Effects of Dry Farming Development on Surface Runoff Characteristics

Sh. Khalighi ¹, M. Mahdavi ², B. Saghafian ³, Sh. Ebrahimi ⁴

¹ Faculty of Natural Resources, University of Tehran, Iran
e-mails: khalighi@ut.ac.ir; sh_khaligh@yahoo.com

² Faculty of Natural Resources, University of Tehran, Iran
³ Soil Conservation and Watershed Management Research Center, Iran
⁴ Faculty of Natural Resources, Mazandaran University, Iran
 

Abstract

Dry farming development and land use changes that has recently occurred in many parts of Iran has brought changes in water regime in many different rivers. The same has happened in the study area in Barandoozchay catchment with an area of 1146 km2 located in northwestern of Iran. In this region during 45 years (1955-2000 for which air photographs and satellite images are available) the dry farming areas increased from 4528 to 20231 ha. NRCS model along with HEC-HMS software were used to simulate rainfall- runoff relation in the catchment area. Results indicate that the flood increased up to 70% during the studied period, but the extent in increase in peak discharge became lower for the higher return periods. In additions in new condition the time of concentration (Tc) is decrease up to 14% and the lowest daily discharge has recession trend during the period.