The livelihoods of poor people living in rural areas of Indus Basin Irrigation System (IBIS) of Pakistan depends largely on irrigated agriculture. Water duties in IBIS are mainly calculated based on crop specific evapotranspiration. Recent studies show that ignoring the spatial variability of factors affecting the crop water requirements can affect the crop production. The first objective of the current study is thus to identify the factors which can affect the water duties in IBIS, mapping of these factors using GIS and then development of the Irrigation Response Units (IRUs), an area representing the unique combinations of factors effecting the gross irrigation requirement (GIR). The Lower Chenab Canal (LCC) irrigation scheme, the largest irrigation scheme of the IBIS, is selected as a case. Groundwater quality, groundwater levels, soil salinity, soil texture and crop types are identified as the main factors for IRUs. GIS along with gamma design software GS+ were used to delineate the irrigation response units (IRUs) in the large irrigation scheme. This resulted in the total 84 IRUs in the large irrigation scheme based on similar biophysical factors. This study provided the empathy of suitable tactics to increase water management and productivity in LCC. It will be conceivable to investigate a whole irrigation canal command in parts (considering the filed level variations). For the assessment of the objective of the study. Soil-Water-Atmosphere-Plant (SWAP) need all the data of irrigation, climatic and crop data. To asses required data the under data scare condition the study was extended to the further estimation of the data from the other sources. Therefore the required groundwater irrigation was assed using water balance approach. For this purpose the separate research component on the groundwater irrigation was performed and the rational of groundwater irrigation is also described. As the sustainable management of the resources is obligatory to us for the next generation to come that what we enjoyed, they will enjoy. Especially in agriculture-based country, where groundwater contribution is significant. In this study groundwater irrigation was estimated at regional scale (Lower Chenab canal command area) in IBIS. For the estimation of groundwater irrigation at different spatio-temporal scale, water balance approach was applied. For the estimation of actual evapotranspiration (ETa) satellite derived MODIS product based surface energy balance algorithm for land (SEBAL) was used. Water balance approach was applied in the unsaturated zone for the estimation of the net groundwater Irrigation (NGWI). Results show that monthly analysis revealed the variation in ETa with minimum average value of 63 mm in January and maximum average value of 110 mm in August, with four cropping years (2011-12 to 2014-15) average value of 899 mm. While, Sum of net canal water use (NCWU) and rainfall for the average of the four cropping years study period was only 548 mm (36% of ETa). For fulfilment of the remaining crop water requirement, farmers abstract the groundwater. Average of the study period shows 739 mm of groundwater abstraction, while the annual based variation ranges between 632 mm and 780 mm. Seasonal analysis revealed 39% and 61% of groundwater abstraction proportion during Rabi and Kharif season, respectively. The fluctuations in four cropping year’s monthly groundwater abstraction ranges between 28 mm to 120 mm. This variation was high in the 2011-12 to 2012-13 cropping year (0 mm to 148 mm), this variation is dependent upon the occurrence of rainfall and crop phenology. Net groundwater irrigation, estimated after incorporating the efficiencies was 503 mm year-1 on average for the four cropping years. It is no doubt that water resources utilization efficiency can only be measured in terms of water productivity for the better management of resources especially under changing climate. Climate change impacts on water productivity is becoming more and more important. In this study, climate change effects were analyzed for the aforementioned water management indicator on wheat, cotton, maize and rice areas under farmers’ fields in the Indus Basin Irrigation System. HadCM3 General Circulation model was used after downscaling it with Statistical Downscaling Model (SDSM) version 4.2 for midcentury under A2 and B2 scenarios. The climate prediction results show significant variation in the climatic Parameters. The analysis for the water management indicators were performed using the Soil-Water-Atmosphere-Plant (SWAP) model. Automatic calibration was performed using the Parameters estimation technique (PEST). Considerable spatial variation in agronomic water productivity (WPagr), farmers’ perspective water productivity (WPff) and water manager perspective water productivity (WPwm) values were observed under the current and changing climate scenarios (A2 and B2) at different time scale. The variation of WPagr from 1.0 to 0.87 kg m-3 was found for wheat during the base period (1980-2010), these variation for the midcentury (2040-2069) was 0.92 to 0.81 kg m-3 under A2 and 0.90 to 0.84 kg m-3 during B2 scenario, respectively. The maximum WPwm was found 0.71 kg m-3 during base period and 0.67 kg m-3 and 0.66 kg m-3 for the midcentury under A2 and B2 scenarios, respectively. The variation in the WPff was found 0.47 kg m-3 to 0.55 kg m-3 during base period, 0.43 kg m-3 to 0.45 kg m-3 under A2 and 0.41 kg m-3 to 0.44 kg m-3 under B2 scenario. Similarly, significant variation was found in the Kharif season under both scenarios. For Cotton, highest value of WPagr, WPwm and WPff was 1.1 kg m-3, 0.58 kg m-3 and 0.39 kg m-3 during base period and lowest was found under 0.9 kg m-3, 0.51 kg m-3 and 33 kg m-3 under B2 scenario, respectively. While for the rice Crop, highest values for WPagr, WPwm and WPff was found 0.75 kg m-3, 0.55 kg m-3 and 0.1 kg m-3 during base period and lowest was 0.68 kg m-3, 0.48 kg m-3 and 0.9 kg m-3 under B2 scenario, respectively.The conclusions suggest that it is significant to develop irrigated agriculture so as to mitigate climate change effects on crop production in the Indus Basin Irrigation System.From the total 84 IRUs during the base period, the highest WPagr of the 1.44 kg m-3 was fond in the IRU1 and IRU11 during the Rabi season. While during the Kharif season, IRUS under the maize crop showed higher water productivity followed by cotton and rice crop.Water productivity variation was not only significant at each IRUs, variation was found significant under changing climate. Water productivity was reduced from the base period due the variation of climatic parameters at different stage of crop. Increase in the temperature during the month of February put the negative impact on the crop production of the wheat. Temperature increases the crop evapotranspiration and increase in the intensity of rainfall was also a major factor for the reduction in water productivity. Water productivity reduction was a little more under the B2 scenario as compared to the A2 scenario of the climate change. The third objective of the research described the upscaling the water productivity in the canal command level. Upscaling the water productivity under changing climate revealed, maximum water productivity for Mian Ali canal command, while minimum was found for Sagar canal command due to the rice growing canal command. Groundwater depletion was found high in Jhang and low in Sagar canal command. Based on the results of the water productivity from the IRUs to the canal command level, the fourth objective of the study suggest the suitable ways for the enhancement of the water productivity under changing climate. The reason of the low water productivity in the LCC system is due to the low irrigation efficiency, traditional flooding system of irrigation and higher losses due to evaporation. The major reason of the low water productivity at the farm scale is due to the higher losses from the unlined farmers field channels and higher evaporation due to flood irrigation. While the reasons of low water productivity at the canal command scale is due to the higher seepage from the system. Seepage losses are total loss of the water in the areas of the poor quality groundwater. For the improvement of water productivity, there is need to adopt the water saving techniques. In rice area reduction in the supply of water from flooded in the traditional sowing to raised bed sowing will enhance the water productivity. Wheat and Rice cultivation on raised bed technology will reduce the irrigation water requirement and put less burden on the aquifer. Reduction in the seepage losses and proper application of this saved water will increase the water productivity especially in the saline areas." xml:lang="en_US