INTEGRATED WATER RESOURCES MANAGEMENT TO OPTIMIZE WATER FOOTPRINT OF CANAL COMMAND CONSIDERING CLIMATE CHANGE

Abstract

The impact of climate change and mismanagement of surface water influences the hydrological processes and water resources availability. Under global warming, the occurrence of extreme events is altered, which causes water scarcity and hurdles in sustainable development. In the recent past, many studies indicated that global warming had altered water availability in many regions of India. As a consequence of climate change, there could be a significant drop in agricultural productivity. Agricultural catastrophe associated to climate change are predicted to blow developing countries hard, as agriculture engages a hefty figure of people and contributes enormously to financial hike. The question arises on how and where to find the remedies to this. The answer probably lies in the problem itself, since agriculture is a part of the problem, agriculture is amongst the most susceptible sectors jolted by climate change and that agriculture can be a decisive part of the outcome for adaptation towards climate change (through emission cutback, carbon isolation, increasing soil organic matter, optimal water utilization, etc.). Climate is a complex phenomenon driven by global and regional processes. However, the impact of severity immediately felt at the local level. Therefore, the assessment of climate change required to be studied at local scales (canal command) to arrive at correct climatic severity. In India, the Green Revolution of the 1970s and 1980s substantially increased food grain productivity by implementing several irrigation projects. In this research, Eastern Ganga Canal (EGC) command has opted for long term trend analysis of climatic variables, change detection in the cropping pattern and future climatic effects on requirement and allocation of available water in the command area. Eastern Ganga Canal originates from the left bank of river Ganga from Bhimgaoda barrage at Haridwar in the Uttarakhand state of India. The EGC project, which lies mainly in Bijnor and Haridwar districts of Uttar Pradesh and Uttarakhand, respectively. The project deliberates on the usage of excess water of river Ganga for the improvement of Kharif (monsoon) season cultivation in the command area. The headworks of the EGC project is located in Haridwar district across the river Ganga. The length of the main canal is 48.67 km, with a discharge of around 164.3 cumecs with 26.90 cumecs for silt ejector. The EGC system irrigates the command through a main canal, 5 branch canals, 37 distributaries and 196 minors, with a total of 155 km in length and around 1489 km of distribution network. EGC project increased irrigation efficiency in the region. But, with time, it also skewed the cropping pattern traditionally practiced. Considering this, the present study focused on the incorporation of climate change factors in optimizing water resources management at the canal command level to acclimate to the inimical impacts of climate change. Such a study is even more significant for a canal command for a better grasping of the relationship between climate change and its effect on agriculture, which will lead to optimum utilization of water resources in the future. In order to optimize the irrigation in the EGC command considering climate change, investigation about spatial and temporal variability of rainfall, temperature, and evapotranspiration are prerequisites. Accordingly, the spatial and temporal variability of rainfall (1901-2012), temperature (1951-2012), and reference evapotranspiration (1992-2017) across EGC command were investigated on monthly, seasonal, and annual basis. The seasonal and annual trend analysis has been carried out to study the behavior of rainfall and temperature pattern in the past using the Mann Kendall test and Sen’s slope estimator. Further, rainfall, and temperature variability is analyzed and discussed at each grid in and around the EGC command. Also, dry and wet year analysis with five year moving average were carried out to establish the possible shift in a time series. In general, the results of trend analysis revealed a decreasing trend in annual and monsoon rainfall in the range of 18.5 to 61.7 mm/decade and 19.4 to 56.7 mm/decade, respectively. Decreasing trend of 1.8 to 2.9 days/decade was observed in some parts of the command area in annual rainy days, whereas some part showed increasing trend in the range of 0.2 to 1.4 days/decade. In case of number of rainy days in monsoon season, the decreasing trend varies from 1.4 to 2.2 days/decade whereas the increasing trend in grid 5 is 1.0 days/decade. A scenario of pre and post climate shift for rainfall and temperature trend analysis has also been carried out. The results of annual precipitation, monsoon precipitation, annual rainy days and monsoon rainy days over the