235.54 and 67.46 ton/month for calibration and validation periods, respectively. The result of this research indicated that the HSPF model could be successfully used for runoff simulation in the study area with limited field measured data.