Publications

Yousaf, W; Awan, WK; Kamran, M; Ahmad, SR; Bodla, HU; Riaz, M; Umar, M; Chohan, K (2021). A paradigm of GIS and remote sensing for crop water deficit assessment in near real time to improve irrigation distribution plan. AGRICULTURAL WATER MANAGEMENT, 243, 106443.

Abstract
This study comprehensively used Remote Sensing (RS) and GIS for independently monitoring crop water adequacy in response to existing irrigation management system in Bari Doab, Pakistan. Canals' rotation plan is developed before start of each cropping season to distribute water on fixed turn basis. The study combines the moderate (Landsat-8) and low resolution (MODIS) satellite imagery to assess near real time crop water deficit in canal command areas (CCAs) of the study area. Landsat imagery were used to develop crop classification and determine cropping pattern using time series of NDVI. MODIS' NDVI product was employed to monitor the current crop health and develop annual reference NDVI cycle based on last 13 years' imagery. Climatic data of WMO stations combined with DEM have also been used to determine reference evapotranspiration based on Penman-Monteith method. These inputs were combined to estimate average crop water deficit in CCAs for ongoing cropping season on 08-day interval, the interval parallel to the canal rotation plan. RS based reflectance crop coefficients (K-CR) of current and reference crop cycle were developed to calculate potential and actual evapotranspiration, and then translated their difference into crop water deficit. Lag time of 08-10 days is limitation of the study due to satellites overpass time, but it can still prove very helpful considering the crop season spanned over 160-180 days. Results revealed that maximum crop water deficit (up to 9 mm) occurred in CCAs during crop growing (mid) stage. Crop water deficit showed inverse relation when plotted against intense rainfall months. Crop water deficit results could be helpful for irrigation managers to modify canals' rotation plan in near real time according to crop health and growing stage. It would not only help in achieving equitable water distribution but also assuring supplies when required by the crops.

DOI:
10.1016/j.agwat.2020.106443

ISSN:
0378-3774