EGC command area showed decreasing trends during the pre-climate shift (i.e., from 1947-1976) and post-climate shift (i.e., from 1978-2012) period. Trends in temperature revealed that there were significant decreasing trends in annual (-0.03 ºC/yr), Kharif ( 0.02 ºC/yr), Rabi (-0.04 ºC/yr) and summer (-0.02 ºC/yr) season temperature during pre-climate shift period, i.e., 1951 to 1976, whereas the significant increasing trend (0.02 ºC/yr) has been observed in all the four parameters during post climate shift period, i.e., 1977 to 2012. This both increasing & decreasing trends will have implications on the irrigation water requirement of the command area. Sentinel-2A satellite imagery was used for crop classification/crop mapping, simultaneously, the crop water requirements were estimated over the command area to find the impact of climate change as well as the change in cropping pattern in the irrigation water demand. Crop mapping showed that sugarcane is the dominating crop in the command area followed by mustard, wheat and vegetable with an overall accuracy of 88.3% and kappa coefficient of 0.85. As per the class-specific accuracy, mustard and vegetable achieved the highest producer’s accuracy of 100% while the lowest for wheat with 75%. The highest user’s accuracy was 95.71% for sugarcane, while 70.59% is the lowest for wheat. The overall user crop class (88.52%) produces better results over producer (87.30%). In the present work, remote sensing based actual evapotranspiration was estimated using METRIC algorithm from the cloud-free scenes for Rabi (November-March) crops. . Landsat 8 Operational Land Imager (OLI) data was used to calculate the crop coefficient (Kc) of the EGC command for the Rabi season. This estimated Kc were compared with worldwide publish FAO’s Kc. Compariosn showed that the percentage variation from FAO’s Kc were negligible, which allowes the study to use FAO’s Kc for Kharif season. Results revealed that the exiting cropping pattern of EGC command comprises of 13.22 % of fodder, 47.87 % of sugarcane, 14.39 % of paddy and 24.52 % others, which is different from initial designed cropping pattern. The highest increase is noticed in the sugarcane based cropping system followed by fodder and the highest reduction is noticed in paddy cropping system followed by others. The designed cropping pattern is having an irrigation requirement of 21257.75 MCM of water, which increased to 23858 MCM for existing cropping for 26 years. The future water requirement is observed to be 25835 MCM and 26503 MCM analogous to RCP 4.5 and RCP 8.5, respectively, for the whole EGC command, assuming no change in the existing cropping pattern for forty years, i.e., from 2020 to 2059. The water requirement has increased in past years under climate change and for the future, it is also predicted to increase by 22.46 % and 23.52 % for RCP 4.5 and RCP 8.5, respectively. When the project is evaluated using traditional performance indicators, it appears that the project is poorly managed and is not performing well on the rational criteria. Analysis for enhancing the performance and water footprint of the project has been done. Study revealed that, there is almost negligible green water footprint of the command area, the maximum demand is fulfilled by blue water at the present time. There is a chance to enhance the performance of the system by boosting the green water footprint of the project. Finally, optimization plans have been formulated for the EGC project command area for optimal allocation of water resources for the design cropping pattern, existing cropping pattern as reported from field, and existing cropping pattern estimated based on identified crops using remote sensing satellites for the Kharif season. Accordingly, eleven alternate resources allocation scenario were developed and solved for the EGC command area. The LINGO model solver has been used for resources planning and management. The model determines the optimal amount of water to be allocated to irrigating crops. Out of all scenarios, the highest green water footprint and lowest blue water footprint was observed for scenario S4. Scenario S4 resulted the maximum benefit amongst other scenarios. By adopting scenario S4, farmers can maximize their net benefits and can maximum resources within all the sub-commands of EGC project. The results of the model will establish the maximum economic returns from a combination of water and crop production and will illustrate the amount of total water conservation that could reasonably be achieved by regulating the release of water in the canal system. This work is a guide in determining the amount of resources conservation possible given certain conditions. These results will be useful in guiding both agricultural producers, in their decision of choosing different cropping pattern and in understanding the value of irrigation water in their region.