[Abstract] The aims of this thesis is enhancing the efficiency of water supply and propose possible solutions adapt to the impact of sea level rise to irrigation systems. This study was conducted in Tu Cau irrigation system, Vu Gia Thu Bon river basin, Vietnam. This research draws upon mostly primary data sources including the status quo ofsalinity intrusion of Vinh Dien river (belongs to Vu Gia Thu Bon river basin), relationships between the real time and tidal characteristics of the South China Sea, operation and management of Tu Cau irrigation system upon Vinh Dien river and regulating reservoirs.This thesis first examines the agricultural irrigation water demand in crops production in the study area, and presents the results. Then compare the results against the value of water supply capacity of Tu Cau irrigation system in the context of salinity intrusion caused by sea level rise. The results of the comparison show that the total volume and occurrence time of water shortage at Tu Cau irrigation system. The author recommends further modification to the way of operating the pumping station based on: (1) the tide amplitude in the sea and; (2) the use of regulating reservoirs as a means of keeping fresh water and then pump more water from Vinh Dien river when the high salt concentration (> 0.8 ‰) into these reservoirs. The anticipated outcome of this thesis was the identification of the total additional water storage volume after changing the operation and management of Tu Cau irrigation system (pumping station, canals, gates, regulating reservoirs, etc.), these new research ideas in the field of irrigation that make important contributions in treating water scarcity issues for agricultural production that are related to salinity intrusion. The findings may be useful in the context of increasingly vulnerable to saline intrusion as sea levels rise in the coastal areas.
Nguyen Duc Viet, Water Resources Management , Vietnam IMPROVEMENT OF WATER SUPPLY FOR AGRICULTURAL PRODUCTION THROUGH OPERATION AND MANAGEMENT BY CONSIDERING SALINITY INTRUSION ADAPTATION CASE STUDY: TU CAU IRRIGATION SYSTEM, VU GIA_ THU BON RIVER BASIN, VIETNAM Master Thesis (MSc) Problem Statement & Goals Currently, climate change is affecting more and more to human life Viet Nam is one of the five countries forecasted to be affected seriously by climate change, specifically the phenomenon of sea level rise and salinity intrusion The main objective is to enhance the water supply efficiency and to propose feasible measures to adapt climate change impacts for Tu Cau irrigation system, Vu Gia - Thu Bon river basin through operation and management Methods Statistics of rice cultivation area of years 2008, 2009, 2010 and 2011 Tu Cau irrigation system (pump units, intake, canals, etc) Propose O&M models to adapt salinity intrusion 450 The Operation and Management (O&M) 400 424.330 Winter - spring crop area 391.200 Summer - Autumn crop area 350 measures are based on existing conditions Assess the status of Tu Cau irrigation system under salinity Concentrate on measures for Operation & Management intrusion such as local reservoirs and tidal regime 308.000 300.000 300 295.000 290.000 250 200 169.000 150 Identify causes of water shortage corresponding to salinity Water balance calculations for agricultural production 175.000 intrusion 100 50 Unit: Oriented research 2008 2009 2010 2011 Application Main causes Water Balance Calculation Some main causes of water supply shortage for Tu Cau irrigation system, Soil cultivation Discussions Stage of rice “Utilization of regulating reservoirs” Meteorology including: Set up operating procedure to take water from Sen and Cung reservoirs to increase CROPWAT 8.0 •Operation of Tu Cau pumping station is affected by salinity intrusion upon Vinh water supply capacity Total water volume permitted to be pumped into the η ST Dien river; ‰ Irrigation area Discharge pump Coefficient of rice (q) (ω) (QP) Days of salinity λ Discharge of water demand for rice Discharge of water supply by Tu Cau Irr system (QWD) (QWSL) Concentration of salt on July 2011 - 7.00AM regulating reservoir: Initial concentration 1‰ 2‰ 3.4‰ 4.8‰ 5.5‰ 8.1‰ Concentration of salt 1.1 00.1 2.1 1.2 0.50.4 0.1 0 3.9 e Low water discharge of Tu Cau Irr system Days of rice stage 105,000 96,500 48,250 32,167 32,167 19,300 Operating the pumping station based on tide amplitude (Vtide) (QWS) 5.2 4.8 Dat 2.4 2.3 Vrl (m ) 4.6 3.2 3.4 2.1 5.2 4.3 • 5.2 6.3 2.3 2.5 3.2 2.5 Total volume of water shortage of Tu Cau Irr (V WS) 2.3 η ST • 1.2 0.8‰ : Efficiency of canal system at Tu Cau irrigation systems; •λ Changing in O&M relating tide amplitude: If salt concentration ≥ 0.8‰: “not pump and measure continuously salt ≥≥ 0.8‰ 0.8‰ Measuring Measuring of of salt salt concentration” : The time percentage of Tu Cau pump station can operate under impact of Salt Salt concentration concentration concentration concentration If salt concentration < 0.8‰: running WXTide_32 version 4.7 software hour 10 12 14 16 18 20 22 24 26 28 30 32 Actual discharge of one pump is about 66% (600m /h in comparison with original developed by Dave Flater at Da Nang estuary: salinity intrusion corresponding to each stage of rice design is 900m /h); hour hour