Title : VEGETATION INDICES BASED CROP COEFFICIENTS TO ESTIMATE EVAPOTRANSPIRATION OF WHEAT.
Loading...
Date
2022-10-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Publisher : Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra.
Abstract
Abstract : Water is regarded as "Blue Gold," and is considered to be the most critical issue of the current century. Water scarcity is continuously becoming the most prominent environmental constraint limiting plant growth in many arid and semi-arid regions and can adversely affect food security worldwide Precise irrigation water management is needed in order to utilize scare water resources effectively. The water requirements of crops are generally estimated by guidelines provided in FAO-56 bulletin in which tabulated values of crop coefficients (Kc) are used. These crop coefficients are point based and actual crop evapotranspiration (ETc) is crucially dependent on crop coefficient curves. Remote Sensing derived multispectral vegetation indices (VIs) have similar pattern as that of crop coefficients (Kc). Therefore, VIs can be used to model crop coefficients and utilized as proxy Kc. The use of VI can give spatial dimension to Kc and thus spatial variability of water requirement can be well captured. Therefore, the present investigation entitled ‘Multispectral Vegetation Indices-based Crop coefficients for Irrigation Water Management’ was undertaken with major objective of finding the most appropriate VI showing close relationship with crop coefficients of rabi sorghum and wheat crops.
The study was carried out in Pratapgarh district situated in Uttar Pradesh. Images of Sentinel 2 A, MSI sensor were used to generate multi temporal commonly used vegetation indices RVI, NDVI, NDWI and SAVI. Spectral behavior of wheat crop indicated that the VIs follows the similar pattern as that of crop coefficients. The crop acreages were computed by utilizing two stage hybrid classification of remote sensing. These estimates showed deviation of 4.43 % from the estimates of Department of Agriculture, for wheat crop.
The values of multi-date vegetation indices RVI, NDVI, NDWI and SAVI were arranged according to the age in terms of weeks. The week-wise crop coefficients (Kc) recommended by MPKV Rahuri were used to form the relationship with VIs. Linear regression analysis was applied and the relationships were established in the form of prediction models. It was found that all the vegetation indices (VIs) have reasonably good correlation with crop coefficients (Kc) with higher R² values. However, NDWI-Kc model and showed best performance in case of wheat crop. For wheat crop, NDWI-Kc model showed highest R² and D values of 0.9485 and 0.991, respectively with lowest values of SE, RMSE and PD of 0.0841, 0.079 and 2.08, respectively. Therefore, NDWI was found most preferred remote sensing indicators for estimation of wheat crop coefficients.
These best performing models were utilized to estimate week-wise crop coefficients. The crop water requirements were estimated and found 405.74 mm for wheat crop. Water demands for wheat crop were estimated. For wheat crop Water demand of Pratapgarh district was found 63.21 Mm3.
Results of this study demonstrate the potential of multispectral vegetation indices for estimating spatial crop coefficients leading to correct site-specific crop water demand resulting in precise irrigation water
Description
Description : The present investigation was conducted at Department of Irrigation and Drainage Engineering, Dr PDKV Akola and Maharashtra Remote Sensing Application Centre (MRSAC), Nagpur during the year 2020-2021 to establish the relationships between vegetation indices and crop coefficients for Wheat crop.
Keywords
Citation
Citation : KOSLE, ABHA ANIE. (2021). Vegetation Indices Based Crop Coefficients to Estimate Evapotranspiration of Wheat. Department of Irrigation and Drainage Engineering, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola. M. Tech. 2021. Print. xiii, 97p. (Unpublished).