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Introduction and Rationale

Introduction and Rationale. Location: Northern Eastern Amhara regional state, Ethiopia rich in fertile soil and has a potential of over 10,000ha of land to irrigate . Groundwater is the main source & irrigation is the main sector . Recharge Abstraction of Groundwater and Pumping scenarios.

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Introduction and Rationale

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  1. Introduction and Rationale Location: Northern Eastern Amhara regional state, Ethiopia • rich in fertile soil and has a potential of over 10,000ha of land to irrigate. • Groundwater is the main source & irrigation is the main sector. • Recharge • Abstraction of Groundwater and Pumping scenarios. • On-farm water management and Irrigation water use efficiency A1. Introduction to IWRM

  2. Major Problems • Low and erratic rainfall distribution limits production & food security. • Absence of scientific and local groundwater resource management is the main factor for sustainable use of ground water. • Due to poor on-farm water management, there is excessive use and this leads to high energy cost. A1. Introduction to IWRM

  3. Key Research Questions • What is the recharge and abstraction of groundwater in the study area? • What are the impacts or drawdown of wells under different well operation scenarios? • How does on-farm water management will be successful to improve irrigation efficiency? A1. Introduction to IWRM

  4. Research Methodology A1. Introduction to IWRM

  5. Field work activities

  6. Major findings • Total recharge is calculated using water balance and Darcy’s approach (94.8MCM & 82.6MCM respectively) • Model simulated total recharge is resulted in 117.9MCM • The water budget of the model domain indicates that the valley gets more recharge from horizontal flux(79.9MCM) than other recharge sources. • Model calibration evaluation shows that the simulated head matches reasonably the observed head with RMSE of 6.63m. • The contour map of the simulated heads is in agreement with the flow direction of conceptual model. • The model was run for two pumping scenarios. Hence a total of 2.79 x104m3d-1 and 5.58 x104m3d-1 abstracted water resulted in an average decline of groundwater level by 14m and 32m respectively. • Groundwater reserve was calculated as 1206MCM for HG &1190MCM for WG basins. • Allowable exploitable amount of water was also estimated as 714MCM for HG & 724MCM for WG sub-basins so as to propose additional wells of 78 & 75 respectively. A1. Introduction to IWRM

  7. Major findings • Comparison b/n observed & simulated head of different scenarios. • The Aqua crop model predicts the irrigation water demand of 404mm for maize but the existing condition uses 730mm of irrigation water pumped from a well of 50l/s average discharge to irrigate an average of 45 ha of land with less production. A1. Introduction to IWRM

  8. Pumping scenarios • Scenario-one scenario-two

  9. Conclusions • The field observation together with the simulated output can be used to realize the aquifer systems of the valley under steady state condition. • The calibrated model was able to reasonably simulate the hydraulic heads that match the observed head with out changing the general hydraulic gradient of the valley. • Groundwater abstractions under scenario-one and two resulted in a maximum groundwater decline of about 26m & 45m respectively at well HG8,which currently has a discharge of 26l/s from 50 l/s. • The calibrated model simulated water budget shows that the valley gets more inflow from high lands through horizontal flux. • The Aqua crop model simulation results clearly indicate how to improve on-farm water management and optimize water use efficiency with a good production. • Additional wells of 78 for Hormat -Golina and 75 for Waja-Golesha sub –basins is proposed keeping the minimum radius influence of 250m based on the allowable exploitable water. A1. Introduction to IWRM

  10. Recommendations • Optimum operation of wells ( up to 35 wells) at a time is recommended keeping the minimum distance between two closer wells at 500m. • The output from this study can be used as a starting point for transient state groundwater modelling for better predictions of pumping effect and for better recharge simulation • Interested professionals can use MODFLOW for similar areas of interest. • Careful attention should be taken regarding the use of pesticides, and over fertilizing that causes groundwater contaminations. • Artificial recharge and water shad-management practices should be enhanced to increase the natural recharge. • Regular monitoring of groundwater level in wells is recommended so as to understand the variations in time for groundwater heads. • River gauging & meteorological stations should be installed in order to improve data availability and better understanding of the sub-basins water balance. A1. Introduction to IWRM

  11. Thank you

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