Hydrological Modelling for Evaluation of Return Flow and Irrigation Planning for Optimal Utilization of Water Resources in the Command of Sanjay Sagar Project in Madhya Pradesh (PDS NO: NIH-28_2017_69)

Abstract

India is an agrarian country that uses its major portion of surface and groundwater resources for irrigation. The losses through conveyance and application are the major losses in irrigation and a significant portion of released water from the reservoir may emerge downstream of the river called regenerated flow. Presently in Madhya Pradesh state, a fixed 10% of water release is used as regenerated flow from the command which needs to be verified using scientific assessment for optimal utilization. The WRD MP and NIH RC, Bhopal took up a collaborative research study to identify different hydrological components for computation of return flow and development of a management model for optimal utilization of irrigation water in the irrigation command. This purpose-driven study under the National Hydrology Project has been taken up on the command of the Sanjay Sagar Project situated on the Bah River in the Vidisha district of M.P. Under the Sanjay Sagar project, a dam is constructed in the year 2014 on river Bah with a gross storage capacity of 86.40 MCM to irrigate 9398 ha area in the command during the Rabi season. In the present study, three different modeling and measurement techniques i.e. water balance, isotopic analyses, and hydrological modeling were used to compute surface and sub surface components of irrigation return flow in an irrigation command. The water balance technique was applied through monitoring and measurement after careful analysis of the system. More than 400 water samples from diverse sources including rainfall, dams, canals, rivers, open/bore wells, and hand pumps were analyzed for isotopic analysis. The end member mixing model was used to identify the contribution in open wells and rivers from rainfall and canal/dam water. The SWAT model was used as the third method, a well-proven model for analyzing large-scale hydrological processes in a basin. The model was initially calibrated and validated for virgin flow for the period of 1991-2013 and then two different runs were made with and without the dam and command for the period of 2014 to 2022 (After the construction of the dam in 2013). For running these scenarios, necessary changes were made in the model structure, and results were compared to compute return flow components. The water balance analysis confirmed that a major portion of released ware from the dam in the range of 12.3 to 35.9% with an average of 22.9% reaching the Bah river as regenerated flow, while 1.9 to 16% with an average of 10.2% reached groundwater as recharge. The isotopic analysis provided qualitative results of contribution in open and confined wells and rivers from irrigation water with nearly 81 % and 9% contribution of canal water to open wells and bore wells respectively. The SWAT model results showed nearly 27.8% emerged as regenerated flow and 8.9% as recharge due to the application of irrigation in Sanjay Sagar‘s command. The field data for soil samples were collected and analyzed for textural analysis and soil water retention properties. Soil water retention is an important characteristic of irrigation planning. The soil is mainly silty loam having field capacity and wilting point of 35.8 and 19.6% respectively. The NAM model for the Bah River up to the G/D site was set up and the model was calibrated and validated for the period from 1991 to 2005 and validated from 2006 to 2013. The coefficient of determination (R2) found during calibration and validation for daily modeling were 0.68 and 0.62 respectively showing a good match between observed and simulated runoff data. After successfully developing the NAM model, a MIKE HYDRO basin model for irrigation management of Sanjay Sagar command was developed in which calibrated parameters of the NAM model were used to determine inflows into the reservoir to feed water to four water user associations (WUAs) as irrigation users. The cropping pattern in the study area is mainly wheat and very small areas of gram. The developed management model in MIKE HYDRO basin was run from 2015 to 2021 and determined yearly demand and deficit for different WUAs. The model was run for four different management scenarios and the best result was found with no deficit was found at 75% conveyance efficiency with the sprinkler irrigation method.