QUANTIFICATION OF LAND USE CHANGES IN COMPLEX CROPPING OF IRRIGATED INDUS BASIN, PAKISTAN USING MODIS VEGETATION TIME SERIES DATA

Quantification of change in area under different crops is vital for conducting macro scale hydrological studies as spatial crop water use depends on type of crops grown. This becomes more challenging in areas with complex cropping systems like irrigated Indus basin of Pakistan. In this study, estimation of cropped area was carried out using Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation time series at six-hectare spatial resolution i.e. Soil Adjusted Vegetation Index (SAW). Two cropping years i.e. 2002-03 and 2013-14 were selected to quantify cropped area as well as assess how the cropping systems had changed over a time span of eleven years. Each pixel was trained to assign the vegetation, a particular crop cluster. Four and five major crops were discerned for rabi (winter) and kharif (summer) seasons, respectively. Wheat is dominant rabi crop while rice (a high delta crop) and cotton are dominant kharif crops. Sugarcane is an annual crop and being grown in different tracts of the basin. A confusion matrix prepared for accuracy test shows an overall accuracy of 79% and 74% for rabi and kharif seasons, respectively. The Kappa coefficient (0.64 and 0.62) expresses moderate agreement between satellite-derived map and on ground situation. Change detection indicates that wheat area has been increased significantly 4.2 mha (38.3%) from 2002 to 2013. Rice and sugarcane have also shown a significant increase of 0.69 mha (26.3%) and 0.29 mha (21.8%), respectively during the time span of eleven years. However, it is highly cautious for water management planners due to higher delta of these crops. This study provides essential information for spatial distribution of major seasonal crops grown in water stressed irrigated Indus basin for efficient agricultural monitoring and water resources management.