Sananda Kundu, Deepak Khare, Arun Mondal
2013 Online) An Online International Journal Available at   unpublished
Various meteorological parameters like temperature, wind speed, radiation, humidity etc. have considerable impact on the water resources. Variation in reference evapotranspiration (ET 0) can have impact on the crop of the area. Thus it is extremely necessary to understand the ET of the region before planning and management. Landuse type, soil type etc also have strong effect on ET of a river basin. In the present study FAO56 Penman-Monteith method has been used for estimating ET 0 for entire
more » ... ET 0 for entire Madhya Pradesh from 1971 to 2000. The results indicate higher ET 0 during the month of May with highest being found in Indore (11.77 mm day-1). The months from April to June have considerably high ET 0 while other months have low ET 0. Minimum rate of evapotranspiration is observed in Jabalpur during the month of December. Among the 13 stations, Pachmarhi has the lowest ET 0 even in May (6.07 mm day-1). Thus wide variation in ET 0 distribution is observed in MP which is due to the effect of other climate parameters. INTRODUCTION Evaporation comprises an important part of the thermal balance occurring on the earth surface. It is also a part of water budget and the surface heat and water conditions are the determinant of formation of the surface ecological environment. Thus the study of evaporative capacity of the land is always one of the major problems in hydrology and geosciences (Ping et al., 2009). The rate of reference evapotranspiration is generally calculated from a reference surface where it is denoted as ET 0 but adequate amount of water is required there. Reference surface for the purpose is a hypothetical grass which is a reference crop with specific characteristics. With the help of ET 0 , many research have been done like aridity/humidity conditions (Wu et al., 2006), ecosystem models (Fisher et al., 2005), estimation of rainfall-runoff and water use in agriculture (Allen, 2000; Hunsaker et al., 2002). The evapotranspiration of reference crop is found on the basis of the meteorological data and the calculation is given by FAO depending on the meteorological parameters and meteorological data. Thus it is difficult to apply the method in the areas where there is lack of meteorological observation data, and recommended the use of evaporating pan observation data for determining the reference crop evapotranspiration by FAO (Allen et al., 1998). Various methods for empirical estimation of ET 0 requires proper and accurate measurements of different parameters like temperature, humidity, wind speed, sunshine, solar radiation etc. But measurement of all these parameters in a place is quite few particularly in any developing country. There are also local changes in ET 0 on the basis of distance from the weather station (Hubbard, 1994; Pielke et al., 2000) and proper integration of different climatic parameters are required which also affect the accuracy of ET 0 (Meek and Hatfield, 1994; Allen, 1996). Various methods for calculations are there among which pan evaporimeter and some ET models use only temperature and thus are less complex (Magliulo et al., 2003). The Hargreaves equation also needs only minimum and maximum temperature (Hargreaves and Samani, 1985) and extraterrestrial radiation (Droogers and Allen, 2002). Thus ET 0 can be measured by various models and methods by different weather parameters (Thornthwaite, 1948; Penman, 1948;