Derivative Discharge and Runoff Volume Simulation from Different Time Steps with a Hydrologic Simulator

Milad Jajarmizadeh,Shatirah Akib,Norman Shah Bin Sabari,Sobri Harun

doi:10.19026/rjaset.8.1076

Abstract

Engineering and water resource management responses to hydrological variability depend on daily, monthly and yearly timeframes. Annual runoff volume and flows are significant for long-term decisions on planning water resources and regulatory programs. The objective of this study was to evaluate the average annual discharge and runoff volume derived from different time steps run by SWAT (Soil and Water Assessment Tool) as hydrologic simulator in order to explore the impact of different time step run simulations on yearly runoff yield. Three scenarios has been performed namely Annual (D), Annual (M) and Annual (Y). Annual (D) and Annual (M) are related with derived average annual flow from daily and monthly run simulations by SWAT. Annual (Y) is yearly simulation run via SWAT. The Nash-Sutcliffe (NS) coefficient, Mean Square Error (MSE) and ratio of the Root-MSE (RSR) on standard deviation of measured data during validation period were 0.73, 6.3 and 0.5 for Annual (D), 0.82, 4 and 0.38 for Annual (M) and 0.81, 4 and 0.38 for Annual (Y), respectively. Also, relative error (%) for validation period obtained 0.97, 0.35 and 0.33 for Annual (D), Annual (M) and Annual (Y) scenarios, respectively. The study concludes that Annual M and Annual Y scenarios obtained closer results in validation period. In regard to relative error for average runoff volume in each year over modeling period, Annual (D) scenario obtained highest contribution with shortest relative errors in comparison with the two other scenarios.

Highlights

Population growth, industrialization, extended drought, severe floods and possible adverse impacts of climate change are major anthropogenic or climatic related problems impacting hydrological systems worldwide (Singh et al, 2014)
Average annual flow derived from daily simulation run via Soil and Water Assessment Tool (SWAT) known as Annual (D) in the following figures and tables
SWAT model was applied for estimating average annual runoff volume in southern part of Iran

Summary

Introduction

Population growth, industrialization, extended drought, severe floods and possible adverse impacts of climate change are major anthropogenic or climatic related problems impacting hydrological systems worldwide (Singh et al, 2014). Arid and semi-arid regions are vulnerable in regard to drought, over-use of groundwater resources and water scarcity, especially in the context of future climate change (Kanae, 2009; Oki and Kanae, 2006; Wang et al, 2013; Longe and Balogun, 2010). Climatic conditions vary greatly across Iran, ranging from subtropical conditions along the Caspian coast and the northern forests to arid or semi-arid conditions across much of the central, eastern and southern sub regions of the country. Some areas of the country experience relatively high annual precipitation levels, especially in the northwest where annual average rainfall varies between 680 to 1,700 mm in the eastern and western parts of the plains region, respectively. The average annual rainfall is only 250 mm which is just one-third of the world’s average rainfall, resulting in water shortages due to the dominant arid and semi-arid climatic conditions

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Conclusion