خلاصة:
Water resources in arid and semi-arid regions are heavily influenced by climate change, water shortage, water regulations, and increased water demands. Monthly discharge is one of the most important factors in hydrological studies. Some of the basins are not equipped with adequate hydrometric equipment. In such a case, average monthly discharge could be estimated by regional monthly water balance models of representative basins. In this study, the following collection of data including: temperature, precipitation and average monthly discharge, and the potential evapotranspiration was calculated by Thornthwaite equations. Remaining parts of water balance equation including: Actual evapotranspiration, soil moisture supply of the area in each month and later months are also estimated via Thornthwaite model. The net water requirements were estimated using the model by assuming that evaporation is the only path for water loss. The results have indicated that timing of recharge is very important in preserving sub-basin hydrology in this region. This modified climate diagram prompts an intuitive understanding of the relationship between recharge and consequent wet spell in Mighan sub-basin of Arak. It may be used as a standard tool to determine adequate water demand in water resources management of the arid regions for wetland protection or restoration.
ملخص الجهاز:
An estimation of Thornthwaite monthly water- balance in Mighan sub-basin1 Tahereh Ensafi Moghaddam*; Research Institute of Forests and Rangelands, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran.
In this study, the following collection of data including: temperature, precipitation and average monthly discharge, and the potential evapotranspiration was calculated by Thornthwaite equations.
Remaining parts of water balance equation including: Actual evapotranspiration, soil moisture supply of the area in each month and later months are also estimated via Thornthwaite model.
This paper is a part of Research Project under title: "Influence of Climate Changes on ground and surface water using fifthy years (Case study: Mighan watershed of Arak)" (2014) which is available in Research Institute of Forests and Rangelands, Tehran, Iran, by 2-09-09-89015 Code.
Water balance can be assessed in the area from the results obtained in statistical data computed about precipitation temperature and evapotranspiration.
In conformity with Tornthwaite’s method by Equation (1) (Thorntwaite & Mather, 1955; 1957), the following equation is used for estimating the water balance in the area.
Geographic features of examined stations (View the image of this page) In this research, Tornthwaite’s method of Water Balance was conducted with a 50 years record (1958-2008) obtained from 69 stations, including monthly maximum and minimum air temperature and precipitation.
"Following collection of data in temperature, precipitation, and average monthly discharge in this sub basin, the potential evapotranspiration was calculated using Thornthwaite formula.
Remaining parts of water balance equation including actual evapotranspiration, soil moisture supply of sub basin in each month and later months are estimated from Thornthwaite model" (Mahdavi & Azarakhshi, 2004).